- Soil Testing
- Checklist: Soil Testing
- Saturated media extract (SME)
- 1:2 dilution method
- Leachate Pour Thru Method
- Sampling Instructions for Media Testing
- Interpretation of a Soil Test Report
- Common Nutrient Problems
- Soil Test Results: What Do They Mean?
- How to Interpret a Soil Test
- Author: Ruth Burke
- Why is it important to get a soil test?
- What happens if I over- or under-fertilize?
- What will the Deer Creek Seed food plot soil test kit tell me?
- A little background on Ruth’s food plot.
- There’s a lot here – what is the most important stuff?
- Top section and bottom section – what does Ruth’s plot need for fertilizer?
- Ruth’s plot is less than an acre – how much N does she need and where can she buy it?
- What if you need N, P, and K inputs?
- What about Ruth’s soil pH? Does she need to lime her food plot’s soil?
- Okay, but what if you DO need to apply lime? Where can you get it and how much will you need?
- You’ve seen our soil test. Now it’s your turn!
- I had my soil tested…but what do the results mean?
- A Gardener’s Guide to Soil Testing
- Soil Test Results
- Soil test list
- Choosing the appropriate soil test package
- Soil Sampling Instructions
- Step 1
- Step 2
- Step 3
- Soil Sampling and Testing
- What Can Be Included in Your Soil Testing Report?
- UNH Cooperative Extension Soil Test Descriptions
- Nutrient Analysis
- Organic Matter Content
- Texture Class
- Lead Screening
- Environmental Package (Heavy Metals)
- Plant Tissue
Checklist: Soil Testing
- Conduct pre- plant media analyses to provide an indication of potential nutrient deficiencies, pH imbalance or excess soluble salts. This is particularly important for growers who mix their own media.
- Conduct media tests during the growing season to manage crop nutrition and soluble salts levels.
- Always use the interpretative data for the specific soil testing method used to avoid incorrect interpretation of the results.
- Take the soil sample for testing about 2 hours after fertilizing or on the same day. If slow-release fertilizer pellets are present, carefully pick them out of the sample.
- In a greenhouse where a variety of crops are grown, take soil samples from crops of different species.
- If a problem is being diagnosed, take a sample from both normal and abnormal plants for comparison.
- Be consistent in all sampling procedures each time you sample.
- Do not compare soil test results from one lab to those obtained from another. Testing methods may vary. How the soil test is interpreted is the key to what action you should take based on the soil test!
A soil test is important for several reasons: to optimize crop production, to protect the environment from contamination by runoff and leaching of excess fertilizers, to aid in the diagnosis of plant culture problems, to improve the nutritional balance of the growing media and to save money and conserve energy by applying only the amount of fertilizer needed. Pre- plant media analyses provide an indication of potential nutrient deficiencies, pH imbalance or excess soluble salts. This is particularly important for growers who mix their own media. Media testing during the growing season is an important tool for managing crop nutrition and soluble salts levels. To use this tool effectively, you must know how to take a media sample to send for analysis or for in-house testing, and be able to interpret media test results.
Determining the pH and fertility level through a soil test is the first step in planning a sound nutrient management program. Soil samples from soilless mixes are tested differently than samples from field soil. There are three commonly used methods of testing soilless media using water as an extracting solution: 1:2 dilution method, saturated media extract (SME), and leachate Pour Thru. The values that represent each method of testing are different from each other. For example, 2.6 would be “extreme” (too high) for the 1:2 method, “normal” for SME, and “low” for leachate Pour Thru. Likewise, values for specific nutrients are likely to differ with testing methods. Always use the interpretative data for the specific soil testing method used to avoid incorrect interpretation of the results. See Table 2, Soluble salts levels determined by different methods of soilless media analysis.
pH and EC Monitoring Equipment
Many horticulture supply companies carry pH and EC testing equipment, usually in the form of pens or meters. Most pens and meters are temperature-compensating; however, the instructions that come with the equipment will help growers determine if any adjustments are necessary related to environmental conditions. A buffer (standardizing) solution (pH 4 or 7) should be purchased with pH meters or pens. A standard solution should also be purchased with EC pens and meters to assure that equipment is calibrated and working properly.
Most fertilizers (except urea) are salts and when placed in solution they conduct electricity. Thus, the electrical conductivity (EC or soluble salts) of a substrate solution is indicative of the amount of fertilizer available to plant roots. In addition to carrying out a complete soil test, growers should routinely check the EC and pH of their growing media and irrigation water. These checks can be done onsite using portable testing meters, or samples can be sent to the University of Massachusetts soil test laboratory. Depending on the crop, and fertilizer practices, growing media should be tested at least monthly.
Sending the leachate solution collected from the Pour Thru method for laboratory analysis at least once during the growing season is a good idea, so that actual nutrient levels in the container can be determined and corrected if needed. The accuracy of EC and pH meters can also be checked by sending a leachate sample to the laboratory at least once during the growing season.
Saturated media extract (SME)
SME is currently “the” method of testing soilless greenhouse media and it is almost universally done by commercial and university labs, including the UMass Soil and Plant Tissue Testing Lab. In this test a paste is made using soil and water and then the liquid portion (the extract) is separated from the solid portion for pH, soluble salt, and nutrient analysis. Special skills and laboratory equipment are required to perform this test. SME is probably not suitable for a grower to use unless the greenhouse operation is large enough to support a lab, a technically trained person is hired to carry out the tests, and there is a commitment to frequent testing and tracking of the results.
1:2 dilution method
This method has been used for many years and has good interpretative data to back it up. In this test an air-dried sample of soil and water are mixed together in the volume ratio of 1 part soil to 2 parts water (e.g., using a measuring cup, 1 fl. oz. of soil + 2 fl. oz. of water). The liquid extract is then separated from the solids using laboratory grade filter paper or a common coffee filter. The extract is then ready for analysis. This is a very easy test to master and quite suitable for on-site greenhouse testing of pH and soluble salt using meters available from greenhouse suppliers. The 1:2 method is a very good choice for occasional pH and soluble salts testing by growers on-site.
Leachate Pour Thru Method
In addition to collecting a soil sample to test, growers can collect leachate from container grown plants using the Pour Thru method. One of the major advantages to leachate pour thru is that there is no media sampling or preparation. Unlike SME and 1:2 methods, plants do not have to be sacrificed or disturbed for testing because the extract is the leachate collected from the container during routine irrigation. The leachate can be analyzed on-site using the pH and EC pens or it can be sent to a commercial laboratory for a complete nutrient analysis. In the reference section there is a fact sheet from North Carolina State University which provides detailed information on the leachate pour thru method.
Leachate pour thru is best used for continuous monitoring and graphical tracking of pH and soluble salts. To make this method work best an irrigation and leachate protocol must be established and carefully followed when sampling takes place. Leachate pour thru is not a good choice for casual checks (use 1:2 method for this). Unfortunately, with casual use, the “numbers” are often quite variable, inconclusive, and probably unreliable.
Sampling Instructions for Media Testing
A soil test can aid in the diagnosis of plant problems and in quality plant production. Sampling can be done at any time; but if pH adjustments are necessary, test as early as possible prior to planting. Avoid sampling soils that have been fertilized very recently. Follow instructions for specific testing methods.
Sampling for 1:2 and SME testing methods
The goal of sampling for a soil test is to efficiently collect samples which best represent the nutrient status of the crop or the problem to be diagnosed. The first step is to identify the crop unit(s) to be sampled – bench, greenhouse, etc. In a mixed greenhouse, crops of different species must be sampled separately for the tests to have any value. If a problem is being diagnosed, it is best to have a sample from both normal and abnormal plants for comparison.
After selecting and recording the crop unit, take several samples of soil at root depth from several pots or from several areas of bag culture or bed (cut flowers, greenhouse vegetables) and mix it together in a clean container. Sampling in this fashion is important because a sample from one pot or flat could be an anomaly (values too high or too low) which does not represent the crop as a whole. Sampling and analyzing soil separately from 10 different pots would be the best way but also the most expensive way!
For the 1:2 and SME tests the actual soil sample is taken by either a core or composite sample from all depths in the pot or from the root zone only (i.e., portion where roots are most active). Never sample from just the surface 1-2″ of the pot – nutrient and soluble salts levels will be always be much higher here than in the root zone and composite samples and, as a result, will overestimate fertility.
Sample about 2 hours after fertilizing or at least on the same day. If slow-release fertilizer pellets are present, carefully pick them out of the sample. If the pellets are left in, they can break during testing and this may result in an overestimation of fertility.
Finally, be consistent in all sampling procedures each time you sample. A lot of variability can be introduced to tests due to inconsistent sampling and this diminishes the value of testing especially if you are trying to track fertility.
Take about one cup of the soil mixture and dry at room temperature. Put the dry soil in a sandwich size zip-type bag and close it tightly. Identify each sample on the outside of the bag for your use. Complete and attach the “Greenhouse Media Submittal Form” available from Soil and Plant Nutrient Testing Laboratory with the following information:
- Name, address and phone number
- Is the sample from a newly-prepared mix or from a mix where a crop is currently being grown?
- Crop being grown, and crop age or development
- Is the sample a soilless mix? If so, what is the commercial brand?
- Does the sample have field soil in it?
- What fertilizer is in use, and what is the rate and frequency of application?
- Is this a routine sample to determine nutrient status or is it for a problem diagnosis?
Label the outside of the bag clearly with your name, address, and your name for the sample (ID).
Send the sample with payment to the University of Massachusetts Soil and Tissue Testing Laboratory, West Experiment Station, 682 North Pleasant Street, UMass, Amherst, MA 01003. For more information, see link to Soil and Tissue Testing Service under Resources.
Soil samples from container crops can be tested onsite for pH and EC. For information, access the online fact sheet “How to Use pH and EC ‘Pens’ to Monitor Greenhouse Crop Nutrition”
Procedure for Collecting and Testing Leachate from Containers for Pour Thru Method
- Irrigate your crop one hour before testing. Make sure the substrate is saturated. If the automatic irrigation system is variable, water the pots/flats by hand. If using constant liquid feed, irrigate as usual. If using periodic feeding (weekly, etc.): a) irrigate with clear water, b) test a day or two before you are to fertilize, and c) test on the same day in the fertilizing cycle each time. Consistency is very important!
- Place saucer under container. After the container has drained for an hour, place a plastic saucer under the container
- Pour enough distilled water on the surface of the substrate to get 1.5 oz of leachate. The amount of water needed will vary with container size, crop and environmental conditions. Use values in Table 1as a guide.
Table 1. Amount of water to apply to various container to obtain 1.5 ounces (50 ml of leachate
Container Size Water to Add: milliliters Water to Add: ounces 4 inch
75 2.5 6.5 inch azalea 100 3.5 1 quart 75 2.5 1 gal. 150 5.0 Flats
606 (36 plants)
1203 (36 plants)
1204 (48 plants)
Containers should be brought to container capacity 30 to 60 minutes before applying these amounts.
**These amounts are estimates. Actual amounts will vary depending on crop, substrate type, and environmental conditions.
- Collect leachate for pH and EC. Make sure to get about 1.5 oz (50 ml) of leachate each time. Leachate volumes over that amount will begin to dilute the sample and give you lower EC readings.
Either, send the leachate to a soil test laboratory or test the leachate on-site using a meter and following steps 5 and 6.
- Calibrate your pH and EC meters prior to testing. The test results are only as good as the last calibrations. Calibrate the instruments every day that they are used. Always use fresh standard solutions. Never pour used solution back in the original bottle.
- Measure pH and EC of your samples. Test the extracts as soon as possible. EC will not vary much over time provided there is no evaporation of the sample. The pH will change within 2 hours. Record the values on the charts specific to each crop.
Interpretation of a Soil Test Report
Interpreting a soil test involves comparing the results of a test with the normal ranges of pH, soluble salts, and nutrient levels set by the testing laboratory. Normal ranges are specific to the lab and its method of testing (Table 2). Some interpretation may be done for you, often by a computer program. Best interpretations take into account the crop, its age or stage of development, the growth media (soil or soilless media), the fertilizer program (specific fertilizer, rate, frequency of application) and any problems with the crop.
If used correctly, the three methods of soil testing outlined here give valuable and useful results for greenhouse crops. To optimize the value of soil tests, care in taking and describing the samples is very important.
pH or Soil Acidity
Most greenhouse crops can grow satisfactorily over a fairly wide pH range. What action to take on pH depends on the specific requirements of the plants being grown and knowledge of the factors which interact to affect the pH of the media. Limestone (rate, type, neutralizing power, particle size), irrigation water pH and alkalinity, acid/basic nature of fertilizer, and effects of mix components (container plants) are major influences on pH.
Optimum pH values have been established for soilless media and media with 20% or more field soil. Optimum pH values are shown in Table 3. The difference in optimum pH between the two types of growing media is related to pH effects on nutrient availability in each.
|Soilless media||5.5 – 6.0|
|Media with 20% or more field soil||6.2 – 6.5|
Low pH (values below the optimum range) is the most common pH problem found in greenhouse growth media in Massachusetts. At low pH, Ca and Mg may be deficient. Low pH is also part of the cause of molybdenum (Mo) deficiency in poinsettia. Other trace elements such as iron and manganese may reach phytotoxic levels when pH is low (<5.8). Excess iron and/or manganese can be toxic to geraniums, New Guinea impatiens, and many bedding plants.
Proper liming prior to planting is the best way to avoid low pH problems. As a general recommendation, growers should add no less than 5 lbs. of dolomitic limestone per yd3 of growth medium. Greater amounts (8 to 10 lbs. per yd3) of limestone may be needed depending on the materials used to make the medium, irrigation water pH and alkalinity, and acid forming tendency of the fertilizer in use. Do not add limestone to commercial brands of growth medium.
It is much more difficult to raise pH after planting. To raise pH, try irrigating with a commercial “liquid limestone” product.
Electrical conductivity (EC)
Soluble salts are the total dissolved salts in the root substrate (medium) and are measured by electrical conductivity (EC). Measuring EC or soluble salts provides a general indication of nutrient deficiency or excess. A high EC reading generally results from too much fertilizer in relation to the plant’s needs, but inadequate watering and leaching or poor drainage are other causes. Sometimes high EC levels occur when root function is impaired by disease or physical damage. Always check the condition of the root system when sampling soil for testing.
The accompanying table shows the “normal range” of soluble salts levels for common greenhouse crops using the SME (saturated media extraction) method. Seedlings, young transplants, and plants growing in media containing 20% or more field soil are less tolerant of excess soluble salts. Soluble salts above the normal range for prolonged periods may cause root injury, leaf chlorosis, marginal burn, and sometimes, wilting. Soluble salts below the normal range may indicate the need for increased fertilization.
|Seedlings and young transplants||0.7-1.0|
|Soilless growth media||1.5-3.0|
|Growth media containing 20% or more field soil||0.8-1.5|
Some ammonium in the fertilizer program is beneficial, but ammonium and urea should not exceed 50% of the total N supplied in soilless growing media. Excess ammonium can cause injury to most greenhouse crops and the occurrence of injury is highest in soilless growth media.
Calcium and Magnesium
In general the major source of calcium (Ca) and magnesium (Mg) is limestone, therefore low pH is often accompanied by low Ca and Mg. Many commercial water-soluble fertilizers supply no Ca and very little Mg. If the soil test indicates low Ca, levels can be increased by alternating application of calcium nitrate and the usual N fertilizer. If Mg is low, apply a solution of Epsom salts every 2 to 3 weeks. This solution is prepared by dissolving 2 to 3 lbs. of Epsom salts in 100 gallons of water.
Common Nutrient Problems
Excess soluble salts
High growth medium electrical conductivity (EC) can injure or inhibit the growth of young transplants. Use low rates (50-100 ppm N) for slowing-growing species in the one to two weeks following transplanting. Whenever a high EC problem occurs, check for root disease.
Some crops, especially zonal geranium, and all types of impatiens are the most susceptible plants to iron (Fe)/manganese (Mn) toxicity. This disorder is sometimes called “bronze speckle” due to the appearance of numerous small brown spots on the leaves. Growth medium pH should be maintained in the recommended range by adequate liming prior to planting, careful selection of fertilizers with low potential acidity, pH monitoring, and the use of liquid limestone
Preparations to raise pH after the plants are established in their containers. Some growers make a routine liquid limestone treatment once the plants are established after transplanting. Raising the pH (6.2-6.5) limits the availability of Fe and Mn and prevents toxicity. Consult the “iron out” nutrient management fact sheet from the University of New Hampshire, https://extension.unh.edu/Greenhouse-Floriculture/Factsheets-and-Publications for more information on this problem.
Iron deficiency symptoms generally show up as an interveinal chlorosis, normally starting at the shoot tips, but often they occur throughout the entire plant. Sometimes the leaves of some Fe deficient plants turn almost white. Calibrachoa, scaevola, snapdragons, and petunias are the vegetative annuals most susceptible to iron deficiency. Preventing Fe deficiency can be accomplished by maintaining a low pH and using an iron chelate fertilizer.
Acid pH favors the availability of Fe to plants, therefore the target pH range for crops susceptible to Fe deficiency is fairly low, 5.5 to 6.0. Most commercial soilless media have pHs in this range and the use of an acid-forming fertilizer like 20-10-20 may be enough to keep the pH in this range. A major exception would be if the irrigation water is highly alkaline and then acid injection would be needed. If a grower mixes his/her own sphagnum peat-based growth medium dolomitic limestone should be added at a rate of no more than 5 lbs./yd. Too much limestone is a aggravating factor contributing to Fe deficiency.
Probably the least complicated way of preventing Fe deficiency is to fertilize with Fe chelate fertilizer from time to time. Most greenhouse supply companies carry Sprint 330® (10% iron), Sprint 138® (6% iron), or similar iron chelate products. Sprint 138®, however, is the preferred chelate if it is available. Sprint is generally applied as a soil drench at the rate of 8 oz./100 gal. (½-¾ tsp. gal.). The chelate is also soluble enough to make a concentrated solution for injection and low rates can be mixed and injected with other fertilizers. At the rate recommended here, Fe chelate can be applied every 3 or 4 weeks if desired.
- Cox D.A. Current Methods of Greenhouse Media Testing and How They Differ. University of Massachusetts Extension.
- Cox D.A. How to Use pH and EC “Pens” to Monitor Greenhouse Crop Nutrition. University of Massachusetts Extension.
- Cox D.A. 2001. How to Prevent Iron Deficiency in Spring Greenhouse Crops
- Fisher P.R. and W.R. Argo. 2001. Iron-Out : A nutritional program for geraniums and other crops prone to iron and manganese toxicity at low media-pH, University of New Hampshire, https://extension.unh.edu/Greenhouse-Floriculture/Factsheets-and-Publications
- Whipker, B.E., Cavins, T.J. and W. C. Fonteno. 1, 2, 3’s of PourThru. North Carolina State University.
Soil Test Results: What Do They Mean?
If you have ever received either soil test results or a soils recommendation report from the Noble Research Institute, perhaps you wondered what all those numbers meant. I will attempt to explain them in this article.
First of all, there are several parts to the report. The top section has information that identifies the soil sample and information you provide us. The middle section contains the results from the laboratory analysis. At the bottom is the recommendation section in two parts, a fertilizer recommendation on the left and written comments on the right.
Let’s look at the results from left to right. Keep in mind that a soil test is a chemical way of estimating the nutrients available to the plant. The pH is a measure of soil acidity. Generally 6.6 or lower indicates acidic soil, 6.7 to 7.3 means neutral soil, and a reading higher than 7.3 means the soil is basic. If the pH is 6.0 or lower, a buffer index will be done to indicate how much lime will be needed to raise the pH to 6.8.
The nitrogen test measures the amount of nitrate in the soil for the next crop. Things to remember are:
- nitrate is water-soluble and can move out of the root zone,
- the test does not account for a previous legume crop,
- the test does not measure recently applied anhydrous ammonia, and
- the test will not show nitrogen from manure until the manure has broken down.
Phosphorus and potassium are relative amounts of the nutrient available in the soil. The soil may contain much more than what is shown, but plants cannot extract and use it. Test results higher than 40 and 220 for phosphorus and potassium, respectively, are sufficient for most crops.
Calcium is associated with soil pH. Soils with a good pH generally have adequate calcium, and soils low in calcium generally need lime. A test result of 500 or higher is adequate.
Magnesium is similar in availability to potassium. The result is an indicator of sufficiency. Look for results higher than 100.
Sodium can be an indicator of a sodic soil. Excessive amounts of sodium may be present when the test is higher than 920. With math and some knowledge of chemistry, this number can be calculated into the amount of exchangeable sodium percentage.
Soluble salts will be shown when the pH is higher than 6.0. Soils with soluble salts at 2,600 ppm or more are classified as saline.
Organic matter is the organic content percentage of the soil. This number would ideally be around 5, but look for a range from 1 to 3.
Cation exchange capacity depends on soil organic matter, texture, and clay content. It is an indicator of the relative ability of the soil to supply potassium, calcium, magnesium, and sodium.
Additional tests can check iron, zinc, manganese, sulfur, copper, and boron levels. These tests are not standard but may be used to ensure that high-value crops have proper nutrition or to identify the cause of some production problems. High pH soils may have iron deficiencies, not because they don’t contain iron, but because it is unavailable to the plants. Zinc is needed in very small quantities. Values above 0.3 are sufficient for all crops except corn and pecans. Manganese will generally not be a concern if the pH range is normal. Sulfur is usually not a concern because it is supplied in sufficient quantities by the soil and air, and copper is seldom a problem in our area. Boron may occasionally be needed on alfalfa and peanuts.
The fertilizer recommendation at the bottom left shows the amount of actual nutrient to apply in pounds per acre. The written recommendation and comments at the bottom right will be similar. The recommendation may give an example of how the nutrients could be applied. Comments will pertain to information you provided us on the soil sample entry form. Adjustments may be noted, depending on criteria such as whether the crop will be hayed or grazed, whether soil fertility should increase or stay at maintenance levels, how and when the fertilizer will be applied, and whether the crop will be irrigated. Always feel free to ask us additional questions.
All the recommendations we give are only as good as the sample itself. For information on how to take a good soil sample, consult OSU fact sheet 2207 or with your county extension agent.
How to Interpret a Soil Test
Author: Ruth Burke
Every week, we get calls and emails from customers who have used our wildlife food plot soil test kit. Usually folks are calling because they want help interpreting the results or they’d like recommendations for fertilizers based on the results. Even if you haven’t used our soil test kit, maybe you’re just curious about what information is included when you perform a soil test.
If any of these apply, then this blog article is just for you. This is a long one folks, but that’s because it’s filled with useful information! Stick it out and you’ll be a pro at understanding your soil test results!
Why is it important to get a soil test?
If you’ve been following our blog articles, then you’ve probably noticed that we mention how important it is to get a soil test before you plant (and certainly before you fertilize!). Plain and simple: soil tests are the only way to know what’s going on in your soil! Without a soil test, you can’t know how much to fertilize or lime your soil – or if you even need to.
A common myth is that you can tell the “fertility level” or “the amount of lime you need” for your soil based on the color. If it’s nice and black, it’s healthy plant soil and it’s good to go! Unfortunately, that’s absolutely false. The color of your soil is dependent on a lot of factors – not all of which have to do with fertility level or lime requirements. Again, a soil test is going to tell you exactly what you need, rather than guessing based on nebulous parameters like soil color.
What happens if I over- or under-fertilize?
Without a doing a soil test, you can be over- or under-applying nutrients and you’d never know until the situation becomes serious. This can have detrimental effects on both your crops and your soil quality.
In the case of wildlife food plots, the most common mistake is to over-fertilize. A lot of hunters and growers forget they aren’t growing crops at production agriculture levels, so they fertilize every year before planting a food plot, and they don’t get soil tests done to make sure they actually need it.
The amount of nutrients needed to grow crops for grain or vegetable production are much higher than to grow crops for forage use by wildlife. Over time, this over-application of fertilizer and/or lime can detrimentally affect the growth of your food plot crops by negatively affecting nutrient uptake in the plants and raising the pH of the soil to inhospitable levels. Plus, you may be contributing to runoff pollution and you’re definitely throwing money down the drain on unnecessary inputs.
What will the Deer Creek Seed food plot soil test kit tell me?
When you use our wildlife food plot soil test kit, you’ll be given basic fertilization recommendations for the most common limiting nutrients: Nitrogen, Phosphorus, and Potassium (also known as the primary macronutrients). Additionally, you’ll see your soil’s pH level with recommended lime requirements if your soil needs it.
The most common questions we get about soil fertility include topics like how to check soil pH, what kinds of fertilizers to use (and how much), and whether or not someone should use lime. We’re going to answer those questions in this article by using the results for a soil test on a food plot that I just dug up for the first time this year!
(Ruth’s new farm – in a break between storms!)
A little background on Ruth’s food plot.
This past spring, I moved out to a small farm in east-central Iowa. The farm is about 5 acres, surrounded by rolling hills, drainage ravines, public hunting forests, and some cropland. On the edge of my property is a flat spot that abuts a hay buffer strip and a forested ravine. Since I saw a lot of deer sign around that part of the property, I decided to dig up a small strip and put in a basic food plot. Perhaps I can entice a doe or two to come into the property this fall!
The folks who lived here before had lawn everywhere – I think they really liked mowing! This food plot was also lawn before I tilled it up (remember this tidbit, it becomes really important when I’m interpreting my soil test results.) After prepping the area, the food plot is about 2,000 square feet – small, long, and narrow – but perfectly enticing for a doe who’s slipping through a forested, gently-sloped ravine.
Two weeks ago, I went out and performed a soil test on the plot using Deer Creek Seed’s wildlife food plot soil test kit. If you need guidance on how to collect soil for a soil test, check out this great tutorial that will walk you through the process.
Our test kit comes with an instruction sheet that you mail along with your soil sample (see my instruction sheet above). There are five basic food plot codes that you can choose from based on the nutrition needs of those crop groups.
Because I’ll be planting the Beets & Sweets mix this year, I chose the food plot code “73” for beets and turnip combinations. I mailed my soil sample and the information sheet into the laboratory and I received my test results (below) a week later. Let’s take a look at them!
(Ruth’s soil test report – nutrient recommendations highlighted in yellow)
There’s a lot here – what is the most important stuff?
There are four main sections on our soil test report. “Nutrient Recommendations” is the top section, “Laboratory Analysis” and “Additional Information” are the middle sections, and “Test Interpretation” is the bottom section. For most people, the top and bottom sections are probably the most valuable, and if their pH is too high or too low, then the middle sections become important.
Take a look at my soil test results and you’ll see that I highlighted a few areas in yellow. In the top section, I highlighted the last column, “Nutrients to Apply (lbs/acre).” This column is the column you should use for the estimates of nutrient quantities that you need to apply to your food plot. Note that I say “estimates” here. These recommendations are not gospel! You can be a little under or a little over and be just fine.
The first column in this section lists the total quantities that your food plot needs, the second column accounts for any fertilizer credits you may get from legumes or manure, and the third column gives you the adjusted total that you should apply. Note, these columns are for pounds (lbs) per ACRE. Make sure you do the backwards math if your food plots are less than an acre in size (I’ll go through the math when calculating what my food plot needs.)
What does N, P2O5, and K2O stand for? Those stand for the commercially available forms of each primary macronutrient in most bagged fertilizers: elemental nitrogen (N), phosphorus (in the form of phosphate), and potassium (in the form of potash). When you go to the store and purchase bagged fertilizer, perhaps you’ve seen a series of three numbers listed on the front of the bag, like 10-10-10? These numbers indicate that the contents of this bag contain 10% elemental N, 10% phosphate-P, and 10% potash-K.
Our soil test is really nice because it converts elemental P and K requirements for you! That removes an extra step when purchasing fertilizer from the store – you know exactly the amount of P2O5 and K2O that you need, instead of having to do the math to convert elemental P and elemental K into commercial fertilizer values.
So, what do my test results indicate? I need 100 pounds per acre of nitrogen and I don’t need any phosphorus or potassium. Now, this struck me as pretty funny. We’re talking about a patch of lawn that hasn’t been farmed in over 50 years (and maybe longer). Conceivably, it hasn’t been fertilized in that amount of time either – I mean, why bother, right? If you’re not growing food or grain, why fertilize? Well, boy was I wrong!
Take a look at the bottom section of the test report – at the second area where I highlighted in yellow. These shaded bars interpret my soil P and K levels. As you can see, they are both excessively high. If you really want to wade into the weeds here, take a look at the “Laboratory Analysis” section in the middle of the report. You’ll see that my P and K ratios (in parts per million) are at 167 and 353, respectively. Now, I won’t go into details on what these values mean except to say that (in general) P and K values for vegetable production shouldn’t exceed 75 and 250 ppm, respectively. My values far exceed those numbers. And those values are for vegetable farmers! I’m not even planting seeds to harvest crops. So, I need even less.
There’s a very good chance that the previous owners probably fertilized their lawn every year with turf fertilizer without getting a soil test first. Over time, soil-immobile nutrients like P and K can build up in the soil if they aren’t taken in by plants. Nitrogen, in contrast, is water soluble and therefore very soil mobile, so it makes sense that of the three nutrients, N was the only one that was low.
What implications does this have for my food plot? Well, elevated levels of P won’t necessarily harm plants, but runoff into the nearby creek could be a concern. And elevated levels of K can cause interruption of a plant’s ability to uptake magnesium (Mg) and calcium (Ca) – two other macronutrients that are important to plant growth. I will be taking pictures of the food plot as the summer wears on because I’m curious to see if the plants will develop Ca or Mg deficiencies due to the excessive amount of K in the soil.
Ruth’s plot is less than an acre – how much N does she need and where can she buy it?
My plot has an area of 2,000 square feet (20 feet by 100 feet). An acre has an area of 43,560 square feet. So, if I need 100 lbs of N per acre, then for my little food plot, I’m actually going to need 4.6 lbs of N.
Ex: 2,000 sq. ft. / 43,560 sq. ft. x 100 = 4.6%
4.6% x 100 lbs = 0.046 x 100 = 4.6 lbs of N
In my case, I’m going to go to the local agricultural cooperative in my area and buy a small amount of bagged urea, which has a fertilizer analysis of 46-0-0. This means that the granular fertilizer in the bag is 46% N, and 0 % P and K.
Conveniently, if I purchase 10 lbs of the bagged urea, I will be getting 4.6 lbs of actual N. The rest of the weight in the bag is filler material to help spread the fertilizer. I will also be using a product to reduce volatilization (urea is infamous for that) and I’ll be incorporating it in to the soil immediately – preferably right before a rain!
Ex: 46% x 10 lbs = 0.46 x 10 = 4.6 lbs of N
What if you need N, P, and K inputs?
So, what happens when you also need P and K? Just for an example, let’s say that your soil test report says that you need to apply 50 lbs N, 40 lbs P2O5, and 50 lbs K2O. And let’s say that your food plot is roughly a half-acre in size. So, you would need to apply 25 lbs of N, 20 lbs of P2O5, and 25 lbs of K2O.
Depending on where you live, you can get basic fertilizer at your local garden center, agricultural cooperative, feed & seed store, country store, or farm supply store. Let’s say that your local garden center has a bagged fertilizer with a guaranteed analysis of 10-10-10. This means that the fertilizer is 10% N, 10% P2O5, and 10% K2O. If you purchase 500 lbs of this fertilizer, you’ll have 50 lbs of each nutrient. But that means you’ve gone over on your P requirement, and you had to buy 500 lbs! You could buy 300 lbs of a 14-14-14 fertilizer and that would get you closer to what you need – 42 lbs of each nutrient.
You will have to play around with numbers to find the fertilizer with an analysis that is easily scaled up to suit what you need. Keep in mind, these nutrient recommendations in the soil test report are not hard-and-fast rules. They are suggested guidelines and as long as you’re close to them, your food plot will be fine. In this scenario, I’d buy 300 lbs of the 14-14-14 and call it day!
It may be beneficial to check with your local agricultural cooperative or county Extension office to get some help if you’re having difficulty finding a bagged fertilizer at the nearby farm or country stores. We would give you recommendations in this blog article for fertilizer sources and types, but this will change depending on your state and location in the U.S.
We definitely recommend that you check with a local agricultural cooperative or county Extension office if you need single nutrients only. There are sources of single nutrient fertilizers (like urea in my case), but these are a little rarer and easier to find at places that specialize in selling agricultural inputs. These same places can give you recommendations on mixing single sources of fertilizer as well as giving you guidance on applying all kinds of fertilizers, in case you are purchasing a fertilizer product that requires special application methods.
(Ruth’s soil test report – pH information highlighted in green)
What about Ruth’s soil pH? Does she need to lime her food plot’s soil?
Take a look at my soil test report again (above) where I’ve highlighted a few things in green. In the middle section, you’ll see that my soil pH is 6.7 and my lime requirement is empty. All the way at the end of the section, you’ll see an N.R. in the box for “buffer code.”
Soil pH is the measure of active acidity or alkalinity in the soil (whether the soil is acidic or basic, respectively). The buffer code is your soil’s buffer pH, or the reserve/potential acidity. The buffer code really comes into play if you already have a soil with a pH that is too low or too high. Essentially, the buffer code indicates how “difficult” it will be to change the soil pH using inputs – you will need to use more inputs to change the pH depending on the buffer code. There’s a bit of math that goes with this calculation but luckily for us, our soil test report does the math for you!
If your pH is too low, there will be a lime requirement listed in tons per acre. If your pH is too high, our soil test will give recommendations for lowering it as well. Because I don’t need to alter my soil pH, I don’t have a lime requirement or a suggestion for lowering it.
The goal for pH is to have it somewhere near neutral, or a little lower than neutral (like 6.7!) If the pH is too low or too high, the chemical reactions in the soil may (and often will) prevent plants from taking in certain nutrients through their roots. You may have an adequate amount of nutrients in the soil, but if your pH is too low or too high, those nutrients won’t be accessible to the plants. They’ll be “tied up” in chemical reactions in the soil.
Okay, but what if you DO need to apply lime? Where can you get it and how much will you need?
So, I’m sure you’re already thinking, “It’s great that you don’t need lime, Ruth, but I DO need lime – my pH is too low. So, what do I do?” And that’s where the “Lime Requirement” in the “Laboratory Analysis” section comes in. This soil report assumes that you will be using “60-69” grade lime. This is a coarser form of lime that is much cheaper, but also takes longer to react in the soil than finer, higher grade lime.
Before we go any further here, we need to emphasize that no matter the grade of lime you apply, it takes much longer to react in the soil than applying fertilizer. As in: it takes several months or even years to fully react and raise your pH. So, it’s really best to test your soil the year before you intend to put in a food plot so that you can treat your soil with lime far enough in advance that the lime has time to take effect.
The same goes for lowering your pH if it’s too high. There are several sulfur products that folks typically use to lower their pH and many of them require additional time to fully react in the soil. So, it’s best to test your soil far enough in advance that you have time to apply these kinds of amendments.
Okay! Now for an example. Let’s say that your pH is on the lower end and the soil test report recommends that you apply 2 tons per acre of 60-69 lime in order to raise it. It’s easiest to find lime at your local agricultural cooperative, farm supply store, or country store. If you can find 60-69 lime, then you’re golden! Just make sure to convert the amount you need for the actual acreage that you have in your food plots. In this example, if you only have a half-acre food plot, then you only need 1 ton of lime.
But what if your local Ag. Coop. only has 80-89 lime? Or what if they only have 50-59 lime? Well, there’s a mathematical equation here that you can use to convert the 60-69 recommendation into either 80-89 or 50-59. You “simply” multiply the lime recommendation value you were given by the ratio of the midpoint of the lime grade listed on your report over the midpoint of the lime grade you want to use (lots of words!).
Ex: 2 x 65/85 = (about) 1.5 tons
This means that 2 tons of 60-69 lime is equal to 1.5 tons of 80-89 lime. This makes sense because 80-89 lime is a finer, higher quality grade of lime (which means it reacts a little faster in the soil). It may be more expensive than the 60-69 lime, but you should do the math because you might save more money going with the higher grade of lime if it also means that you have to buy less overall.
The same calculation can be applied to “downgrading” to 50-59 lime but be aware this means you’ll have to buy more lime to achieve the same soil effect, and it will take longer for the lime to react in the soil.
Ex: 2 x 65/55 = (about) 2.4 tons
You’ve seen our soil test. Now it’s your turn!
Phew, there was a ton of information in this blog article! And we really only covered the basics! Your soil test report will potentially have other recommendations, including some micronutrient considerations if things are really off. This article answers basic questions, and for most of our readers, this is enough. But if your report contains additional information you have questions about, feel free to give us a call at our customer service number and we’ll do our best to get you straightened out.
Here are a few final points we’d like to make:
1. Be wary of soil tests offered by companies that also sell high-value fertilizer products – think about this for a second and you’ll realize why we say that. We recommend that you obtain a soil test from an objective source of information – not a company that has interests in selling you fertilizer products. Even though we don’t offer fertilizer products on our website, if you’d rather not buy a soil test kit from us, that’s totally fine! Contact your local Extension office or county NRCS location for more information on a nearby soil test laboratory.
2. The soil test kit we offer is geared towards wildlife food plots. It’s not really meant for garden soil testing or lawn / turf soil testing. Again, your local Extension office will be able to guide you in the right direction if you want to test your garden or lawn soil. And stay tuned to our website, because Deer Creek Seed plans to offer these kinds of soil test kits in the near future!
I had my soil tested…but what do the results mean?
Given the way this winter has gone so far, it’s possible the ground will thaw soon if it hasn’t already. That gives gardeners a prime opportunity to take their spring soil samples earlier than normal. But, sending in the sample is only the first step, next you will need to make sense of the results that come back.
When you receive your results, the first thing to look at is the pH of your soil. pH measures acidity and the number seven represents neutral. Anything below a seven means your soil is acidic; anything above a seven means your soil is alkaline. Plants generally prefer slightly acidic soils with pH values between six and 6.5. Of course there are some notable exceptions such as blueberries, which thrive at pH levels between 4.5 and five.
If your soil pH is out of line with what you want to grow, you can add lime to increase the pH or sulfur to decrease it. The recommendations section of your soil test result sheet will tell you what and how much you need.
Next you want to look at the nutrients. Three of the most important plant nutrients are nitrogen, phosphorus, and potassium.
Nitrogen levels change quickly in the soil and aren’t easy to test accurately. UNH doesn’t test nitrogen, instead, we make recommendations on how much nitrogen fertilizer to add based on what your crop needs.
Organic matter contains nitrogen. The soil test will tell you the percentage of organic matter you have in your soil and will “credit” you a certain amount of nitrogen for it. This will minimize the risk of applying excess nitrogen which might then wash out of your soil and into surrounding waterways.
Phosphorus levels in the soil tend to be high here in New Hampshire, particularly if your garden has received a lot of compost or manure in the past. This is because when you supply the right amount of compost and manure to meet the crops nitrogen needs for the year you also put on more phosphorus than you need. If the level in your soil is excessive you will likely get a recommendation to limit or even stop your use of manures and composts until the levels start to come back down.
High levels of phosphorus in the soil are a concern primarily because the phosphorus could wash into waterways causing excess algae growth. If your phosphorus levels are too high, the best thing you can do is to keep plants growing in that spot to use up the phosphorus and minimize the risk of erosion.
Potassium helps your plants resist drought and may be low in your soil depending on how you or previous owners have historically used the land. If that is the case, the recommendations will tell you how much potassium to add and give you some examples of products that contain it.
Calcium and magnesium are also considered major plant nutrients. Magnesium helps your plants photosynthesize and calcium is important for plant growth. Lime products contain calcium and in some cases magnesium. Other products may also be used if you need calcium or magnesium but don’t need to adjust your pH. In fact, if your grandparents used Epsom salts in their garden, they were most likely trying to increase the amount of magnesium in their soils.
Finally, your soil test will also give you a value for the amount of lead in your soil and tell you whether or not that level is potentially harmful. Old landfills, factory sites or gardens near older homes with lead paint on the siding are the most likely places to find high levels of lead.
If you have any questions or concerns about your soil test results, call the Infoline at (877) 398-4769.
A Gardener’s Guide to Soil Testing
Soil Test Results
Skip to Soil Test Results
After the soil-testing lab receives your sample, it dries the soil and conducts tests to determine the soil pH, humic matter content (the chemically active portion of organic matter), nutrient content, and exchange capacity (ability to hold nutrients). The lab chemically removes elements from the soil and measures them for their plant availability. The quantity of available nutrients in the sample, except for nitrogen, is used to determine the amount of fertilizer that will be recommended.
Test results and suggested lime and fertilizer application rates will be posted on the Agronomic Services Division’s Public Access Laboratory-information-management System (PALS). The turnaround time is about two weeks during the summer and several months in late fall or early winter.
The report has two sections-test results and lime and fertilizer recommendations. The test results section includes measurements of pH, phosphorous (P), and potassium (K). The Recommendations sections will provide guidance for applications of lime as well as N-P-K fertilizer.
Understanding soil-test report terms
Soil class: Each soil sample is classified according to humic matter content. The classes are:
MIN: Mineral soil. Low percentage of humic matter. Target pH 6.0.
M-O: Mineral-organic soil. Medium percentage of humic matter. Target pH 5.5.
ORG: Organic soil. High humic matter content. Target pH 5.0.
Target pH is the soil pH that is best for most plants. Mineral soils need to be limed to a higher pH than the two other types of soil to reduce aluminum (Al) to levels that will allow optimum growth. Mineral-organic and organic soils are higher in organic matter and lower in aluminum.
HM percent: Humic matter percent is a measure of the chemically active fraction of organic matter. The humic matter values are usually much lower than the actual organic matter content.
W/V: The soil weight/volume is shown in grams/cubic centimeter and is used to determine the soil class. Soils high in sand have high W/V, while soils high in organic matter have low W/V. Loamy and clayey soils are intermediate.
CEC: Cation exchange capacity is a measure of the soil’s capacity to hold basic cations such as potassium, calcium, and magnesium, plus the acidic cations hydrogen and aluminum. CEC increases as soil organic matter, pH, and clay content increase. This calculation is given in milliequivalents per 100 grams of soil. Cations are positively charged ions such as calcium (Ca++), magnesium (Mg++), and potassium (K+). The larger the CEC value, the more cations the soil is able to hold against leaching.
BS%: Base saturation percent is the percent of the CEC that is occupied by the basic cations . BS% indicates the pH and lime status of the soil. As pH increases, BS% also increases. On soils that are properly limed, BS% should range from 70 to 90. On acidic soils, BS% ranges from 50 to 60.
Ac: Exchangeable acidity is the portion of the CEC that is occupied by acidic cations . The amount of acidity decreases as soil pH increases.
pH: Soil pH is a measure of the active acidity in the soil solution.
P-1 and K-1: Phosphorus (P) and potassium (K) are shown as indexes used to evaluate nutrient availability to plants. Fertilizer recommendations for P and K decrease as the index increases. An index of 25 or lower is considered too low for optimum plant growth. A range of 26 to 50 is medium, and an index of greater than 50 is high. Adding more phosphorus when the index is greater than 50 should not generate a response. Fertilizer rates are given as pounds of P2O5 and K20 per acre or per 1,000 square feet.
Ca and Mg%: Both calcium (Ca) and magnesium (Mg) are shown as percentages of CEC. Soil calcium is seldom low enough to limit plant growth. In general, calcium is the most common cation in the soil. Calcium percentage is essential for calculating CEC and to evaluate the relationship between calcium, magnesium, and potash (K). If the magnesium percent is low, magnesium will be recommended in the form of dolomitic lime or of a fertilizer containing magnesium.
S (sulfur), Mn (manganese), Zn (zinc), Cu (copper): An index is determined for each of these nutrients. An index of 25 or lower is considered too low for optimum plant growth. A range of 26 to 50 is medium, and a range of greater than 50 is high. Adding more nutrients should not generate a response when the index is greater than 50. Sulfur is difficult to interpret since, like nitrogen, it leaches readily from sandy soils.
SS-1: The soluble salt index is a measure of the amount of fertilizer elements and sodium that are soluble in the soil. This test is normally done for greenhouse production and problem area soil samples. A moderate level of soluble salts is desirable, but an excessive amount can injure plants. The degree of injury from soluble salts depends on the soil type, soil moisture, and crop sensitivity.
Na: Sodium is reported as meq/ dm3. Sodium can harm plant growth when it exceeds 15 percent of the CEC. You can leach excessive sodium from the soil by applying gypsum (land plaster).
N (nitrogen) is not routinely a part of the soil-test regimen because the test has limited predictive value. Nitrogen is quite mobile in the soil and may be leached out before planting.
Recommendations for its use are based on the amount of nitrogen normally needed for plant growth in a year.
Lime and fertilizer recommendations
When the soil pH is in the ideal range for optimum plant growth, no lime recommendation is given. If the pH was determined to be too low, a recommendation is made to apply lime at a given rate per M. The M stands for 1,000 square feet. Occasionally, the recommendation is given in tons per acre. An acre is 43,560 square feet, and a ton of lime weighs 2,000 pounds. One ton per acre equals 46 pounds per 1,000 square feet.
Sometimes soils with an identical pH will have different lime recommendations. Soils low in organic matter or high in sand require less lime to change the pH than clayey soils or those with high organic matter. Clayey soils contain more potential acidity than sandy soils. As the pH falls below 5.5, aluminum becomes soluble at levels toxic to plants. In addition, soluble aluminum reacts with water to produce hydrogen ions, further reducing soil pH. The purpose of liming is to reduce exchangeable aluminum to levels that are not toxic to plants.
Calculating the Amount of Lime and Fertilizer to Apply
A 1,000-square-feet area is an area 50 feet by 20 feet. Multiply the length of the area by the width of the area to determine the number of square feet. Divide by 1,000 to obtain the number of units to be treated. Multiplying the number of units by the pounds of material to treat 1,000 square feet will give you the amount of fertilizer and lime needed.
If the area is 500 feet by 20 feet, and the suggested lime or fertilizer treatment is 30M (pounds per 1,000 square feet):
500 feet × 20 feet = 10,000 square feet
Divide 10,000 square feet by 1,000 = 10 units
Multiply 30 pounds by 10 units = 300 pounds of material (fertilizer or lime)
Liming to raise soil pH
Two general classes of liming material may be used to raise the soil pH. Calcitic lime is composed of calcium carbonate and can be used on soils high in magnesium. Dolomitic lime is a mixture of calcium and magnesium carbonates; it should be used on soils low in magnesium. Many organic soils and some piedmont soils are naturally high in magnesium, while most sandy soils in the coastal plain are low in magnesium. Dolomitic lime provides the major portion of calcium and magnesium required for plant growth. Gypsum, also called land plaster, is calcium sulfate. It is an economical source of calcium and sulfur, but it does not affect soil pH.
All limestone sold in North Carolina must have a label showing the guaranteed percentage of calcium, magnesium, and calcium carbonate equivalent, as well as the pounds of material that equal 1 ton of standard lime.
Lime can be purchased in powder or pellet form. The finer the powder, the more rapidly it becomes effective. Pelletized lime contains finely ground dolomitic lime bound into pellets. The pellets disintegrate and release the lime when they contact water. It is usually more expensive, but easier and less messy, to apply pelletized lime than powdered lime. The lime will act more quickly if the soil is retilled several days after the pellets have been mixed into the soil and have had time to soften.
Changing the soil pH
If the soil pH is too acidic, lime can be used to raise the pH. It can be applied any time of the year. Lime raises the pH, providing a more favorable environment for soil microorganisms. Also, plants utilize fertilizers more effectively at the proper pH. Ideally, lime should be applied and incorporated into the soil before planting.
If the soil pH is too alkaline for the plant to be grown, lower the soil pH by incorporating an acidic soil amendment such as pine bark or peat moss or by applying elemental sulfur. Apply sulfur with caution since applying too much can harm plants.
Lime must be mixed with acidic soil and have adequate water to react with the soil. To be effective, lime should be spread and thoroughly incorporated. Lime is only slightly soluble in water and does not move into soil as effectively as soluble fertilizers. With adequate moisture, lime begins to react immediately; however, it can take 6 to 12 months to realize the total benefit from lime.
Surface-applied lime reacts more slowly than lime incorporated into the soil. However, a surface application is better than no application. Most of the surface-applied lime stays in the top 1 to 2 inches of soil. For established lawns, gardens, and ornamentals, up to 50 pounds of lime per 1,000 square feet can be surface applied in one application. For rates over 50 pounds, wait several months to make a repeat application. In lawns, it’s best to aerate the soil before applying lime.
Substituting different grades of fertilizer
The soil-test report gives recommendations for a rate and grade of fertilizer to apply per 1,000 square feet. One grade of fertilizer can be substituted for another, but you will need to make a few calculations. For example, when the report recommends 10 pounds of 10-10-10 to apply 1 pound of nitrogen per 1,000 square feet but you want to use a 15-15-15 fertilizer, use the following formula:
Pounds of nitrogen desired per 1,000 square feet ÷ Percentage of nitrogen in fertilizer you plan to use divided by 100 = 1 ÷ (15 ÷ 100) = 1 ÷ .15 = 6
When the soil has a high phosphorus index (P-I), the report may recommend an unusual fertilizer grade such as 15-0-14 or 8-0-24. A fertilizer that contains a small amount of phosphorus (the middle number in the fertilizer analysis) can be substituted for a fertilizer grade that may be next to impossible to find. When the phosphorus index is below 25, a fertilizer with a high phosphorus content is recommended. An alternative method to apply adequate phosphorus is to use a high phosphorus fertilizer, such as 0-46-0, and a conventional fertilizer, such as 10-10-10.
Some fertilizer recommendations pertain to nitrogen only, such as 1 pound of actual nitrogen per 1,000 square feet instead of pounds of a complete fertilizer. This type of recommendation usually is given when the P and K indexes are over 50. To determine the amount of fertilizer to use when only nitrogen is recommended, divide 100 by the first number in a fertilizer analysis (percent nitrogen). For example, if you are using 33-0-0 fertilizer and want to apply 1 pound of actual nitrogen per 1,000 square feet, divide 100 by 33 = 3.3 pounds of actual fertilizer to apply. Table 1 gives the amount of several materials to use if only nitrogen is needed. Unless the soil is deficient in other nutrients, a fertilizer high in nitrogen or containing only nitrogen is often the best buy.
|Application rates per:|
1,000 Square Feet
100 Square Feet
10 Square Feet
Soil test list
We offer four soil test packages:
- Grazing – the grazing test package provides general information and is usually quite sufficient in most grazing applications, however, if you know from previous testing that you only need to monitor phosphorus and sulfur levels then a basic package.
- Cropping – the cropping test package is a better choice for cropping and horticulture circumstances and also where more detail is required than in a grazing situation.
- Horticulture – the horticulture test package contains all the features in the cropping package, plus testing for the trace elements boron, zinc, chloride, copper and manganese. This package will be of most use to horticulturalists. If other trace elements are needed leaf/tissue analysis may be more appropriate than soil tests.
In cropping areas a deep nitrogen test may be required. This test requires special sampling and packaging for transportation to the laboratory. Please talk to your advisor or Customer Service before sending samples for deep nitrogen testing.
Choosing the appropriate soil test package
To assist you in selecting the appropriate soil test package the table below describes the application of each test offered.
If you have not previously had soil tested we suggest you talk to your advisor, district agronomist, district horticulturist or phone our customer service unit on 02 6626 1103 to determine the most appropriate package for your needs. In addition to our soil test packages, over 50 types of soil tests are available on request. Please contact Customer Service for current prices.
pH is a measure of acidity and alkalinity. Soil pH can affect nutrient uptake.
Electrical conductivity is an indirect measure of salinity. Many plants are affected by high soil salinity.
This test is useful in assessing the need to fertilise crops and pastures with phosphorus.
Phosphorus buffering index (PBI)
This test is a measure of the soil’s ability to tie up phosphorus. It can assist in determining fertiliser requirements.
KCI extractable sulfate sulfur
Test used to determine sulfate availability in soils.
Exchangeable cations and Cation Exchange Capacity (CEC)
The major exchangeable cations are calcium, magnesium, potassium, sodium and aluminium. CEC is a major factor affecting soil structure, nutrient availability, soil pH and also the soil’s response to fertiliser.
Organic carbon is a measure of the organic matter level of a soil. This in turn is very important for soil structure and plant nutrient intake.
Chloride is the most commonly occurring soluble anion in Australian soils. the importance of this anion in land-use assessment is due to its possible accumulation in soil profiles to levels that are detrimental to plant growth.
Total soil nitrogen provides an indication to the soil’s long term nitrogen supplying capacity.
Boron, hot CaCl2 extractable
Test used to obtain an index of soil boron status for plant growth.
DTPA micronutrients (Fe, Mn, Zn, Cu)
Measures plant-available forms of these elements.
Other tests that may be required include:
Carbon is the organic material in soil which improves moisture holding capacity, increases soil structural stability and protects soil from erosion. Carbon:Nitrogen ratio is used when making compost from organic material.
Full ICP scan (AL, Ca, B, Cr, Cu, Fe, K, Mg, Mn, Ni, Pb, Zn, As, Cd, P, Na, S, Co, Mo, V)
This test will assist in identifying any nutrient/metal deficiencies or toxicities in your soil or organic fertiliser. It is important to check for metals in organic fertilisers, particularly those sourced from human and animal waste.
Nutrient ICP scan (B, Ca, Cu, Fe, K, Mg, Mn, Na, P, S, Zn)
A nutrient scan will assist in solving nutrient deficiency or toxicity problems that you may have with your soil or organic fertiliser.
Nitrogen requirements before planting a crop.
Soil Sampling Instructions
A soil test is no better than the soil sample submitted for analysis. Take samples as follows:
Agronomic, Vegetables, Small Fruit, and Home Garden Crops
Using a trowel, shovel, or auger, and a clean pail, obtain thin slices or borings of soil from at least 13 places in a given area. Follow the diagram below to properly locate the samples. For contour strips, take 6 samples 20 feet in from the edge of the entire strip and 6 samples from the opposite side of the strip. Sample to plow depth in cultivated land or to a depth of 6 inches. Sample to a depth of 3 or 4 inches in permanent pastures. If the field varies in soil type, previous fertilizer or lime application, or cropping history, sample each area separately.
Taking a Soil Sample for Agronomic Crops (Video)
Square, Rectangular Field or Garden
Using a soil sampling tube, auger or trowel, and a clean pail, obtain thin slices or borings of soil from 12 or more locations. Follow the diagram below to properly locate the samples. Sample to a depth of 2 to 3 inches.
If the area varies in kind of soil, previous fertilizer or lime treatments, use separate mailing kits for each different area. Discard all grass and accumulated thatch material. Do not contaminate soil with fertilizer or other materials.
If you have a situation where a maintenance recommendation for an existing turf area is desired and also a recommendation for establishing a new turf area is desired, you must use separate soil test kits for each area.
Collect soil cores to an 8-inch depth just inside the drip line of the canopy. Collect soil cores from at least 15 to 20 locations to form a representative composite sample. Avoid unusual areas that are not representative of the whole area.
Mix the soil taken into one composite sample. Spread soil on newspaper in a warm room to air dry overnight. Do not heat.
Take 1 cup of representative sample and place in the soil mailing kit bag. Mail soil sample and submission form to The Pennsylvania State University, 111 Ag Analytical Srvcs Lab, University Park, PA 16802-1114.
Soil Sampling and Testing
To grow good plants, you need good soil. The only way to tell what your soil really needs is to take a soil test. Applying too much fertilizer could be detrimental to your plants. You could waste money or pollute the environment. Adding too little fertilizer or the wrong fertilizer could produce little or no results. Therefore, for optimum plant growth, it is highly recommended to test your soil pH and nutrient status every 3 to 5 years.
Proper soil sampling techniques are important to obtain accurate soil test results. Purdue Extension publication HO-71 entitled Collecting Soil Samples for Testing provides specific advice on how to take a proper soil sample.
A basic soil test usually measures phosphorus, potassium, soil pH and organic matter. A proper pH is important for nutrient availability to plants. Take the soil sample well before planting, so there is time to add what the soil needs. For the most accurate results, use the services of a commercial soil testing lab rather than a soil testing kit. Purdue does not do soil testing for homeowners. You can get your soil tested in central Indiana by contacting one of the following labs. Generally you need to collect enough soil to fill a plastic sandwich bag. Indicate the type of plants that will be grown in the sampled area (such as lawn, trees and shrubs, flowers, vegetable garden or fruit trees). You may want to e-mail or telephone the soil testing labs prior to sending your soil sample to obtain current soil processing procedures and fees.
Soil Testing Labs
A&L Great Lakes Laboratories, Inc.
3505 Conestoga Drive
Fort Wayne, IN 46808-4413
Phone: (260) 483-4759
Fax: (260) 483-5274
E-mail: [email protected]
Lawn & Garden Soil Analysis, $20.00. Includes Soil pH, Buffer pH, Available Phosphorus, Exchangeable Potassium, Organic Matter, Magnesium, Calcium, Cation Exchange Capacity, and Percent Base Saturation of Cation Elements. Provides graphic display of results and suggested fertilizer materials for lawn, garden and landscape. Once received, the turnaround time for processing samples is 3 working days.
Several different tests are offered the University of Massachusetts lab including the following): 1) Standard Soil Test ($10.00) – Provides pH, Buffer pH, Extractable Nutrients, Extractable Heavy Metals (eg. Lead), Cation Exchange Capacity, and Percent Base Saturation. Recommendations for nutrient and pH adjustment are included with results. 2) Standard Soil Test with Organic Matter ($15.00) – Same as Standard Soil Test plus a determination and interpretation of the organic matter in the soil sample.
Other soil testing laboratories are listed online: http://extension.illinois.edu/soiltest/
Reference to businesses here is not an endorsement to the exclusion of others that may be similar. Other commercial soil testing labs are welcome to be included with this information (e-mail).
What Can Be Included in Your Soil Testing Report?
UNH Cooperative Extension Soil Test Descriptions
The choice of soil test methods used vary from state to state and it is important that the method chosen is reflective of soil, climate and research results conducted in the state or area you live. In New Hampshire we use a Mehlich 3 extractant which was developed in North Carolina in the 1980s. We changed to this extractant in the early 90s because of its ability to accurately extract nutrients and metals over a wide range of soil characteristics. In recent years it has also been found very useful in predicting environmental risk for nutrient movement, especially phosphorus.
The Standard Gardening Test on the Home, Grounds & Garden form includes conventional and organic recommendations; nutrients include extractable calcium, magnesium, potassium and phosphorus; organic matter content, and soil pH. Also included is a soil lead screening analysis.
The Field Test on the Corn, Forage & Pasture, Commercial Fruit, Commercial Vegetable, Christmas Trees and Non-Commercial Hay & Pasture forms includes conventional fertilizer recommendations; extractable calcium, magnesium, potassium and phosphorus, along with pH and Mehlich lime buffer pH. Results include calculated Cation Exchange Capacity (CEC), base saturations and phosphorus saturation.
The Field Test on the Commercial Field Nursery and Commercial Landscape form includes conventional fertilizer recommendations; extractable calcium, magnesium, potassium and phosphorus, along with pH.
The Field Test on the Biosolids form includes organic matter content, extractable calcium, manesium, potassium, and phosphorus, along iwth the pH and Mehlich lime buffer pH. Results include calculated Cation Exchange Capacity (CEC), base saturation, and phsophorus saturation. This test is required for land application of biosolids or septage.
Standard Compost – Includes percent solids (and moisture), organic matter, pH, soluble salts, total nitrogen, total carbon and the carbon to nitrogen ratio (C:N). This test is recommended as an initial test for feedstocks to help determine appropriate mixing ratios.
Standard Compost with Extracted Nutrients – Includes percent solids (and moisture), organic matter, pH, soluble salts, total nitrogen, total carbon and the carbon to nitrogen ratio (C:N), plus ammonium nitrogen, phosphorus and potassium.
Standard Compost with Total Nutrients – Includes percent solids (and moisture), organic matter, pH, soluble salts, total nitrogen, total carbon and the carbon to nitrogen ratio (C:N), plus ammonium nitrogen, phosphorus and potassium, plus ammonium nitrogen, phosphorus, potassium, aluminum, calcium, magnesium, manganese, sodium, copper, iron, sulfur and zinc.
The Mehlich 3 extractant is used to remove nutrients from your soil sample in an amount that is reflective of how much is available to the plant. Due to the volatile nature of nitrogen in the environment, nitrogen analysis is not preformed on basic soil samples. The amount of nitrogen needed by the crop is estimated based on the field history, certain soil characteristics, organic matter content if available, and the crop to be grown.
Organic Matter Content
For soil samples, a measured amount of soil is weighed and heated to 360 degrees C to burn off the combustible part of the sample. This represents the organic portion and is related to the amount of residual nitrogen available to the crop. For composts, the determination is similar but at a higher temperature (550 degrees C).
This procedure determines the amount of sand, silt and clay along with the textural class as determined by the relative percentages of the three soil fractions. This test is sometimes used by landscape architects, golf course superintendents, municipal park managers, and those who supply sand, soil and other mixtures used by these professionals in maintenance and construction activities. For further information contact your county office of UNH Cooperative Extension.
A lead screening analysis is included in the Home, Grounds & Gardens test. If lead levels are high, we sometimes recommend a “Total Lead” analysis based on the US Environmental Protection Agency Method (USEPA) 3050/3051 plus 6010. This will provide a more accurate picture of the risk of lead contamination in your soil sample and whether you need to adjust your plans for gardening and use of the area.
Environmental Package (Heavy Metals)
This test measures the levels of six trace elements sorbed (held on) to the soil. The method used is USEPA method 3050/3051 plus 6010. This test can assist in monitoring soils that have been amended with residuals or other materials. An individual soil test for lead can also be run when it is recommended by the lead screening test (part of the homes and grounds soil test package).
Plant tissue analysis is a valuable tool in a crop management program. In NH, the major use of this analysis is in commercial fruit production such as apples, blueberries and strawberries. For more information contact your local county Extension office.