What can you add to soil to increase its phosphorus level

Phosphorous is one of the 3 key nutrients required for healthy plant growth. Lack of this element can lead to poor plant productivity and severely limit the yield of your crop. In this article, we will explore ways to increase phosphorous in soil to ensure a healthy and happy garden.

Effects of low Phosphorous levels in your soil

First of all, phosphorous is largely responsible for root growth and the flower and fruit development of your plants. This is one of the building blocks of the NPK fertilizer trio. Ensuring they are at proper levels throughout the growing season are available through organic and synthetic ways.

Therefore, the effects of having a phosphorus deficiency will end up diminishing a crops growth. It is very difficult to identify when there are low levels of phosphorous in your soil, but some telltale signs can be shown in your plants if you keep an eye out. The most typical symptoms are of a phosphorous deficiency are:

  • Abnormal discoloration in the leaves – Dark purple pigments or darker greenish/blue coloration along the outer leaves
  • Lack of flower maturity and seed development late into the growing season

How to Increase Phosphorus Levels In The Soil Organically

Luckily, there are plenty of options for amending your soil with phosphorous, and they are all relatively easy to find. The most effective methods of adding phosphorous to your soil include:

  • Bone meal – a fast acting source that is made from ground animal bones which is rich in phosphorous.
  • Rock phosphate – a slower acting source where the soil needs to convert the rock phosphate into phosphorous that the plants can use.
  • Phosphorus Fertilizers – applying a fertilizer with a high phosphorous content in the NPK ratio (example: 10-20-10, 20 being phosphorous percentage)
  • Organic compost – adding quality organic compost to your soil will help increase phosphoos content
  • Manure – as with compost, manure can be an excellent source of phosphorous for your plants
  • Clay soil – introducing clay particles into your soil can help retain & fix phosphorus deficiencies.
  • Ensure proper soil pH – having a pH in the 6.0 to 7.0 range has been scientifically proven to have the optimal phosphorus uptake in plants

In conclusion, you can see it’s fairly simple to ensure you have a balanced amount of phosphorous in soil. It is a key macronutrient that cannot be ignored if you want to grow strong and hearty plants and vegetables. As mentioned in other soil articles, the only way to be sure that you have a phosphorus deficiency is to perform a soil test. Soil tests are simple to do and I highly suggest this soil test kit.

If you have any questions about amending your soil with phosphorus nutrients or any other garden questions, feel free to reach out to me in the comments below and I will get back to you ASAP.

Garden Analyst

Managing Phosphorus for Crop Production

It is also critical in biological energy transfer processes that are vital for life and growth. Adequate phosphorus results in higher grain production, improved crop quality, greater stalk strength, increased root growth, and earlier crop maturity. For over one hundred years, phosphorus has been applied to crops as fertilizer—first as ground bone and now as some chemical reaction product of ground rock. Yet, for all that experience, its management cannot be taken for granted.

Phosphorus is not lost into the atmosphere—rarely does it leach beyond the reach of roots—and its availability to crops can be accurately estimated by soil testing. The challenge is that phosphorus is a macronutrient in plants but behaves somewhat like a micronutrient in soils. The concentration of soluble phosphate in the soil solution is very low, and phosphorus is relatively immobile in the soil. That is important because crops take up phosphorus only from the soil solution. The crop depends on replenishment of the soil solution with phosphate from the other forms existing in the soil. The rate of replenishment, which determines the availability of phosphorus, is related to soil pH, phosphorus levels in soil, its fixation by the soil, and placement of added phosphorus. The crop manager must deal with each of these factors to avoid crop phosphorus deficiency. Phosphorus deficiency symptoms include reduced growth and yield, delayed maturity, and generally purple coloring along the edge of the lower plant leaves, especially on younger plants.

In addition, the manager needs to consider possible “side effects” of crop production; specifically, nutrient pollution of streams or other surface water near crop fields. Water can be polluted with phosphorus primarily as a result of erosion and runoff of phosphorus in the soil or phosphorus applied either from fertilizer or manure. The amount of phosphorus lost due to runoff of manure, fertilizer, or soil may be relatively small as far as fertilizer costs are concerned. However, these small losses may have serious effects on the quality of water. The main problem with phosphorus pollution is eutrophication resulting in excessive growth of plants and algae in the water. This can seriously limit the use of the water for drinking, industry, fishing, or recreation. Pollution reduction may not be simply a direct economic problem for the farmer, but a responsibility that extends beyond the farm fence. For more information see the Penn State publication “Agricultural Phosphorus and the Environment.”

Availability of phosphorus to crops

In general, crop use of any nutrient depends on a two-step process: soil supply of that nutrient in an available form, and uptake of that available nutrient by the crop. There are certain constants involved that the crop manager cannot change. Selecting among the options presented by nature constitutes management.

Soil supply

Figure 1 shows an overview of the behavior of phosphorus in the soil. The soil solution is the key to plant nutrition because all phosphorus that is taken up by plants comes from phosphorus dissolved in the soil solution. Because the amount of soluble phosphorus in the soil solution is very low, it must be replenished by as many as 500 times during a growing season to meet the nutritional needs of a typical crop. Although very little phosphorus is in the soil solution at any time, there is a large amount of phosphorus in most soils. The bulk of the soil phosphorus is either in the soil organic matter or in the soil minerals. A large proportion of the phosphorus in both of these fractions is in very stable, unavailable forms, while a much smaller proportion is in available forms that can dissolve in the soil solution and be taken up by plants. The dynamic and available phosphorus phosphorus in these fractions, such as phosphorus added in fertilizer or manure, can be quickly fixed into stable, unavailable forms in the soil. This is why, even with optimum management, the efficiency of plant uptake of phosphorus is very low—usually less than 20 percent. At the same time as the soil solution phosphorus is depleted by crop uptake, unavailable phosphorus can slowly be released to more available forms to replenish the soil solution. This slow release can sustain plant growth in many natural systems, but is usually not rapid enough to maintain adequate phosphorus availability in intensively managed cropping systems without some supplemental phosphorus in the form of fertilizer, manure, or crop residues.

Figure 1. Behavior of phosphorus in the soil-plant system.

Organic phosphorus availability depends on microbial activity to breakdown the organic matter and release this phosphorus into available forms. Thus, availability of organic phosphorus is very dependent on conditions in the soil and on the weather, which influence microbial activity. The mineralization of organic phosphorus to inorganic forms is favored by optimum soil pH and nutrient levels, good soil physical properties, and warm moist conditions. The inorganic phosphorus is bound with varying adhesiveness to iron and aluminum compounds in the soil. Replenishment of the soil solution with phosphate from inorganic forms comes from slow dissolution of these minerals. The solubilities of the compounds holding phosphorus are directly related to the soil pH. The pH range of greatest phosphorus availability is 6.0 to 7.0. At a lower pH, when the soil is very acidic, more iron and aluminum are available to form insoluble phosphate compounds and, therefore, less phosphate is available. At very high pH, phosphorus can react with excess calcium to also form unavailable compounds in the soil.

Crop Uptake

Crop response to phosphorus depends on the availability of phosphorus in the soil solution and the ability of the crop to take up phosphorus. The availability of phosphorus in the soil solution has already been discussed. The ability of a plant to take up phosphorus is largely due to its root distribution relative to phosphorus location in soil. Because phosphorus is very immobile in the soil, it does not move very far in the soil to get to the roots. Diffusion to the root is only about 1/8 of an inch per year, and relatively little phosphorus in soil is within that distance of a root. Thus, the roots must grow through the soil and basically go get the phosphorus the plant needs. Therefore root growth is very important to phosphorus nutrition. Any factor that affects root growth will affect the ability of plant to explore more soil and get adequate phosphorus. Soil compaction, herbicide root injury, and insects feeding on roots can all dramatically reduce the ability of the plant to get adequate phosphorus. Young seedlings can suffer from phosphorus deficiency even in soils with high available phosphorus levels because they have very limited root systems that are growing very slowly in cold, wet, early early-season soil conditions. This is why some crops respond to phosphorus applied at planting in starter fertilizers even in relatively high phosphorus soils. (Starter fertilizer management is discussed later in this fact sheet. See also Penn State Agronomy Facts #51, “Starter Fertilizer.”)

Managing Soils for Phosphorus

The availability of phosphorus to crops is more than just having phosphorus in the soil. It will depend on soil pH, how supplemental phosphorus is applied, crop root growth, and the other management factors that influence root growth.

Soil Test

The most important tool in phosphorus management for crops is a soil test. Soil testing reveals soil pH, the soil phosphorus level, and determines the recommended application amount of phosphorus for the crop to be grown. Consistent and representative soil sampling is very important for correct interpretation of soil test results. Take as many cores as practical. Sampling depth is extremely important for both pH and phosphorus, especially in reduce and no-tillage systems where there is little or no mixing to homogenize the soil. In Pennsylvania, the recommendation is to sample to “plow depth,” even in no-till fields where phosphorus is concentrated within several inches of the soil surface.

There is no specific “available” fraction of phosphorus in soils. The available phosphorus is what is in solution plus what can be expected to become soluble from minerals and organic matter over the growing season. Therefore, soil tests cannot extract the exact available amount from the soil, but rather an amount that reflects what might become available. Research on Pennsylvania soils is then used to interpret the amount extracted by the soil test in terms of what is required for optimum crop production. This research has shown that on our soils, if the Mehlich 3 soil test used, in Pennsylvania extracts between 30 and 50 parts per million (ppm) phosphorus it is optimum for production of agronomic crops. Below 30 ppm phosphorus, additional phosphorus must be applied to build up the soil for optimum crop production. Above 50 ppm phosphorus, there will be no benefit to adding additional phosphorus. In some cases, applying a small amount of phosphorus as a starter on soils testing above 50 ppm may be beneficial. In the optimum range range—between 30 and 50 ppm phosphorus—phosphorus is often recommended to offset crop removal (Table 1) and thus maintain the soil in the optimum range over time. Current phosphorus recommendations for agronomic crops in Pennsylvania can be found on the Agricultural Analytical Services Laboratory Web site.

Phosphorus Materials

The common phosphorus fertilizers, their sources, and some important properties are listed in Table 2.

Table 2. Description of common phosphorus fertilizer materials.

Material Analysis
Calcium orthophosphates Manufactured by treating rock phosphate with acid
Ordinary superphosphate 20% P2O5, 90% water soluble, 8–10% sulfur Not used anymore in commercial crop production. Replaced by triple superphosphate
Triple superphosphate 46% P2O5, 95% water soluble, no sulfur Common material used in no-nitrogen blends
Ammonium phosphates Manufactured by reacting anhydrous ammonia with phosphoric acid
Monoammonium phosphate MAP 52% P2O5, 11% N, 100% water soluble Very high phosphorus analysis. Excellent material for use in starter fertilizer
Diammonium phosphate DAP 46% P2O5, 18% N, 100% water soluble Most common phosphorus fertilizer. Used extensively as the basis for blended fertilizers
Ammonium polyphosphate Solid: 55% P2O5, 11% N
Liquid: 34% P2O5, 10% N
Liquid form is very common N and P fluid fertilizer
Miscellaneous phosphates
Rock phosphate Very low water solubility 27–45% total phosphorus recommended for soluble P fertilizer Must be finely ground to be effective. Increase rate 3 to 4 times that

Inorganic Phosphorus Fertilizers

By Pennsylvania law, mineral phosphorus materials sold as fertilizer must be labeled with the percentage “available phosphoric acid”, which is defined as the amount of fertilizer phosphorus that dissolves in neutral ammonium citrate. This analysis must be given as a percent P2O5/A) in the material. Fertilizers do not really contain any P2O5/A) but this expression is a carryover from past analytical methods. Fertilizer recommendations are also given as pounds of P2O5/A) per acre and are based on the amount of this “available phosphoric acid” that should be available to the crop over the period of the growing season. Mineral phosphorus materials that have not been reacted with acid, such as raw rock phosphate and basic slag materials, must also be labeled with the total P equivalent and the material’s degree of fineness. The phosphate availability of phosphorus materials that have not been reacted with acid is low, as the availability then depends on reaction in acidic soil, particle size determines the speed of that reaction. Bone and other natural organic phosphate materials must be labeled only with the total P content. Don’t confuse total P with available P—the availability of phosphorus in these forms depends on the mineralization, or breakdown, of the material by bacteria in soil and cannot be guaranteed.

Immediate phosphorus availability can be defined by the percentage of the available P that is water-soluble. This is not a labeling requirement, but it is described for various materials in Table 2. A high percentage of water solubility is important for short-season, fast-growing crops, crops with a restricted root system, crops receiving a starter fertilizer application, and crops grown in a low phosphorus soil where less than optimum rates of phosphorus are applied. Where the importance of high water solubility, or quick reaction in the soil, is not so great (such as in fertilizing a permanent pasture or where soil phosphorus levels are already optimum), a more economical form of phosphorus can be applied. Most of the common phosphorus fertilizer materials are highly water soluble (Table 2).

Although the calcium orthophosphate fertilizers are manufactured by reaction with an acid, they do not acidify the soil. The ammonium phosphates and the ammoniated superphosphates, on the other hand, do ultimately have an acidic effect on soil because of the ammonium nitrogen that they contain—not because of their phosphate content.

The physical form of the applied phosphorus does not make any difference to the plant if the materials have similar chemical properties. The same reactions eventually occur in soil whether liquid or solid fertilizer is applied. Though all of the phosphorus in true solution fertilizer will be water soluble, the same materials applied in dry form are just as efficient.

Manure Phosphorus

Average manure phosphorus values for various animal types are shown in Table 3, but however good the averages are, the manure phosphorus content on individual farms may vary considerably from the average. The true value can only be known by manure analysis.

Table 3. Average manure P analyses. (Actual analyses vary considerably from farm to farm. Manure analysis is strongly recommended.)

Lactating cows 4 lb/ton or 13 lbs/1000 gal
Dry cows 3 lb/ton
Calves and heifers 2 lb/ton
Broilers 75 lb/ton
Layers 55 lb/ton
Turkeys 80 lb/ton
Gestation 35 lb/1000 gal.
Lactation 20 lb/1000 gal.
Nursery 40 lb/1000 gal.
Farrow to feeder 35 lb/1000 gal.
Grow finish 55 lb/1000 gal.

Phosphorus in animal wastes is generally less water-soluble than fertilizer phosphorus. However, over a normal growing season the availability of manure phosphorus is usually similar to fertilizer phosphorus and can be substituted on a 1 to 1 basis. Even so, manure is not a substitute for starter fertilizer because it ordinarily has a lower water-soluble phosphorus content. As long as physical losses do not occur, handling or application methods do not affect phosphorus content or availability.

Figure 2. Imbalance between crop nutrient requirement and manure nutrient content.

Phosphorus from manure applications can be a potential pollutant. There are several reasons for this. First, as livestock and poultry farms have become more intensive, greater amounts of feed are imported onto the farms resulting in accumulation of excess nutrients in manure beyond what can be used by the crops on the farm. Even when there is no overall excess of nutrients on the farm, application of manure nutrients is commonly done based on meeting the nitrogen requirement of the crop with the nitrogen content of the manure. Since the relative amounts of nutrients required by crops is different from the relative amounts contained in most manures, there will usually be an excess of phosphorus and potassium (K) applied in this system. This is illustrated with corn and dairy manure in Figure 2. Notice that when manure is applied to exactly match the available nitrogen—requirement of the crop, almost twice as much phosphorus is applied as is required by the corn crop. The relative differences will vary with different crops and manures but a similar trend will be observed.

Ultimately we need to move toward a better overall balance that minimizes the application of excess nutrients. In the meantime, management strategies are being developed to help farmers make decisions about when, where, and how to apply their manure to maximize the agronomic and economic benefits from the manure nutrients and minimize the potential environmental impact. Since the major losses of phosphorus from fields is through runoff and erosion, best management practices that reduce these processes can be very helpful in minimizing the environmental impact of the excess phosphorus that is applied. An important tool in making these management decisions is the Phosphorus Index, which helps evaluate the sources of phosphorus and the potential transport of phosphorus from the farm fields to give an indication of the risk of phosphorus pollution and to guide improved management. For more information see the Penn State publication “Agricultural Phosphorus and the Environment.”

Finally, there are interactions between phosphorus and other nutrients that can affect crop production. When the ratio of phosphorus to zinc (Zn) in a soil becomes excessively high, a phosphorus-induced Zn deficiency may result that can limit yield. However, few cases of Zn deficiency are found in Pennsylvania in spite of many corn fields testing high or excessive in phosphorus. Manure application that results in soil phosphorus buildup also contributes Zn to the soil. Therefore, phosphorus-induced Zn deficiency is usually only seen when excessive soil phosphorus levels are due to phosphorus fertilizer and not to manure application. Often when there is concern about zinc deficiency, farmers will add zinc to the banded fertilizer, which usually also contains a high level of phosphorus. This practice will likely reduce the effectiveness of the added zinc. A more efficient approach is to broadcast zinc every few years on soils that are known to respond to added zinc.


Because of phosphorus immobility and soil fixation, placement of fertilizer phosphorus can affect its availability to plants. Fertilizer that is broadcast and plowed down is mixed uniformly with a large amount of soil. Thus, the probability of root contact with the fertilizer is maximized. At the same time, though, added fertilizer is in greater contact with absorbing surfaces in the soil, thereby increasing phosphorus fixation. When the fertilizer is applied as a concentrated band, contact with the soil—and thus fixation—is minimized. However, lack of phosphorus movement from point of placement also means that the number of roots in contact with the fertilizer may be less then when broadcast and plowed down. The greater the ability of the soil to fix phosphorus, the greater the importance in overriding the fixation capacity with a concentrated band. Crop response to fertilizer phosphorus placement is further complicated by crop root characteristics, soil phosphorus levels, and soil temperature.

Placement limitations imposed by sod crops and no-till culture often result in an accumulation of nutrients near the soil surface (Figure 3). Provided proper residue management is practiced, corn root distribution appears to respond to differences in soil moisture and nutrient location in no-till culture with greater root density within the surface 6 inches of soil (Figure 3). Nutrient uptake of surface-applied fertilizer equals or exceeds uptake under conventional till management.

Figure 3. Distribution of soil test (Bray I extractable) phosphorus after two years of different tillage practice and rooting pattern in conventional and no-till corn. (Source: J. K. Hall, The Pennsylvania State University)

Is band or broadcast application the better method?

The answer to this question depends mostly on the soil phosphorus status. On soils with optimum to high levels of phosphorus, banding has less advantage and broadcast applications are generally adequate (sometimes superior to banding). Row crops in general, and corn in particular, appear to yield better when soils contain relatively high levels of phosphorus throughout the rooting profile. In tests with the recommended phosphorus application split between band and broadcast, versus all by one method, the maximum yields have been obtained with a combination. The advantage to building up the general soil level of phosphorus is probably due to the need of all roots to take up some phosphorus; while banding near the seed can reduce fixation and increase uptake early in the season.

Small grains, on the other hand, have limited rooting systems and thus less capacity to explore soil. In addition, they are short-season crops and often grown in cooler temperatures. Therefore, phosphorus placement seems more critical for small grains than for row crops and perennials. Greater yield response to banded phosphorus is common, especially on low phosphorus soils or soils with a greater ability to fix phosphorus. Recommendations of incorporated broadcast phosphorus for small grains have frequently been higher than if the phosphorus were banded, because higher soil phosphorus levels compensate for reduced phosphorus uptake ability of the crop. Where soils are built up to optimum or above phosphorus levels, however, banded or broadcast-P can be equally effective.

Starter Fertilizer

Starter fertilizer is a specific band application at a specific time. Even if you are planning to broadcast the majority of the required phosphorus as fertilizer or manure, a banded starter application may be important for spring-planted crops, particularly corn. Limited root growth — combined with cold and wet soils early in the season, especially in notill fields — reduces the availability of phosphorus and the plant’s uptake ability. Early plant vigor, and final yield, are often improved by starter phosphorus applied close to seedling roots, even when soil phosphorus levels are high or when manure has been applied. Phosphate applied in combination with ammonium-N results in greater phosphorus uptake. Phosphorus itself has a low salt effect and may be placed close to the seed. However, if applied with N and K the rate should be limited so as to supply no more than 70 pounds total of N plus K2O if placed 2 by 2 inches from the seed. High water solubility of the starter phosphorus source is important, and the ammonium phosphates meet that criteria as well as supplying N. However, diammonium phosphate (DAP) reacts with soil water to produce ammonia, that which can be toxic to seedling roots. Therefore, the rate of DAP used as a starter source of N and P should be kept low and placement should be at least 2 inches from the seed to be safe.

The best time to think about starter fertilizer for alfalfa establishment is in the years before rotating a field to alfalfa. Yield response to starter fertilizer is most likely when the alfalfa seedlings will be stressed by low fertility level or by adverse soil or moisture conditions. High soil phosphorus level is required by the forage, so plan ahead by building phosphorus levels into the optimum range during the last year of corn, and soil test in the fall prior to alfalfa establishment. If fertility is optimum by planting time, starter fertilization can usually be omitted. See Penn State Agronomy Facts 51 “Starter Fertilizer” for more detail.


Crop phosphorus nutrition depends on the ability of the soil to replenish the soil solution with phosphorus as the crop removes it and on the ability of the plant to produce a healthy and extensive root system that has access to the maximum amount of soil phosphorus. There are many good fertilizer sources of phosphorus, and manure is an excellent source of phosphorus for crops. Application of fertilizer and manure must be done to maximize the chemical and physical availability of the phosphorus to crops while minimizing the risk that the phosphorus might be lost to the environment by runoff or erosion. Conservation best management practices are critical to good phosphorus management.


  1. Test soil to determine pH and phosphorus levels and lime and fertilizer recommendations.
  2. Use lime to raise and maintain soil pH in the range 6.0 to 7.0.
  3. Match the phosphorus fertilizer to the crop, soil phosphorus level, and purpose of the fertilizer.
  4. Use a starter fertilizer when planting in cold, wet soils — particularly when soil tests are not high.
  5. Account for the phosphorus in manure and recognize that excess phosphorus may be applied with manure; try to balance this over the crop rotation.
  6. Let soil phosphorus levels, crop, and soil characteristics guide your decision on fertilizer and manure rates, timing, and methods of application.
  7. Use best management practices to reduce erosion and runoff to avoid phosphorus losses and to protect water quality.

Prepared by Douglas B. Beegle, professor of agronomy, and Philip T. Durst, former extension associate.

Plants get many of the elements they need through the air. Oxygen, carbon and hydrogen are readily available. In addition, plants can create glucose and other substances through sunlight. However, basic elements cannot be created through photosynthesis, and plants must extract these elements through the soil. Even though air contains a significant amount of nitrogen, plants cannot absorb it. As a result, they must get it from the soil. Nitrogen becomes depleted in soil quickly, and the primary benefit of fertilizer is the nitrogen it provides. Plant cells also depend on potassium and phosphorous, which are rare.

Fertilizer contains a large amount of these elements, which ensures that plants stay healthy. Plants can generally grow without fertilizer, but they may take more time to get the elements they need to thrive. Fertilizer is essential in modern farming, and almost all farmers depend on it to keep their fields healthy and productive. Gardeners often use small amounts of fertilizer as well to ensure that their flowers and other plants look their best.

Fertilizer is a material that provides one or more nutrients plants needed, helping improve soil physical and chemical properties and raise soil fertility. Both types and brands of fertilizer in the market are in a great variety, which is divided into mineral fertilizer and organic fertilizer. It is of great importance for plants to use fertilizer.

Required elements of higher plants:
Macronutrients: carbon, hydrogen, oxygen, nitrogen, phosphorus, and potassium.
Secondary elements: calcium, magnesium, and sulphur.
Micronutrients: iron, boron, manganese, copper, zinc, and molybdenum.

The Effects of Different Fertilizer on Plants
1.Providing multi-nutrition
Fertilizer, especially compound fertilizer, can supply various supplements. Compound fertilizer is the fertilizer that made from not less than two types of nutrients, such as calcium phosphate and ammonium nitrate.
Decomposition of fertilizer is slow. Plants, using compound fertilizer as base fertilizer, should apply fertilizer in accordance with fertilizer requirement pattern. This kind of fertilize can provide several quick nutrients and play a catalytic role in plants growth. It has an important effect on raising the utilization ratio of fertilizer and improving the quality of farm products.

2.Soil amelioration
The physicochemical properties of soil are basic elements for plants. Mineral nutrition is significant material foundation in living activities. There are great differences in demand of minerals for different plants.
Organic fertilizer is the a general designation that uses local materials in the countryside. It contains diluted urine, composting heap, green manure, miscellaneous manure and cake fertilizer, etc. These materials provide necessary ingredients for improving the soil. Soil organic matter can improve the physical and chemical properties of soil, which is conducive to the formation of soil crumb structure, thus contributing to plant growth and fertilizer absorption.

The substances, such as vitamins, black rot acid, fulvic acid, brown rot acid, and low molecular weight organic acid and butyric acid, have a direct impact on nutrition functions of plants in physical activity and stimulation, respiration enhancement and root growth promotion. Organic fertilizer business develops super fast in the world. Most potential investors show great interest in Organic Fertilizer Production Process, and make good preparation for their new business.

3.Increasing production
When soil is barren and plants growth is slow, it is time to use fertilizer. Although the types of fertilizer are different, the common goal is to increase production. Fertilizer is characterized of quick efficiency, high use ratio and remarkable effect, widely used in agriculture.
Only when using fertilizer properly can attain objectives. The inappropriate preparation or using too much fertilizer may cause side effect. Therefore, keeping just enough use level can help plants growth, increasing further plants production.

4.Slow release
The period of validity of fertilizer absorption is limited and short. To make a variety of regulatory mechanisms for initially delaying release of nutrient and extending use of plants to absorb nutrients for its effective validity, so that nutrients release becomes slow by setting the nutrient release rate. The solubility in water is small. Slow release of nutrients in the soil reduces the loss of nutrients. Long-term and stable fertilizer efficiency are able to supply plant nutrients in the entire production period.

The above effects are a few advantages in using fertilizer. As a matter of fact, fertilizer performs a number of functions in the process of plants growth. There are a variety of types of fertilizer. To choose applicable fertilizer is needful according to different demands. As long as using fertilizer moderately and accurately, it helps plants grow rapidly and effectively.

You are here

Home > News

Fertilizer 101: The Big 3 – Nitrogen, Phosphorus and Potassium

It’s the earth’s cultivated cropland that keeps humanity alive and thriving. Plants provide food, fiber, housing and a host of other benefits, and fertilizer plays a key role in this process. As the world population is expected to exceed 9 billion by 2050, fertilizer will be needed more than ever to boost crop production to keep people fed and healthy.

All growing plants need 17 essential elements to grow to their full genetic potential. Of these 17, 14 are absorbed by plants through the soil, while the remaining three come from air and water.

Generations of soil science have yielded knowledge of how to test nutrient levels in soil, how plants take them up and how best to replace those nutrients after harvest. That’s where fertilizer comes in.

Nitrogen, phosphorus and potassium, or NPK, are the “Big 3” primary nutrients in commercial fertilizers. Each of these fundamental nutrients plays a key role in plant nutrition.

Nitrogen is considered to be the most important nutrient, and plants absorb more nitrogen than any other element. Nitrogen is essential to in making sure plants are healthy as they develop and nutritious to eat after they’re harvested. That’s because nitrogen is essential in the formation of protein, and protein makes up much of the tissues of most living things. Below is a picture of corn that is nitrogen deficient.

The second of the Big 3, phosphorus, is linked to a plant’s ability to use and store energy, including the process of photosynthesis. It’s also needed to help plants grow and develop normally. Phosphorus in commercial fertilizers comes from phosphate rock. Below is a picture of corn that is phosphorus deficient.

Potassium is the third key nutrient of commercial fertilizers. It helps strengthen plants’ abilities to resist disease and plays an important role in increasing crop yields and overall quality. Potassium also protects the plant when the weather is cold or dry, strengthening its root system and preventing wilt. Below is a picture of corn that is potassium deficient.

The Big 3—nitrogen, phosphorus and potassium—provide the foundational nutrients of today’s commercial fertilizers. Keep following The Voice as we continue to explore fertilizer in-depth in the weeks ahead.

For more information on the the “Big 3” nutrients in commercial fertilizers, check out the 4R Educational Modules on nitrogen, phosphorus and potassium.

The Importance Of Phosphorus In Plant Growth

The function of phosphorus in plants is very important. It helps a plant convert other nutrients into usable building blocks with which to grow. Phosphorus is one of the main three nutrients most commonly found in fertilizers and is the “P” in the NPK balance that is listed on fertilizers. Phosphorus is essential to a plant’s growth, but what does it mean if you have high phosphorus in your soil, or a phosphorus deficiency? Keep reading to learn more about the importance of phosphorus in plant growth.

Phosphorus Deficiency in the Soil

How can you tell if your garden has a phosphorus deficiency? The easiest way to tell is to look at the plants. If your plants are small, are producing little or no flowers, have weak root

systems or a bright green or purplish cast, you have a phosphorus deficiency. Since most plants in the garden are grown for their flowers or fruit, replacing phosphorus in the soil if it is lacking is very important.

There are many chemical fertilizers that can help you with replacing phosphorus and getting a good nutrient balance in your soil. When using chemical fertilizers, you will want to look for fertilizers that have a high “P” value (the second number in the fertilizer rating N-P-K).

If you would like to correct your soil’s phosphorus deficiency using organic fertilizer, try using bone meal or rock phosphate. These both can help with replacing phosphorus in the soil. Sometimes, simply adding compost to the soil can help plants be better able to take up the phosphorus that is already in the soil, so consider trying that before you add anything else.

Regardless of how you go about replacing phosphorus in the soil, be sure not to overdo it. Extra phosphorus can run off into the water supply and become a major pollutant.

High Phosphorus in Your Soil

It’s very difficult for a plant to get too much phosphorus due to the fact that it’s difficult for plants to absorb phosphorus in the first place.

There’s no understating the importance of phosphorus in plant growth. Without it, a plant simply cannot be healthy. The basic function of phosphorus makes it possible to have beautiful and abundant plants in our gardens.

Phoslab Blog

By Joseph Mas

Phosporus (P) is an essential soil nutrient for plant growth and metabolism and is mainly responsible for flowering, fruit growth and root development. It plays key roles in many plant processes such as energy metabolism, the synthesis of nucleic acids and membranes, photosynthesis, respiration, nitrogen uptake and enzyme regulation. Adequate phosphorus nutrition enhances many aspects of plant development and works in conjunction with Nitrogen, and Sulfur.

To maximum efficiency of soil for commercial agriculture, home gardens or lawns it is important to know when to use phosphorus fertilizers and how to manage its usage. In agricultural systems, phosphorus in the harvested crops is removed from the system, resulting in Phosphorus deprived soils if no Phosphorus is supplemented in the form of fertilizer. Fertilizer in the form of rock phosphate or phosphate salts are applied in large quantities each year to soils in the United States.

Phosphorus Pollution

It is important to have you soil tested before applying Phosphor to make sure you have a proper balance of nutrients. According to a study by the American Society of Agronomy many farmers often apply up to four times the phosphate that is removed by the harvest. This practice leads to phosphate pollution of lakes, streams and groundwater. The consequence of Phosphorus pollution in our water sources is an exuberant growth of algae and other aquatic plants in P-polluted water systems, a process known as Eutrophication. That process kills fish and can cause serious imbalances in aquatic ecosystems. In addition, over abundance of Phosphorus in agricultural soil can cause distortion of plant growth by stunting growth and giving plants a deep green hue.

Inorganic phosphorus plays a major role in biological molecules. Plants need phosphate from the soil to make their DNA and RNA.. Phosphorus is one of the 17 nutrients found in healthy soil. Also, it is one of the three nutrients found in synthetic fertilizers: NPK = nitrogen, phosphorus, potassium. It must be taken up by plants – particularly when seedlings and very young – for proper growth. Proper growth depends on cell division, and on growing tips aka meristems. Plants lacking proper amounts of phosphorus will look stunted, from the shoots down through the roots. Phosphates are important to plants as they encourage root growth and so increase the uptake of other nutrients.

For healthy crops and plants (or lawns) first have an accurate soil sample test performed to determine what fertilizer you may need. When looking for a fertilizer rich in nitrogen, check the middle number labeled on the fertilizer bag. Usually the bags are labeled with numbers such as 13-35-24 or some other combination. The first number is Nitrogen, the second is Phosphorus and the third is Potassium. Fertilizers high in Phosphorus are usually determined by a high middle number. A simple soil test will help determine exactly what is needed to give you the highest yielding crops, most delicious fruits and greenest lawn.

Phosphorus: Essential to Life—Are We Running Out?

by Renee Cho |April 1, 2013

Fertilizing a corn field in Iowa. Photo credit: U.S. Department of Agriculture

Phosphorus, the 11th most common element on earth, is fundamental to all living things. It is essential for the creation of DNA, cell membranes, and for bone and teeth formation in humans. It is vital for food production since it is one of three nutrients (nitrogen, potassium and phosphorus) used in commercial fertilizer. Phosphorus cannot be manufactured or destroyed, and there is no substitute or synthetic version of it available. There has been an ongoing debate about whether or not we are running out of phosphorus. Are we approaching peak phosphorus? In other words, are we using it up faster than we can economically extract it?

In fact, there is plenty of phosphorus left on Earth. Animals and humans excrete almost 100 percent of the phosphorus they consume in food. In the past, as part of a natural cycle, the phosphorus in manure and waste was returned to the soil to aid in crop production. Today phosphorus is an essential component of commercial fertilizer. Because industrial agriculture moves food around the world for processing and consumption, disrupting the natural cycle that returned phosphorus to the soil via the decomposition of plants, in many areas fertilizer must now be continually applied to enrich the soil’s nutrients.

Most of the phosphorus used in fertilizer comes from phosphate rock, a finite resource formed over millions of years in the earth’s crust. Ninety percent of the world’s mined phosphate rock is used in agriculture and food production, mostly as fertilizer, less as animal feed and food additives. When experts debate peak phosphorus, what they are usually debating is how long the phosphate rock reserves, i.e. the resources that can economically be extracted, will hold out.

Pedro Sanchez, director of the Agriculture and Food Security Center at the Earth Institute, does not believe there is a phosphorus shortage. “In my long 50-year career, “ he said, “once every decade, people say we are going to run out of phosphorus. Each time this is disproven. All the most reliable estimates show that we have enough phosphate rock resources to last between 300 and 400 more years.”

In 2010, the International Fertilizer Development Center determined that phosphate rock reserves would last for several centuries. In 2011, the U.S. Geological Survey revised its estimates of phosphate rock reserves from the previous 17.63 billion tons to 71.65 billion tons in accordance with IFDC’s estimates. And, according to Sanchez, new research shows that the amount of phosphorus coming to the surface by tectonic uplift is in the same range as the amounts of phosphate rock we are extracting now.

Global meat consumption from 1961 to 2009. Photo credit: FAO

The duration of phosphate rock reserves will also be impacted by the decreasing quality of the reserves, the growing global population, increased meat and dairy consumption (which require more fertilized grain for feed), wastage along the food chain, new technologies, deposit discoveries and improvements in agricultural efficiency and the recycling of phosphorus. Moreover, climate change will affect the demand for phosphorus because agriculture will bear the brunt of changing weather patterns. Most experts agree, however, that the quality and accessibility of currently available phosphate rock reserves are declining, and the costs to mine, refine, store and transport them are rising.

Ninety percent of the phosphate rock reserves are located in just five countries: Morocco, China, South Africa, Jordan and the United States. The U.S., which has 25 years of phosphate rock reserves left, imports a substantial amount of phosphate rock from Morocco, which controls up to 85 percent of the remaining phosphate rock reserves. However, many of Morocco’s mines are located in Western Sahara, which Morocco has occupied against international law. Despite the prevalence of phosphorus on earth, only a small percentage of it can be mined because of physical, economic, energy or legal constraints.

In 2008, phosphate rock prices spiked 800 percent because of higher oil prices, increased demand for fertilizer (due to more meat consumption) and biofuels, and a short-term lack of availability of phosphate rock. This led to surging food prices, which hit developing countries particularly hard.

With a world population that is projected to reach 9 billion by 2050 and require 70 percent more food than we produce today, and a growing global middle class that is consuming more meat and dairy, phosphorus is crucial to global food security. Yet, there are no international organizations or regulations that manage global phosphorus resources. Since global demand for phosphorus rises about 3 percent each year (and may increase as the global middle class grows and consumes more meat), our ability to feed humanity will depend upon how we manage our phosphorus resources.

Unfortunately, most phosphorus is wasted. Only 20 percent of the phosphorus in phosphate rock reaches the food consumed globally. Thirty to 40 percent is lost during mining and processing; 50 percent is wasted in the food chain between farm and fork; and only half of all manure is recycled back into farmland around the world.

Eutrophication in the Caspian Sea. Photo credit: Jeff Schmaltz, NASA

Most of the wasted phosphorus enters our rivers, lakes and oceans from agricultural or manure runoff or from phosphates in detergent and soda dumped down drains, resulting in eutrophication. This is a serious form of water pollution wherein algae bloom, then die, consuming oxygen and creating a “dead zone” where nothing can live. Over 400 coastal dead zones at the mouths of rivers exist and are expanding at the rate of 10 percent per decade. In the United States alone, economic damage from eutrophication is estimated to be $2.2 billion a year.

As the quality of phosphate rock reserves declines, more energy is necessary to mine and process it. The processing of lower grade phosphate rock also produces more heavy metals such as cadmium and uranium, which are toxic to soil and humans; more energy must be expended to remove them as well. Moreover, increasingly expensive fossil fuels are needed to transport approximately 30 million tons of phosphate rock and fertilizers around the world annually.

Sanchez says that while there is no reason to fear a phosphorus shortage, we do need to be more efficient about our use of phosphorus, especially to minimize eutrophication. The keys to making our phosphorus resources more sustainable are to reduce demand and find alternate sources. We need to:

  • Improve the efficiency of mining
  • Integrate livestock and crop production; in other words, use the manure as fertilizer
  • Make fertilizer application more targeted
  • Prevent soil erosion and agricultural runoff by promoting no-till farming, terracing, contour tilling and the use of windbreaks
  • Eat a plant based diet
  • Reduce food waste from farm to fork
  • Recover phosphorus from human waste

Cow dung to be used as fertilizer drying in Punjab. Photo credit: Gopal Aggarwal http://gopal1035.blogspot.com

Phosphorus can be reused. According to some studies, there are enough nutrients in one person’s urine to grow 50 to 100 percent of the food needed by another person. NuReSys is a Belgian company whose technology can recover 85 percent of the phosphorus present in wastewater, and turn it into struvite crystals that can be used as a slow fertilizer.

New phosphorus-efficient crops are also being developed. Scientists at the International Rice Research Institute discovered a gene that makes it possible for rice plants to grow bigger roots that absorb more phosphorus. The overexpression of this gene can increase the yield of rice plants when they are grown in phosphorus-poor soil. Rice plants with this gene are not genetically modified, but are being bred with modern techniques; they are expected to be available to farmers in a few years.

A breed of genetically modified Yorkshire pigs, called the Enviropig, has been developed by the University of Guelph in Canada to digest phosphorus from plants more efficiently and excrete less of it. This results in lower costs to feed the pigs and less phosphorus pollution, since pig manure is a major contributor to eutrophication. Last spring, however, the Enviropigs were euthanized after the scientists lost their funding.

The Agriculture and Food Security Center is working on food security in Africa and attempting to eliminate hunger there and throughout the tropics within the next two to three decades.

In the mountains of Tanzania along Lake Manyara, Sanchez’ team has discovered deposits of “minjingu,” high-quality phosphate rock that is cheaper and just as efficient as triple super phosphate (a highly concentrated phosphate-based fertilizer) in terms of yields of corn per hectare.

Minjingu Mines & Fertilisers Ltd.. Photo credit: IFDC Photography

Minjingu deposits are formed by the excreta and dead bodies of cormorants and other birds that roost and die in the mountains, forming biogenic rock phosphate or guano deposits. Guano, the feces and urine of seabirds (and bats), has a high phosphorus content, and in the past was often used as fertilizer.

Sanchez’ researchers have also discovered a common bush called the Mexican Sunflower that is an efficient phosphorus collector. It grows by the side of the road, fertilized by the excreta dumped there by farmers. The farmers cut it down and use it as green manure, an organic phosphorus fertilizer which helps grow high-quality crops like vegetables.

Mexican Sunflower. Photo credit: John Tann

The Agriculture and Food Security Center team also helps farmers contain erosion and runoff by encouraging them to keep some vegetative cover, either alive or dead, on the soil year-round. This is done through intercropping, leaving crop residue in the fields, contour planting on slopes or terracing.

“There is no data to support the idea of peak phosphorus,” said Sanchez. “Just fears. New deposits are continually being discovered. We also have more efficient extraction that is getting more phosphate rock out of land-based sediments. And there is an enormous 49-gigaton deposit of phosphorus in the continental shelf from Florida to Maritime Canada that scientists have known about for years. Now there is some experimental extraction going on off the coast of North Carolina.”

Pedro Sanchez, author of Properties and Management of Soils in the Tropics published in 1976, which continues to be a bestseller, is currently working on Tropical Soils Science, an update of his previous work. It will be published by 2015.

Correction: This post was updated on March 22, 2019 to remove a statement that phosphorus is a renewable resource.

Get our newsletter

I’d like to get more stories like this.

Phosphate Fix: The Sweet Side of Greens

Putting dirt in your mouth isn’t a very popular pastime. But when it comes down to it, everything you eat comes from dirt and from air. This is true whether you eat rice, tomatoes, eggs, cows, or candy bars. We could even argue that humans come from dirt. We eat plants and some of us also eat other animals, like chickens. Chickens eat plants and insects, and many insects eat plants as well. So everything comes back down to plants, which come from dirt and air.

Plants need sunlight, water, carbon dioxide, and nutrients to grow. Click for more detail.

To grow, plants need sunlight, water, and carbon dioxide from the air. Plants also need nutrients like nitrogen and phosphorus, which most plants get from the soil. There are more than 7 billion people on the Earth and that number grows every day. It’s important to think about how we’re going to feed everybody. This means that, no matter what we eat, we need to figure out more efficient ways to grow crops.

You may think that we’ve already figured it out. After all, while not everyone in the world gets enough food, most of us do. Many of us even waste a lot of food. Yet, in a little over 100 years, the Earth’s human population exploded from 1.6 billion in 1900 to over 7 billion people. Such an increase in population wouldn’t have been possible without lots of food. So how did humans manage to grow more food?

Fertilizer From Air

In the early 1900s two German chemists, Fitz Haber and Carl Bosch, were studying gases. They figured out how to use nitrogen from the air to make ammonia, a plant fertilizer. Using nitrogen as well as phosphorus fertilizers allowed us to grow enough food to feed billions of people. However, using lots of fertilizer had an unexpected effect.

Over many generations, fertilization can cause plants to have small roots. Click for more detail.

With lots of nutrients available to plants, there was no advantage to larger roots. Plants with small roots, but big leaves or more seeds, reproduced more and passed on their genes. This led to more and more of our crops ending up with small root systems. We figured out a way to keep making plenty of nitrogen to use on these small rooted plants. But the situation is different for another nutrient, phosphorus.

You may not have heard of phosphorus before, yet it is a very important element. It stiffens our bones. It’s in our DNA. It’s in adenosine triphosphate (ATP), which is the molecule that provides the energy for nearly every single thing your cells do. Plants also need it to get energy from the sun.

Plants gather phosphorus from the soil in the form of phosphate. Phosphate is simply a phosphorus atom bonded to four oxygen atoms. We use tons of phosphate fertilizer on our crops to produce the yields we depend on. Yet unlike nitrogen, phosphate can’t come from the air. The renewal of phosphate depends on the movement of the Earth. Lands and continents have to shift and push up new rocks that hold phosphate. These changes take thousands or millions of years.

Phosphate used to be mined from bat guano (poop) but now phosphate is mined from phosphate rock. Click to enlarge.

The Future of Phosphate

Historically, phosphate was mined from bat guano, but bats can only poop so much. So now the majority of phosphate comes from phosphate rock. Yet, just like the bat guano, there’s only so much phosphate rock to go around. In fact, it is projected that at current rates, we will run out of phosphate in the next 50 to 100 years.

The human population is continuing to grow at faster rates. If we run out of phosphate for fertilizer, we won’t be able to support a population at today’s level. And we definitely won’t be able to support the billions of additional people that will exist in 50 to 100 years.

As if that’s not bad enough, most of the phosphate in fertilizer isn’t even used by plants. With their small root systems, they can only use a small amount at any given time. Much of the phosphate is washed or blown away. In this form, it actually acts as a pollutant. If it makes it to lakes or streams, it causes algae to grow so fast that they use up the oxygen in the stream or lake and kill off the fish. Phosphate that stays in the soil can sometimes bind to the soil so strongly that it makes it very difficult for plants to use it.

Finding Phosphate

Between pollution and limited supply, we need to be more careful with phosphate. There are two main ways we can attack this problem. We can capture extra phosphate and recycle it, or we can help plants take up and use phosphate more effectively.

Lots of phosphorus is wasted because it is washed away with farmland runoff water. Click to enlarge.

The first way, we would have to catch the extra phosphorus from all the farms before it reaches the streams. Then we would have to separate it from the dirt and other material we picked up with it, and ship it back out to the farms. This process would allow us to continue to dump a bunch of fertilizer on crops again and again, but it would be very costly and time consuming.

The second way involves changing plants, so that they are better at getting and using phosphate. Then we could use less fertilizer in the first place and still get the same amount of food.

For the past couple of decades, researchers have been working on the second approach using genetics. They have modified the genes of plants so some plants are able to grow more roots that are longer. These plants can better absorb phosphate from the soil so that we don’t have to use as much fertilizer and there’s less waste. If we can expand their work to major crops, it could be the answer to our phosphorus problem.

Leave a Reply

Your email address will not be published. Required fields are marked *