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Fertility Management

Nutrient management planning considers crop nutrient inputs to resemble money budgets. You must know two things:

  • What you have
  • What you need

Determining what you have simply requires using a well-designed soil testing program to determine the current soil fertility status. The absolute number given for P or K per acre is usually not the most important information given on the report. There will be an index value for the mineral nutrients which is very important. These indices are usually very low, low, medium, or high. Some laboratories are beginning to use the term "adequate" to describe the medium or high indices.

An index of high (or sometimes very high) for a nutrient indicates it is very unlikely plants would benefit from the application of additional nutrient. On the other end of the scale, a very low index for soil supplied P or K indicates a growing crop would likely have a measurable response to addition of the nutrient.

What you need is determined by realistic personal assessment of a farming operation. It is not possible to underestimate the value of record-keeping in nutrient management. Yield history and management level should provide a reasonable starting point to project future yields. With realistic yield goals, it is possible, using resources available from farm advisors, to estimate nutrient requirements of any future crop.

It is important to make the difference between nutrient uptake and removal. Plants utilize nutrients throughout their entire system from the roots to the pollen. This is not all removed by crop harvest and remains in the field. As much as 45 percent of some crops' (non-root or tuber crops) biomass actually may be below ground.

Another consideration in nutrient removal is the mode of harvest. For example, most forage crops have substantial quantities of K in the leaves and stems, thus K fertility must be monitored closely when hay is harvested and hauled from the field.

It is impossible to balance crop nutrients inputs and outputs to absolute accuracy, but a "virtual" balance can be calculated. Once this balance is determined, application of either purchased fertilizer or on-farm animal manures should follow best management practices (BMP's).

BMP's are:

  • simple
  • economical
  • common-sense
  • doable
  • proven

It is simple to illustrate these points with one example. When applying chicken litter near a small stream, simply drive far enough away from the water that no litter goes into it. It's a simple practice, it's cheap, it's doable, and it is well-proven that buffer zones of no application reduce off-site movement of nutrients. And it's all common sense.

Soil Fertility Best Management Practices

  • Use soil testing to assess fertility status.
  • Use common-sense, attainable yield goals.
  • Determine nutrient and moisture content of manure.
  • Base nutrient applications (either manures or purchased fertilizer) on crop needs as determined by the soil test.
  • Rotate fields receiving manure to avoid nutrient buildup and maximize nutrient utilization.
  • Use only sufficient fertilizer required for attainable crop yield goals.
  • Incorporate fertilizer and manure when possible.
  • Calibrate all application equipment.
  • Avoid applying fertilizer, or manure, on wet soils to minimize compaction, runoff and leaching/denitrification.
  • Avoid applying fertilizers and manure near streams, ponds, or other water bodies.
  • Use grass filter strips along ditches and waterways to reduce soil erosion, runoff and nutrient losses.
  • Time applications to when nutrients are needed by the crop as possible.
  • Utilize fall cover crops to minimize soil erosion and runoff and to maximize nutrient utilization from manure applications.


Extension Soils/Fertilization publications
Soil Testing for the Farmer
Cotton Fertility
Soybeans -- Liming and Fertilization
Nitrogen in Mississippi Soils
Phosphorus in Mississippi Soils
Managing Animal Wastes
You and Animal Wastes


Other Soil Information

Natural Resources Conservation Service
Land Application of Animal Wastes
American Society of Agronomy
Soil and Water Conservation Society
Conservation Tillage Information Center
National Cotton Council
United Soybean Board
National Corn Growers Association
The International Plant Nutrition Institute
The Fertilizer Institute
Environmental Working Group
Fertilizer Management

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Publication Number: IS0894
Publication Number: P1782
Publication Number: IS1853
Publication Number: IS1587
Publication Number: IS1038


A marker stating “Common Vetch” stands in a section of tall green grass.
Filed Under: Crops, Soils, Weed Control for Crops January 22, 2018

STARKVILLE, Miss. -- Producers who plant winter crops with no intention of harvesting them reap the benefits of soil conservation, weed control and nutrient retention.

On the flip side, however, the practice of almost constant production in a field creates issues with pest management. Farmers who “plant green” have to balance these challenges to best prepare the way for good crops each year.

Filed Under: Soils, Soil Testing May 25, 2017

New manager of operations Keri Jones recently joined the Mississippi State University Extension Service Soil Testing Laboratory, and she's ready to enhance the unit's efficiency."

"My primary goal is to provide accurate soil analysis in a timely manner," said Jones, an Extension associate who has worked in the MSU Department of Plant and Soil Sciences since 2016. "I hope to improve the overall efficiency of the lab as well as update soil nutrient application recommendations."

Eddie Stevens, farm supervisor at Mississippi State University’s R. R. Foil Plant Science Research Center in Starkville, was applying a liquid fertilizer to a corn field on April 5, 2016. Correct application of nutrients is a key part of environmental stewardship and efficient farm management. (Photo by MSU Extension Service/Kevin Hudson)
Filed Under: Soils April 13, 2016

STARKVILLE, Miss. -- One major cost of producing a good crop is ensuring plants are fertilized well, an operational expense that may consume a significant part of farm budgets.

Bryon Parman, an agricultural economist with the Mississippi State University Extension Service, said nutrient application and replenishment may consume more than 13 and 14 percent of total operating expenses for cotton and soybeans.

“For crops with high nutrient demand such as corn, this nutrient cost may comprise more than 40 percent of variable costs,” Parman said.

Larry Oldham, Mississippi State University soil specialist, samples soil in a Delta field on Oct. 17, 2014. (Photo by MSU Ag Communications/Kat Lawrence)
Filed Under: Crops, Soils, Soil Health May 21, 2015

STARKVILLE, Miss. -- Mississippi farmers should not take the state’s rich soil for granted, but the question of the best way to treat this valuable resource sparks debate.

“Soil can be thought of as a living organism that must be kept healthy to provide some of the crop requirements and make efficient use of inputs, especially fertilizer,” said Larry Oldham, soil specialist with the Mississippi State University Extension Service.

Poor weather conditions often stretch out Mississippi's row crop planting season as overly wet or cool fields keep planters in the barn. (File Photo by MSU Ag Communications/Scott Corey)
Filed Under: Farming, Crops, Soils April 17, 2015

STARKVILLE, Miss. -- Seeing planters in the field is an expected part of spring in rural areas, but a lot of effort goes into making sure they run at the right time.

Planting season in Mississippi begins with corn in late February to early March and often runs into July as the last of the soybeans are planted after wheat harvest. The long planting window allows producers the opportunity to get a crop in the ground even when the weather is not ideal at typical peak planting times.


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