IS1169 Forage Summary of Forage Crop Fertilization Guidelines

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Forage and Pasture Crop Fertilization Guidelines

Forage producers should fertilize pasture and hay crops according to the results of a soil test. Test soil before forage establishment and every 2 to 3 years thereafter. Fertilizer guidelines listed in the chart are based on a soil rated “low” in phosphate and potash, as determined by a soil test. The amount of fertilizer recommended will be less if the soil is rated “medium” or “high” or if animal wastes are applied.

Establishment of over-seeded grasses will require a soil pH of 5.8 to 6.5 and a 60-20-40 fertilizer. For example, applying 400 pounds of 15-5-10 per acre will supply 60 pounds of N (nitrogen), 20 pounds of P₂O₅ (phospate) and 40 pounds of K₂O (potash). If using conventional tillage to establish the crop, incorporate corrective levels of phosphate and potash during plowing and disking. Base subsequent applications of phosphate and potash on the results of a soil test as part of an overall nutrient management plan.

Maintenance rates are based on soil test levels building from “low” to “medium,” and on crop removal. One ton of hay (2 round bales) per acre removes approximately 40 to 50 pounds of nitrogen, 8 to 12 pounds of phosphate, and 40 to 60 pounds of potash. If a pasture is used just for grazing, the fertilizer requirements will be lower than if it were used for hay removal. Only 7 to 8 pounds of phosphate, and 1 pound of potash are removed per 500 pound steer or heifer.

A forage crop’s nitrogen requirements are similar whether the crop is being used for grazing or for hay. Nitrogen rates are generally not based on a soil test. Perennial plants, such as most permanent forage crops, need a continuous supply of readily available nitrogen. Best forage growth is achieved by splitting nitrogen applications on most grasses. Nitrogen usage by plants is complex, and nitrogen fertilizer is more effective when applied in small, frequent applications than when applied once in large quantities (see Extension Information Sheet 767, Nitrogen in Mississippi Soils). Do not apply more than 60 to 90 pounds of actual nitrogen per acre at any one application; applying nitrogen in amounts greater than 90 pounds/acre may lead to livestock nitrate toxicity.

Establishment of legumes such as over-seeded alfalfa and clovers will require a soil pH of 6 to 6.8 and the equivalent of a 20-60-60 fertilizer plus 1 pound of Boron per acre. A successful stand of alfalfa requires a well drained soil with a pH of 6.5 to 6.8 and soil test levels of phosphate and potash in the “medium” to “high” range.

Legumes normally convert nitrogen from the atmosphere to a form used by plants, if they are properly inoculated with the correct soil bacteria. Clovers and other legumes supply some nitrogen fertilizer to the grass. Nitrogen fertilizer requirements for a grass growing with a legume can be reduced by 40 to 60 percent, compared to nitrogen recommendations for a grass growing without legumes.

Crop	Yield Range	Maintenance^1,2
Crop	Yield Range	Grazing	Hay
Mixed Summer Perennial Grass With Legume⁴	1-2 tons/acre	90-20-60	120-40-80
	2-4 tons/acre	180-20-80	240-80-200
	2-4 tons/acre	90-20-80	120-80-200
Common Bermuda Grass With Legume⁴	1-2 tons/acre	90-20-60	120-40-80
	2-4 tons/acre	180-40-80	240-80-200
	2-4 tons/acre	90-40-80	120-80-200
Hybrid Bermudagrass (Coastal, Alicia, Tifton, Sumrall, etc.)	2-4 tons/acre	180-40-80	240-80-200
	4-6 tons/acre	240-60-120	300-100-240
Johnsongrass	2-4 tons/acre	180-40-80	240-80-200
Johnsongrass	4-6 tons/acre	240-60-120	300-100-240
Browntop Millet Crabgrass	1-2 tons/acre	90-20-60	120-40-80
Pearl Millet Sorghum-Sudan Hybrids	2-4 tons/acre	180-40-80	240-80-200
Pearl Millet Sorghum-Sudan Hybrids	4-6 tons/acre	240-60-120	300-100-240
Perennial Winter Grass (T. Fescue) With Legume⁴	2-4 tons/acre	150-40-80	180-80-200
Perennial Winter Grass (T. Fescue) With Legume⁴	2-4 tons/acre	75-40-80	90-80-200
Oats, Rye, Wheat	1-2 tons/acre	60-20-60	80-40-80
Oats, Rye, Wheat	2-4 tons/acre	150-40-80	180-80-200
Ryegrass With Legume⁴	2-4 tons/acre	150-40-80	180-80-200
	4-6 tons/acre	200-60-120	240-100-240
	4-6 tons/acre	100-60-120	120-100-240
Alfalfa	2-4 tons/acre	0-60-120 + 3B³	0-80-200 + 3B³
Alfalfa	4-6 tons/acre	0-80-160 + 3B³	0-100-240 + 3B³
Clovers (All)	2-4 tons/acre	0-60-120 + 1B³	0-80-200 + 1B³

¹Fertilizer recommendations are based on a soil test rated “Low” in phosphate (P₂O₅) and potash (K₂O).
²All Fertilizer rates are pounds of actual N, P₂O₅, and K₂O per acre, respectively.
³B = Boron.
⁴Inoculate all legume seed with the proper bacteria to insure maximum nitrogen fixation.

Recommendations in this publication do not endorse any commercial products or trade names.

By David J. Lang, Ph.D., Associate Professor and Forage and Pasture Crops Specialist and Malcolm Broome, Ph.D., Extension Forage Specialist

Mississippi State University does not discriminate on the basis of race, color, religion, national origin, sex, age disability, or veteran status.

Information Sheet 1169
Extension Service of Mississippi State University, cooperating with U.S. Department of Agriculture. Published in furtherance of Acts of Congress, May 8 and June 30, 1914. JOE H. MCGILBERRY, Interim Director

(rev-2M-8-01)

Copyright 2001 by Mississippi State University. All rights reserved.

This document may be copied and distributed for nonprofit educational purposes provided that credit is given to the Mississippi State University Extension Service.

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