Use of Computer Software to Manage Manure Nitrogen

Ronald E Hermanson, Agricultural Engineer

Washington State University


While manure is a good source of plant nutrients, including nitrogen, phosphorus, and potassium, excessive applications potentially contribute to the contamination of water through leaching and runoff. Because nitrogen in the nitrate form is a public health hazard, it is the primary manure rate-limiting nutrient.


A software program, Manure Nutrient Balancer (MNB), has been developed to compute manure application rates and to determine the appropriate balance of manure nutrients with soil nutrients and crop needs. Included in MNB’s data base are eight types of livestock and poultry manure, twelve Washington crops, and three soil-climate zones. The user is guided to input relevant farm details such as livestock information, manure system components, manure and soil test data, crop yield goals, and field history from previous years. From this information, the MNB model will estimate recommended manure application amounts.


Crop nitrogen needs are based on yield goal and nitrogen use efficiency factors. Phosphorus and potassium requirements are based on Washington fertilizer guides. Manure application rates can be calculated on the basis of nitrogen, phosphorus, or potassium optimization.


WSU College of Agriculture and Home Economics faculty developed the MNB program. The following Washington State University personnel cooperated in the effort: Ronald Hermanson, Extension Agricultural Engineer, Water Quality; A.C.S. Rao, Post Doctoral Research Associate, Department of Crop and Soil Sciences; William L. Pan, Associate Professor, Department of Crop and Soil Sciences; Kathleen Duncan, Systems Analyst, and M. Anthony Wright, Computer Coordinator, Information Department and Wayne Madson, Chair, Stevens County Cooperative Extension.


MNB can be used for many organic wastes and wastewaters by testing them for N, P, and K, and by soil testing. These values and the volume or weight to be applied to land enable MNB to calculate the application rate for the desired crops. MNB is versatile and is designed so the user can change tabulated coefficients if necessary.


For those who do not use computers, there is a bulletin for converting nutrient units reported by laboratories to units the user chooses for land application calculations.


1) MNB: Manure Nutrient Balancer may be purchased from the Bulletin Office for $25.00. Request MCP0026.

2) Manure Sampling for Nutrient Analysis with Worksheets for Calculating Fertilizer values may be purchased from the Bulletin Office for $1.00. Request EB1819.


Bulletin Office

Cooperative Extension

Cooper Publications Building

Washington State University

Pullman, WA 99164-5912

(800) 723-1763

Web Site:

Whatcom County Agriculture Page | Whatcom County Home Page