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United States Department of Agriculture

Agricultural Research Service

Title: The Use of on-Farm Quick Tests to Measure Manure Nitrogen

Authors
item Van Kessel, Jo Ann
item Reeves Iii, James

Submitted to: Sustainable Agriculture
Publication Type: Abstract Only
Publication Acceptance Date: February 23, 2000
Publication Date: N/A

Technical Abstract: An experiment was conducted to evaluate six Quick Tests for their accuracy in predicting manure nitrogen concentrations. Quick Tests included the hydrometer, electrical conductivity meter and pen, reflectometer, Agros N Meter, and Quantofix- N-Volumeter. The hydrometer was used to predict total N, while the remaining tests were used to predict NH4+-N. Samples (107) were collected from dairy farms in five northeastern states. Samples were analyzed for total N and NH4+-N by traditional laboratory methods and using each of the Quick Tests. Manure compositions ranged from 1.4% to 38.6% DM, 0.09% to 0.94% total N, and 0.02% to 0.47% NH4+-N. The estimated concentration of N or NH4+-N determined by each Quick Test was regressed against laboratory-determined values. The hydrometer did not perform well as a predictor of total N, however, Quick Test prediction of NH4+-N was accurate. The strongest prediction of NH4+-N was with the Quantofix-N-Volumeter followed by the Agros N Meter, the reflectometer, and the electrical conductivity meter and pen. When the samples were split into high (> 12%) and low DM (£ 12%) groups, the r2 for the regression equations were higher for the low DM group than for the high DM group. These data indicate that, several Quick Tests are viable options for estimating NH4+-N in dairy slurries and solids.

Last Modified: 8/30/2014
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