Rapid on-farm analysis of manure nutrients using quick tests

Quick tests enabling rapid, on-farm assessment of manure nutrient content c ould appreciably enhance manure management. The objectives of this study we re to review the literature on the accuracy of quick tests, describe their operation, and to assess their ease of use and their suitability for routin e on-farm use, These quick tests are the hydrometer, electrical conductivit y (EC), ammonia electrode, reflectometer, Agros N Meter (or Nova meter), an d Quantofix-N-Volumeter. The ammonia electrode provided accurate direct mea surement of slurry ammonium; however, its fragility and the difficulty of s etting it up, suggested limited suitability for on-farm use. The hydrometer indirectly measures total N and total P based on relationships with dry ma tter (total solids) content and specific gravity, Results have been variabl e between regions and species. Electrical conductivity is used as an indire ct measurement of ammonium and K; the limited results to date have been con sistently good for ammonium N, and variable for K. The Agros N Meter and Qu antofix-N-Volumeter both directly measure ammonium N and possibly some orga nic N, For both, agreement with lab analyses of ammonium N has been general ly very good. The reflectometer measures the color intensity of test strips ; limited results with ammonium N in slurries are promising. Several quick tests have the potential for accurately measuring manure nutrients on the f arm, They generally were more effective with slurries than solid manures. F or each quick test, single farm or regional calibrations with lab analysis are recommended, and in some cases necessary.