Study On Rapid Measurement Methods For The Nutrient Contents Of Dairy Manure

Volumes of manure from large scale dairy can cause pollution problems. In order to apply manure as useful resource, an estimation of fertilizer value in manure is necessary. This experiment studied rapid prediction methods for the fertilizer value of dairy manure based on physical / chemical analysis and near-infrared reflectance spectroscopy (NIRS) technology.In order to test methods of rapidly estimating fertilizer value of dairy manure based on physical and chemical analysis, 89 manure samples were selected. One part of each manure sample was analyzed for physical and chemical properties, such as electrical conductivity (EC), specific gravity (SG) and pH; the other part of each manure sample was to measure total nitrogen, total phosphorus, total potassium and ammonium nitrogen contents. This paper studied the correlativity of physical and chemical properties and fertilizer value. Analytical results showed that: (1) EC and pH could be evaluated for estimating total nitrogen (R2=0.645, p<0.001). EC, SG and pH could be evaluated for estimating total nitrogen (R2=0.675, p<0.001); (2) EC could be evaluated for estimating total potassium (R2=0.687, p<0.001); (3) EC and pH could be evaluated for estimating ammonium nitrogen (R2=0.717, p<0.001).In order to investigate the feasibility of near-infrared reflectance spectroscopy (NIRS) technology for rapidly analysis of the fertilizer value of dairy manure, diverse dairy manures (n=89) were collected. This study developed calibrations using partial least-squares regression. Analytical results showed that: (1) total nitrogen, ammonium nitrogen and total phosphorus content of dairy manure had good predictability by NIRS. The R2 values of calibration model were 0.9640,0.9530 and 0.9307 respectively, and ratios of SD/SEE (RPD) were 5.09, 4.33 and 3.68 respectively. (2) Total potassium could be predictable by NIRS (R2=0.8729, RPD=2.60).