Evaluation of on-farm quick tests on slurries from southern Chile dairy farms.

Francisco Salazar1*, and Marianela Rosas1

Currently in Chile, there is a lack of tools to determine the real-time nutrient contribution of slurries. This study aims to evaluate three quick tests for their accuracy in estimating the total contents of N (TN), P (TP), K (TK), and ammonium-N (N-NH4+) in dairy slurries. The quick tests included the Agros Nova Meter, Quantofix N Volumeter, and a hydrometer. While the Agros and Quantofix meters directly measure the ammonium-N content; the hydrometer indirectly estimates the total content of N, P, and K based on linear relationships with the slurry DM. Samples (73) were collected from dairy farms along Southern Chile (39º to 44º S and 71 to 73º W). Analyses were carried out on laboratory conditions using conventional techniques as well as using each of the quick tests. Results were subjected to straight-line regression analyses. Agros and Quantofix N-NH4+ measurements were accurate (P < 0.01; r2 > 0.80). The hydrometer estimations of TN, TP, and TK were also reliable (P < 0.01). Best results were obtained with P (r2 = 0.87) and N (r2 = 0.79) total contents. To evaluate the kits on-farm and transfer those to dairy producers may constitute a next step towards an efficient management of organic residues in dairy farms in Chile.

Keywords: Slurry, organic residue, chemical analysis, nutrients.
1Instituto de Investigaciones Agropecuarias INIA, Carretera Panamericana Sur km 8 Norte, Osorno, Chile. *Corresponding author (fsalazar@inia.cl).