Comparative analysis of cost on slurry application in Chile and Argentina dairy farms Charlon Verónica 1 *, Salazar Sperberg Francisco 2 , Manazza Francisco J. 3 , Herrero María A. 4 (1) Instituto de Investigaciones Agropecuarias, INTA-Rafaela, C.C. 22, 2300, Santa Fe, ARG (2) Instituto de Investigaciones Agropecuarias, INIA-Remehue, Casilla 24-O, Osorno, CHL (3)Instituto de Investigaciones Agropecuarias,INTA-San Luis, C.C.17, 5730, S.Luis, ARG (4) Universidad de Buenos Aires, F. Cs. Veterinarias, Chorroarín 280, 1427, Bs.As., ARG *Corresponding author: vcharlon@rafaela.inta.gov.ar Selected Paper prepared for presentation at RAMIRAN 15th International Congress, Versailles France 3-5 June, 2013. Abstract The objective of this study was to evaluate slurry application costs and economical balance at dairy farm level, considering slurry nutrient contents in both countries. Benefit-cost analysis was carried out using information from 110 dairy farms in each country. Slurry dry matter content (SLDM%) presented significant differences between countries (p<0.01), with medium values of 0.62% for AR and 1.3% for CH. Low SLDM% brings low nutrient content, reducing its economic value. Considering a slurry application rate of 50 m 3 ha -1 , the 40% of CH and 99.2% of AR farms had a negative economical balance. Increasing 1% of SLDM represents 19.56 USD for AR and 44.79 USD for CH. While slurry application is a feasible cost efficient technology in Chilean dairies, strategies to improve water use efficiency on milking routine and slurry management in both countries, specially on Argentine dairies that are required to extend its adoption Introduction In the last years has been an intensification of South American dairy systems, being based in increasing use of technology, fertilizer and feeds. This has implied a high milk production but at the same time and increase of dairy slurry production. The efficient use of slurry on soil could reduce the use of inorganic fertilizer, which can be important on decrease cost for farmers. Dairy slurry has been used as organic fertilizer in many crop and pasture with positive effects from the agronomic point of view, however, there are only few studies published evaluating economical aspects, which is a key aspect for farmers. In Argentina and Chile dairy farms are based on grazing systems where animals are only partially housed. Main component of dairy slurry is water from cleaning milking facilities and rainwater, therefore, slurry dry matter content are very low (c.2-4%). Slurries are applied to soil mainly using irrigation pumps and slurry tank, however, there is no information on cost of this management practices and the slurry value. The objective of this study was to evaluate cost of slurry application and the economical balance considering the contribution of nutrients in slurry on dairy farms in Argentina and Chile. Materials and methods Benefit-cost analysis was carried out using information collected in 110 dairy farms, which were surveyed for each country and slurry sample collected. Dairy slurry was analyzed for dry matter content and total nitrogen (N), total phosphorus and total potassium, an informed as kilograms of N, P 2 O 5 and K 2 O for m -3 of slurry, respectively, which are the same nutrient form in inorganic fertilizers.