Nutrient Balances in Organic Dairy Farms S1
Askegaard, M. & Eriksen, J.
Department of Soil Science, Danish Institute of Plant and Soil Science, Research Centre Foulum, P.O. Box 23, DK-8830 Tjele, Denmark
|In organic farming nutrients occur as a limited resource. In order to obtain a sustainable plant production minimization of nutrient leaching from the fields is of great importance. In this respect livestock density,crop rotation and type of manure are significant factors and a better understanding of their effect on nutrient leaching might contribute to improve nutrient management on organic farms. Nutrient balances on field level are a tool for evaluating the sustainability of farming systems. Results are presented from a field experiment with four different organic dairy farming systems: two livestock densities (0.9 and 1.4 livestock units per ha) and two manure types (slurry and a deep litter dominated system). Each combination of the treatments livestock density and manure type was replicated four times in a six field crop rotation. Leaching of N, K and S were estimated from concentrations in soil water and net drainage. Soil water were sampled in 1 m depth using porous ceramic cups (288 in total) and net drainage was estimated by a water balance model. Nutrient balances for N, P, K and S were estimated for each crop and treatment. The paper presents results from two years (1994 and 1995). The influence of livestock density, manure type and crop rotation on nutrient leaching and nutrient balances in the four farming systems are discussed in relation to essential problems and possibilities in organic farming.