The relationships between the nutrient content in soils fertilized with organic and inorganic sources, and the nutrient contents and productivities of potato as well as the relationships of applications and the leaching of N and exchangeable bases were determined. Soil samples were collected from the 0-20, 20-40 and 40-60 cm layers in 18 areas of potato production receiving annual applications of farm yard manure for the last 2 to 40 years and, as control, four areas under non-fertilized pasture. Soil and plant samples were analysed for N, P, K, Ca and Mg concentrations. The yield of large tubers had a positive relationship with the input of N while total yields related with total soil N. Only Ca in the soil correlated with the levels in the plant, but not with productivity. Exchangeable bases increased in the three layers following increases in applied manure, while total soil N increased only in the 0-20 and 20-40 cm layers. The translocation of nutrients to deeper layers represents economic loss and possible environmental risk.
Solanum tuberosum; manure; lixiviation
