Soil fertility in a long‐term fertilizer trial with different tillage systems

Abstract

The presented results originate from a field experiment established in 1972 on an Eutric cambisol with two main factors: soil tillage (conventional‐, reduced‐, and no‐tillage) and NPK fertilization. The test plants were maize and winter wheat in two years rotation. The long‐term soil fertility without and with optimum fertilization, the influence of fertilization, tillage and crop sequence on grain yields, the organic carbon content (Corg) and the nitrate infiltration are discussed. In the course of years without any NPK fertilization grain yields of maize and winter wheat decreased significantly and reached a minimum level which was modified however by the actual climatic conditions. The analogous yield level of optimum NPK fertilization at maize showed a growing tendence while at wheat it remained mostly constant. The method of soil tillage influenced grain yield of winter wheat to a lesser extent than the yield of maize. Grain yields of maize and winter wheat were consistently lower with no‐till as compared to reduced or conventional tillage, however the differences with w. wheat were much smaller. The effect of tillage was especially high at N0 P0 K0. Crop rotation had a positive effect on the yields of maize. For winter wheat at N0 P0 K0 oneself was the better forecrop, while at optimum N and PK maize performed a little better. Corgcontent of soil slightly increased in the course of 25 years not only on the fertilized plots but on the nil plots too. Increasing N‐doses showed only a little effect on the Corg. There was a little positive effect of no‐till on Corg content of soil as well as compared fall ploughing. Soil tillage did not much influence the total amount of nitrate in the soil profile. The distribution of nitrate‐N in the soil profile was more affected by the actual climatical circumstances than by the system of tillage. However big nitrate accumulations were found in the subsoil according to different soil tillage systems at some other times, as well as lack of it, which suppose the possibility of a relative quick nitrate infiltration.