Desenvolupament d'una tecnologia per a la millora de les recomanacions en la fertilització nitrogenada dels cereals d'hivern. (I) Cereals d'hivern a la Catalunya interior

Abstract

Several field experiments on nitrogen fertilisation for wheat under rainfed conditions were carried out at different sites within central Catalonia. Three different methods that are considered interesting for the improvement nitrogen fertilisation practices were tested. These were the nitrogen balance method, the mineral nitrogen method and the nitrate content at the base of the stem method (CNSBT). All the experiments were conducted on deep, well drained, non-saline and medium-textured soils and there was no limited for wheat crop development, with the only exception of one of the trials that was carried out on a moderately deep soil. So, these soils can be considered as having a medium-high production potential. This is also true from the point of view of chemical fertility. Under the conditons studied the nitrogen balance method has shown to be very powerful, on the studied conditions, for determining fertiliser needs. The mineral nitrogen method was also very effective for this purpose. On the other hand the CNSBT method was not useful on the sites studied, where rain-fall is usually a limiting factor for crop growth. Several factors which do not allow an adequate adjustment of nitrogen fertilisation, were identified. These were a poor estimation of the objective yield, the difficulty for predicting the available nitrogen from organic fertilisers, the difficulty of soil sampling for nitrate determination and the bottleneck for nitrogen fertilisation strategy that random distribution on time of water availability represents.