Utilization of the nutrient contents of organic manure and mineral fertilizers in long-term experiments 2. P balance

The effect of stable manure, wheat straw, maize stalks and fertilizer on the P content of plants grown in a maize-wheat diculture are studied in two long-term experiments set up on neutral and calcareous variants of a chernozem soil with forest residues in Martonvasar. The mean values of P content, together with the deviation and extreme values of the data are presented for the main and by-products over the period 1956-1991. The P content of maize was significantly influenced by the nutrient supplies. Neither the P percent of winter wheat nor the specific P quantities harvested per unit grain yield, with the relevant by-products changed as the result of the treatments, or only to a slight extent. The difference between the P contents of individual wheat varieties exceeded the differences caused by fertilization