Comparison of the effect of equivalent nutrients given in the form of farmyard manure or fertilizers in Hungarian long-term field trials

A database of Hungarian field trials to compare the effects of farmyard manure and mineral fertilizers on the basis of NPK nutrient equivalence was compiled for the years 1955-1975. Among the various treatments, the yields of the absolute control, the farmyard manured treatment and the one with equivalent amounts of NPK in the form of mineral fertilizer were evaluated. In the experiments, grouped according to their soil texture-with the exception of extremely clayey soils-, annual fertilization was more favorable in all cases than periodic manure application. Differences between yield surpluses obtained per kg of nutrient declined with increase of soil clay contents. The efficiency of fertilization in both farmyard manured and fertilized treatments was the greatest on sandy soils, which have the poorest natural nutrient supplying capacity. The correlation between the changes in the organic matter (OM) content of control plots of the long-term field trials' soils, and differences or ratio of the responses to farmyard manure (FYM) and fertilizer (FER), resp., could be both described by hyperbolic functions, using the data set of the 37 Hungarian long-term field trials found in literature. A similar correlation was established between the AL-(ammonium lactate)111 soluble K contents and differences or ratio of the responses to farmyard manure (FYM) and fertilizer (FER), resp. It was found that as the values of these two soil parameters rose, the advantage of the nutrients given in the form of fertilizer over farmyard manure declined. In the given experiments no correlation could be found between the AL-soluble P2O5 content and the yield differences.