CLIMATE CHANGE AND FERTILIZATION INTERACTIONS ON PEA (PISUM SATIVUM L.) YIELD

Interrelations between NPK nutrients and precipitation were evaluated from 197 1 to 2003 using pea as an indicator plant in a long-term fertilization experiment (code: OMTK A-17) was set up on calcareous chernozem soil in Nagyhorcsok in autumn 1967. In the average year the yield on control plots was 2.4 t ha(-1). In dry years the yield dropped to 1.1 t ha(-1) without fertilization, a yield reduction of 54 % compared with the average year (2.4 t ha(-1)). The yields recorded in treatments with N, NP, NK and NPK (1.9 t ha(-1)) indicated that the yield loss that could be attributed to dry weather was 39 %. In the case of drought the pea yield on control plots was 54 % lower than in the average year, while this was reduced to 43.3 OX, in the N, NP and INK treatments and to 45.2 % in the NPK plots. In excessively wet years yield losses compared to the average years were 41.7 %) on unfertilized plots, 25.7 % on N, NP and NK plots and 25.8 % on NPK plots, so fertilization was able to counteract 16 % of the negative effect of excessive rainfall. The correlations is with rainfall during the vegetation period, N, NP, NK and NPK nutrition and the yield Could be described using quadratic functions for each nutrition level (0: R 0.9388***, nitrogen: R 0.8850***, NP: R = 0.9038***, NK: R 0.8470***, NPK: R = 0.8747***). The results could serve as a good basis for the scientific description of the complex yield-determining effect of processes making the climate wetter or drier, on a Hungarian, EU and international scale.