Our research work was based on the IOSDV/ILTE field experimentin Hungary, University of Pannonia Georgikon Faculty Keszthely. The aim of our study was to reveal the main reasons which usually cause the measurable and significant fluctuation in yield of maize over the years in the long-term field experiment. The agronomic factors, the treatments and the whole LTFE were unchanged in the period of 1984–2013, but the climatic factors, mainly the amount and distribution ofthe precipitation and temperature are different each year and growing seasons. During the 30 years, 10 crop rotation turns had occurred and it is presumable, that the database included every types of years what are typical around the experimental site. The statistical methods to analyse the results and the effects of the annual climatic conditions were the following: Duncan’s multiple range test, ANOVA strip plot, grand mean comparisons (G), Pearson correlation matrix, coefficient (CV%) of variation.

In brown forest soils reaching of high maize yields is realisable only with using of fertilizers and consequential organic material management. The yield data of the examined years show significant fluctuation based on the experimental main averages. The coefficient of variation indicated 30.08% (2227 kg ha-1) yield fluctuation in this area in average of the 30 examined years. Based on the 30 years correlation matrix, there is a positive correlation between the precipitation and every treatment, while between the temperature and every treatment there is a negative correlation. The amount and distribution of June precipitation has a significant role, which was confirmed by the tight and significant correlation values

Keywords: long-term field experiments (LTFE), fertilization, cropping years, annual yield fluctuation