Changes in Soil Characteristics in a Mono- and Triculture Long-term Field Experiment

<b>The effects of fertilization, irrigation and crop rotation on the major soil parameters and microbiological soil properties were studied at Debrecen-Látókép in the 16</b> ^th <i> and 17</i> ^th <i> years of the fertilization experiment on calcareous chernozem soil. The results can be summarized as follows: In the examination period the moisture content of the experimental soil increased by 2-3% due to irrigation. With increasing fertilizer doses, the pH value of soils reduced both in aqueous and <i>M</i> KCl suspension, but it did not change considerably at medium and high fertilizer doses. The hydrolytic acidity increased with decreasing pH values. The nitrate-N, AL-soluble phosphorus and potassium contents increased gradually with increasing fertilizer doses. Among the soil microbial parameters, the total number of germs increased slightly, while the amount of nitrifying bacteria was significantly higher due to fertilization. As a result of <i>fertilization</i> , a significant increase was detected in the phosphatase and urease activityin both crop rotations and irrigation treatments. The activity of saccharase and catalase was reduced at medium and high fertilizer doses. In addition to changing the moisture content of soils irrigationincreased the total number of germs and the amount of nitrifying and cellulose decomposing bacteria. Irrigation provided more favourable conditions for CO ₂ production, increasing the microbial biomass C content and for the functioning of phosphatase and urease enzymes. </i> In triculture the number of nitrogen-fixing and cellulose decomposing bacteria was higher than in monoculture, especially in the case of medium and high fertilizer doses. The activity of phosphatase, saccharase and urease enzymes was significantly higher in triculture than in monoculture.