THE EFFECT OF MINIMUM STRIP-TILLAGE COVER CROP SYSTEM ON QUALITY SOIL INDICATORS IN VEGETABLE CROPS

This study compares a few agro-physical and chemical soil features submitted to influences of minimum strip-tillage cover crop system and conventional tillage system in cabbage, carrot, garden bean and sweet corn crops. From 2005 to 2008 comparative tests have been performed by the two tillage systems in Apahida (Cluj-Napoca), situated in an area of temperate continental climate (average annual temperature of 8 to 10°C, average annual rainfall of 590 mm; the soil is alluvial, sandy-clay, slightly plastic, moderately developed, mildly alkaline pH = 7.7, humus content of 3.4% and good potassium, phosphorous and nitrogen content). Soil reaction values and the high organic matter and nitrogen content have been measured before the experiment. Not too deep changes were recorded in the chemical soil reaction (pH), being still mildly alkaline. After three years of tests, in 2007 a 7.15 pH was recorded with conventional tillage and a 7.24 pH with minimum tillage. Total nitrogen content was medium in both crop variants (0.198% total N with conventional tillage and 0.192% total N with minimum tillage). P mobile content in the soil was also good: 125 ppm P with conventional tillage and 136 ppm P with minimum tillage. K mobile soil supply was high to very high – 210 ppm K mobile with conventional tillage, 232 ppm K mobile with minimum tillage. The humus level in the soil recorded a significant increase. At the beginning of the tests as of 2005, the humus in soil was of 3.40%; after two years of experimenting a 3.90% increase was recorded; after three years of testing the humus content was of 4.5% with the minimum strip-tillage cover system. The soil texture is medium, with a high degree of plasticity and adherence, water and air permeability, with a good water and nutrient retention. Following analyses soil structure modification was recorded, rates increasing from 78% to 83% with the minimum strip-tillage cover crop system, being noted that the higher the soil structuring level, the more increased the fertility