Sustainability of Soil Fertility Status under Different Management Systems at Middle Egypt Region

摘要

Soil fertility status after two crop cycles of 3-years crop rotation was evaluated in a long-term trial (1995-2001) conducted at Middle Egypt Region (Sids Res. Stn) clay loamy soil; under different management systems, i.e. 4 levels of NPK fertilizers(0, low, recommended and high); water quality (fresh and drainage); water quantity (farmer and recommended level) and two crop rotations (prevailing and proposed).Post harvest soil residuals of N, P and K after each crop cycle were significantly increased by increasing NPK fertilizer level and the obtained values after the second cycle surpassed those after the first cycle. Meanwhile the available Fe, Zn and Mn were generally reduced by NPK levels after the first cycle, however, there were a restoration in the concentrations of these micronutrients after the second crop cycle, since no differences in the residuals of these micronutrients between the zero-fertilized plots and those received NPK levels were detected after the second cycle.- Under the proposed crop rotation (Rot. IT), with intensive cropping system, soil residuals of the available N, P and Kwere higher than those of the prevailing one (Rot. I), while the soil residuals of Fe, Zn and Mn as well soil organic matter percentage was not affected by crop rotation.- The available soil N and K contents after each crop cycle under the recommended water regime were higher than underthe farmer regime, while the residual of P was not affected by water regime. Soil organic matter and Fe and Mn residuals were improved by recommended water regime after the second cycle.- The residual soil-N of plots received drainage water was improved after each crop cycle as compared with those receivedfresh water, while the other nutrient residuals showed inconsistent results during the two crop cycles.