EFFECT OF PRECEDING WINTER CROPS, RELAY CROPPING, INTERCROPPING SYSTEM AND NITROGEN FERTILIZER RATES ON SOME SOIL PHYSICAL, HYDROPHYSICAL AND CHEMICAL PROPERTIES

Abstract

Field experiments were carried out on clay soil at the experimental farm of El-Gemmeiza Agricultural Research Station, El-Gharbia governorate, during two years (2006 and 2007), to investigate the effect of preceding winter crops, relay cropping, intercropping system and N fertilization levels on soil properties. The experiments were conducted in randomized complete block design in a split–plot, with three replicates, where preceding winter crops (i.e., wheat, sugar beet and faba bean) occupied the main plots and nitrogen fertilizer rates for maize plant (90, 105, 120 and 135 Kg N/fed.) were assigned to the sub plots, in both years. Results can be summarized as follows:- 1- All preceding winter crops induced significant changes in all soil properties under study, but faba bean was more effective than wheat or sugar beet on decreasing the values of soil bulk density (Db), settling %, water consumption (CU), soil reaction (pH), soluble Ca, Mg and HCO3 andC/N ratio of the soil, where take the following order: faba bean > sugar beet > wheat. On the other hand, the effects of preceding winter crops on total porosity (E), void ratio (e), pore size distribution (>9µ, 9-0.2 µ and <0.2 µ), hydraulic conductivity (Kh), soil moisture content (θw) just before harvesting, saturation percentage (SP), field capacity (FC), wilting point (WP), available water (AW), water use efficiency (WUE), soil salinity (EC), soluble Na, K, Cl, SO4, total N, organic carbon (OC) and availability of soil macronutrients (N, P and K) were increased these characters and take the same order. 2- Faba bean planting as a preceding winter crop with the addition of 90 Kg N/fed to maize in summer season gave the lowest values of (CU), while faba bean with 135 Kg N./fed to maize was the best treatment, since it gave the highest value of (WUE) in the first and second years. 3- The addition of 135 Kg N/fed resulted in a decrease of (pH), soluble HCO3 and C/N ratio of the soil and increase in (WUE), total N, organic carbon (OC) and availability of soil macronutrients (N, P and K). 4- It could be concluded that the sowing of faba bean, sugar beet and wheat plants in winter season, relay cropping and intercropping system with increasing nitrogen fertilizer for summer crops led to a markedly improvement in soil physical, hydrophysical and chemical properties as well as the status of nutrients which reflect on higher yield of summer season crops.