SPATIAL VARIABILITY OF SOIL PROPERTIES AND EFFECTS ON RICE YIELD GROWN ON EL-GEMMIEZA CLAYEY SOIL (MIDDLE OF NILE DELTA OF EGYPT)

Understanding the relationships between rice yield and soil properties is very critical importance in precision farming. The objective of this work was to evaluate the relationships between special variability of soil properties and rice yield (Oryza sativa). The area under study is 41.67 ha in EL-Gemmieza Agriculture Research Station, of the Agric. Rese. Center (ARC), El Gharbiah Governorate, Egypt (Middle of Nile Delta). The studied location divided into two sites varied in their productivity of rice. Soil pH was found slightly alkaline at site (1) and alkaline at site (2). The EC and CEC in site (1) were higher than at site (2). On contrary values of ESP were higher at site (2) than at site 1. Higher exchangeable cations were observed under site (1) than site (2) except of exchangeable -Na showed a contrary behavior. Data also showed that values of soil bulk density were lower under site 1 than site (2) whereas; total porosity, hydraulic conductivity and infiltration rate were higher in site (1) than site (2). Higher values of grain yield, straw yield, harvest index and NPK content and uptake in grain and straw were found in site (1) than in site (2). The values of variation coefficients (CV) of the most studied traits showed low variability (< 20). At site 1 there is a significant correlation at 5% level with positive trends between grain yield and the traits of CEC, soluble K, exchangeable Ca, Mg, available N and K, total porosity and hydraulic conductivity. While, negative significant correlations at 5% level with negative trends were noticed between exchangeable Na and bulk density. On the other hand, result of satirical analysis of site 2 indicated a positive and significant correlations between grain yield of rice plant and all the traits of harvest index, N and K uptake in straw, CEC, O.M, exchangeable Ca& K, available N & available -P, total porosity and hydraulic conductivity. As the results of the stepwise regression analysis of site (1), it can arrange the soil physical characteristics, as their effective on rice yield, in the following order of: infiltration rate > soil total porosity > saturated hydraulic conductivity (Ksat). While the order of soil chemical characteristics were: ESP > pH > EC > O.M. As for soil available nutrients, their continuation factors were 90.7, and 7.0 % for soil available–K & available– N, respectively. For site (2) it can arrange the soil physical characteristics, as their effective on rice yield, in the following order of: bulk density > saturated hydraulic conductivity. While the order of soil chemical characteristics was: ESP > pH > CEC > O.M. As for soil available nutrients, their continuation factors were 91.1 and 5.6 % for soil available–K, and P, respectively.