CHALLENGES FACING FOOD PRODUCTION IN UPPER EGYPT: P AMENDMENTS BETWEEN GOVERNMENTAL REGULATIONS AND LOW EFFICIENCY FERTILIZERS

Abstract

One of the challenges that faces food production recently in upper Egypt is the governmental obligations for applying gypsum to arable lands which contains 50 g P kg-1total P (called phospho-gypsum). Although these soils are not sodic and contain high soil-P residual from the previous soil fertilization for many years. The current research aimed at investigating the effectiveness of using the pH reducing amendment (elemental sulfur) or P-dissolving bacteria (phosphorin) to improve the use efficiency of P from soil and the phospho-gypsum and thus improve the grain yield of maize cultivars SC 3084 and SC 10. Growing plants in the presence of superphosphate fertilizers was taken into consideration for result comparison. The key findings indicate that inoculating maize seeds with phosphorin increased the grain yield production and, at the same time, increased the P-use efficiency. On the other hand, the application of phospho-gypsum caused further significant increases in the grain yield production without any further effect for the co-application of either elemental sulfur or even seed inoculation with phosphorin. Also, the application of superphosphate fertilizers increased significantly the production of grain yield over the increases recorded by application of the phospho-gypsum. However, P-applications reduced drastically P-use efficiencies; accordingly, we can consider the biological approach as efficient and responsive practices for increasing the efficiency of P-utilization by maize plants in soil with high residual soil-P content without further increases in the costs of production; or even soil pollution with contaminants that can be found as impurities in the used amendments.