Reclamation of saline-sodic soils for sustainable agriculture in Egypt

Abstract

Soil salinity has emerged as the most significant problem of present agriculture of Egypt. Scanty rainfall coupled with high temperature is always conducive to the accumulation of salts. These conditions are predominantly found in Egypt. In Egypt, improving salt-affected soils is essential for ensuring secure agricultural productivity. The study involved leaching experiments on a saline-sodic soil using soil column techniques assessing the efficiency of soil amendments of phosphogypsum (a gypsum-rich material, a by-product of superphosphate manufacture), standard gypsum, sulfuric acid, and rice straw. The soil amendments used in this experiment were standard gypsum (NG), phosphogypsum (PG), sulfuric acid (SA), and rice straw (RS). Application of the above three amendments was based on the gypsum requirement (GR) equation according to USDA taking in consideration a required final value of exchangeable sodium percent (ESPf) of 12, and an actual exchangeable sodium percent (ESPi) of the initial value of 29.8 was found in the soil. Air-dried straw was chopped into shredded pieces less than 5 cm long using a suitable hand chopper. The shredded straw pieces at the rate of 130 g/column (60 Mg ha−1) were homogenously incorporated into the soil before the beginning of the leaching process. The obtained data showed intermittent leaching 0.4 PV (L3) was more effective in decreasing EC, soluble ions, ESP, and exchangeable magnesium and increasing exchangeable calcium as well as improving physical properties (i.e., water-stable aggregates and hydraulic conductivity) than the other ones (i.e., intermittent leaching 0.1 PV or 0.2 PV). On the other hand, the intermittent leaching was more effective in decreasing EC, soluble ions, ESP, and exchangeable magnesium and increasing exchangeable calcium as well as improving physical properties than continuous. There was a decrease in pH, EC, and ESP values for the degraded soil reclaimed using all amendments. Also, infiltration rate of water increased due to amendments through enhancement of soil aggregation. Also, the thorough mixing application showed superiority over the surface application of gypsum, whether standard gypsum “NG” or phosphogypsum “PG” was used. All amendments proved to have higher efficiency compared to the control treatment. The efficiency of soil amendments will be presented in this chapter.