Use of environmental friendly fertilizers in saline and saline sodic soils

Abstract

Economics of agriculture, especially smaller farmers have been getting verse year to year. Lack of resources with government and various external factors had been limiting crop revenue potential whereas input costs have been on continuing rise. One of the way out is a new look to agronomy and soil science for increasing yield per acre at sustainable coast. In Pakistan about 6.2 mha. land is saline. The under ground water also contains some concentrations of carbonates and bicarbonates. These carbonates and bicarbonates are harmful for young plants. If 20 liter per acre sulphuric acid or hydrochloric acid are applied as fertigation it could be saved the plants from harmful effects of salts. The acid can be applied at the time of soil preparation before sowing. This acid provides native calcium present in the soil available. In others words the acid makes gypsum available. By lowering the pH of soil, micronutrients become available to crop. It improves soil environment by reducing impact of salinity and high pH. Reduce soil compactness and enhance soil porosity by replacing sodium of soil with calcium. If brackish water is being used for irrigation the acid can be used in standing crop as fertigation. The acid should be used at 10 liter per acre in first two irrigations. Due to the application of H 2 SO 4 at 10 liter per acre in standing crop of wheat with first two irrigations as fertigation in the project area (three districts of Punjab Province) the yield of wheat was increased three times. In control where no acid was applied, grain yield per acre was only 12 monds. The field where H 2 SO 4 was applied grain yield per acre was 35 monds. This increase in grain yield was due to the availability of native calcium. The possible mechanism involved may be: Sulphuric acid may be used in place of gypsum in calcareous sodic soils. Sulphuric acid reacts with lime to form gypsum (CaSO 4 .2H 2 O). The gypsum formed in this reaction has same effect as applied from outside. Following chemical reaction takes place. (gas) H 2 SO 4 +CaCO 3 +H 2 O====> CaSO 4 .2H 2 O+CO 2 (Lime) (Na + )( Ca +2 ) Soil Colloid+CaSO 4 ====>Soil Colloid +Na 2 SO 4 (Leach down out of root zone).