Maintaining Silage Corn Production Under Sodic Irrigation Water Conditions in a Semi-Arid Environment

The Zayandeh-Rud watershed of Iran has had water scarcity for decades, giving rise to pressures toward limiting water allocation for the agriculture sector. Marginal waters can be an alternative source for irrigated agriculture in water-scarce regions if adequately managed. One of the critical hazards for sustainable agriculture and the environment is the accumulated salinity–sodicity problem as a consequence of irrigating with unconventional waters. Applying additional water beyond the crop water requirement, known as leaching application, has been suggested as a solution to this problem. A physical model was built to investigate the effects of the severe sodicity and salinity conditions of irrigation water by creating 250 mm diameter soil columns (27 columns) filled with sandy clay loam soil. The severity of the irrigation water’s sodicity (sodium adsorption ratios (SAR): 5.27, 16.56, and 28.57) and its interactions with various leaching fractions (0%, 15%, and 30%) on critical soil chemical characteristics and corn yield were studied. Implementing a 30% leaching fraction reduced the SAR and salinity in the soil’s first layer (0–10 cm) when irrigating with saline–hyper-sodic water (SAR = 28.57 and ECiw = 9 dS/m). However, an elevated level of sodicity accumulation in the soil profile was observed, emphasizing the importance of adding calcium and magnesium amendments during the irrigation season. A noticeable increase in the efficiency of leaching applications in reducing accumulated salts and the sodicity level in the corn rootzone was detected with higher levels of irrigation water sodicity. The reduction in the accumulated salinity and sodium in the first soil layer due to implementing a 30% leaching fraction resulted in a 223.3% increase in the total biomass of silage corn. Applying a 30% leaching fraction also increased the corn biomass by 58% and 114.56% when irrigating with waters with 5.57 and 16.56 SAR values. The effectiveness of a 15% leaching fraction for enhancing the soil and crop conditions was significantly lower than that of the 30% leaching fraction. Nevertheless, in case of unavailability of sufficient water supply for irrigation purposes, applying a 15% leaching fraction could mitigate the consequences of sodic water irrigation. The results demonstrate that in the absence of the proper calcium amendments, the implementation of leaching management could still be effective in enhancing corn production under sodic water irrigation conditions.