Effects of watertable depth, irrigation water salinity, and fertilizer application on root zone salt buildup

Salt buildup due to irrigation water salinity and fertilizer application wa s studied in field lysimeters planted with green peppers (Capsicum annuum). Water was applied by subirrigation, and the fertilizers were incorporated at the soil surface. Three subirrigation water salinities, 1, 5, and 9 dS/m and two watertable depths, 0.4 and 0.8 m, were used. The soil salinity was determined by first measuring the bulk soil salinity by time domain reflec tometry (TDR) and then converting it to soil solution salinity (ECsw). It w as found that the salinity of the subirrigation water affected ECsw in the upper soil profile when the: watertable was maintained at 0.4 m depth. The subirrigation water also affected the lower half of the soil profile when t he watertable was maintained at 0.8 m depth; however, it did not affect any salt buildup in the upper half. Also, the addition of N, P, and K fertiliz ers did not contribute to the salt buildup in the soil. Although watertable depth and subirrigation water salinity affected ECsw they did not affect t he green pepper yield. The experiment was conducted using field lysimeters filled with a sandy soil and covered with a plastic sheet to simulate arid conditions. Therefore, caution should be exercised in extrapolating the res ults of this study to field conditions and other soils.