Importance of Some Soil Amendments on Improving Growth, Productivity and Quality of Soybean Grown under Different Irrigation Intervals

EGYPT is currently experiencing water shortage, which causes a threat to crop productivity and efficiency of water use, especially in light of the current climatic changes. A field experiment was done to study effect of irrigation intervals (12, 16 and 20 days), soil amendments (compost, biochar, polyacrylamide "PAM" and hydrogel) beside control and their interaction on root, morpho-physiological, yield and quality traits of soybean. 1- Prolonging irrigation intervals up to 20 days significantly decreased root characters (length and dry weight of root, number and dry weight of nodules/ plant and nitrogenase activity), morphological characters (plant height, leaves number/ plant, leaf area and total dry weight/ plant), physiological traits (relative water content and chlorophyll), yield (pods number/ plant, number and weight of seeds/ pod, 100-seed weight and seed yields/ plant and fed) and quality (protein% and oil and protein yields/fed). 2- Application of soil amendments caused a significant and positive effect on root, morphophysiological characters as well as yield and seed quality compared to control. Hydrogel application produced the highest values of most abovementioned characters. 3- The interaction revealed that highest values of most characters were obtained when plants were irrigated every 12 days and treated with hydrogel. Plants irrigated every 16 days produced the highest values of root length and oil yield when treated with PAM and hydrogel, respectively. 4- Irrigation every 16 and 20 days can save water amounted to 18.62 and 27.82% compared to irrigation every 12 days, respectively. Irrigation every 16 days associated with hydrogel produced the highest values of water use efficiency (WUE) indicating that it was more effective for productivity and water consumption.