The effects of bio-based superabsorbent polymers on the water/nutrient retention characteristics and agricultural productivity of a saline soil from the Yellow River Basin, China

To investigate the effects of superabsorbent polymers (SAPs) on the water/nutrient retention characteristics and agricultural productivity of a saline soil from the Yellow River Basin, soil column leaching and pot experiments were carried out. Three types of SAPs were used: a commercial SAP (CSAP), a starch-grafted SAP (SGSP), and a modified SGSP (MSSP). Six treatments were set up in the leaching experiment, including MS (MSSP alone was applied), CF (chemical fertilizer alone was applied), CF+CS (chemical fertilizer and CSAP were applied), CF+SS (chemical fertilizer and SGSP were applied), CF+MS (chemical fertilizer and MSSP were applied), and CF+ 70%MS (chemical fertilizer and MSSP were applied, but MSSP dosage was 70% of that in CF+MS). Six treatments were set up in the pot experiment as well, including CK (no fertilizer or SAP was applied), MS, CF, CF+CS, CF+SS, and CF+MS. Results of the leaching experiment showed that water and nutrient leaching loss from the saline soil was reduced by 12.6–22.7% and 14.2–65.0%, respectively, in the treatments with SAP application. In addition, both soil pore number and soil porosity were significantly increased in the 0–10 cm soil layer. In the pot experiment, maize yield was increased by 25.9–32.1% and fertilizer use efficiency was significantly increased with the application of SAP. Taken together, SAP application in the saline soil improved soil moisture and nutritional conditions and promoted crop growth. This work provides a reference for improving crop productivity and water management of the large area of saline soils in the Yellow River Basin.