Effects of Superabsorbent Polymer on Soil Water Content and Sugarcane Germination and Early Growth in Sandy Soil Conditions

Drought is one of the major environmental stress factors limiting sugarcane production. Under rainfed conditions, sugarcane crops are highly at risk of drought, especially after planting. The use of superabsorbent polymers capable of absorbing huge amounts of water is of great prospect; however, information on its use in sugarcane production under drought is relatively scarce. Greenhouse experiments were thus carried out to examine the effects of polymer application at planting on sugarcane germination and early growth as well as water content in sandy soils. When mixed with sandy soils in different ratios (0, 0.1, 0.3, and 0.5% in Experiment 1; 0, 0.05, 0.1, 0.15, and 0.2% in Experiment 2), the polymers significantly improved soil water-holding capacity as the ratios increased, though the treatments did not affect the water release rate. The best germination rates were obtained with the applications of 0.1% and 0.15% polymer in Experiments 1 and 2, respectively, which further yielded the highest biomass production. Despite higher water contents, the applications of 0.3% and 0.5% polymer remarkably lowered the germination rates in Experiment 1. One of the possible reasons for its negative impact is that the water contents greatly exceeded the optimum level for sugarcane germination in the sandy soil. From this study, it is suggested that the application of 0.15% polymer is likely to be most suitable. Meanwhile, the available water in the soil at the time of polymer application must be considered as high moisture contents rather resulted in impairing sugarcane germination and growth.