Superabsorbent polymers used for agricultural water retention

Exploring the optimization of water and fertilizer management practices for potato production in the sandy loam soils of Northwest China based on PCA

The application of superabsorbent polymers (SAPs) is hindered because their absorption capability is greatly affected by the electrolytes in a solution. A novel modified water-absorbent polymer was fabricated by solution polymerization of sulfamic acid-modified starch and acrylic acid; the swelling ratios of this absorbent polymer were 1026 g/g in deionized water and 145 g/g in 0.9% sodium chloride solution and increased by 99.5 and 13.4%, respectively, when compared with ordinary starch-grafted acrylic SAPs. The water absorption capacity was measured in water at different pH values, salt concentrations, and temperatures. In addition, water and fertilizer retentions were studied by simulated leaching tests in a soil column. The results showed that water absorption capacities of the modified SAP in salt solutions were improved due to the adsorption and transfer of water molecules by the sulfonic acid groups. Compared to the losses when there was no superabsorbent treatment, the water, nitrate, ammonium nitrogen, and water-soluble potassium losses during the salt-tolerant superabsorbent treatment were significantly reduced by 18.5, 22.8, 88.0, and 63.8%, respectively. The method introduced in this study could guide the development and wide application of salt-tolerant SAPs in agriculture and horticulture.

Salt-Tolerant Superabsorbent Polymer with High Capacity of Water-Nutrient Retention Derived from Sulfamic Acid-Modified Starch

Superabsorbent polymer characteristics, properties, and applications

The water-retaining and yield-increasing capacity of super-absorbent polymer (SAP) are essential for soil remediation in arid and semi-arid areas. Therefore, it is of great significance to investigate the influencing factors and mechanisms of SAP effects on soil environments and crop growth for the precise management of agricultural water-saving irrigation. In this study, we adopted SAP as a soil conditioner and monitored changes in soil temperature, photosynthetic rate, leaf transpiration rate, chlorophyll, crop growth indexes (plant height, stem diameter, leaf area index, dry matter accumulation), and yield under different SAP doses during the growth stage of maize, on the basis of which the improvement mechanism of SAP in arid and semi-arid soil was analyzed. The results demonstrated the following: (1) 45 kg/hm2 of SAP application could increase the temperature of the soil layer, effectively reduce the diurnal temperature variation of the soil surface, and promote the stable growth of maize; (2) when different SAP doses were applied, the leaf surface temperature of maize increased by 0.95 °C on average. In particular, when 135 kg/hm2 of SAP was applied, the leaf surface temperature increased by 1.55 °C; (3) SAP could promote the photosynthetic rate of maize. In addition, the plant height, leaf area index, and dry matter accumulation of maize gradually increased with an increasing amount of SAP; (4) the application of SAP not only increased the grain row number, ear row number, and average 100-seed weight, but also increased the crop yield by nearly 6%. The application of SAP demonstrated a comprehensive utility (redistribution of soil water and temperature, synergy between SAPs and plants), which suggests that the most basic goal, to ensure socio-economic and ecological sustainability in dryland systems, was obtained.

https://www.mdpi.com/2071-1050/12/18/7825/pdf

Effects of Super-Absorbent Polymer on Soil Remediation and Crop Growth in Arid and Semi-Arid Areas

Superabsorbent polymers, new water-saving materials and soil conditioners, are used widely in dry-farming agriculture. However, little is known about their effects on the soil physical properties under dry-farming conditions. To elucidate the effects of two SAPs (Wote and microbe) at different doses on the soil bulk density, water status, potato growth, yield, and economic benefit in a dry-farming region, we conducted a 2-year fixed field position experiment in the semiarid drought-prone area of Ningxia, China. The two SAPs were diluted 1:10 (product:soil) and applied at different rates before planting, i.e., Wote SAP 30 kg ha−1, Wote SAP 60 kg ha−1, Wote SAP 90 kg ha−1, microbe SAP 30 kg ha−1, microbe SAP 60 kg ha−1, and microbe SAP 90 kg ha−1. The treatment without SAP was used as the control. The tilth soil bulk density decreased under different SAP doses compared with the control, and the soil total porosity improved greatly, where the Wote SAP treatments had the greatest effects. The soil bulk density (0–60 cm) under Wote SAP 90 kg ha−1 was significantly decreased by 6.4% compared with the control. The Wote SAP treatments had the greatest effects on water conservation during the critical potato growth stage, where the soil water storage (0–100 cm) was significantly higher than the control. The Wote SAP treatments promoted potato growth in the later period, where the plant height and stem diameter were higher than the control. Higher yield and commodity rate improvements were achieved by the application of Wote and microbe SAP compared with the control, where the optimum dose was 60–90 kg ha−1 for Wote SAP. The application of Wote SAP 90 kg ha−1 significantly increased crop water use efficiency compared with no SAP, and the commodity rate was highest with Wote SAP 60 kg ha−1. The mean potato yield, commodity rate, and net income increased significantly using Wote SAP at 60 and 90 kg ha−1, i.e., by 38.2 and 50.5%, 18.5 and 14.1%, and 28.5 and 35.0%, respectively, compared with no SAP. The application of SAPs can decrease soil bulk density and significantly improve soil porosity and soil water conservation capacity, thereby promoting potato growth. The application of Wote SAP 60–90 kg ha−1 significantly increased potato yield and net income in a dry-farming region of Ningxia, China.

Wenshou He

Papers

Superabsorbent polymers influence soil physical properties and increase potato tuber yield in a dry-farming region

Effects of planting density on potato growth, yield, and water use efficiency during years with variable rainfall on the Loess Plateau, China