Assessment of Super Absorbent Polymer in Soybean Cultivation under Variable Irrigation Conditions in Nebraska

Authors

• Ankit Chandra, University of Nebraska - LincolnFollow
• Abia Katimbo, University of Nebraska - LincolnFollow
• Ronaldo Marchezan, University of Nebraska - LincolnFollow
• Martha Nabaggala, University of Nebraska - LincolnFollow

Date of this Version

Summer 5-1-2026

Document Type

Technical Report

Citation

Chandra, A., Katimbo, A., Machado, R., & Nabaggala, M. (2026). Assessment of Super Absorbent Polymer in Soybean Cultivation under Variable Irrigation Conditions in Nebraska. Department of Agricultural and Biological Systems Engineering: Presentations and White Papers. University of Nebraska-Lincoln.

Abstract

Water limitation is a primary constraint to soybean productivity in both irrigated and rainfed systems. Soil-applied superabsorbent polymers (SAPs) have been proposed as a strategy to buffer crops against episodic drought stress; however, their physiological and agronomic performance under varying irrigation regimes remains insufficiently quantified. Here, we evaluate three biodegradable polymer formulations: broader granules (BB), original granules (OG), and powder (PWR) applied at low (17.7 lb/ac) and high (120 lb/ac) rates under full (100% ET), reduced (50% ET), and no irrigation conditions in western Nebraska. Polymer application had negligible effects under full irrigation, with yields comparable to untreated controls. Under reduced irrigation, high-rate applications substantially improved yield, with OG 120 and BB 120 increasing yields by up to 21 bu/ac relative to control. Under rainfed conditions, yield divergence was most pronounced: BB 120 (55.1 bu/ac) and OG 17.7 (52.4 bu/ac), representing more than a twofold increase of yields relative to untreated plots. Soil moisture measurements confirmed modest but consistent increases in volumetric water content across polymer treatments, particularly in surface and mid-root zones. These gains were accompanied by substantial improvements in water use efficiency. Water productivity increased from 0.042 to 0.094 bu/ac/mm under rainfed conditions and by 40-50% under reduced irrigation. Similarly, irrigation efficiency more than doubled under deficit irrigation, exceeding 0.30 bu/ac/mm in high-rate polymer treatments compared to 0.146 bu/ac/mm in the control. These results demonstrate that superabsorbent polymers function primarily as drought-buffering agents rather than yield-enhancing inputs under optimal conditions. The magnitude of benefit increases with water limitation, suggesting that SAPs may offer a viable strategy for stabilizing soybean production in water-constrained agroecosystems.