Development of Superabsorbent Polymer (SAP) Seed Coating Technology to Enhance Germination and Stand Establishment in Red Clover Cover Crop

Drought conditions after sowing threaten the seedling establishment of all seeds, including cover crops. Cover crops are commonly broadcast and, thus, often susceptible to drought stress sowing. Our hypothesis was that seed coating with superabsorbent polymers (SAPs) would enhance germination in lab and stand field by increasing water availability single seeds. Red clover (Trifolium pratense L.) seeds were coated following selected SAP formulations at 2% their weight: cross-linked potassium polyacrylate (PAL), polyacrylamide-based polymer (PAM), PAM graphite (PAM+G), Starch-g-2-Propenoic acid (potassium salt) (STR). The absorbency each formulation >200 g water/g polymer; STR had greatest absorbency, 352 polymer. A method developed, resulting uniform application from seed. All treatments increased compared 0% controlled environment studies lab. Three trials conducted for treatment, providing a range climatic soil conditions. Within trial, higher sown broadcasting followed raking incorporate first two under more stressful PAM+G performed best no raking. Collectively, improved stands non-treated controls.