Corn-stalk composite slows fertilizer release in laboratory soil tests

A phytic-acid-modified corn-stalk composite superabsorbent adsorbed substantial quantities of fertilizer solution and reduced early nutrient release when incorporated into soil, according to a laboratory materials study. Researchers prepared the composite, abbreviated PCS-SAPs, through graft copolymerization of itaconic acid, acrylamide, vinyl pyrrolidone and phytic-acid-treated corn stalk material. Tests of different corn-stalk contents showed that fertilizer-solution adsorption first increased and then decreased as the proportion of phytic-acid-treated corn stalk rose.

The maximum reported in this series occurred at 15 wt% PCS, where the material adsorbed 106 g of urea solution per gram and 22 g of potassium dihydrogen phosphate, or KDP, solution per gram. A separately optimized PCS-SAP formulation achieved reported adsorption capacities of 360.5 g/g for urea solution and 40.5 g/g for KDP solution. These figures measure the mass of solution adsorbed per gram of material, rather than the mass of pure urea or phosphate retained.

The clearest slow-release result came from soil tests using an addition of 0.5 wt% PCS-SAPs. Under those conditions, the cumulative urea released over five days decreased from 83.04% without the composite to 47.56% with it. KDP release over 2.5 days fell from 89.14% to 73.96%.

The measurements therefore show reduced early release over the specified test periods. They do not establish how long the slower release persists, how the material behaves across different soils or whether the same effects occur under field conditions. Ultrasonic pretreatment partially destroyed its crystal structure and severely disrupted the original fibrous framework.

Radical copolymerization then further reduced crystallinity and converted the corn-stalk component to an amorphous phase. The researchers associated these changes with a greater specific surface area and more homogeneous dispersion within the polymer matrix. The resulting PCS-SAPs displayed a rough, porous and fluffy morphology, while the water-swollen material formed interpenetrating network skeletons with interconnected pores.

The study frames PCS-SAPs as a possible agricultural material for retaining fertilizer solutions and slowing release, with potential relevance to arid regions. Its reported attributes include low cost, high fertilizer adsorption, favorable slow-release behavior and environmental compatibility, but the supplied abstract does not provide comparative cost data or direct environmental measurements. The evidence presented here is limited to fabrication, characterization, adsorption capacities and laboratory release tests.

Subject of Research: Materials engineering of corn-stalk superabsorbents for fertilizer adsorption and slow release

Article Title: Adsorption and slow release of fertilizer by phytic acid-modified corn stalk composite superabsorbents

Article References: Li, Y., Wan, T., Yang, H., Liu, J., & Zhao, L. (2026). Adsorption and slow release of fertilizer by phytic acid-modified corn stalk composite superabsorbents. Polymer Bulletin, 83(12), Article 688. https://doi.org/10.1007/s00289-026-06735-5

Image Credits: AI Generated

DOI: 10.1007/s00289-026-06735-5

Keywords: corn stalk composite, superabsorbent polymer, fertilizer adsorption, slow-release fertilizer, phytic acid, urea, potassium dihydrogen phosphate, graft copolymerization, laboratory soil test, agricultural materials, Adsorption, slow