Cornstarch-based, Biodegradable Superabsorbent Polymer to Improve Water Retention, Reduce Nitrate Leaching, and Result in Improved Tomato Growth and Development

Abstract

In arid and semi-arid climates, water scarcity and nutrient availability are major constraints for food production. Excess fertilization to make up for the limited nutrient availability in dry soils leads to nitrogen runoff and groundwater contamination. Reducing nitrogen leaching into surface water while providing adequate nutrition remains a major challenge. Superabsorbent polymers (SAPs) can reduce water loss and improve nutrient retention and therefore minimize leaching and increase crop yields. SAPs are made from petroleum or natural products, but plant-based SAPs have been gaining popularity because they have fewer long-term effects on the environment. However, there is little known about how SAPs made from cornstarch effect plant growth and production in tomatoes. So, we evaluated total nitrogen and water retention in SAP-treated soils and evaluated their effects on growth and development of tomatoes (Solanum lycopersicum). Soils were amended with different rates of cornstarch-based SAP (i.e., 0 kg SAP, 0 kg SAP+N, 0.5 kg SAP+N, 1 kg SAP+N, 1.5 kg SAP+N, and 2 kg SAP+N). Results indicate that the mean volume of water and nitrates retained in the soils amended with cornstarch-based SAPs increased with increasing rate of SAP. The treatment containing the highest dose (i.e., 2 kg SAP) decreased the amount of leachate and nitrates from soil 79.34% and 93.11% at 3 days after fertilization (DAF) and 78.84% and 81.58% at 9 DAF in comparison with the soil-only and fertilizer-only treatments, respectively. The results also indicate cornstarch-based SAP significantly improved plant growth and yield parameters compared with the treatments without SAP. Furthermore, the greatest number of leaves, flowers, fruits, and dry matter production were found in the 1-kg SAP treatment. Therefore, application of cornstarch-based SAPs can improve tomato production in times of drought stress by retaining more water and nutrients in the active rooting zone and can reduce environmental pollution by reducing nitrogen runoff.

Rational Design of a Multifunctional Hydrogel Trap for Water and Fertilizer Capture: A Review

“…For instance, Nassaj-Bokharaei et al observed a significant decrease in dry weight and fresh weight of tomato plants grown under nonwater stress conditions (soil moisture content 85%) when the amount of added hydrogel increased from 0.3% to 0.6%. A similar conclusion was reached by Kathi et al…”

“…For instance, Nassaj-Bokharaei et al 150 observed a significant decrease in dry weight and fresh weight of tomato plants grown under nonwater stress conditions (soil moisture content 85%) when the amount of added hydrogel increased from 0.3% to 0.6%. A similar conclusion was reached by Kathi et al 131 In addition, the entire life cycle of hydrogels poses certain ecological and environmental risks. 151 For instance, commercially available hydrogels are predominantly synthetic organic polymer hydrogels composed of poly(acrylic acid) and polyacrylamide, with residues of acrylic acid and acrylamide generated during their synthesis being detrimental to aquatic environments and human health, as they are carcinogenic compounds.…”

“…The addition of hydrogel can effectively inhibit the leaching loss of soil nitrogenous fertilizer, with a progressively enhanced inhibitory effect observed with increasing amounts of hydrogel. 130 Kathi et al 131 discovered that compared to the control treatment without hydrogel, the cumulative leaching loss of N decreased by 35.89%, 57.86%, and 91.79%, respectively, when adding 0.05%, 0.10%, and 0.20% (by weight) of hydrogel.…”

Advanced applications of sustainable and biological nano-polymers in agricultural production

“…This demand for increased productivity without expanding agricultural lands could be achieved with the use of nanotechnology. Nanotechnology can address several agricultural issues such as the controlled release of active compounds (Singh et al, 2021), selective targeting of pests (Hao et al, 2020;Monteiro et al, 2021), efficient delivery of fertilizers (Guilherme et al, 2010;Ekanayake and Godakumbura, 2021), photoprotection of light-sensitive herbicides (Nguyen et al, 2012), and a way to remediate depleted or dry soils (Kathi et al, 2021;Barajas-Ledesma et al, 2022), but have yet to see widespread practical use. The hesitation surrounding nano-enabled agriculture stems from the many "unknowns" concerning nanomaterials in the environment: what is their fate in soil (Singh and Gurjar, 2022)?…”