Commercial versus synthesized polymers for soil erosion control and growth of Chinese cabbage

Enhancement of soil physical properties and soil water retention with biochar-based soil amendments

The soil physical properties are deteriorating due to changing rainfall patterns and intensities, as well as climate change-induced temperature fluctuations. Pot experiments were carried out to examine the impacts of synthesized soil amendments on soil water retention and plant growth. Soil amendments (biochar, polyacrylamide (PAM), and moringa) were used at different rates (0 (control), 2.1, 4.2, and 8.3 g kg^-1) to improve the physical properties of the soil. As a result of soil amendment application, it was found that the mean weight diameter of soil aggregate increased by 188% during the 8.3 g kg^-1 treatment, forming stable soil particles. Soil water retention improved by up to 128.9% during the 8.3 g kg^-1 treatment, and it was analyzed that it was due to the high surface area of biochar, porosity, and high molecular weight of PAM. Pellet treatment increased all plant growth parameters (height, stem diameter, leaf number, and fresh and dry weight) for both beans and maize. The dry weight of beans (C₃ plant) and maize (C₄ plant) increased by 92.9 and 146.4%, respectively in an 8.3 g kg^-1 pot. The soil physical condition was stabilized by the high carbon content of biochar and the improvement of soil coagulation between PAM and moringa. This had a positive effect on the C₄ plant. The findings of this study indicate that if the soil amendments are properly mixed and applied based, they will improve soil stability and plant productivity.

Ecotoxicological Properties of Tulipalin A-Based Superabsorbents versus Conventional Superabsorbent Hydrogels

The Phytotoxicological Aspects of a Novel Superabsorbent/Hydrogels: poly(acrylamide-co-sodium 4-hydroxy-2-methylenebutanoate), prepared from renewable monomer Tulipalin A, on the growth and development of monocotyledonous Avena sativa and dicotyledonous Raphanus sativus, was investigated and compared with the effect of borate-crosslinked poly(vinyl alcohol), poly(acrylamide), and poly(acrylamide-co-sodium acrylate) conventional hydrogels. Tulipalin A-based superabsorbent hydrogels revealed superior properties in terms of the combination of the tested properties. The results confirmed excellent suitability of Tulipalin A-based hydrogels for application as reservoirs of water during plant stress condition. Values of fresh matter (yield) and shoot height of the examined plants growing in soil amended with these hydrogels were ca 10% higher than those of plants growing in soil without hydrogels. Reference borate-crosslinked PVA hydrogels (containing increasing amount of borax cross-linker) revealed harmful effect on plants. The negative effect was observed on most of the investigated properties, increasing with content of the hydrogel in soil and concentration of the borax in it.

Biomimetic Hydrogel Composites for Soil Stabilization and Contaminant Mitigation

We have developed a novel method to synthesize a hyper-branched biomimetic hydrogel network across a soil matrix to improve the mechanical strength of the loose soil and simultaneously mitigate potential contamination due to excessive ammonium. This method successfully yielded a hierarchical structure that possesses the water retention, ion absorption, and soil aggregation capabilities of plant root systems in a chemically controllable manner. Inspired by the robust organic-inorganic composites found in many living organisms, we have combined this hydrogel network with a calcite biomineralization process to stabilize soil. Our experiments demonstrate that poly(acrylic acid) (PAA) can work synergistically with enzyme-induced carbonate precipitation (EICP) to render a versatile, high-performance soil stabilization method. PAA-enhanced EICP provides multiple benefits including lengthening of water supply time, localization of cementation reactions, reduction of harmful byproduct ammonium, and achievement of ultrahigh soil strength. Soil crusts we have obtained can sustain up to 4.8 × 10³ kPa pressure, a level comparable to cementitious materials. An ammonium removal rate of 96% has also been achieved. These results demonstrate the potential for hydrogel-assisted EICP to provide effective soil improvement and ammonium mitigation for wind erosion control and other applications.

Abatement costs of soil conservation in China's Loess Plateau: balancing income with conservation in an agricultural system

This study proposes the use of marginal abatement cost curves to calculate environmental damages of agricultural systems in China's Loess Plateau. Total system costs and revenues, management characteristics and pollution attributes are imputed into a directional output distance function, which is then used to determine shadow prices and abatement cost curves for soil and nitrogen loss. Marginal abatement costs curves are an effective way to compare economic and conservation tradeoffs when field-specific data are scarce. The results show that sustainable agricultural practices can balance soil conservation and agricultural production; land need not be retired, as is current policy.