Guangdong nongye kexue (Jun 2023)
Evaluation of the Effectiveness of a Nutrient Inhibitor Applied to High Cadmium-Risk Double-Cropped Rice Fields
Abstract
【Objective】The study aimed to address the conspicuous problem of excessive cadmium (Cd) in rice by developing and applying a nutrient inhibitor in the field to evaluate its effectiveness in reducing Cd uptake by rice and improving soil nutrients.【Method】One about 3.33 hm2, high-risk, double-cropped rice field was selected as a demonstration area in each of three cities in the Pearl River Delta. The nutrient inhibitor was applied to the soil before rice seedling transplanting in both the early and late cropping seasons. Its impact on the mass fraction of Cd in brown rice from different rice varieties over both cropping seasons were studied and assessed, as well as its influence on soil properties.【Result】The results showed that the nutrient inhibitor did not significantly impact the early or late cropping season rice yields in any of the three demonstration areas. However, it did reduce the mass fraction of Cd in brown rice, with reduction ranging from 8.43% to 72.5%. The nutrient inhibitor influenced soil properties differently. Compared to the control area, the nutrient inhibitor increased the pH of the soil in the double-cropped rice fields of the three demonstration areas by 0.10~0.42 units. The nutrient inhibitor increased the mass fractions of soil exchangeable calcium (Ca), magnesium (Mg), and available silicon (Si) which reached peak increases of 66.2%, 109%, and 53.0% respectively. However, the nutrient inhibitor did not noticeably change the mass fraction of soil hydrolytic nitrogen (N). In the demonstration area Ⅰ and Ⅱ, the inhibitor improved the mass fractions of available phosphorus (P) and available potassium (K) with peak increases of 78.3% and 24.6%, respectively, while in the demonstration area Ⅲ, the inhibitor insignificantly changed them. The nutrient inhibitor significantly reduced the mass fraction of available Cd in the soil in the demonstration area Ⅰ by 4.9%~7.3%, but it had no significant effect on that in the demonstration area Ⅱ and Ⅲ.【Conclusion】The nutrient inhibitor has ability to decrease the Cd accumulation in brown rice, and its impact on soil macro and moderate nutrients, and Cd bioavailability differentiates along with some conditions, while the inhibitor does not adversely affect soil properties or rice yields. Therefore, the nutrient inhibitor has the potential for safe and effective application to high-risk Cd-contaminated rice fields in the Pearl River Delta region.
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