Context and problem

Water management is one of the most important practices to determine rice yield, water use efficiency (WUE), uptake of arsenic (As) and cadmium (Cd) by plants, and greenhouse gas (GHG) emissions from the paddy field. However, few studies measured all of these outcomes simultaneously at a whole system level.

Objective

The objective of this study was to test the hypothesis that an alternate wetting and moderate drying regime (WMD) could achieve multiple goals of increasing rice yield, saving water, and reducing As and Cd contents in the grain and GHG emissions from the paddy field, either with or without wheat straw incorporation.

Methods

A high-yielding rice variety was grown in the field and three irrigation regimes were conducted including conventional irrigation (CI), WMD, and alternate wetting and severe drying (WSD), either with wheat straw incorporation (+WS) or without wheat straw incorporation (-WS) in each regime. In CI regimes, the field was continuously flooded except drainage in the mid-season. In WMD and WSD regimes, fields were not irrigated until the soil water potential reached − 15 kPa and − 30 kPa at 15–20 cm depth of the soil, respectively.

Results

Compared with CI regimes, WMD regimes significantly increased grain yield by 6.18–8.15 % in -WS plots and by10.1–11.1 % in +WS plots, whereas WSD regimes markedly decreased it, with less reduction in the +WS plots. The WMD regimes increased available nitrogen and microbial biomass carbon contents in the soil. Both WMD and WSD regimes pronouncedly increased water use efficiency and decreased As content in the grain. The WMD decreased, while the WSD increased, Cd content in the grain. Either WMD or WSD substantially reduced CH₄ emissions and increased N₂O emissions from the field. However, the reduction in CH₄ emissions far overweighed the increases in N₂O emissions in CO₂ eq in both regimes. The emission of CO₂ was increased in WSD regimes, whereas it showed no significant difference between WMD and CI regimes. The WMD regimes significantly decreased global warming potential and yield-scaled global warming potential in either –WS or +WS plots.

Conclusions

A WMD regime could produce more and healthier rice food with less environmental risk.

Implications

This study provides useful information for rice production to produce more and healthier food and reduce environmental risk by improving water management.

中文翻译：

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适度的润湿和干燥制度生产出更多、更健康的大米食品，环境风险更小

背景和问题

水管理是决定水稻产量、用水效率 (WUE)、植物对砷 (As) 和镉 (Cd) 的吸收以及稻田温室气体 (GHG) 排放的最重要实践之一。然而，很少有研究在整个系统层面同时测量所有这些结果。

客观的

本研究的目的是检验这样一个假设，即交替润湿和适度干燥状态 (WMD) 可以实现增加水稻产量、节水、减少谷物中 As 和 Cd 含量以及稻田温室气体排放的多重目标，有或没有小麦秸秆掺入。

方法

在田间种植了一种高产水稻品种，并进行了三种灌溉制度，包括常规灌溉 (CI)、WMD 和干湿交替 (WSD)，包括小麦秸秆掺入 (+WS) 或不掺入小麦秸秆(-WS) 在每个制度中。在 CI 制度下，除了在中期排水外，田地不断被淹没。在 WMD 和 WSD 方案中，直到土壤水势在 15-20 厘米深度分别达到 - 15 kPa 和 - 30 kPa 时才灌溉田地。

结果

与 CI 制度相比，WMD 制度在 -WS 地块中显着增加谷物产量 6.18-8.15%，在 +WS 地块中增加 10.1-11.1%，而 WSD 制度显着降低产量，+WS 地块减产较少。大规模杀伤性武器制度增加了土壤中可用氮和微生物生物量碳含量。WMD 和 WSD 制度都显着提高了水的利用效率并降低了谷物中的砷含量。WMD 降低，而 WSD 增加，谷物中的 Cd 含量。WMD 或 WSD 都大大减少了该领域的CH ₄排放量并增加了 N _{2 O 排放量。然而，CH 4}排放量的减少远远超过了CO _{2中 N 2} O 排放量的增加两种制度中的均衡器。_{CO 2}的排放量在WSD 制度中增加，而WMD 和CI 制度之间没有显着差异。大规模杀伤性武器制度显着降低了全球变暖潜能值和在-WS 或+WS 地块中按产量衡量的全球变暖潜能值。

结论

大规模杀伤性武器制度可以生产出更多、更健康的大米食品，而且环境风险更小。

启示

这项研究为水稻生产提供了有用的信息，以生产更多、更健康的食物，并通过改善水资源管理来降低环境风险。