Context

Increasing rice yield is crucial for meeting the demand of the fast-growing population in sub-Saharan Africa. Mid-season drainage can reduce iron toxicity, which is one of the major constraints to rice production in this region, and increase rice yield and water productivity.

Objectives

The objectives of this study were to evaluate the effects of mid-season drainage on iron toxicity, rice yield, and water productivity and identify the factors that favor rice yield in the fields with mid-season drainage relative to continuous flooding.

Methods

Experiments were conducted during the wet season over two years in 30 farmers’ fields in two irrigated schemes in the region of Bouake, central Côte d′Ivoire. Each farmer’s field was subdivided into three plots consisting of three water management practices: continuous flooding, mid-season drainage at 25 days after transplanting followed by two drying phases of seven days each separated by a flooded phase of three days or by alternate wetting and drying.

Results

Large variations in soil properties, management practices, iron toxicity score (based on leaf bronzing), rice yield, and water productivity were observed in farmers’ fields. Under continuous flooding, lower rice yield was associated with higher iron toxicity, and this was observed in the fields with higher soil organic carbon, and in which farmers applied lower amounts of phosphorus fertilizer. Mid-season drainage practices significantly reduced iron toxicity, irrigation water amount, and relatively increased water productivity. On average across farmers’ fields, rice yield was not significantly different among water management practices. However, when data at the individual field level were considered to calculate differences between the treatments, gains in rice yield in the fields with mid-season drainage at 25 days after transplanting followed by alternate wetting and drying relative to continuous flooding were associated with higher soil organic carbon, earlier application of the second split of fertilizer, and a large reduction in the iron toxicity score in the fields with mid-season drainage at 25 days after transplanting followed by alternate wetting and drying compared to continuous flooding.

Conclusions

Mid-season drainage at 25 days after transplanting followed by alternate wetting and drying combined with appropriate fertilizer management could be recommended to the smallholder farmers to reduce iron toxicity, and increase rice yield and water productivity in fields with high soil organic carbon and iron toxicity.

Significance

This study addressed a gap in the literature concerning the potential of mid-season drainage to reduce iron toxicity, and increase rice yield and water productivity and the suitable domains for its application.

中文翻译：

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季中排水对西非热带草原农业生态区灌溉系统铁毒性、水稻产量和水分生产率的影响

语境

提高水稻产量对于满足撒哈拉以南非洲快速增长的人口需求至关重要。季中排水可以降低铁毒性（该地区水稻生产的主要制约因素之一），并提高水稻产量和水分生产率。

目标

本研究的目的是评估季中排水对铁毒性、水稻产量和水分生产率的影响，并确定相对于持续洪水而言，季中排水田有利于水稻产量的因素。

方法

在科特迪瓦中部布瓦凯地区的两个灌溉计划的 30 个农田中，在两年多的雨季期间进行了实验。每个农民的田地被细分为三个地块，由三种水管理措施组成：连续灌水，移栽后 25 天的季中排水，然后是两个为期 7 天的干燥阶段，每个阶段由三天的淹水阶段或干湿交替隔开.

结果

在农田中观察到土壤特性、管理实践、铁毒性评分（基于叶片青铜色）、水稻产量和水分生产率的巨大差异。在连续洪水下，较低的水稻产量与较高的铁毒性相关，这在土壤有机碳较高且农民施用较少量磷肥的田地中观察到。季中排水措施显着降低了铁毒性、灌溉用水量，并相对提高了水生产率。平均而言，水稻产量在不同的水资源管理措施中没有显着差异。然而，当考虑单个田间数据来计算处理之间的差异时，

结论

可以向小农推荐移栽后 25 天进行季中排水，然后干湿交替结合适当的肥料管理，以减少铁毒，并在土壤有机碳和铁毒高的田地提高水稻产量和水分生产率。

意义

本研究解决了文献中关于季中排水降低铁毒性、提高水稻产量和水分生产率的潜力及其应用领域的空白。