Context

Phosphorus (P) deficiency is a crucial factor restricting lowland rice production in tropics. Farmyard manure (FYM)—a mixture of animal feces and crop residues—is a potential P resource for smallholder farmers with limited access to mineral fertilizers. Nevertheless, there is a lack of knowledge regarding which types of FYM are effective in various soil types for lowland rice production, despite the high variability in nutrient composition of FYM.

Objective

The aim of this study was to determine the characteristics of FYM and soil, and their interaction to maximize rice growth under P deficiency.

Methods

Two-year experiment was conducted in three paddy fields with contrasting but P deficient soil properties in the central highlands of Madagascar. Six treatments were implemented for rice cultivation in each field: no fertilizer (control), three types of FYM in different nutrient compositions, mineral P fertilizer, and dolomite. Nitrogen and potassium were sufficiently applied to all the treatments.

Results

The application of FYM significantly increased grain yield and total P uptake of rice when the soil of fields had low pH, low total carbon (C) content, low cation exchange capacity, and low oxalate-extractable iron content. In these FYM responsive fields, the FYM with high P content and low C:P ratio were most effective and increased grain yields by 0.8–3.1 t ha⁻¹ compared to the control. These increases were considerably attributed to the P supply and partly to the increased pH by FYM applications because the single dolomite application also showed similar effects in one of these fields. In contrast, the field with high pH, high total C content, and low oxalate-extractable iron content, indicating high P-fixing capacity, did not respond to either mineral P or any type of FYM application.

Conclusions

The application of FYM, particularly with high P content and low C:P ratio, is effective to increase lowland rice yields under P deficiency except when the fields have soils with high pH and high P-fixing capacity.

Implications

Our findings facilitate efficient organic fertilizer application based on their characteristics and soil types to improve lowland rice yields in P-deficient fields.

中文翻译：

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在缺磷土壤中施用农家肥可增加低地水稻产量，但在高 pH 值和固磷能力的土壤中则不然

语境

磷（P）缺乏是限制热带低地水稻生产的关键因素。农家肥 (FYM)——动物粪便和农作物残茬的混合物——对于获取矿物肥料有限的小农来说是一种潜在的磷资源。然而，尽管 FYM 的营养成分变化很大，但仍缺乏关于哪种类型的 FYM 在低地水稻生产的各种土壤类型中有效的知识。

客观的

本研究的目的是确定 FYM 和土壤的特征，以及它们在缺磷情况下使水稻生长最大化的相互作用。

方法

为期两年的实验在马达加斯加中部高地的三个稻田中进行，这些稻田具有对比鲜明但缺磷的土壤特性。每个田间水稻栽培实施六种处理：不施肥（对照）、三种不同营养成分的FYM、矿物磷肥和白云石。各处理均足量施氮、钾。

结果

当田间土壤 pH 值低、总碳 (C) 含量低、阳离子交换能力低和草酸盐可提取铁含量低时，FYM 的应用显着提高了水稻的粮食产量和总磷吸收。在这些 FYM 响应田中，具有高 P 含量和低 C:P 比的 FYM 是最有效的，与对照相比，谷物产量增加了 0.8-3.1 t ha ^{-1 。}这些增加在很大程度上归因于 P 供应，部分归因于 FYM 应用增加的 pH 值，因为单一白云石应用在其中一个领域也显示出类似的效果。相比之下，具有高 pH 值、高总碳含量和低草酸盐可提取铁含量的田地，表明高固磷能力，对矿物磷或任何类型的 FYM 应用均无反应。

结论

施用 FYM，特别是高 P 含量和低 C:P 比的 FYM，可有效提高缺磷条件下的低地水稻产量，除非田间土壤具有高 pH 值和高固磷能力。

启示

我们的研究结果有助于根据土壤特征和土壤类型有效施用有机肥，以提高缺磷田低地水稻的产量。