湘南丘陵区水田改旱地后土壤磷的有效性及淋失风险

The availability and leaching risk of phosphorous after paddy field conversion to upland in hilly red soil area of south Hunan Province

杨昌富 ¹张璐 ²陈波浪 ³文石林 ²蔡泽江²

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作者信息

1. 中国农业科学院农业资源与农业区划研究所/北方干旱半干旱耕地高效利用全国重点实验室,北京 100081;中国农业科学院衡阳红壤实验站/湖南祁阳农田生态系统国家野外科学观测研究站,湖南祁阳 426182;新疆农业大学资源与环境学院,新疆乌鲁木齐 830000
2. 中国农业科学院农业资源与农业区划研究所/北方干旱半干旱耕地高效利用全国重点实验室,北京 100081;中国农业科学院衡阳红壤实验站/湖南祁阳农田生态系统国家野外科学观测研究站,湖南祁阳 426182
3. 新疆农业大学资源与环境学院,新疆乌鲁木齐 830000
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摘要

[目的]研究不同母质发育的水稻土改旱地后土壤有效磷变化特征及主要影响因素,为红壤区磷素高效利用提供依据.[方法]采集 3 种母质(石灰岩、第四纪红色黏土和砂页岩)发育的水稻土及相邻的水田改旱地土壤样品,分析了土壤全磷、有效磷、水溶性磷和无机磷组分(Al-P、Fe-P、Ca-P和O-P)的变化特征,通过主成分分析(PCA)和随机森林分析,探究水田改旱地后土壤磷素有效性变化的主要驱动因子.[结果]水田改为旱地后,石灰岩、砂页岩发育的土壤有效磷含量分别增加了 20.48 和 17.60 mg/kg(P<0.05),但水溶性磷含量均低于磷素环境阈值;土壤磷活化系数分别提高了 2.67 和 2.22 个百分点;Al-P含量分别增加了 46.07 和 51.28 mg/kg;石灰岩发育的土壤Fe-P含量增加了 62.11 mg/kg.相关分析表明,水田改旱地后,Fe-P、Al-P与磷活化系数呈显著或极显著正相关,PCA和随机森林分析结果表明Fe-P、Al-P是土壤磷素有效性变化的主要驱动因子.[结论]湘南红壤丘陵区水田改为旱地后,第四纪红色黏土发育的红壤磷素有效性未发生显著变化,石灰岩和砂页岩发育的土壤磷素有效性由于铁磷和铝磷在全磷中比例的增加而显著提升.3 种母质发育的水田改旱地后,其水溶性磷含量均低于环境磷阈值,引发磷淋失的风险较低.

Abstract

[Objective]This study investigated the variation of soil P availability when the field become upland from paddy field,and the major factors causing the variation.The research will provide a basis for academic phosphorus fertilization in the uplands.[Methods]Soil samples were collected in the paddy fields developed from parent materials of limestone,quaternary laterite and sand shale,and in the neighboring uplands derived from paddy fields,respectively.The total,available,and water-soluble P content,and the contents of inorganic P fractions(Al-P,Fe-P,Ca-P,and O-P)were analyzed.Principal component analysis(PCA)and random forest analysis method were used to evaluate the contribution of soil properties to the change of P availability,and to screen the main factors causing the variation.[Results]After transferred from paddy field to upland,the available P content in the quaternary laterite-developed soil was not changed significantly,neither the tested inorganic P fractions.While the available P contents in limestone-and sand shale-developed soils were increased by 20.48 and 17.60 mg/kg(P<0.05),and soil phosphorus activation coefficients increased by 2.67 and 2.22 percent points,the Al-P increased by 46.07 and 51.28 mg/kg,Fe-P in limestone-developed upland was increased by 62.11 mg/kg.The water soluble P contents in all the three uplands were not exceeding the P risk threshold.According to the correlation analysis result,the P activation coefficients in the derived uplands were positively correlated with Fe-P(P<0.05)and Al-P(P<0.01).PCA and random forest analysis showed that Fe-P and Al-P were the main factors driving the change of availability of soil phosphorous.[Conclusions]In the hilly area of southern Hunan Province,transferring paddy fields to uplands has caused increase of the phosphorus availability in limestone-and sand shale-developed red soils,due to the enhanced proportion of Fe-P and Al-P in total P,not in the quaternary laterite-developed red soil.The water soluble P contents in all the transferred uplands are lower than the P risk threshold,showing low risk of soil P leaching.

关键词

红壤/成土母质/水田改旱地/磷活化系数/无机磷组分/磷淋失风险

Key words

red soil/parent material/transferring paddy field to upland/phosphorus availability coefficient/inorganic P fraction/P leaching risk

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基金项目

国家重点研发计划项目(2021YFD1901201)

出版年

2024

植物营养与肥料学报

中国植物营养与肥料学会

植物营养与肥料学报

CSTPCD北大核心

影响因子：2.331

ISSN：1008-505X

参考文献量26

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