长期弃耕降低红壤稻田土壤磷库  

Long-term abandonment of reddish paddy fields decreases soil phosphorus pool

作　　者：龚梦瑶 李巧云[1,2] 陈安磊 葛体达 李宇虹[4] 秦红灵 马国辉 GONG Meng-yao;LI Qiao-yun;CHEN An-lei;GE Ti-da;LI Yu-hong;QIN Hong-ling;MA Guo-hui(College of Resources and Environment,Hunan Agricultural University,Changsha,Hunan 410128,China;Guangzhou Xinhua University,Guangzhou,Guangdong 523133,China;College of Agronomy,Human agricultural University,Changsha,Hunan 410128,China;Key Laboratory of Agro-Ecological Processes in Subtropical Region/Institute of Subtropical Agriculture,Chinese Academy of Sciences,Changsha,Hunan 410125,China;Institute of Plant Virology,Ningbo University,Ningbo,Zhejiang 315211,China;State Key Laboratory of Hybrid Rice/Hunan Hybrid Rice Research Center,Changsha,Hunan 410125,China)

机构地区：[1]湖南农业大学资源环境学院,湖南长沙410128 [2]广州新华学院,广东广州523133 [3]湖南农业大学农学院,湖南长沙410128 [4]中国科学院亚热带农业生态研究所/亚热带农业生态过程重点实验室,湖南长沙410125 [5]宁波大学植物病毒学研究所,浙江宁波315211 [6]杂交水稻国家重点实验室/湖南杂交水稻研究中心,湖南长沙410125

出　　处：《植物营养与肥料学报》2022年第8期1398-1408,共11页Journal of Plant Nutrition and Fertilizers

基　　金：国家重点研发计划项目(2017YFD0301504);湖南省自然科学基金项目(2022JJ30644,2020JJ4654);湖南创新型省份建设专项经费(2021NK2028)。

摘　　要：【目的】施用磷肥会显著提升土壤磷的活性,弃耕不仅导致土地资源浪费还会带来环境风险。探讨弃耕后稻田土壤全磷、各磷素组分的变化规律及趋势,为弃耕土壤管理提供理论依据。【方法】红壤稻田弃耕长期定位试验于2007—2014年在湖南桃源进行,弃耕前(1991—2006年)为双季稻定位试验,包括不施肥对照(CK)、施氮钾(NK)和氮磷钾(NPK)化肥3个处理。分析了弃耕前后(2006和2014年)土壤全磷、速效磷(Olsen-P)、微生物生物量磷(MBP)及各个磷组分(Hedley法)含量。【结果】弃耕8年后,土壤全磷较弃耕初期下降了19.3~160.8 mg/kg,Olsen-P下降了0.7~14.1 mg/kg,下降幅度分别为5.4%~23.4%和11.0%~45.4%,其中NPK处理的全磷和Olsen-P分别显著下降了23.4%和45.4%(P<0.05)。Hedley-P分级结果表明,弃耕前、后稻田土壤各磷组分的含量高低均为Residual-P>NaOH-P_(o)>NaOH-P_(i)>Sonic-P_(i)>NaHCO_(3)-P_(o)>HCl-P>Sonic-P_(o)>NaHCO_(3)-P_(i)>Resin-P。除Resin-P和Sonic-P_(o)外,NPK处理土壤的其它磷组分含量均显著高于CK和NK处理(P<0.05),而NK和CK处理间多数磷组分含量无显著差异(P>0.05)。从磷组分的活性来看,稳定态磷含量(Residual-P)弃耕后基本不变;活性磷(Resin-P、NaHCO_(3)-P_(i)和NaHCO_(3)-P_(o))、中活性磷(NaOH-P_(i)、NaOH-P_(o)、Sonic-P_(i)、Sonic-P_(o))和低活性磷(HCl-P)含量在弃耕后都呈下降趋势,下降幅度最大的是中活性磷,含量下降了10.0~100.8 mg/kg,贡献了磷下降总量的51.7%~78.6%;其次为活性磷,下降了2.8~29.1 mg/kg,贡献了磷下降总量的14.5%~18.1%。中活性磷含量的下降主要源于无机态磷(NaOH-P_(i)和Sonic-P_(i))的显著降低,而只有NPK处理的有机态磷(NaOH-P_(o)和Sonic-P_(o))下降达到显著水平(P<0.05)。MBP含量较为稳定,维持在15.1~16.7 mg/kg,CK和NK处理的土壤MBP是Olsen-P的3倍左右。弃耕后杂草固持磷量为21.3~48.3 kg/hm^(2),分别能解释CK、NK处理土壤磷库损失的40.6%和54.9%,但仅能�【Objectives】Long-term abandonment of paddy fields in the reddish soil region is not only a waste of soil resources but also poses a risk to the environment due to the high levels of active phosphorous(P)fertilization.Here,we studied the changes in soil P compositions of abandoned reddish paddy fields.【Methods】The experiment was conducted from 2007 to 2014 in Taoyuan,Hunan Province.Before abandonment,the soil was under an 16-years rice fertilization experiment(1991–2006),including three treatments:no fertilizer control(CK),application of chemical fertilizer nitrogen and potassium(NK)and application of chemical fertilizer nitrogen phosphorus and potassium(NPK).Topsoil samples were collected from the three treatment plots to determine total phosphorus,available phosphorus(Olsen-P),microbial biomass P(MBP),and P fraction.【Results】The abandonment of the paddy field reduced TP and Olsen-P content by 5.4%–23.4%and 11.0%–45.4%,respectively.This corresponds to a reduction of 19.3–160.8 mg/kg total-P and 0.7–14.1 mg/kg Olsen-P.The pre-NPK treatment(high P soil)showed the highest(P<0.05)reduction in total-P(23.4%)and Olsen-P(45.4%)content.The P fractions in the treatments were in the order of Residual-P>NaOH-P_(o)>NaOH-P_(i)>Sonic-P_(i)>NaHCO_(3)-P_(o)>HCl-P>Sonic-P_(o)>NaHCO_(3)-P_(i)>Resin-P.All the P fractions in the pre-NPK treatment were higher than in pre-CK and pre-NK treatments(P<0.05)except Resin-P and Sonic-P_(o).However,there were no significant differences between the P fractions in the pre-CK and pre-NK treatments(P>0.05).Residual-P was stable P fraction,and abandonment did not affect its content.Labile P(Resin-P+NaHCO_(3)-P_(i)+NaHCO_(3)-P_(o)),moderately labile P(NaHO-P_(i)+NaOH-P_(o)+Sonic-P_(i)+Sonic-P_(o)),and low active P(HCl-P)showed a downward trend after abandonment.Moderately labile P recorded the highest reduction(decreased by 10.0–100.8 mg/kg),accounting for 51.7%–78.6%of the total-P reduction.This was followed by active P(decreased by 2.8–29.1 mg/kg),accounting for a 14.

关 键 词：红壤稻田 弃耕 土壤全磷 磷素组分 损失途径 

分 类 号：S153.6[农业科学—土壤学]