基于微生物化学计量学研究有机肥促进稻田土壤磷转化的作用

Effects of Organic Fertilization on Soil Phosphorus Transformation in Paddy Field by Using Microbial Stoichiometry

为了研究有机肥对稻田土壤磷组分的影响以及微生物化学计量学在土壤磷转化过程中的作用,开展了基于不同氮施用量的有机肥100%替代化肥试验,包括0(N_(0))、75(N_(75))、150(N_(150))、225(N_(225))和300 kg·hm^(-2)(N_(300))5个处理,分析了水稻不同生育期土壤磷组分和微生物量碳氮磷含量的变化及其相互关系。结果表明:施用有机肥第3年,与不施肥处理相比,所有有机肥处理在水稻苗期与收获期均增加了土壤速效磷含量(12.9%~153%)以及总磷含量(5.80%~40.6%)。进一步分析土壤磷组分变化发现,有机肥处理主要增加了土壤可利用态磷(树脂提取态磷、碳酸氢钠提取态无机磷、碳酸氢钠提取态有机磷)、次生矿物磷(氢氧化钠提取态无机磷、氢氧化钠提取态有机磷)及有机磷(活性有机磷、中等活性有机磷、稳态有机磷)含量,增长率分别为37.3%~142%、7.50%~41.3%和3.41%~32.2%;但随着有机肥施用量的增多(N 225和N_(300)),土壤有效磷(包括速效磷及可利用态磷)含量未呈梯度增加。通过冗余分析及Pearson相关性分析发现,稻季苗期土壤微生物量碳(MBC)和微生物量氮(MBN)含量与土壤速效磷、可利用态磷、次生矿物磷及活性有机磷含量呈显著负相关(P<0.05),而收获期土壤微生物量磷(MBP)、土壤速效磷(Olsen-P)及土壤无机磷含量呈显著正相关(P<0.05)。在水稻苗期,微生物化学计量比(MBC/MBP和MBN/MBP)与土壤活性有机磷含量呈显著负相关(P<0.05),而在水稻收获期,微生物化学计量比(MBC/MBP和MBN/MBP)与土壤Olsen-P和无机磷含量呈显著负相关(P<0.05),表明微生物化学计量的变化显著影响土壤有效磷和有机磷含量,促进了土壤有机磷向有效磷的转化。

Organic fertilizers significantly increases soil phosphorus(P)pools in paddy soils.Microbial stoichiometry can play an important role in the process of reflecting soil P transformation.Based on 100%replacement of chemical fertilizers with organic fertilizers at different nitrogen application rates,including 0(N_(0)),75(N_(75)),150(N_(150)),225(N_(225))and 300 kg·hm^(-2)(N_(300)),this study analyzed the effect of organic fertilizers on soil P pools in paddy fields and the effect of microbial stoichiometry on soil P transformation in different rice-growing stages.The results show that in the third year,compared with no fertilizer treatment,all organic fertilizer treatments increased the concentration of soil Olsen-P by 12.9%-153%and TP by (5.80%-40.6%),respectively,at rice seedling stage and harvest stage.Further analysis of the soil P components changes showed that the available P(Resin-P,NaHCO_(3)-Pi,NaHCO_(3)-Po),secondary-P(NaOH-Pi,NaOH-Po),and organic P(Po)(Labile Organic P,Moderately Labile Organic P,Stable Organic P)increased by 37.3%-142%,7.50%-41.3%and 3.41%-32.2%,respectively.With the further increase of organic fertilizer application(N 225 and N_(300)),soil labile P(including Olsen-P and available P)did not increase.Through Redundancy Analysis and Pearson Correlation Analysis,it was found that soil MBC and MBN were significantly negatively correlated with soil Olsen-P,available P,secondary-P and labile organic P(LPo),indicating that the increase of microbial biomass decreased the soil labile P concentration.However,MBP was significantly positively correlated with soil Olsen-P and soil inorganic P(Pi)components at harvest stage,because rice roots changed the rhizosphere environment,which in turn affected soil microbial biomass and soil Pi.During the growth period of rice seedling season,the microbial stoichiometric ratio(MBC/MBP and MBN/MBP)was significantly negatively correlated with soil LPo,while in the rice harvest stage,the microbial stoichiometric ratio(MBC/MBP and MBN/MBP)was significantly negatively correlated with soil Olsen-P and Pi.It showed that microbial stoichiometry significantly affected soil labile P and Po,and promoted the conversion of soil Po to labile P.This study aims to provide a theoretical basis for guiding the application of organic fertilizers to promote P in paddy soil and increase its efficiency.