长期有机肥替代化肥对水稻土有机碳稳定性的影响

Effects of Long-term Organic Fertilizer Instead of Chemical Fertilizer on Organic Carbon Stability of Paddy Soil

针对不同有机肥替代化肥比例下红壤性水稻土有机碳稳定性不明确的科学问题,以第四纪红色黏土发育的水稻土的长期定位试验为研究对象,选取不施肥处理(CK)、化肥处理(100F0M)、化肥处理中30%、50%及70%的氮量被有机肥替代(70F30M、50F50M、30F70M)5个处理,明确长期不同有机肥替代化肥比例对水稻土活性/惰性碳组分含量及有机碳化学结构稳定性的影响。结果表明:不同有机肥替代化肥比例均提高了水稻土有机碳、活性碳、惰性碳的含量,活性碳含量表现为70F30M、30F70M>CK、50F50M,惰性碳含量表现为30F70M>70F30M、50F50M>100F0M>CK。随着有机肥替代比例的增加,惰性碳比例从69.67%逐渐增加至77.26%。不同有机肥替代比例下土壤有机碳的化学结构种类相同,相对含量百分比表现出相同的趋势:芳香碳(33.28%~37.79%)、烷基碳(27.81%~31.19%)最高,烷氧碳(16.19%~20.10%)、羰基碳(10.35%~12.07%)居中,羧基碳(2.52%~5.75%)最低。同时随着有机肥替代化肥比例的增加,芳香度从0.40增加至0.44,脂族碳/芳香碳和烷基碳/烷氧碳的比值均降低,有机碳的稳定性增强。pH(P<0.05)和阳离子交换量(CEC,P<0.01)是活性碳含量的主要影响因素,pH、CEC、碱解氮(AN)、碳投入(有机肥、水稻根系、水稻留茬)(P<0.01)是惰性碳含量的主要影响因素。因此,30F70M不仅提高了活性、惰性碳的含量,同时增加惰性碳的芳香度,更有利于提高土壤有机碳的稳定性。

【Objective】The effects of long-term and different proportions of organic fertilizer on the content of labile/non-labile carbon components and the stability of the chemical structure of organic carbon in paddy soil were determined.【Method】This study selected a long-term positioning test of paddy soil developed by Quaternary red clay as the research object.Five treatments were selected:no fertilizer treatment(CK),chemical fertilizer treatment(100F0M),30%,50%and 70%of the nitrogen in chemical fertilizer treatment was replaced by organic fertilizer(70F30M、50F50M、30F70M).During the study,we measured the content of total organic carbon,labile/non-labile organic carbon pool,the chemical structure of organic carbon,and soil properties.【Result】The contents of organic carbon,labile carbon and non-labile carbon in paddy soil were increased by different proportions of organic fertilizer instead of chemical fertilizer.The contents of labile carbon were 70F30M,30F70M>CK,50F50M,and the contents of non-labile carbon were 30F70M>70F30M,50F50M>100F0M>CK.With an increase in the replacement proportion of organic fertilizer,the proportion of non-labile carbon gradually increased from 69.67%to 77.26%.Under different organic fertilizer substitution ratios,the chemical structure of soil organic carbon remained the same,and the relative content percentage shows the same trend:aromatic carbon(33.28%-37.79%),alkyl carbon(27.81%-31.19%),alkoxy carbon(16.19%-20.10%),carbonyl carbon(10.35%-12.07%),and carboxyl carbon(2.52%-5.75%).Alky,carbonyl,and carboxyl carbons made up the largest,second largest and lowest proportions,respectively.With the increase in the proportion of organic fertilizer instead of chemical fertilizer,the aromaticity increased from 0.40 to 0.44 while the ratios of aliphatic carbon/aromatic carbon and alkyl carbon/alkoxy carbon decreased,suggesting an increase in the stability of organic carbon.PH(P<0.05)and Cation exchange capacity(CEC,P<0.01)were the main influencing factors of activated carbon content.pH,CEC,Alkali hydrolyzed nitrogen(AN)and carbon input(organic fertilizer,rice root and rice stubble)(P<0.01)were the main influencing factors of non-labile carbon content.【Conclusion】30F70M not only improved the content of labile and non-labile carbon but also increased the aromaticity of organic carbon,which is more conducive to improve the stability of soil organic carbon.