再生稻种植对土壤肥力和有机碳化学结构的影响

The effects of ratoon rice cultivation on soil fertility and chemical structure of soil organic carbon

“双改单”背景下,再生稻种植对稳定全国粮食产量具有重要意义。为研究再生稻种植对土壤有机碳及其肥力水平的影响,选取了单季稻、双季稻、再生稻3种稻作模式,并分析了三者土壤化学性质和有机碳化学结构的差异。结果表明:与单季稻相比,再生稻种植显著降低了土壤pH值,但其与双季稻无明显差异;土壤主要养分的含量均呈双季稻田>再生稻田>单季稻田的趋势,相对应地,三者的土壤肥力指数分别为0.66、0.47、0.40,且其差异达到了显著水平。不同稻作模式显著影响了土壤有机碳的化学结构,再生稻田中土壤烷基碳的相对含量显著高于单季稻但低于双季稻,而其烷氧碳的相对含量却显著高于双季稻但低于单季稻。再生稻田土壤的烷基碳/烷氧碳比值较单季稻显著提高了23.81%,但较双季稻则显著降低了30.67%;且该比值与土壤有机碳含量(R^(2)=0.95,P<0.001)和肥力指数(R^(2)=0.96,P<0.001)呈显著正相关。综上,再生稻的土壤肥力水平高于单季稻,却显著低于同为两稻模式的双季稻,这与不同稻作模式下的肥料投入、淹水周期和作物养分吸收利用密切相关。

The ratoon rice cultivation is important to stabilize rice production under the background of double rice system shifting to single rice system.To investigate the effects of ratoon rice cultivation on soil organic carbon(SOC)and soil fertility,we analyzed the differences of soil nutrients and chemical structure of SOC among single,double,and ratoon rice systems.Soil pH of ratoon rice field was significantly lower than that of single rice field,but no difference with double rice field.The contents of main nutrients in soils generally followed the order:double rice filed>ratoon rice field>single rice field.Accordingly,soil fertility index(SFI)of three rice systems was 0.66,0.47,and 0.40,with significant difference among each other.The chemical structure of SOC was significantly different among the three rice cultivation systems.The proportion of soil Alkyl-C in ratoon rice field was significantly higher than that in single rice field but lower than that in double rice field.In contrast,the proportion of soil O-Alkyl-C in ratoon rice field was significantly lower than that in single rice field but higher than that in double rice field.The ratio of Alkyl-C/O-Alkyl-C under ratoon rice filed increased by 23.81%compared to single rice field,but decreased by 30.67%compared to double rice field.The Alkyl-C/O-Alkyl-C ratio was significantly and positively correlated with SOC content(R^(2)=0.95,P<0.001)and SFI(R^(2)=0.96,P<0.001).In conclusion,soil fertility of ratoon rice filed is higher than that of single rice field but lower than that of double rice field,which is closely related with fertilizer input,flooding period,and crop nutrient uptake.