不同土壤条件下秸秆还田量对土壤还原性物质及水稻生长的影响

Effects of Straw Return Rate on Soil Reducing Substances and Rice Growth Under Different Soil Conditions

[目的]在不同土壤上研究水稻秸秆还田后还原性物质的形成及其与水稻生长的关系。[方法]在砂壤土(S1)和粉壤土(S2)上进行2年盆栽试验,模拟低(RL)中(RM)高(RH)产量下秸秆全量还田,以秸秆不还田(R0)为对照,测定土壤还原性物质总量、Eh、亚铁离子、锰离子和铵态氮含量,分析水稻分蘖、根系干质量、根系活力和水稻产量等指标。[结果]秸秆还田后生育前期土壤Eh显著降低,还原性物质数量增加,S2的还原性物质高于砂壤土。与对照相比,2021年在移栽后56d之前秸秆还田处理还原性物质总量、铁和锰离子含量分别提高了8.36%~199.64%、1.43%~160.03%和8.43%~57.68%。2022年在移栽后45 d前对应增加了2.95%~163.61%、0.77%~19.74%和3.28%~64.96%。随着秸秆还田量增加,还原性物质总量、铁和锰含量有增加趋势。在移栽后56 d前(2021年)和35 d前(2022年)秸秆还田显著增加了土壤铵态氮含量11.28%~50.67%和10.79%~351.53%。秸秆还田使水稻分蘖期和拔节期的根系干质量降低15.06%~45.80%,秸秆还田显著降低了砂壤土上水稻分蘖期和拔节期的根系活力,在S2土壤上RL和RM增加了拔节期根系活力,RH降低了根系活力。秸秆还田后水稻分蘖数在水稻生育期降低了7.23%~48.44%,干物质积累量降低了3.59%~43.57%。RL和RM处理第二年水稻产量降低不明显,RH处理2年均显著减产。砂壤土中氧化还原电位高于S2,S2还原性物质总量、锰离子含量、铵态氮含量、根系干质量、根系活力、分蘖数、干物质积累量和产量均高于砂壤土。[结论]在本研究条件下,秸秆还田显著增加还原性物质总量,抑制水稻早期生长。黏重土壤上秸秆全量还田引起减产,砂壤土上中低产量下秸秆全量还田不会造成穗数显著降低,因促进大穗形成不会造成显著减产。采取有效措施减少秸秆还田下还原性物质危害是秸秆还田技术优化的重点。

【Objective】The study investigates the formation of reductive substances following rice straw incorporation and its impact on rice growth across different soil types.【Method】A two-year pot experiment simulated full straw incorporation at low(RL),medium(RM),and high(RH)rates on sandy loam(S1)and silty loam(S2)soils,with no straw incorporation(R0)as the control.Total soil reducing substances,Eh,ferrous ions,manganese ions,and ammonium nitrogen contents were measured,alongside analyses of rice tillering,root dry weight,root vigor,and rice yield.【Results】Soil Eh decreased significantly,and the concentrations of reducing substances increased after straw incorporation,with S2 exhibiting higher levels than S1.Compared to the control,straw incorporation up to 56 days after transplanting in 2021 increased the levels of total reducing substances,Fe,and Mn by 8.36%-199.64%,1.43%-160.03%,and 8.43%-57.68%,respectively.Similar increases occurred before 45 days after transplanting in 2022,ranging from 2.95%to 163.61%,0.77%to 19.74%,and 3.28%to 64.96%.There was a positive correlation between straw incorporation and the levels of total reducing substances,Fe,and Mn.Straw incorporation significantly elevated soil ammonium N content by 11.28%-50.67%and 10.79%-351.53%before 56 days(2021)and 35 days(2022)after transplanting,respectively.Root dry weight at the tillering and jointing stages decreased by 15.06%-45.80%due to straw incorporation.In S1 soil,RL and RM increased root vigor at the jointing stage,while RH decreased root vigor on S2 soil.The number of rice tillers and dry matter accumulation decreased by 7.23%-48.44%and 3.59%-43.57%,respectively,during the rice reproductive period after straw incorporation.Rice yield was not significantly affected in the second year of RL and RM treatments,whereas RH treatment significantly reduced yield in both years.S1 exhibited higher oxidation-reduction potential than S2,with S2 displaying higher levels of reducing substances,manganese ions,ammonium nitrogen,root dry weight,root activity,tiller number,dry matter accumulation,and yield.【Conclusion】Straw incorporation increases the early-stage content of reducing substances and inhibits rice growth in cold areas.The impact of straw return on rice yield varies with soil type,with significant yield reductions observed on sticky soil following straw incorporation.Medium straw incorporation does not significantly affect the number of tillers but promotes the formation of larger panicle without reducing yield significantly.Optimizing straw incorporation technology requires effective measures to mitigate the negative effects of reducing substances.