秸秆还田对土壤还原性和水稻根系生长及产量的影响

为明确油菜秸秆还田对土壤环境及水稻根系生长的影响,该研究采用田间试验与栽培模拟试验相结合的方法,分析了油菜秸秆还田后,稻田土壤氧化还原电位(EH值)、还原性物质总量和Fe2+含量的变化规律及水稻苗期根系数量、质量、体积、长度和伤流强度等的变化规律。结果表明,1)油菜秸秆覆盖或翻埋条件下,稻田土壤氧化还原电位日均变化量(RCEH值)表现为先降低后增加的趋势,而土壤还原性物质总量日均变化量(RCRRM值)和土壤二价铁含量日均变化量(RCFe值)表现为先增加后降低的趋势;其中水稻移栽后14~18 d土壤RCEH值最低,移栽后10~14 d和14~22 d土壤RCRRM值(0.28~0.62 cmol/(kg·d))和RCFe值(5.0~31.6μg/(kg·d))达到最大。2)油菜秸秆覆盖或翻埋条件下,随着秸秆还田量的增加,水稻根系总量(数量、质量、体积和长度)、白根数量和根系伤流强度显著降低;与覆盖相比,油菜秸秆翻埋对水稻根系伤流日均变化量(RC_(RBI))的影响时间更长,水稻根系体积日均变化量(RCRVT值)和质量日均变化量(RCRQT值)的缓慢增长期延长了4 d。3)水稻移栽后10~22 d,油菜秸秆还田对稻田土壤环境和水稻根系生长的影响最显著;移栽后27~32 d,油菜秸秆还田对水稻根系生长的影响程度显著降低。油菜秸秆还田条件下,随着秸秆还田量增加,水稻苗期的土壤氧化还原电位显著降低,土壤还原性物质总量和Fe2+含量显著增加;水稻根系总量(数量、质量、体积和长度)和根系活力(白根数量和根系伤流强度)显著降低。在四川油稻两熟区,油菜秸秆还田量以全量还田为宜,适宜机械作业的田块以油菜秸秆翻埋还田为宜。

Effect of straw incorporated into soil on reducibility in soil and root system and yield of rice

Abstract: There is great meaning to research the effect of oil-seed rape straw incorporation on reducing material change in soil and the growth of rice root, with the objective of founding reasonable filed management for straw incorporation technology, by investigating the reason why rice growth was slow under the condition that oil-seed rape straw was retuned into the rice field. By field experiment and simulation experiment, this paper analyzed the dynamic change of the potential of oxidation-reduction (EH), and the reducing material and Fe2+ content in rice field, and investigated the dynamic change of root number, root weight, root volume, root length and root bleeding intensity. The results showed that: 1) The daily mean variation of potential of oxidation-reduction (RCEH) had a trend of ascending after descending, and the lowest value was found after 14-18 d of rice planting, while the values of daily mean variation of reducing material (RCRRM) and Fe2+ (RCFe) performed a trend of ascending and then descending, with the highest RCRRM value after 10-14 d of rice planting and the highest RCFe value after 14-22 d of rice planting. 2) Under the condition that oil-seed rape straw was incorporated into the rice field, with the increasing of oil-seed rape straw incorporation amount, rice number, rice weight, rice volume, rice length, white root amount and root bleeding intensity increased significantly. Compared with straw mulching method, the affecting period of straw incorporation on the daily mean variation of root bleeding intensity (RCRBI) under straw ploughing method was longer; the slow grow period of rice root system extended by 4 days under straw ploughing method. 3) After 10-22 d of rice planting, there was negative correlation between rice root growth (daily mean variation of (RCRNT, RCRQT, RCRLT and RCRVT) and soil environment (RCEH value, RCRRM value and RCFe value) and negative correlation between rice root and straw incorporation amount; after 27-32 d of rice planting, there was a positive correlation between rice root and soil environment and also a positive correlation between rice root and straw incorporation amount. As the time went on, the impacts of straw incorporation on root growth of rice became less and less, and after 27-32 d of rice planting, its impacts decreased significantly. The conclusions are as follows: Under the condition that oil-seed rape straw is incorporated into the rice field, with the increase of straw incorporation amount, the Eh decreases significantly, while the reducing material and Fe2+ content increase significantly; rice root (number, weight, volume and length), white root (number and length) and root bleeding intensity decrease significantly during seedling stage of rice. As the time goes on, the impacts of straw incorporation on root growth of rice become less. The affecting period of straw incorporation on soil environment and root growth with straw ploughing method is longer than straw mulching method, and incorporating oil-seed rape straw into soil with ploughing method is better than straw mulching method for rice yield. Under the condition that is feasible to use agricultural machine, ploughing method is a better method to return oil-seed rape straw into field.