Abstract:

Based on a long-term experiment on conservation tillage systems, this research was conducted with 6 treatments including conventional tillage (T), ridge tillage (R), conventional tillage with half amount of straw mulching (TS1), ridge tillage with half amount of straw mulching (RS1), conventional tillage with full amount of straw mulching (TS2) and ridge tillage with full amount of straw mulching (RS2), to study the effects of different conservation tillage systems on the root development, soil environment, and soil organic carbon of broad bean rhizosphere. The results showed that:conservation tillage could have an impact on the root growth of broad bean. Straw mulching treatment on the both conditions of (T) and (R) could improve the root biomass, root length, root surface area and root average diameter, the order of control results from the high to lower was as follow:TS2 > TS1 > T, RS2 > RS1 > R. Straw mulching could heighten the soil aspiration at later growth period of broad bean. However, straw mulching with ridge tillage treatment could decrease the soil aspiration of the whole growth period. Conservation tillage showed a significant advantage of organic carbon accumulation. Compared with (T), DOC content and POC content in rhizosphere soil were higher under TS2 and RS2 treatment, however, TS1 and RS1 did not show a significant difference. MBC content in rhizosphere soil were higher under TS1, RS1, TS2 and RS2 than (T). Especially the treatment of TS2 and RS2 showed a significant increment compares TS1 and RS1. Mineralization intensity of SOC under the treatment of TS2 and RS2 was lower than (T). The result indicated that straw mulching with ridge tillage treatments would improve the soil micro environment and good affection for agriculture production.

Key words: Ridge tillage, Straw mulching, Broad bean, Root growth, Soil environment, Rhizosphere soil organic carbon

摘要：

依托西南紫色土丘陵区坡耕地长期定位试验，采用传统平作（T）、垄作（R）、传统平作+秸秆半量覆盖（TS1）、垄作+秸秆半量覆盖（RS1）、传统平作+秸秆全量覆盖（TS2）、垄作+秸秆全量覆盖（RS2）6个处理，研究保护性耕作对蚕豆（Vicia faba L.）根系生长动态、土壤环境及根际土壤有机碳动态的影响。结果表明：保护性耕作能显著影响蚕豆根系生长发育。秸秆覆盖在平作和垄作下均能提高蚕豆根系生物量、单株根长度、根总表面积和根平均直径，各指标总趋势表现为：T < TS1 < TS2，R < RS1 < RS2。同时，相对于传统平作（T），秸秆覆盖可以提高蚕豆生育后期根系呼吸速率，而垄作（R）和垄作+秸秆可降低土壤呼吸速率。保护性耕作措施较传统平作（T）表现出明显的有机碳积累优势。TS2和RS2处理的水溶性有机碳（dissolved organic carbon，DOC）含量和颗粒态有机碳（particulate organic carbon，POC）含量均显著高于传统平作（T），而TS1和RS1处理与之相比差异不显著。TS1、RS1、TS2、RS2均可以显著增加根际微生物碳（microbial biomass carbon，MBC）含量，且TS2、RS2的增幅大于TS1、RS1。TS2和RS2的根际土壤矿化强度显著低于传统平作（T）。因此，秸秆覆盖+垄作的保护性耕作措施有利于改善土壤微环境，促进作物生长，具有良好的农田综合效应。

关键词: 垄作, 秸秆覆盖, 蚕豆, 根系生长, 土壤环境, 根际土壤有机碳组分