长期不同轮作模式对黄壤团聚体组成及有机碳的影响

Effects of Different Long-term Rotation Patterns on Aggregate Composition and Organic Carbon in Yellow Soil

依托23年的黄壤长期定位田间试验,对比研究玉米单作(MM)、小麦||绿肥–玉米轮作(WMR)和油菜–玉米轮作(RMR)对土壤团聚体组成及有机碳的影响。结果表明:各处理机械稳定性团聚体和水稳性团聚体均以大团聚体(>0.25 mm的团聚体)为优势团聚体,占比高达93.04%和74.59%以上;WMR和RMR处理较MM处理显著提高了5~2 mm和2~1 mm机械稳定性团聚体含量及>5 mm和5~2 mm水稳性团聚体含量;WMR处理的水稳性团聚体MWD(平均重量直径)较MM处理显著增加了50%;WMR、RMR处理的PAD(团聚体破坏率)和ELT(土壤团聚体不稳定团粒指数)较MM处理分别显著降低了31.32%、25.97%和35.90%、30.65%;不同粒级水稳性团聚体中均以WMR处理的有机碳含量最高,>5、1~0.5、0.5~0.25 mm粒级团聚体的有机碳含量比MM处理显著增加了17.60%、34.41%、45.67%;土壤团聚体有机碳主要集中在>0.25 mm的大团聚体中,而在微团聚体中含量较少,轮作主要提高了>5 mm水稳性团聚体中有机碳的贡献率,WMR、RMR处理较MM处理分别提高了23.18和9.16个百分点。小麦||绿肥–玉米轮作能有效改善土壤团聚体组成,提高团聚体稳定性和有机碳含量,可作为贵州黄壤旱地较佳的轮作模式。

The effects of rotation patterns on soil aggregate composition and soil organic carbon were studied in this paper in order to setup rational rotation pattern in yellow soil based on a successive 23-year field experiment,in which three treatments were chosen:maize monoculture system(MM),wheat(intercropping green manure)-maize rotation(WMR)and rape-maize rotation(RMR).The results showed that>0.25 mm aggregates were the dominant component of the mechanically stable and water stable aggregates with the proportion beyond 93.04%and 74.59%respectively.Compared with MM treatment,WMR and RMR treatments significantly improved the contents of 5–2 mm,2–1 mm mechanical stability aggregates and the contents of>5 mm,5–2 mm water stable aggregates;WMR treatment significantly increased MWD(mean weight diameter)of water stable aggregates by 50%;WMR and RMR treatments significantly decreased PAD(percentage of aggregate destruction)and ELT(soil aggregates unstable mass index)by 31.32%,25.97%and 35.90%,30.65%respectively.WMR treatment had the highest organic carbon content in different size levels of water stable aggregates,and organic carbon contents in>5,1–0.5,0.5–0.25 mm aggregates increased by 17.60%,34.41%and 45.67%respectively compared with MM treatment.The contents of soil aggregate organic carbon was mainly in>0.25 mm aggregates,higher than that in microaggregate(<0.25 mm).Rotation measures mainly increased the contribution rate of organic carbon in>5 mm water stable aggregates,WMR and RMR treatments increased 23.18 and 9.16 percentage points respectively compared with MM treatment.In summary,wheat(intercropping green manure)-maize rotation can effectively improve the composition of soil aggregates,improve the stability of soil aggregates and organic carbon content,thus,is a reasonable rotation pattern in the yellow soil of Guizhou.