耕作方式对甘肃引黄灌区灌耕灰钙土团聚体分布及稳定性的影响

2014—2017年在连续翻耕8年的玉米地上设置连续翻耕(CT)、旋耕(RT)、深松(ST)、免耕(NT)和翻耕-免耕(CT-NT)、深松-免耕(ST-NT)6个耕作处理,研究不同耕作方式对甘肃引黄灌区灌耕灰钙土团聚体分布及稳定性的影响.结果表明: NT和ST-NT处理促进了0～40 cm土层大团聚体形成,并提高了其稳定性;CT和RT处理由于对土壤的强烈扰动,耕层土壤团聚体大小分布和稳定性都显著降低.机械稳定性团聚体以NT处理最佳,＞0.25 mm团聚体含量(R_0.25)、平均重量直径(MWD)、几何平均直径(GMD)分别比RT处理增加5.8%、8.0%和13.0%,分形维数(D)降低3.6%.水稳性团聚体以ST-NT处理最佳,R_0.25、MWD、GMD分别增加55.3%、15.1%和8.7%,D值降低0.8%.NT、ST-NT处理的团聚体破坏率(PAD)和不稳定团粒指数(E_LT)也最低,PAD分别比RT处理降低了5.9%和7.7%,E_LT分别降低了5.8%和7.2%.综合分析认为,深松-免耕(ST-NT)的轮耕模式更有利于土壤团聚体含量和稳定性的增加,也符合当地农民的操作习惯,是比较理想的耕作方式,在该区域农业可持续发展中具有一定的应用价值.

Effects of tillage types on soil aggregate distribution and stability in irrigated sierozem of Gansu Yellow River irrigation area,China

A total of six treatments, including continuous conventional tillage (CT), rotary tillage (RT), subsoiling (ST), no-tillage (NT), conventional-no tillage (CT-NT) and subsoiling-no tillage (ST-NT), were conducted to examine the effects of different tillage types on soil aggregates distribution and stability of irrigated sierozem on continuous 8-year-tillage maize fields in the Gansu Yellow River irrigated area in 2014-2017. The results showed that the aggregation and stability of large aggregates in 0-40 cm soil layer were increased by NT and ST-NT treatments, while the size distribution and stability in plough layer were significantly decreased by CT and RT treatments due to strong soil disturbance. Compared with RT, the mechanical stability of aggregates under dry sieving NT was the best. The contents of >0.25 mm aggregate (R_0.25), mean weight diameter (MWD) and geometric mean diameter (GMD) increased by 5.8%, 8.0%, and 13.0%, respectively, and fractal dimension (D) decreased by 3.6%. The water-stable aggregates in ST-NT was the best, with R_0.25, MWD and GMD increased by 55.3%, 15.1% and 8.7%, respectively, and D value decreased by 0.8%. The percentage of aggregate destruction (PAD) and unstable aggregate index (E_LT) of NT and ST-NT treatments were the lowest. PAD was reduced by 5.9% and 7.7% compared with RT, E_LT was reduced by 5.8% and 7.2%, respectively. All the results indicated that the subsoiling-notillage (ST-NT) rotation mode was more conducive to the enhancement of soil aggregate content and stability and consistent with the local farmers operating habits, which would be an ideal tillage method and had certain application value for the sustainable agricultural development in this area.