深松深度对灌耕灰钙土团聚体分布及稳定性的影响

Effects of subsoiling tillage depth on soil aggregate distribution and stability of irrigated sierozem farmland in Gan-su Yellow River irrigation area,Northwest China

为改善引黄灌区的土壤结构,以旋耕(RT)为对照,设置深松30、35、40、50和60 cm 5个处理(ST30、ST35、ST40、ST50、ST60),通过5年定位试验研究了深松深度对甘肃引黄灌区灌耕灰钙土团聚体分布和稳定性的影响。结果表明,深松促进了0~40 cm土层大团聚体的形成,并提高了其稳定性。干筛法下,>0.25 mm团聚体含量(R0.25)、平均重量直径(MWD)、几何平均直径(GMD)分别比RT处理增加6.16%、8.53%和13.38%,分形维数(D)降低3.81%;湿筛法下,R0.25、MWD和GMD分别增加44.78%、10.08%和5.81%,D值降低0.63%。深松5个处理平均的团聚体破坏率(PAD)和不稳定团粒指数(ELT)也分别比RT处理降低了5.77%和5.88%。R0.25、MWD、GMD随深松深度的增加而增加,大小顺序为ST60>ST50>ST40>ST35>ST30>RT,不同粒径团聚体含量也有大致相同的趋势,PAD、ELT和D则呈现相反的顺序。综合分析认为,深松耕能显著提高土壤团聚体含量和稳定性,深松深度越深,对土壤结构的改良效果越好,若考虑深松效益和机械动力配置,建议至少深松35 cm以上。

Taking rotary tillage(RT)as control,five treatments of subsoil tillage depth of 30,35,40,50 and 60 cm(ST30,ST35,ST40,ST50,ST60)were set up to study the effects of subsoiling depth on aggregate distribution and stability in irrigated sierozem of Gansu Yellow River irrigation area through a 5-year field experiment.The result showed that the aggregation and stability of large aggregates in 0~40 cm soil layer were significantly increased by subsoiling tillage treatments.Compared with RT,under dry sieving,>0.25 mm aggregate content(R0.25),mean weight diameter(MWD)and geometric mean diameter(GMD)increased by 6.16%,8.53%and 13.38%,respectively,and the fractal dimension(D)decreased by 3.81%by subsoiling tillage.While under wet sieving,R0.25,MWD and GMD increased by 44.78%,10.08%and 5.81%,respectively,and D value decreased by 0.63%with soiling tillage,compared with RT.The percentage of aggregate destruction(PAD)and unstable aggregate index(ELT)of subsoiling tillage treatments were reduced by 5.77%and 5.88%compared with RT,respectively.R0.25,MWD and GMD increased with the increase of subsoiling depth,and the order of the value was ST60>ST50>ST40>ST35>ST30>RT.The aggregate content of different sizes also had the same trend,while PAD,ELT and D showed the opposite order.All the results indicated that subsoiling could significantly improve the content and stability of soil aggregates.The deeper the subsoiling depth is,the better the improvement effect of soil structure will be.In consideration of subsoiling benefit and mechanical power configuration,the subsoiling depth was recommended to be at least 35 cm.