摘要
为探讨耕作深度对第四纪红黏土土壤水稳性团聚体特征的影响,本研究依托2015年设置的红壤坡耕地合理耕作深度定位试验,试验设置免耕(NT)、翻耕10 cm(P_(10))、翻耕20 cm(P_(20))和翻耕30 cm(P_(30))共4种试验处理,利用湿筛法测定了土壤2~8 mm,0.25~2 mm,0.25~0.053 mm和<0.053 mm粒径的团聚体的百分含量,并计算了>0.25 mm水稳性团聚体的百分含量(R_(0.25))、平均质量直径(MWD)、平均几何直径(GWD)和分形维数(D)。结果表明:4种试验处理下土壤团聚体含量均以0.25~2 mm粒径最高,其次是0.053~0.25 mm粒径。与NT相比,2~8 mm粒径的土壤团聚体含量在P_(10),P_(20)和P_(30)处理下均显著下降(p<0.05),微团聚体(<0.25 mm)含量在P_(10)和P_(30)处理下在整体上呈上升趋势,而微团聚体(<0.25 mm)含量在P_(20)处理下变化较小。土壤团聚体的R_(0.25),MWD,GMD值在NT和P_(20)处理下整体上高于P_(10)和P_(30)处理,且土壤团聚体的D值在NT和P_(20)处理下低于P_(10)和P_(30)处理,表明NT和P_(20)处理的土壤性团聚体稳定性比P_(10)和P_(30)处理更好。此外,耕作扰动下(P_(10),P_(20),P_(30))花生产量与0.25~2 mm粒径的土壤团聚体含量呈极显著正相关(p<0.01),与土壤团聚体的R_(0.25)和GMD值呈显著正相关(p<0.05),表明红壤坡耕地0.25~2 mm粒径的土壤水稳性团聚体含量能为土壤肥力的表征提供物理性诊断指标,而土壤团聚体的R_(0.25)和GMD值一定程度上能反映土壤肥力的水平。
In order to investigate the effects of tillage depth on the characteristics of water-stable aggregates of Quaternary red clay soil, the positioning field experiment was conducted from 2015 to 2017. The experiment was designed into four treatments, including no-tillage(NT), tillage 10 cm(P_(10)), tillage 20 cm(P_(20)) and tillage 30 cm(P_(30)). Soil samples were collected from the 0~15 cm and 15~30 cm soil layers of the plots of the four treatments. proportions of the aggregate sizes of 2~8 mm, 0.25~2 mm, 0.053~0.25 mm and <0.053 mm were determined by using the wet screening method., The amount of >0.25 mm aggregate(R_(0.25)), mean weight diameter(MWD), mean geometric diameter(GMD) and fractal dimension(D) of the fractions of soil aggregates were calculated, respectively. The results showed that the content of soil aggregate of 0.25~2 mm particle was the highest under the all experimental treatments, followed by the size of 0.053~0.25 mm; compared to NT, the content of soil aggregate of >2 mm decreased significantly under the treatments of P_(10), P_(20) and P_(30)(p<0.05), and the content of microaggregate(<0.25 mm) increased under the treatments of P_(10) and P_(30) as a whole; the microaggregate(<0.25 mm) content changed little under P_(20) treatment. The values of R_(0.25), MWD, and GMD of the aggregates under NT and P_(20) treatments were higher than those of P_(10) and P_(30), and values of D of soil aggregates under NT and P_(20) treatments were lower than those of P_(10) and P_(30). It was indicated that the stability of soil aggregates under NT and P_(20) treatment were more stable than P_(10) and P_(30) treatments. In addition, the peanut yield was significantly positively correlated with the content of soil aggregate of 0.25~2 mm under the treatment of P_(10), P_(20) and P_(30)(p<0.01), and was significantly positively correlated with the values of R_(0.25) and GMD of the aggregates(p<0.05). It could thus be concluded that the content of soil water-stable aggregate of 0.25~2 mm could be used as the physical indicator to evaluate fertility of red soil sloping field, and the values of R_(0.25) and GMD of the aggregates could well indicate the soil fertility.
引文
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