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| DOI：10.13522/j.cnki.ggps.2019269 |
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| The Movement of Colloids in Purple Soil is Affected by Tillage |
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WANG Hong, XU Yaling, LIU Haitao, LIN Chaowen*, ZHANG Qi
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Soil and Fertilizer Institute, Sichuan Academy of Agricultural Sciences, Chengdu 610066, China
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| Abstract: |
| 【Background】Colloids facilitate migration of contaminants, such as heavy metals, phosphorous, pesticides, in soil, in which colloid sizes play an important role. However, there is a paucity of study on this under field condition.【Objective】The objective of this study is to experimentally study the impact of colloids of different sizes on their movement through both surface runoff and subsurface flow in soils under different tillage. 【Method】The experiment was conducted from July to September in 2019 at a field in Sichuan province. The tillage we compared included conventional tillage, ridge tillage, conventional tillage with full straw mulching, ridge tillage with full straw mulching, conventional tillage with pulverized straw mulching, and ridge tillage with pulverized straw mulching. In all treatments, we measured the subsurface flow and colloids concentration at depths of 20 cm, 40 cm, 60 cm, 80 cm, 100 cm and 120 cm in the soil. 【Result】Straw mulching significantly reduced surface runoff and increased subsurface flow, especially in conventional tillage with full straw mulching. In all treatments, subsurface flow rate decreased with soil depth. The ridge tillage and ridge tillage with straw mulching reduced migration of the colloids larger than 0.22 μm in both surface runoff and subsurface flow, compared to the conventional tillage. Fine colloids migrated more easily with surface runoff than large colloids, whereas large colloids moved more easily with subsurface flow and their concentration decreased with soil depth.【Conclusions】Among all tillage we studied, ridge tillage and ridge tillage with pulverized straw mulching can reduce colloids migration with both surface runoff and subsurface flow. Colloids migration flux in soil decreased with soil depth and the fine colloids migrated faster than the coarse colloids with both surface runoff and subsurface flow. |
| Key words: ridge cultivation; straw mulching; colloids; surface runoff; subsurface flow. |
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