Abstract [Background] The process mechanism and conservation technology of tillage erosion are the key research domains of science and technology for soil and water conservation at current stage in China. Most of researches on the tillage erosion have focused on the effect of towed or hanging mechanized tillage and manual or animal-powered non-mechanized tillage on soil translocation and soil loss. However, there is few researches about the processes and factors of soil redistribution by the direct-connected rotary cultivator tillage. [Methods] The magnetic tracer method was used to label soils of 84 experimental plots with different gradients ranging from 5.7% to 30.9%, and to quantitatively evaluate the rate and pattern of soil redistribution by rotary cultivator tillage on the steep land of purple soil in Sichuan Basin,southwestern China. Ilmenite powder was selected as magnetic tracer, because its contrasting color distinguished from the surrounding soil and high level of magnetic strength, and it could be closely adsorbed on soil surface and move simultaneously with the eroded soil. In order to determine effects of tillage speed and directions on tillage erosion rate, three tillage directions of i) parallel to the contour ii) downward along the slope and iii) upward along the slope, and two tillage speeds of high and low gear for each tillage direction were set up in the study. [Results] The results showed that at each tillage direction, any single tillage by rotary cultivator caused soil moving in both upslope and downslope simultaneously, and net translocation of soil was in the downslope direction due to gravity. While at different tillage speeds, the net translocation rates were significantly correlated with slope gradient incontour and upward tillage (P < 0.01), respectively, but not significantly correlated in downward one (P >0.05). Net soil translocation rate decreased in the order: contour at high gear (11.53 kg/ m),downward at high gear (11.40 kg/ m), upward at high gear (7.59 kg/ m), downward at low gear (7.33kg/ m), contour at low gear (6.87 kg/ m), and upward at low gear (6.29 kg/ m). Tillage erosion rates induced by upslope-downslope alternative were less than those by contour at high gear operation, however, they were equivalent at low gear operation. Tillage erosion rate (4.54 - 7.68 t/ hm2 under downslope parcel length of 15 m conditions) by rotary cultivator was much lower than by traditional farming implements (52.89 and 53.06 t/ hm2 for hoeing tillage and ox-drawn ploughing, respectively),i. e. , more than 85% erosion rate decreased. [Conclusions] Therefore the expanding application of rotary cultivator should play a critical role in reducing tillage erosion and preventing soil from degradation on the sleep land of purple soil.
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