Conservation tillage practices reduce nitrogen losses in the sloping upland of the Three Gorges Reservoir area: No-till is better than mulch-till
2020
Zhang, Yang | Xie, Deti | Ni, Jiupai | Zeng, Xibai
Nitrogen (N) losses contribute to a series of ecological problems such as non-point source pollution and aquatic eutrophication. The effects of tillage practices on N losses in the sloping upland of the Three Gorges Reservoir (TGR) area was studied by comparing N losses of three conservation tillage practices (no-till, mulch-till and minimum till) in a short-term field experiment with the conventional one. N losses from plots of the no-till and minimum till treatments were less than those from plots of the conventional tillage treatment by 19.03 and 6.33 kg N ha⁻¹, respectively. Moreover, a meta-analysis of related data published between 1991 and 2017 was showed that conservation tillage (bootstrap confidence intervals of −57.35% to −7.86%) significantly reduced N losses more than conventional tillage. No-till (bootstrap confidence intervals of −48.76% to −13.23%) was more effective in reducing N losses than mulch-till (bootstrap confidence intervals of −56.65% to 14.52%). Moreover, the effect of no-till was stronger (bootstrap confidence intervals of −66.38% to −34.29% and −69.32% to −34.29%, respectively) on carbon-poor (<10 g kg⁻¹) and N-poor (<0.7 g kg⁻¹) soils. These results indicate that the conservation tillage practice significantly reduced N losses (especially N losses via surface runoff) in the sloping upland of the TGR area compared with conventional tillage and the no-till was more effective at reducing N losses than mulch-till in the nutrient-poor soil. Moreover, no-till did better in reducing the N losses in surface runoff than in subsurface leachate. Therefore, we recommend the use of no-till as a farming practice to reduce N losses and facilitate the sustainable development of agriculture in the sloping upland of the TGR area.
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