Dairon R, Dutertre A, Tournebize J, Marks-Perreau J, Carluer N
Arvalis-Institut du végétal, 3 rue Joseph et Marie Hackin, Paris, France.
Irstea, UR MALY, 5 rue de la Doua, Villeurbanne, France.
Environ Sci Pollut Res Int. 2017 Mar;24(8):6866-6877. doi: 10.1007/s11356-016-8123-x. Epub 2017 Jan 11.
Influence of more than 20 years (1988-2010) of reduced tillage (RT) practices on water and pesticide balances and dynamics is analyzed and compared to results from a conventional tillage plot (CT). The field study soils are described as silty clay stagnic luvisol, developed on a low permeable schist layer. A drainage network was set up according to French criteria (0.9 m deep, 10 m space) to avoid soil winter waterlogging. Climate is temperate oceanic and drainage generally occurs from November to March. Data were analyzed at yearly, weekly (pesticides) and hourly (water) time steps. Over the long term, cumulated drainage decreases significantly on RT (3999 mm) compared to CT (5100 mm). This differentiation becomes significant from 1999, 10 years after plowing was stopped. Strikingly, hourly drainage peak flows are higher under RT, especially during the second period (2000-2010), associated with low or no base flow. These results suggest a strong influence of the macropore network under RT practice. In particular, drainage peaks are higher at the beginning of the drainage season (mid-October to December). Consistently, pesticides applied in late autumn, which are the most quantified on this site, are often significantly more exported under RT. For atrazine, applied in spring, fluxes are linked to cumulative flow and are de facto higher under CT. For others pesticides, losses appear to be heterogeneous, with generally low or null export rates for spring application. Generally speaking, higher concentrations are measured on RT plot and explain observed exportation rate differences. Finally, there is no clear evidence of correlation between pesticide losses and long-term impacts of RT on hydrodynamics, pointing the importance of studying the short-term effect of tillage on water and especially solute flow.
分析了20多年（1988 - 2010年）少耕（RT）措施对水分和农药平衡及动态的影响，并与传统耕作地块（CT）的结果进行比较。田间研究土壤被描述为粉质粘质潜育淋溶土，发育于低渗透性片岩层上。根据法国标准（深0.9米，间距10米）建立排水网络，以避免土壤冬季积水。气候为温带海洋性，排水一般发生在11月至3月。数据按年、周（农药）和小时（水分）时间步长进行分析。从长期来看，与CT（5100毫米）相比，RT的累计排水量显著减少（3999毫米）。这种差异从1999年开始变得显著，即停止耕作10年后。引人注目的是，RT下的小时排水峰值流量更高，特别是在第二个时期（2000 - 2010年），且基流较低或无基流。这些结果表明少耕措施下大孔隙网络的强烈影响。特别是在排水季节开始时（10月中旬至12月）排水峰值更高。一致的是，在该地点秋季后期施用的农药，在RT下通常出口量显著更多。对于春季施用的莠去津，通量与累计流量相关，实际上在CT下更高。对于其他农药，损失似乎是不均匀的，春季施用时出口率通常较低或为零。一般来说，在RT地块上测得的浓度较高，这解释了观察到的出口率差异。最后，没有明确证据表明农药损失与少耕对水动力长期影响之间存在相关性，这表明研究耕作对水分尤其是溶质流动的短期影响的重要性。
