INRA, UMR ECOSYS, Université Paris-Saclay, 78850 Thiverval-Grignon, France; Forman Christian College, Lahore 54600, Pakistan.
INRA, UMR FARE, Université de Reims Champagne-Ardenne, 51100 Reims, France; COMSATS Institute of Information Technology, Abbottabad 22060, Pakistan.
J Contam Hydrol. 2018 Jul;214:54-64. doi: 10.1016/j.jconhyd.2018.05.008. Epub 2018 May 31.
Crop residues left on the soil surface as mulch greatly influence the fate of pesticides in conservation agricultural practices because most of the applied pesticide is intercepted by mulch before passing to the soil. Modelling of pesticide losses from wash-off and leaching will greatly improve our understanding of the environmental consequences of pesticides in these systems. The PASTIS model, which simulates water transfer, mulch decomposition, and pesticide dynamics, was adapted in this new version to model the interactions between pesticides and mulch in order to simulate the impact of mulch on pesticide dynamic. Parameters of mulch dynamics and pesticide degradation and retention processes were estimated using independent incubation experiments. The PASTIS model was tested with experimental laboratory data that were obtained from two pesticides (Glyphosate and s-metolachlor) applied to soil columns where mulch composed of maize and dolichos was placed at the soil surface impacted by two rain intensities (a high and infrequent intensity and a light and frequent intensity). Simulations indicated good agreement between simulated and experimental values. After 1 day, 45-46% of the pesticides leached from the mulch and 54-55% remained in the mulch for both pesticides and both rain intensities. During the experiment, pesticide wash-off was greater for the high and infrequent rain (56-57%) compare to light and frequent rain (39-45%) for both pesticides. A smaller amount of S-metolachlor washed off with the light and frequent rain intensity (39%) than glyphosate (45%) because of its lower desorption rate from mulch residues. Glyphosate was more degraded (37-45%) than s-metolachlor (17-37%), which agrees with preliminary incubation experiments that were used for parameter estimation. A sensitivity analysis indicated that the saturation index of mulch at which pesticides started their diffusion in the rainwater and the time of the first rainfall were the two parameters that influenced the most output variables of our model. This study suggests that the PASTIS model developed for pesticide dissipation in mulch is a useful tool to evaluate the potential risk of pesticide leaching to the groundwater in conservation agriculture systems.
残留在土壤表面的作物秸秆作为覆盖物对保护性农业措施中农药的命运有很大影响，因为大部分施用到土壤上的农药在到达土壤之前被覆盖物截留。对淋洗和淋溶损失的农药进行建模将极大地提高我们对这些系统中农药环境后果的理解。PASTIS 模型模拟水分转移、覆盖物分解和农药动态，在这个新版本中进行了改编，以模拟农药和覆盖物之间的相互作用，从而模拟覆盖物对农药动态的影响。覆盖物动态和农药降解和保留过程的参数使用独立的孵育实验进行了估计。PASTIS 模型使用从两种农药（草甘膦和 s-甲草氯）应用于土壤柱的实验实验室数据进行了测试，在这些土壤柱中，玉米和多利科斯组成的覆盖物放置在表面受到两种降雨强度（高而不频繁的强度和轻而频繁的强度）影响的土壤表面。模拟结果表明，模拟值与实验值吻合较好。在 1 天内，两种农药在两种降雨强度下，从覆盖物中淋溶出 45-46%，在覆盖物中残留 54-55%。在实验过程中，高而不频繁的降雨导致农药淋洗量（56-57%）大于轻而频繁的降雨（39-45%），这两种农药均如此。由于 s-甲草氯从覆盖物残体中的解吸率较低，因此与轻而频繁的降雨强度（39%）相比，s-甲草氯（39%）的淋洗量较小。草甘膦的降解量（37-45%）大于 s-甲草氯（17-37%），这与用于参数估计的初步孵育实验一致。敏感性分析表明，在雨水开始扩散到覆盖物中以及第一次降雨时间这两个参数中，影响模型输出变量最多的是覆盖物的饱和度指数。本研究表明，开发用于覆盖物中农药消散的 PASTIS 模型是评估保护性农业系统中农药淋溶对地下水潜在风险的有用工具。
