Agriculture must now feed the planet with the lowest environmental impact. Landscape management is a means to protect natural resources from the adverse impacts. In particular, the adequate management of ditches could improve crop quality. Here, we review ditch design and maintenance. We found the following major points: (1) ditch networks have been primarily designed for waterlogging control and erosion prevention. Nonetheless, when properly managed, farm ditches provide other important ecosystem services, namely groundwater recharge, flood attenuation, water purification, or biodiversity conservation. (2) All ditch ecosystem services depend on many geochemical, geophysical, and biological processes, whose occurrence and intensity vary largely with ditch characteristics. (3) The major ruling characteristics are vegetative cover; ditch morphology; slope orientation; reach connections such as piped sections and weirs, soil, sediment and litter properties, biota, and biofilms; and network topology. (4) Ditch maintenance is an efficient engineering tool to optimize ecosystem services because several ditch characteristics change widely with ditch maintenance. For instance, maintenance operations, dredging, chemical weeding, and burning improve waterlogging and soil erosion control, but they are negative for biodiversity conservation. Mowing has low adverse effects on biodiversity conservation and water purification when mowing is performed at an adequate season. The effects of burning have been poorly investigated.

[1] An infiltration test was performed from a ditch with the purpose of monitoring the evolution of the piezometric levels using self-potential measurements made at the ground surface. We used a set of 18 piezometers and a network of 41 nonpolarizable (Pb/PbCl 2 ) electrodes. The variations of the self-potential signals are linearly correlated to the piezometric level changes with an apparent voltage coupling coefficient of À5.5 ± 0.9 mV m À1 . We measured, independently of this infiltration test, the three material properties entering the macroscopic field equations. They are the resistivity distribution of the soil, its mean hydraulic conductivity, and its intrinsic streaming potential coupling coefficient (À5.8 ± 1.1 mV m À1 ). Then, we modeled numerically the infiltration test and the associated self-potential signals using a two-dimensional finite difference code. The numerical model reproduces fairly well the observed results. This investigation demonstrates the effectiveness of the self-potential method in field conditions to monitor small variations (<0.60 m) of the water table. It offers for the first time a test of the electrokinetic theory in the field with independent evaluation of the material properties entering the field equations.

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Glyphosate is the most applied herbicide for weed control in agriculture worldwide. Excessive application of glyphosate induces water pollution. The transfer of glyphosate to freshwater and groundwater is largely controlled by glyphosate sorption to soils and sediments. Sorption coefficients are therefore the most sensitive parameters in models used for risk assessment. However, the variations in glyphosate sorption among soils and sediments are poorly understood. Here we review glyphosate sorption parameters and their variation with selected soils and sediment. We use this knowledge to build pedotransfer functions that allow predicting sorption parameters, Kd, Kf and n, for a wide range of soils and sediments. We gathered glyphosate sorption parameters, 101 Kf, n and equivalent Kd, and associated soil properties. These data were then used to perform stepwise multiple regression analyses to build the pedotransfer functions. The linear (Kd) and Freundlich (Kf, n) pedotransfer functions were benchmarked against experimental data. We found the following major points: (1) Under current environmental conditions, sorption is best predicted by the Kd pedotransfer function. (2) The pedotransfer function is Kd = 7.20*CEC -1.31*Clay ? 24.82 (Kd in L kg -1 , CEC in cmol kg -1 and clay in %). (3) Cation exchange capacity (CEC) and clay content are the main drivers of Kd variability across soils and sediments. Freundlich parameters are additionally influenced by pH and organic carbon. This suggests that the formation of complexes between glyphosate phosphonate groups and soil-exchanged polyvalent cations dominates sorption across the range of analyzed soils.