The role of cover crops for cropland soil carbon, nitrogen leaching, and agricultural yields – a global simulation study with LPJmL (V. 5.0-tillage-cc)

[摘要] Land management practices can reduce the environmental impact ofagricultural land use and production, improve productivity, and transformcropland into carbon sinks. In our study we assessed the biophysical andbiogeochemical impacts and the potential contribution of cover croppractices to sustainable land use. We applied the process-based, globaldynamic vegetation model LPJmL (Lund–Potsdam–Jena managed Land) V. 5.0-tillage-cc with a modified representationof cover crops to simulate the growth of grasses on cropland in periodsbetween two consecutive main crops' growing seasons for near-past climateand land use conditions. We quantified simulated responses of agroecosystemcomponents to cover crop cultivation in comparison to bare-soil fallowingpractices on global cropland for a period of 50 years. For cover crops with tillage, we obtained annual global median soil carbonsequestration rates of 0.52 and 0.48 t C ha −1  yr −1 for the firstand last decades of the entire simulation period, respectively. We foundthat cover crops with tillage reduced annual nitrogen leaching rates fromcropland soils by medians of 39 % and 54 % but also the productivity ofthe following main crop by an average of 1.6 % and 2 % for the 2 analyzed decades. The largest reductions in productivity were found for rice and modestly lowered ones for maize and wheat, whereas the soybean yield revealed analmost homogenously positive response to cover crop practices replacing bare-soil fallow periods. The obtained simulation results of cover crop with tillagepractices exhibit a good ability of the model version to reproduce observedeffects reported in other studies. Further, the results suggest thathaving no tillage is a suitable complementary practice to cover crops, enhancingsoil carbon sequestration and the reduction in nitrogen leaching, whilereducing potential trade-offs with the main-crop productivity due to theirimpacts on soil nitrogen and water dynamics. The spatial heterogeneity of simulated impacts of cover crops on thevariables assessed here was related to the time period since theintroduction of the management practice as well as to environmental andagronomic conditions of the cropland. This study supports findings of otherstudies, highlighting the substantial potential contribution of cover croppractices to the sustainable development of arable production.

[学科分类] 大气科学