Including cover crops during fallow periods for increasing ecosystem services: Is it possible in croplands of Southern South America?

Abstract

The integration of cover crops (CC) into annual crop rotations improves the provision of multiple ecosystem services in time and represents an alternative paradigm to achieve sustainability goals. In spite of the benefits that several authors have exposed, CC are seldom included in rotations because their water consumption could affect cash crops development. We evaluated the possibility of including CC in the agricultural area of Rio de la Plata grasslands and identified its optimal duration depending on both environmental conditions and crop rotations. Fallow areas were located based on NDVI time series derived from MODIS satellite images and the influence of CC on the subsequent cash crop was evaluated based on modeled changes in soil water contents at the sowing date of the cash crop. Our land use classifications revealed that single crop rotations, mostly summer crops with winter fallow periods, occupy a large proportion (89%) of the agricultural portion of the Rio de la Plata grasslands studied. In most of the region, sowing CC of 3 to 5 months of length during fallow periods had little impact on soil water contents at the sowing date of the following cash crop. As expected, the optimal CC duration in the different sub-regions increased with the average rainfall occurred during the fallow period. The possibility of sowing CC without affecting cash crops yields opens the opportunity for intensifying crop sequences in the region, oriented to mitigate environmental concerns raised by monocultures and agricultural simplification.