Description of the Business As Usual (BAU):
Bare soil, which is managed by removing any organic material and without application from other sources. Conversely, mulching is a practice conducted in some agricultural systems, consisting of leaving organic material on the ground or applying organic residues from outside the farm. In conventional cropping systems, the harvest residues are usually removed in annual crops, and the soil tilled. Likewise, the sowing is performed with a standard sowing machine.
Description of the system change:
Mulching is the practice of covering the soil with mulch. Mulch is a layer of material(s) that covers the soil surface, usually organic material such as stubble, plant residues, pruning residues, etc. Mulching is a water conservation technique that increases water infiltration into the soil, retards soil erosion and reduces surface runoff. The mulch reduces direct evaporation improving the soil water balance. Furthermore, the C released from the residue decomposition is a carbon input into the soil that improves organic carbon.
In annual crops, this technique is usually performed by the harvest residues from previous crop as mulch. To maintain the mulch throughout the growing season, direct seeding of the following crop under No till system is needed. For homogeneous residues distribution, the necessary accessories, such as residue spreading systems and deflectors, must be available in the harvester of the previous crop to chop and sprinkle the crop residues. Thus, these are spread evenly and changes in ground coverage are avoided, facilitating the sowing and the regulation of the no till drill.
To control weeds in no-till systems, herbicides are typically used as part of integrated weed management. Synergies between herbicide applications and mulching systems should be considered; harvest residues left on the soil surface help control weeds by restricting light and nutrient availability, and the straw mulch cover prevents soil-seed contact, hindering and reducing weed germination. Crop diversification and rotation are also recommended to break the cycle of weeds, pests, and diseases.
The use of organic mulches helps counter agricultural threats like weeds and low soil organic matter content, and improves physical and chemical properties, increasing the resilience of
agriculture. Nevertheless, possible conflicts or restrictions of the mulching technique should be taken into account. The presence of an excessive amount of mulch can pose difficulties for poorly adapted no-till drill and planting machines. In addition, the soil temperature reduction by residue mulch could hinder the seed emergence in cold areas. A practice among farmers is removing a fraction of the harvest residue to facilitate field operations, but this can reduce the potential for carbon sequestration.