In the Direct Planting System, the maintenance and/or sustainability of the production system necessarily involves strategies that maintain or improve the physical, chemical or biological properties of the soil. Implementing a soil cover in the off-season is important as a strategy for nutrient cycling and the supply of some nutrients to the crop in succession, in addition to physical protection and soil structuring.
Benefits of using cover crops
With the end of the soybean harvest, the resulting straw, which remains on the soil surface, delivers approximately 50 kg/ha of nitrogen to the system. Due to its dynamics, this nitrogen can be easily lost if there is no soil cover cycling it. In addition, the potassium accumulated in the straw quickly returns to the soil and needs to be absorbed and maintained on the soil surface.
Therefore, the importance of ground cover plants with the objective of cycling these nutrients is clear. In addition, the straw left by soybeans is inefficient for good physical protection of the soil due to the amount left on the surface, as well as its rapid decomposition. Therefore, one of the alternatives found is covering the soil with plants that can improve soil structure, increase the suppression of weeds and increase the supply of some important nutrients for the crop in succession and not host to pests and diseases.
Given this, cover crops are species cultivated to improve the production environment, they have several benefits:
Stimulate soil microbiota and nutrient cycling;
They incorporated organic matter into the system;
They help in the suppression of weeds;
They reduce erosive processes, as they protect the soil surface; It is
They increase the storage and infiltration capacity of water in the soil, as this straw reduces water losses by evaporation and minimizes temperature variations on the soil surface, which favors biological activity.
In addition, cover crops can be used as tools for a greater supply of some nutrients to the crop in succession, as is the case of forage radish, which increases the supply of nitrogen in wheat grown in succession. Ground cover plants can be worked alone or together with other species, characterizing the crop mix.
Choice of cover crops
There is no one type of cover plant that fits all and every condition. For decision-making, it is necessary to make a proper diagnosis of each situation and understand what you want with these cover crops.
Thus, there are characteristics that we should look for when choosing a crop for soil cover, such as: easy establishment, fast growth, good soil coverage, vigorous root system and not being a preferred host of diseases, pests and nematodes. All these characteristics mentioned above are difficult to find in a single plant species, in this case, we can adopt the use of a mix of plants.
When we perform the association of plants with different desired characteristics, we achieve the proper functioning of the system. So, the combination of grasses, crucifers and/or legumes, provide greater interaction between roots, while the cycling and availability of nutrients will depend on which cultures are being worked on in the Mix.
The mixtures are interesting because these plants have different capacities for extracting nutrients and exploring the soil through their root system. Therefore, when the objective is a greater supply of nutrients to the crop in succession, we must prioritize cover crops that decompose quickly after handling. On the other hand, if the objective is the physical protection of the soil, the longer the straw from this cover remains on the soil surface, the better. That is why the mixture of these two species can be interesting in these aspects.
Therefore, turnip, Sudan grass, buckwheat and millet are examples of some crops that can be used alone or in a mix of plants, and with the consortium it is possible to explore the benefits that each plant has.
Conclusion
The 21/22 and 22/23 harvests were examples of the importance of having a well-structured soil with an increase in its infiltration capacity and storage of water available to plants. Therefore, keeping the soil covered all year round is essential to minimize losses and ensure system profitability.
Text written by Lucas de Mattos and Thaysla Vezaro Wiedemann, students of the Agronomy course at UFSM, Frederico Westphalen campus, members of the Tutorial Education Program – PET Agricultural Sciences, under the supervision of the tutor, Professor Dr. Claudio Jose Basso.
