Lecture addresses the use of cover crops in the Direct Planting System

“Cover Plants in the Direct Planting System in the Cerrado” was the theme of a lecture given by Embrapa Cerrados (DF) researcher Arminda Carvalho, on May 16, at the Senar stand, during the program of AgroBrasília 2018 – International Cerrados Fair, which ended at May 19th, at the Ivaldo Cenci Technological Park, located at PAD-DF.

The researcher began her talk by showing photos of agricultural areas in a marked process of degradation due to inadequate soil management. The photos portray a reality from 30 years ago, when there was conventional soil preparation and it was common to observe soil erosion and compaction. “We hope that what we see in these photos never happens again. Nowadays, the direct planting system predominates in Brazilian agriculture and we are able to manage it using cover crops without causing soil degradation”, she emphasized.

The use of cover crops provides, among other benefits, the maintenance of humidity and soil cover in the dry season and an increase in the richness of plant species in agroecosystems. When choosing the cover plant, the producer must check whether the species has the desirable characteristics: high biomass production, deep root system, association with bacteria, such as the genera Rhizobium and Azospirillum, association with mycorrhizal fungi, high tolerance drought, high production of easy-to-harvest seeds, possibility of mechanization, compatibility with the production system and synchrony with the main crop.

The researcher shows that monoculture causes damage and that the loss of organic matter is one of the most negative impacts of this agricultural practice. According to Arminda Carvalho, the “mix” of legumes and grasses is an alternative with the potential to promote benefits to agroecosystems. This is because each species has its favorable characteristics. For example, sunn hemp promotes high biological nitrogen fixation and millet has a deep root system, with high efficiency in nutrient cycling and use of water from deeper layers of the soil.

The alternative plant species in the succession of crops are sunn hemp, pigeon pea, sunflower, Ceará bush beans, millet, as well as mucunas and fodder radish. In the case of the ILP (Crop-Livestock Integration) and ILPF (Crop-Livestock-Forest Integration) systems, Brachiaria spp and sorghum are in common and successful use.

Arminda Carvalho also presented some research results, from studies carried out in 1989 on dry matter production, nitrogen fixation and absorption by green manures to more recent ones, such as those carried out on corn yield with and without nitrogen application in top dressing. in the 2016/2017 harvests.

The results of the latest research indicate that some cover crops such as Ceará wild beans and sunn hemp partially replace nitrogen in corn cover and that the use of brachiaria ruziziensis, before corn cultivation, does not dispense with the recommended dose of N for culture. In this case, there was a significant increase in productivity (3.682,16 kg/ha) when compared to not supplying nitrogen in corn top dressing. While in the succession of corn with wild beans-do-ceará and sunn hemp, this increase was 670 and 1493 kg/ha, respectively.