Consórcios de segunda safra para o ecótono cerrado-amazônia : alterações nos atributos físicos do solo

Abstract

Brazil stands out as one of the main global food providers. However, due to recent climatic events, involving global warming and other occurrences worldwide, environmental pressures on the agricultural sector have increased, mainly from international markets in developed countries. With the advancement of Brazilian agriculture into the Amazon Biome, particularly in the states of Mato Grosso and Pará, it is of paramount importance to seek agricultural systems aimed at sustainable, resilient production with minimal environmental impact. To address this challenge, it is crucial to direct efforts towards developing management alternatives that promote soil sustainability and increase agricultural production efficiency. Thus, the aim was to evaluate the effects of cover crops intercropped or not with second crop maize on soil physical quality. The study was conducted at Santana farm located in the municipality of Sorriso – MT. The experiment consisted of seven treatments and five replications, using a completely randomized design (CRD). Soybean (Glycine max) / maize (Zea mays) succession, which is the most widely used cultivation system in Brazil, was used as a control. This production system presents some problems such as low dry matter production, resulting in soil carbon losses and soil cover failures, especially when used in the Amazon Biome. The experimental area had a high degree of compaction and low organic matter content. As an alternative to monoculture maize, maize intercropped with Urochloa ruziziensis (syn. Brachiaria ruziziensis), maize with Brachiaria ruziziensis, and Crotalaria spectabilis were tested as second crops. As an alternative to maize, intercropping of forage sorghum BRS Ponta negra with Crotalaria and grain sorghum BRS 373 with stylosanthes BRS Bela were tested. An alternative for dry matter production tested was the intercropping of Brachiaria ruziziensis with Crotalaria. Additionally, a polyculture involving six cover plants was tested. All treatments were established under no-till system with the intention of improving soil physical quality. Undisturbed soil samples were collected after the end of each of the two crops to determine soil physical attributes. In the 0.0 to 0.1 m layer, the maize intercropped with brachiaria consortium had the lowest bulk density value, however, this effect was not a result of the cover crops but rather of tillage performed at the experiment site. The grain sorghum consortium intercropped with stylosanthes reduced compaction in the 0.1 to 0.2 m layer. There was an increase in available water regardless of treatments compared to the first year for the layers of 0.1 to 0.2 m and 0.2 and 0.3 m, thus the soil subjected to different intercropping underwent changes after two years of second crop cultivation.