Abstract

No-tillage is an agricultural system that is proposed as a sustainable soil management system. This paper aims to evaluate the short-term effects of cover crops on a no-tillage system, by assessing a number of physical and chemical attributes of soil of the Brazilian Amazon region. The experiment was carried out in a typical Ferralsol under a no-tillage system from March to December, 2014. A randomized block design, with four replicates was used. The performance and effects of fourteen cover crops (Cajanus cajan, Canavalia ensiformis, Crotalaria juncea, Crotalaria ochroleuca, Crotalaria spectabilis, Stizolobium aterrima, Stizolobium cinereum, Pennisetum glaucum, Sorghum bicolor, Sorghum sudanense, Urochloa brizanha cv. Xaraés, Urochloa brizantha cv. Piatã and Urochloa ruziziensis and Zea mays) and fallow (control treatment) on the soil quality were assessed. The cover crops were sown in the off season in April 2014, before the summer crop (maize). The levels of P, K, Ca²⁺, Mg²⁺, Al³⁺, H+Al, saturation by aluminum, sum of bases, organic matter, pH and resistance to soil penetration were evaluated following the end of the cover crops growth. Some near-surface soil attributes were affected by the cover crops. Urochloa species improved the levels of potassium in the soil at depths up to 5 cm below the surface. The highest penetration resistance was observed in the superficial layer between 12 and 16 cm deep, with penetration resistance values varying between 2472 and 2912 kPa. The Urochloa exhibited satisfactory agronomic performance when grown under a simulated crop livestock integration system. It is concluded that the use of cover crops in a no-till system has the potential to improve the chemical quality of soil in the Southwestern Amazon region.

Key words: No-tillage, ecological intensification, sustainability, Rondonia, green manure.