Sistemas de produção de longa duração na melhoria do perfil do solo sob plantio direto

Abstract

No-till systems with diversified crop rotations have stood out as one of the most effective strategies to improve the sustainability of farming in tropical and subtropical regions. The benefits of production systems on the chemical, physical, and biological attributes of the soil are more evident in the long term. A long-term experiment was conducted on a clayey mesoferric Red Latosol in the Campos Gerais region of Parana, Brazil, involving six production

systems: I: hairy vetch-corn-oat-soybean-wheat-soybean (HV-CO-OA-SO-WH-SO), II: oat- corn-wheat-soybean (OA-CO-WH-SO), III: wheat-soybean (WH-SO), IV: ryegrass-corn- ryegrass-soybean (RY-CO-RY-SO), V: alfalfa-corn (ALF-CO), and VI: hairy vetch-corn- wheat-soybean (HV-CO-WH-SO). After 31 years of establishing these systems, soil samples

were collected in the soil profile at depths of 0–10, 10–20, 20–40, 40–60, 60–80, 80–100, 100– 130, 130–160, and 160–200 cm. The samples were analyzed for active acidity (pH in CaCl2 and pH in water), ∆pH (pH in KCl – pH in water), exchangeable acidity (Al), total acidity (H + Al), and the contents of total organic carbon (TOC), hot water-extracted carbon (HWEC), permanganate-oxidizable carbon (POXC), total nitrogen (TN), calcium (Ca), magnesium (Mg), potassium (K), phosphorus (P), sulfur-sulfate (SO4 2- -S), boron (B), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu). Soil density was also determined at the 0–10 and 10–20 cm depths,

and stocks of TOC, HWEC, POXC, and TN were calculated in the 0–20 cm layer. The ALF- CO semiperennial system stood out, providing greater increments of TOC, K, S-SO4

2- and B in depth, and higher levels of NT, P, Ca, Cu, Fe, Zn, and Mn in the soil surface layers. No significant differences were found between production systems for bulk density and TOC, CAQ, COXP and NT stocks. After 31 years, the OA-CO-WH-SO system had the highest C input. In this same period, the HV-CO-WH-SO system had the highest corn and soybean grain yields per season, highlighting the importance of a diversified crop rotation and the cultivation of legumes before corn for improving the availability of N in the soil. The β-glucosidase enzyme activity was higher in the ALF-MI system, which accumulated more TOC in the soil.