No-till system organic vegetable production under green manure: effect on yield and soil properties

In horticulture, the commonly applied agricultural practice of soil tillage often favours soil degradation. Even under organic cultivation, agricultural mechanization can stimulate organic matter mineralization and, consequently, cause soil quality losses. To maintain the soil properties in this production system, it is imperative to adopt a management system that minimizes soil disturbance, avoiding aggregate breakdown and exposure of organic matter to oxidation. This study evaluated the effect of different organic soil management systems on vegetable yield and the physical, chemical and biological properties that define soil quality. Three soil management systems were evaluated: NT- no-till system; CT-RH—conventional tillage with a rotary hoe; and CT-PH- conventional tillage, ploughing and harrowing. Soil aggregation, organic carbon (C) content in aggregates, penetration resistance, gravimetric moisture, organic matter light fraction, soil carbon, epigeal fauna and edaphic macrofauna were evaluated. The study showed that vegetable yields were similar in the different management systems; penetration resistance was the most sensitive physical indicator of soil management; carbon contents in soil macroaggregates and free light fraction (FLF) were the most sensitive chemical indicators to differentiate organic management systems in the soil surface layer. The highest FLF and C contents in soil macroaggregates were observed under CT-RH, followed by NT; the NT system promoted a greater density and richness of soil faunal groups, and multivariate analysis indicated a higher correlation with these biological properties. In conclusion, vegetable crop yields did not differ among the organic production management systems.