Uso de cultivo de cobertura y laboreo reducido sin utilización de agroquímicos en horticultura: Evaluación del grado de enmalezamiento y disponibilidad de nitrógeno en tres cultivos de cebolla

The soils traditionally used for horticultural production in our country have undergone erosion and degradation processes. The high frequency of tillage and low soil cover, low organic matter input to the soil, problems with systematization and excessive use of agrochemicals largely explain the acceleration of these processes. The sustainability of productive systems depends on the development and application of techniques and/or technologies that aim to reverse the deterioration. The use of cover crops and reduced tillage (CC-RT) can promote soil health and functionality, but its applicability in systems aiming to reduce the use of agrochemicals is challenging. The general objective of this work is to contribute to the generation of knowledge that allows for the feasibility of using CC-RT technology without the use of agrochemicals in vegetable systems. For this purpose, two tillage practices were compared for soil preparation prior to onion transplantation: conventional tillage (CT) and reduced tillage (RT) at three sites. The variables analyzed included: quantity and quality of cover crop biomass, weed biomass and soil cover, soil mineral nitrogen (SMN), onion crop biomass, foliar nitrogen concentration (FN), and soil coverage. The aboveground biomass production of cover crops ranged from 3.9 to 7.1 Mg dry matter ha^-1, with higher biomass and weed coverage in RT, lower SMN and FN content, reduced growth of onion plants, and greater soil coverage compared to CT. The results demonstrate the possibility of implementing RT without the use of agrochemicals. However, nitrogen availability and increased weed pressure in reduced tilled soil are limitations for its application, requiring further research to address these constraints.