Environmental sustainability in alternative leafy vegetables production system: no-tillage low input

Abstract

Leafy vegetables production in a conventional way involves excessive soil disturb, high water consumption, and organic matter acquisition out of the farm, which increase production costs. In addition, the high inputs, combined with the leaf vegetable short cycle and surface root system can result in losses of nutrients and other agrochemicals to the environment as well as their undesirable effects. The production system proposed in this project (no-tillage - NT - low input) proposes the reduction of soil tillage, inclusion of cover crops to the production system in place of acquisition of organic fertilizers, drip irrigation associated to fertirrigation and optimization of the fertilizers chemicals input. The premise is that the productivity of vegetables should be at least equivalent to that of the conventional system, and lower environmental impacts. The objective of this project is to evaluate sustainability indexes in the proposed production system with variations in cover crops and nitrogen supply compared to conventional production management (CP), in autumn-winter and spring-summer. The low input NT system and its variations will be compared with CP by the following indices: a) nitrate, ammonium and potassium leaching below the arable layer of the soil; b) changes in soil fertility in layers 0-10; 10-20; 20 - 40, and 40 - 60 cm after two successive crops; c) nutrient balance and recycling with Brachiaria decumbens or Avena sativa after two crops; d) population of weeds and soil phytonematodes; e) irrigation water monitoring; f) changes in soil physical attributes, g) lettuce quality and commercial yield. The trials will be in randomized blocks, with four replications, in two consecutive cycles. Experiment 1 will be carried out in autumn-winter arranged in 4 x 3 + 1 factorial scheme plus an additional control. The factors will be nitrogen topdressing inputs (0, 60, 120 and 180 kg ha-1 of N) and soil management (NT on White oats - Avena sativa, NT on Java - Macrocyloma axillare and without cover), with top dressing fertilization by fertigation in drip system. Additionally, a control (chicken manure in place of green manure, conventional soil tillage and micro sprinkler irrigation) will be evaluated. Experiment 2 will be carried out in the spring-summer with the same treatments, except for the cover crops, which will be adapted to this growing season, with Crotalaria juncea and Brachiaria ruziziensis being evaluated. The data will be submitted to analysis of variance. For the quantitative data, the averages will be compared by the Tukey test at 5% probability and for the quantitative data will be adjusted regression curves. (AU)