Cover plants can contribute on macronutrient accumulation in agroforestry systems during off-season

Abstract

Agroforestry systems are an alternative of land management and landscape restoration, where we can manage cover crops for increasing macronutrient cycling during off-season following harvesting, saving fertilization. However, it is necessary to find out the most effective species to maximize macronutrient cycling and biomass productivity. This study was carried out under a completely randomized design with four repetitions in a stabilized agroforestry system located in Goiânia, Brazil, during 2015 and 2016, among nine years old baru and bark trees. Cover crops were sown in single systems: Pigeon pea (PP); Stylosanthes Campo Grande (ST); Guinea grass (GG); and intercropping systems: PP + GG; and ST + GG. Dry biomass productivity and, plant shoot, and nutrient accumulations (nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur) were quantified twice during the growing season. Our results showed that GG was the best alternative as a cover crop to increase biomasss, potassium, magnesium and sulphur cycling in a single system, with 75% and 65% more shoot dry biomass than ST and PP, respectively. GG and ST increased phosphorus and calcium cycling. The low dry biomass productivity of legumes resulted in similar nitrogen accumulation in grasses and leguminous species. The accumulations of nitrogen, phosphorus, calcium and sulphur are similar between GG, ST and the ST + GG consortium. Our findings suggest that GG is the best alternative to increase macronutrient cycling in agroforestry systems, due its greater supply of biomass compensating the higher nutrient content found in legumes.