Biochar and legumes improve pastures in Brazil: environmental and socioeconomic analysis of three forage grasses in a field experiment

Abstract Pasturelands, often degraded, represent most of the converted lands globally. Here we present the results from a field experiment in Brazil where we tested the impact of different soil enhancers on soil quality and productivity of three tropical forages grasses: Brachiaria (Syn. Urochloa) brizantha cv. Marandu, Brachiaria brizantha cv. BRS Piatã, and Brachiaria brizantha cv. BRS Paiaguás. Soil enhancers included: biochar - a carbon-rich product from biomass pyrolysis, moinha, a local charcoal residue, traditional fertiliser containing nitrogen, phosphorus and potassium, lime and forage peanut (Arachis pintoi cv. Amarillo). Independent of treatment and Brachiaria cultivar, dry matter tended to be greatest in the first harvesting period, decreasing sharply in the second. Considering the total biomass produced over the experiment (sum of four harvests), the highest production (dry biomass) was for Piatã cultivar (14.07 Mg ha-1; treatment with the biochar application rate of 30 Mg ha-1). For Marandu and Piatã, the highest forage biomass increases were observed with the treatment that included biochar at the rate of 30 Mg ha-1. Marandu and Piatã yields generated an income of U$ 1,291 per year and U$ 1,183, respectively. For Paiaguas, the treatment that generated the greatest yield increase was forage peanut forage + 15 Mg ha-1 with its total income peak at U$ 991. The results reflected positive changes in soil characteristics such as improvement in cation exchange capacity, pH and nutrient contents. This research was developed in collaboration with the landowners within a bottom-up approach. Views of the landowners regarding land management are included in the discussion. Improved management of tropical pasturelands holds opportunity for more sustainable food production and also ecosystem services protection and recuperation, for example, biodiversity net-gain, water regulation and carbon sequestration.