Abstract
ABSTRACT This study aimed to determine the doses of maximum agronomic and economic efficiency as a function of different amounts of roostertree [Calotropis procera (Ait.) R.Br.] biomass added to the soil, that results in the maximum yield of green grains of cowpea in the semi-arid of Rio Grande do Norte state, Brazil. The experiment was conducted at the “Rafael Fernandes” Experimental Farm of the Universidade Federal Rural do Semi-Árido (UFERSA), Alagoinha, RN, from August to November 2013. In the experiment was used a randomized completely block design with 5 replicates. The treatments consisted of 20, 35, 50, and 65 t ha-1 (on a dry matter basis) of roostertree biomass added to the soil. The evaluated characteristics were: number of green pods per m2, productivity and dry mass of green pods, number of green grains per pod, weight of 100 green grains, and dry mass of green grains. The following economic indicators were determined: gross and net incomes, production operational costs, rate of return, and profit margin. The maximum agronomic efficiency of the yield of cowpea green grain was reached at the yield of 3.05 t ha-1, using 61.0 t ha-1 of roostertree biomass in the soil. The maximum economic efficiency yielded a net income of R$ 8,701.42, at the production of 3.02 t ha-1 green grains with 53.57 t ha-1 of roostertree biomass added to the soil. The use of roostertree as a green manure presents technical-economic feasibility in cowpea cultivation for green grains in the semi-arid conditions of Rio Grande do Norte.
Highlights
Agricultural practices have been modified in the recent decades through the development of new technologies that are capable of boosting food production with low use of chemical inputs
This study aimed to determine the doses of maximum agronomic and economic efficiency as a function of different amounts of roostertree biomass added to the soil, which results in the maximum yield of cowpea
Crescent linear response was observed in the number of green pods per m2 and in the productivity of green pods with increasing amounts of roostertree biomass added to the soil
Summary
Agricultural practices have been modified in the recent decades through the development of new technologies that are capable of boosting food production with low use of chemical inputs. Increasing public concern about the consumption of healthy food has led farmers to incorporate farming techniques for a clean production, which are based on a dynamic interaction between soil, plants, animals, people, ecosystem, and environment These novel agricultural technologies include plant- or animal-derived organic fertilization, with an emphasis on green manuring, which are common techniques used in the production of vegetable crops. Green manuring is the practice of adding plant residues (produced on-site or externally added) to the soil, with an aim to preserve or restore the organic matter and soil nutrient contents (OLIVEIRA et al, 2011) This technique promotes the cycling capacity and mobilization of nutrients, improves the nitrogen levels, and increases the water storage capacity and cation exchange, while decreasing the aluminum levels and controlling the growth of pests, diseases, and weeds (SILVA et al, 2010; GRAHAM; HAINES, 2006). That the effects of green manuring on the soil chemical properties are quite variable, depending on several factors (BORGES et al, 2014), such as the species used, biomass management, time of planting and cutting of green manure, time of permanence of the residues in the soil, local conditions, and the interactions among them
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