Journal of Agricultural Science; Vol. 10, No. 12; 2018 ISSN 1916-9752 E-ISSN 1916-9760 Published by Canadian Center of Science and Education 329 Yield of ‘Pingo de Ouro’ Cowpea Bean Under Different Sowing Densities and Goat Manure Doses in the Region of Mossoró, Brazil Rogério Alexandrino da Silva 1 , Paulo César Ferreira Linhares 1 , Anielson dos Santos Souza 2 , Maria Francisca Soares Pereira 1 , Janilson Pinheiro de Assis 1 , Roberto Pequeno de Sousa 1 , Ariana Morais Neves 1 , Lunara de Sousa Alves 3 & Rita Ianáskara Gomes da Silva 1 1 Jitirana Research Group, Department of Agronomic and Forestry Sciences, Federal Rural Semi-Arid University, Mossoró, RN, Brazil 2 Center of Food Science and Technology, Federal University of Campina Grande, Pombal, PB, Brazil 3 Federal University of Paraiba, Campus Areia, Areia, PB, Brazil Correspondence: Rogério Alexandrino da Silva, Jitirana Research Group, Department of Agronomic and Forestry Sciences, Federal Rural Semi-Arid University, Mossoró, RN, Brazil. E-mail: agrogerio@hotmail.com Received: August 18, 2018 Accepted: September 28, 2018 Online Published: November 15, 2018 doi:10.5539/jas.v10n12p329 URL: https://doi.org/10.5539/jas.v10n12p329 Abstract Using goat manure may substantially increase cowpea bean productivity. This study evaluated the yield of ‘pingo de ouro’ cowpea bean under different sowing densities and goat doses in the region of Mossoró, Brazil. The experiment was conducted from October to December 2016 at the Experimental Farm Rafael Fernandes, Mossoró-RN, Brazil. Treatments arranged in two-way factorial with four goat manure doses (0.0, 0.5, 1 and 2 kg m -1 ), and two sowing densities of bean (75,000 and 37,500 plants ha -1 ), with three replicates. The experiment was performed in complete randomized blocks design. We evaluated the number and length of pods per plant, number of seed per pod, weight of 100 dry grains and dry grain yield. Higher grain yield occurred using 2.0 kg m -1 of goat manure (1,162.4 kg ha -1 or 234 kg 2,000 m -2 ) and 75,000 plants ha -1 (693.4 kg ha -1 or 138.6 kg 2,000 m -2 ). High sowing density in combination with goat manure is an affective. Keywords: organic fertilizer, sustainability, Vigna unguiculata 1. Introduction The cowpea (Vigna unguiculata (L.) Walp) is one of the main food sources of tropical regions because it contains substantial lipids, sugars, calcium, iron, potassium, phosphorus and several essential amino acids (Cardoso & Ribeiro, 2006). In the state of Rio Grande do Norte, Brazil, the cultivation of cowpea generates employment and income. The cultivation takes place in small areas, where the farmers cultive varieties adapted to the climatic conditions of the region. Brazil stands out among the bean-producing countries, occupying the third position, with an average production of 1.083 kg ha -1 (IBGE, 2017). The rusticity, precocity and the wide adaptability allow the cultivation of cowpea in aggressive environments, an essential characteristic for the northeastern region of Brazil (Souza et al., 2013). In this region, climate is semi-arid, and string beans stand out as a significant crop that used as major source of proteins and carbohydrates, in the form of dry and green grains (Lima, 2014). The Brazilian states with the highest per capita consumption of beans are Ceará and Piauí, predominantly using cowpea (Wander, 2007). Despite the low productivity of grains in the Northeast, the cultivation of cowpea beans can be an alternative of consumption and income through the cultivation of the ‘Pingo de Ouro’ variety. Many farmers in the State of Rio Grande do Norte consider the ‘Pingo de Ouro’ variety more productive than other local varieties, such as ‘Centa de Vaca’ and ‘Canapu’. The use of local varieties contributes greatly to the reduction of production costs (Carpentieri-Pípolo et al., 2010). Goat manure is a source of organic matter that is easily available and can be used for fertilization. A positive effect of goat manure application was found in sunflower (Pereira et al., 2014), maize (Oliveira et al., 2016) and lettuce (Figueiredo et al., 2012).