Para obter produtos de qualidade e em quantidade ao longo do ano, é necessário o planejamento do plantio, observando a produtividade esperada, o preço praticado no comércio e os custos relativos aos fatores de produção, como despesas com mão de obra e aquisição de fertilizantes, os quais ditam o sucesso do investimento. O objetivo deste trabalho foi avaliar a rentabilidade do rabanete cv. Crimson Gigante adubado com diferentes quantidades de biomassa de flor-de-seda, em distintos tempos de incorporação ao solo e cultivado em duas épocas (outubro-dezembro e abril-julho), no semiárido de Pernambuco. O delineamento experimental utilizado em ambos os experimentos foi o de blocos completos casualizados com os tratamentos arranjados em esquema fatorial 4 × 4, com três repetições, sendo o primeiro fator: as quantidades de flor-de-seda (5,4; 8,8; 12,2 e 15,6 t ha-1 em base seca), e o segundo: os tempos de incorporação ao solo deste adubo (0, 10, 20 e 30 dias). Além da produtividade comercial de raízes e dos custos de produção, foram determinados os indicadores econômicos: renda bruta, renda líquida, taxa de retorno e índice de lucratividade. As maiores receitas bruta e líquida foram observadas com a quantidade de 15,6 t ha-1 de flor-de-seda. A incorporação da flor-de-seda 22 dias antes do plantio do rabanete foi considerada ideal à viabilidade econômica do investimento.

Desempenho agronômico do rabanete adubado com Calotropis procera (Ait.) R. Br. em duas épocas de cultivo 1 Agronomic performance in radish fertilised with Calotropis procera (Ait.

The use of green manures in vegetable crop production systems has increased, but there is still a lack of information about the correct handling of the species for better use by culture. Two field experiments were conducted in Serra Talhada in the semiarid of Pernambuco state, Brazil, to evaluate the effects of amounts of biomass and times of Calotropis procera incorporation into the soil in the agronomic performance of the beetroot 'Early Wonder' in two growing seasons (fall and spring-summer). The experimental design was a randomized block in three replications. The treatments were arranged in a 4 x 4 factorial scheme, with the first factor corresponding to the quantities of C. procera biomass (5.4, 8.8, 12.2, and 15.6 Mg ha -1 on a dry basis) and the second to the times of incorporation into the soil (0, 10, 20, and 30 days before sowing of beetroot). The following characteristics were assessed in the beetroot: plant height, number of leaves per plant, root diameter, total productivity, commercial productivity, and dry mass of roots. The amount of C. procera as well as the time of incorporation and growing season directly influenced the agronomic performance of beetroot. Regardless of the assessed agronomic characteristics, increasing amounts, and decreasing the time of incorporation proportionally influenced the performance of beetroot. The best agronomic performance of the beetroot was obtained by fertilization with 15.6 Mg ha -1 of C. procera. The ideal time of incorporation of green manure coincided with the date of the sowing of beetroot. The cultivation in the fall season resulted in higher total and commercial productivity of beetroots fertilized with C. procera.

The use of green manure from spontaneous species has gained prominence for vegetable crops focused on environmental sustainability and is an alternative method for the Semiarid region in the Northeast of Brazil. Two experiments were conducted in two growing seasons (autumn and spring-summer), in Serra Talhada, PE, Brazil, to evaluate the effects of different amounts of biomass of Calotropis procera (roostertree) and incorporation times on the agro-economic performance of beet crops. A randomized block experimental design was used, with three replications, in a 4 × 4 factorial arrangement; the first factor consisted of amounts of C. procera biomass (5.4, 8.8, 12.2, and 15.6 Mg ha-1 on a dry basis) and the second factor consisted of times of incorporation into the soil (0, 10, 20, and 30 days before planting beet). Commercial root yield, production costs, and the following economic indicators were determined: gross income, net income, return rate, and profitability index. The use of 15.6 Mg ha-1 of C. procera biomass resulted in the highest gross and net incomes and the use of 5.4 and 12.2 Mg ha-1 resulted in the best return rates and profitability indexes in autumn and spring-summer seasons, respectively; the planting time was considered as ideal for the biomass incorporation. The spring-summer growing season resulted in a higher economic return than the autumn growing season. The use of C. procera as a green manure for beet production is economically viable, regardless of the factors evaluated.