Economic nitrogen doses via fertigation for corn cultivation in a semiarid environment

Producers in the northeastern semiarid region of Brazil have been cultivating irrigated corn. The commercialized product comprises mainly green ears and silage. However, the irrigation of crops for dry grain has been questioned regarding costs and price competitiveness in relation to the same non-irrigated product cultivated in other regions. In recent years, the use of drip tapes and fertigation has spread among corn producers in the region. The aim of this study was to determine the N dose, via fertigation, which provides the maximum economic production of corn for dry grain, in two crop seasons (summer and winter), in the semiarid region of Brazil. The experimental design was performed in randomized blocks, with four replications. In both crops, the treatments consisted of four doses of N (0, 80, 160, and 240 kg ha-1) applied in the form of urea. In the hybrid corn (Bt Feroz), the N content was evaluated in terms of leaves, grain yield, gross and net incomes, the rate of return, and the profitability index. Independent of the crop season, the yield of dry grain (5,441.03 kg ha-1) was highest when the corn was fertigated with a dose of 104.05 kg ha-1 N. The highest net incomes of the dry grain were obtained with 80 kg ha-1 N in summer (R$ 1,190.78 ha-1) and 160 kg ha-1 N in winter (R$ 2,757.54 ha-1). The winter crop was more favorable to the economic production of dry grain.

CONSUMO HÍDRICO E EXIGÊNCIA TÉRMICA DA PALMA FORRAGEIRA EM AMBIENTE SEMIÁRIDO

CONSUMO HÍDRICO E EXIGÊNCIA TÉRMICA DA PALMA FORRAGEIRA EM AMBIENTE SEMIÁRIDO ANTÔNIO SUASSUNA DE LIMA1; PATRÍCIA FERREIRA DA SILVA2 ; RIGOBERTO MOREIRA DE MATOS3; JOSÉ DANTAS NETO4; LUCIANO MARCELO FALLÉ SABOYA5 E HERMES ALVES DE ALMEIDA6 1Doutor em Engenharia Agrícola, Rua Aprígio Veloso, 882 - Universitário, Campina Grande - PB, Brasil, 58428-830, e-mail: [email protected] 2Pós- doutoranda em Engenharia e Gestão dos Recursos Naturais, Rua Aprígio Veloso, 882 - Universitário, Campina Grande - PB, Brasil, 58428-830, e-mail: [email protected] 3Doutor em Engenharia Agrícola, Rua Aprígio Veloso, 882 - Universitário, Campina Grande - PB, Brasil, 58428-830, e-mail: [email protected]. 4Professor Doutor, Universidade Federal de Campina Grande, Unidade Acadêmica de Engenharia Agrícola, Rua Aprígio Veloso, 882 - Universitário, Campina Grande - PB, Brasil, 58428-830, e-mail: [email protected]. 5Professor Doutor, Universidade Federal de Campina Grande, Unidade Acadêmica de Engenharia Agrícola, Rua Aprígio Veloso, 882 - Universitário, Campina Grande - PB, Brasil, 58428-830, e-mail: [email protected]. 6Professor Doutor, Universidade Estadual da Paraíba, Rua Baraúnas, 351 - Universitário, Campina Grande - PB, 58429-500, Brasil, e-mail: [email protected]. 1 RESUMO O objetivo deste estudo foi avaliar o consumo hídrico e estabelecer a exigência térmica de três variedades de palma forrageira nas diferentes fases de desenvolvimento em ambiente semiárido. O experimento foi desenvolvido em condições de campo no munícipio de Santa Luzia, PB, Fazenda Poço Redondo. Para a determinação da evapotranspiração da cultura (ETc), foram utilizados três lisímetros de drenagem localizados no centro da área experimental. Cada lisímetro continha quatro plantas com características semelhantes e sob o mesmo sistema de manejo das plantas externas. Um quarto lisímetro foi utilizado com grama para determinar a evapotranspiração de referência ET0. Cada lisímetro representa uma área efetiva de evaporação de 1,17 m2. Pela ordem de emissão dos cladódios juntamente com o somatório de graus dias determinou-se as quatro fenofases da palma forrageira. A evapotranspiração de referência foi de 7,2 mm dia-1. Os valores de evapotranspiração da cultura ETc e coeficiente de cultivo (Kc), foram respectivamente: 4,8; 4,8 e 4,6 mm dia-1 e 0,72; 0,70 e 0,70, para as variedades orelha de elefante, baiana e miúda. A temperatura basal foi de 18 °C e a soma térmica acumulada no período foi superior a 4000 °C. Keywords: coeficiente de cultivo, fases fenológicas, graus-dias, temperatura base. LIMA, A. S.; SILVA, P. F.; MATOS, R. M.; DANTAS NETO, J.; SABOYA; L. M. F.; ALMEIDA, H. A. WATER CONSUMPTION AND THERMAL REQUIREMENT OF THE FORAGE PALM IN A SEMIARID ENVIRONMENT 2 ABSTRACT This study aimed to evaluate the water consumption and establish the thermal requirement of three varieties of forage palm in different stages of development in a semiarid environment. The experiment was conducted under field conditions in the municipality of Santa Luzia, PB, Poço Redondo Farm. To determine the culture evapotranspiration (ETc), three drainage lysimeters located in the center of the experimental area was used. Each lysimeter contained four plants with similar characteristics and under the same management system as the external plants. The fourth lysimeter was used with grass to determine the reference evapotranspiration ET0. Each lysimeter represents an effective evaporation area of 1.17 m2. By the order of emission of the cladodes with the sum of degree days, the four phenophases of the forage palm were determined. The reference evapotranspiration was 7.2 mm dia-1. The evapotranspiration values of ETc culture and cultivation coefficient (Kc), were respectively: 4.8; 4.8 and 4.6 mm dia-1 and 0.72; 0.70 and 0.70, for Orelha the Elefante, Baiana and Miúda varieties. The basal temperature was 18 °C and the thermal sum accumulated in the period was over 4000 °C. Keywords: cultivation coefficient, phenological phases, degree-days, base temperature.

Agro-economic efficiency of immature cowpea-radish intercropping systems in semiarid environment

The objective of this work was to evaluate the agro-economic efficiency of immature cowpea-radish intercropping systems in a semiarid environment in Brazil. The experiments were carried out in two cropping seasons, in a randomized complete block design with four replicates. The treatments consisted of a 4x2 factorial arrangement for the combination of four cowpea (Vigna unguiculata) cultivars (BRS Tumucumaque, BRS Cauamé, BRS Guariba, and BRS Itaim) and two radish (Raphanus sativus) cultivars (Crimson Gigante and Zapp). The agro-economic indices - system productivity index (SPI), land equivalent coefficient (LEC), and monetary equivalent ratio (MER) - were obtained using single plots of each cultivar in each block. 'BRS Tumucumaque' and 'BRS Guariba' showed the highest productivity of immature cowpea pods, and 'Crimson Gigante' showed the highest yield of marketable radish roots. The cultivation of either 'BRS Tumucumaque' or 'BRS Guariba' cowpea with 'Crimson Gigante' radish provides a greater agro-economy efficiency and sustainability for immature cowpea-radish intercropping.