The management of soil cover plants (intercropping) in orchards can contribute to increase productivity of citrus trees. Thus, the present research aimed to evaluate different planting systems for Tahiti acid lime grafted onto Flying Dragon trifoliate orange, a dwarfing rootstock, at high planting density (1,157 trees ha −1). The study was set up in four tillage systems, using Urochloa ruziziensis as an intercrop species in the orchard, and conducted for 5 years: no-tillage (NT), no-tillage and no-herbicide (NT-NH), minimum tillage (MT) and conventional tillage (CT; without intercropping). Dry matter (DM) production of biomass in the row and interrow of the orchard was evaluated yearly, as well as weed density, soil physical and chemical characteristics, plant water and nutritional status, and fruit yield of trees. Greater deposition of DM of biomass was observed in the row of citrus planting for treatments NT and NT-NH compared to CT and MT treatments, which led to reduced undesirable weed populations. The NT treatment also provided increases of 79% in potassium (K) nutrient concentrations in the leaves of trees and 60% in exchangeable K in the soil surface layer, in the first 2 years evaluated. The maintenance of the Urochloa ruziziensis mulch in the NT system also provided higher soil volumetric moisture content and consequently lower soil resistance penetration and water stress on trees, evidenced by the predawn plant leaf water potential (<1 MPa). Moreover, the NT treatment provided an average increase of 56% of fruit yield from trees compared to the CT treatment during three harvests. This long-term study demonstrated the contribution of the no-tillage system using a favorable cover crop to increase the yield of Tahiti acid lime fruits and maintain the soil quality most required for the sustainability of citrus production.

Peanut crop (Arachis hypogaea L.) mechanization has been improved over the years; however there are drawbacks that affect the quality of operations. Thus, this article's objectives were to evaluate the operational performance of the mechanized sowing of peanut crop according to seeding densities (10, 14, and 18 seeds m -1 ) and seed sizes (21 and 23 mm). It was observed that the seeds of 23 mm had shorter average number of days to emergence and a higher percentage of emergences, occurring the opposite to the seeding density of 18 seeds m -1 . The higher the seeding density, the largest was the plant stand, whereas the 23 mm seed obtained the best results and the same with the seeding density of 14 seeds m -1 that had a higher percentage of normal spacing. The densities of 14 and 18 seeds m -1 reflected in higher yields, being always superior to the 23 mm seeds. KEYWORDS:Arachis hypogaea L., agricultural mechanization, seeder-fertilizer. QUALIDADE DA SEMEADURA MECANIZADA DE AMENDOIM EM FUNÇÃO DE DENSIDADES DE SEMEADURA E TAMANHO DAS SEMENTES RESUMO:A mecanização da cultura do amendoim (Arachis hypogaea L.) vem evoluindo ao longo dos anos, todavia ainda existem empecilhos que afetam a qualidade das operações mecanizadas. Dessa forma, objetivou-se, no presente trabalho, avaliar o desempenho da semeadura mecanizada de amendoim em função de densidades de semeadura (10; 14 e 18 sementes m -1 ) e tamanhos de sementes (21 e 23 mm). Observou-se que, para as sementes de 23 mm, o número médio de dias para emergência foi menor, e a porcentagem de emergência superior, ocorrendo o contrário para a densidade de semeadura de 18 sementes m -1 . Quanto maior a densidade de semeadura, maior foi a população de plantas, sendo que a semente de 23 mm obteve os melhores resultados, em que a mesma, na densidade de semeadura de 14 sementes m -1 , apresentou alta porcentagem de espaçamentos normais. As densidades de 14 e 18 sementes m -1 refletiram em maiores produtividades, sendo sempre superior para as sementes de 23 mm. PALAVRAS-CHAVE:Arachis hypogaea L., mecanização agrícola, semeadora-adubadora.

RESUMO:A mecanização da cultura do amendoim (Arachis hypogaea L.) vem evoluindo ao longo dos anos, todavia ainda existem empecilhos que afetam a qualidade das operações mecanizadas. Dessa forma, objetivou-se no presente trabalho avaliar o desempenho operacional do conjunto mecanizado trator-semeadora-adubadora na qualidade da semeadura mecanizada de amendoim em função de densidades de semeadura (10, 14 e 18 sementes m -1 ) e tamanhos de sementes (21 e 23 mm). Observou-se que o desempenho operacional do conjunto trator-semeadora-adubadora foi homogêneo. A média geral de força média e de pico apresentaram valores de 11,29 e 13,09 kN e a potência média e de pico 17,89 e 20,47 kW, respectivamente. O consumo horário e operacional de combustível e a capacidade de campo operacional médios foram de 11,24 L h -1 , 7,34 L ha -1 e 1,53 ha h -1 , respectivamente. A velocidade média de deslocamento foi de 5,7 km h -1 , a patinagem dos rodados traseiros apresentou média de 4,30% e dos dianteiros 9,25% para tracionar a semeadora utilizada. PALAVRAS-CHAVE:Arachis hypogaea L., energia na agricultura, mecanização agrícola. ABSTRACT:The mechanization of the peanut cultivation (Arachis hypogaea L.) has evolved over the years, but there are still obstacles that affect the quality of the mechanized operations. Thus, the aim of this work was to evaluate the operational performance and quality of the tractor-seeder set due to seeding rates (10, 14, and 18 seeds m -1 ) and seed size (21 and 23 mm). It was observed that the operating performance of the tractor-seeder was homogeneous. The overall average of mean and peak force were, respectively, 11.29 and 13.09 kN and the average and peak power were 17.89 and 20.47 kW, respectively. The fuel hourly consumption, the fuel operational consumption, and the mean field operational capacity were 11.24 L h -1 , 7.34 L ha -1 , and 1.53 ha h -1 , respectively. The average travel speed was 5.7 km h -1 , and the sliding of the rear and front axles averaged 4.30% and 9.25%, respectively.