José Barbosa Duarte Júnior

Adubos verdes e seus efeitos no rendimento da cana-de-açúcar em sistema de plantio direto

The objective of this experiment was to evaluate green manures and their effects in the sugarcane yield using no-tillage system (SPD). The experiment was carried out at Campos dos Goytacazes, Rio de Janeiro State, from december/2003 to july/2005. The experimental design was a randomized complete block with four replications. The treatments were jack bean (Canavalia ensiformis), velvet bean (Mucuna aterrimum) and sun hemp (Crotalaria juncea) under no-tillage and spontaneous vegetation in conventional tillage (PC) (control). The sunhemp 35 days after emergency (DAE) showed higher rate of soil cover 87% and 92 DAE produced 17.852 kg ha-1 of dry matter, 41%, 78% and 407% superior to jack bean, velvet bean and spontaneous vegetation, respectively, besides overcoming them in accumulation of K, Mg, S, Zn and Fe. Jack bean and velvet bean showed the highest content of N in the aerial part than other covering plants. Jack bean showed higher contents of P and Ca than sun hemp and velvet bean. The spontaneous vegetation showed the highest content of K in aerial part in relation to the cover plants. The legumes accumulated higher amounts of N and Cu than the spontaneous vegetation. Sun hemp and the jack bean accumulated 66% more of P in the aerial part than velvet bean. The SPD using green manures contributed significantly to sugarcane, yield that was 135.863 kg ha-1, being 37% superior to PC with the spontaneous vegetation.

A cana-de-açúcar em sistema de plantio direto comparado ao sistema convencional com e sem adubação

The objective of this study was to evaluate the agronomic characteristics of sugarcane as a function of the no-tillage system (NTS) compared to the conventional one (CS) with, and without, manuring. The experimental design was completely randomized, using four repetitions, in a factorial scheme 4 x 2. The treatments were: sugarcane NTS on sunnhemp (Crotalaria juncea); sugarcane NTS on jack bean (Canavalia ensiformis); sugarcane NTS on black mucuna (Mucuna aterrima) and sugarcane CS with incorporation of spontaneous vegetation (control), being duplicated, since each one was with, and without, manuring. In nutritional terms, the sugarcane CS on leguminosae was 43% superior in content of K, and the prominence was jack bean and mucuna that on average provided 26% more foliar N in relation to sugarcane CS. The nutritional diagnosis also indicated N and K as the main limitants of the productivity of sugarcane CS, while Ca, Fe, Zn and Cu were independent limitants of the management system. K was the main nutrient limitant of the productivity of unfertilized sugarcane. Sugarcane NTS on leguminosae provides larger foliar contents of N and K, besides increasing in 27, 32 and 37%, respectively, the number, the diameter and the productivity of stems in relation to the sugarcane of CS. The sugarcane in NTS on leguminosae, besides being more productive, guarantees larger preservation of the environment due to the harvesting of the cane without prior burning.

Produtividade de milho cultivado em sucessão à adubação verde

The use of previous crops which have the capacity of supplying nitrogen to maize by symbiotic fixation or nutrient recycling is important to yield maintenance. This study aimed at evaluating the yield of maize grown in succession to green fertilization . A completely randomized blocks design was used with four replications and the following treatments: maize grown on black oat, black oat + oilseed radish, black oat + white lupin, white lupin, crambe, spontaneous vegetation (fallow ground) and spontaneous vegetation (fallow ground) + topdressing nitrogen fertilization. Concerning grain yield, significant differences were observed among treatments. The maize grown on black oat + white lupin straw reached the highest yield (10,817 kg ha -1 ), resulting in a higher income and differing from the one grown on black oat and crambe straw and spontaneous vegetation. The use of white lupin , black oat + white lupin and black oat + oilseed radish showed to be a viable alternative for a higher grain yield, making the topdressing nitrogen fertilization unnecessary.

Desempenho de trator-implemento na cana-de-açúcar em sistemas de plantio direto e convencional

This research evaluated the performance of automated groups using slippage, tractor speed, and operational viability of planting sugarcane (Saccharum spp.) in no-tillage (SPD) and conventional (PC) systems under different plant coverings. The experimental design was completely randomized, using three repetitions in a split-split plot. There were twenty four treatments: A1-SPD the sugarcane on sunnhemp (Crotalaria juncea); a2-SPD the sugarcane on the jack bean (Canavalia ensiformis); A3-PC the sugarcane on incorporated black mucuna (Stilozobium aterrimum); A4-PC the sugarcane (control); sub-plots: B1-FORD 8430 DT + two row crop planter; B2-FORD 8430 DT + three lines furrow opener; B3-FORD 5610 + two lines furrow opener; and, sub-sub-plots: C1 - first reduced gear, and C2 - second reduced gear. The research verified that the slippage and speed results for furrow opening operations for subsequent manual or sugarcane planting operations in direct planting system on plant covering without previous management with cutter or roll-knife were possible and equally efficient when compared to the operational costs due to a reduction in the direct planting of sugarcane.

Características agronômicas de seis cultivares de amendoim cultivadas em sistema convencional e de semeadura direta

Objetivou-se no presente trabalho avaliar o desempenho agronomico de seis cultivares de amendoim em sistema convencional e de semeadura direta nos municipios de Marechal Cândido Rondon e Tupassi, PR, na safra 2011/2012. O delineamento experimental adotado foi de blocos ao acaso com quatro repeticoes num esquema de parcelas subdivididas. Foram utilizados, nas parcelas, dois sistemas de manejo de solo, o sistema convencional e sistema de semeadura direta e seis cultivares de amendoim de habito de crescimento contrastante, um de porte ereto e cinco de porte rasteiro, nas subparcelas. Nao houve diferenca entre os sistemas de manejo conservacionista e convencional no rendimento de vagens e graos, no numero de estruturas reprodutivas nem no indice de rendimento de graos do amendoim, nos dois locais avaliados. No municipio de Marechal Cândido Rondon as maiores produtividades foram obtidas pelos cultivares IAC 503, IAC Caiapo, IAC 213, Runner IAC 886 e Cavalo, respectivamente, independentemente do sistema de manejo de solo. Em Tupassi a produtividade de graos variou apenas entre os tipos de ramificacao dos materiais cujos maiores valores foram observados para cultivares de ramificacao alternada (Virginia).