ABSTRACT The Least Limiting Water Range (LLWR) is an indicator of soil physical quality, contributing in information to propose soil management systems in agricultural farming process. This work aimed to assess the usage of LLWR and critical soil bulk density for physical-water quality evaluations, as well as its effect on sugarcane farming under no-tillage and reduced-tillage, in Oxisol. Undisturbed soil samples were collected in 0.00-0.10 and 0.10-0.20 m soil layers, to determine the following attributes: soil bulk density, soil penetration resistance (PR), volumetric water content at field capacity and permanent wilting point and minimum aeration porosity. The LLWR proved to be a good soil physical water quality indicator in sugarcane farming under conservation tillage system. No-tillage presented a greater range of the LLWR when compared to the reduced-tillage, regardless to the PR value adopted as restrictive for sugarcane roots development, increasing the yield of stalks and sugars contents. The critical soil bulk density under no-tillage is between 1.48 and 1.53 Mg m-3 at the RP of 2 and 4 MPa, while under reduced-tillage it is between 1.44 and 1.51 Mg m-3.

RESUMO A busca pela otimização dos sistemas agrícolas, por meio da adequação dos conjuntos mecanizados na semeadura do milho, é essencial visando a melhoria do desempenho operacional, da eficiência energética e do estabelecimento inicial da cultura. Neste contexto, objetivou-se avaliar o desempenho de uma semeadora-adubadora e a qualidade da semeadura do milho, em Latossolo Vermelho Distroférrico manejado sob preparo reduzido, em função do tipo de sulcador, da profundidade de deposição da semente e da velocidade da operação de semeadura. O delineamento experimental foi inteiramente casualizado, em esquema de parcelas subdivididas com três repetições, sendo as parcelas o tipo de mecanismo sulcador (haste sulcadora ou disco-duplo) e as subparcelas três velocidades de deslocamento (3,20; 5,15; 7,32 km h-1) e duas profundidades de semeadura (35 e 40 mm). A melhor qualidade de semeadura do milho segunda safra, a menor exigência de força na barra de tração do trator, os menores consumos específico e horário de combustível e a menor taxa de redução de percurso são obtidos quando o disco-duplo e a profundidade de deposição de sementes de 35 mm são usados na configuração do conjunto trator-semeadora-adubadora. A adoção de velocidades de deslocamento maiores resulta em aumento das capacidades de campo operacional e efetiva, bem como menor demanda energética na semeadura do milho quando o conjunto trator-semeadora-adubadora desenvolve velocidade próximo ou superior a 7,32 km h-1, independentemente do sulcador e da profundidade do solo.

ABSTRACT The search to optimise agricultural systems by adapting mechanised sets for sowing maize, is essential for improving operational performance, energy efficiency and initial crop establishment. The aim of this study was to evaluate the performance and sowing quality of a planter-fertiliser for maize, in a dystroferric Red Latosol managed under reduced tillage, as a function of the type of furrower, depth of seed deposition and operating speed of the planter. The experimental design was completely randomised, in a split-plot scheme with three replications, where the plots represented the type of furrowing mechanism (shank or double-disk) and the subplots represented three displacement speeds (3.20, 5.15 and 7.32 km h-1) and two sowing depths (35 and 40 mm). The best sowing quality for second-crop maize, the lowest power requirement at the tractor drawbar, the lowest specific and hourly fuel and consumption time, and the lowest travel reduction ratio are achieved when the tractor-planter-fertiliser set is configured to use a double-disk at a sowing depth of 35 mm. The adoption of higher displacement speeds results in increased operational and effective field capacity, as well as a lower energy demand when the tractor-planterfertiliser set develops speeds close to or greater than 7.32 km h-1, irrespective of furrower type or soil depth.