Machine traffic and conventional tillage can cause structural degradation of the soil, affecting the physical attributes and, consequently, the production and longevity of the sugarcane field. The objective of this study was to evaluate the production components of sugarcane cultivars (RB965902, RB985476, RB966928, RB855156, RB975201, RB975242, RB036066 and RB855536) and physical attributes of a Dystroferric Red Latosol (Oxisol) under no-tillage and reduced-tillage systems. The experiment was conducted using a completely randomized experimental design in an 8 × 2 factorial arrangement, with four replicates. The soil attributes evaluated were density, total porosity, macroporosity, microporosity and penetration resistance. The production components evaluated were stalk length and diameter, number of tillers (NT), tons of cane per hectare (TCH), sucrose content (Pol), tons of sucrose per hectare (TPH), soluble solids content (Brix), total recoverable sugars (TRS) and plant fiber. Cultivars RB965902, RB966928, RB855156 and RB985476 have productivity and technological attributes that are superior to the other cultivars, whereas these are lower for RB036066 in both soil tillage systems. Cultivars RB966928, RB855156, RB975242 and RB855536 exhibited higher TCH and TPH in the no-tillage system, and all cultivars displayed equal or higher performances than those observed in the reduced-tillage system. In the no-tillage system, which exhibits lower penetration resistance values between wheel tracks and in the subsurface layer of the planting row (0.20-0.40 m), cultivars RB985476 and RB975242 had a higher NT, and RB855156 had higher stalk lengths and NT.

O estabelecimento de manejos conservacionistas do solo traz benefícios em sistemas de produção de culturas anuais, mas para a cana-de-açúcar são incipientes as informações sobre tais efeitos na qualidade de solos. Objetivou-se avaliar os sistemas de preparo reduzido e plantio direto, bem como o local de amostragem nos atributos físicos de um Latossolo Vermelho Distroférrico cultivado com cana-planta. O trabalho foi realizado na Universidade Federal da Grande Dourados (UFGD), onde a área experimental foi dividida em duas subáreas, compostas pelo plantio direto e preparo reduzido. Em cada preparo foram plantadas oito cultivares de cana-de-açúcar em delineamento inteiramente casualizado, com quatro repetições. Nas unidades experimentais, coletaram-se amostras de solo com estrutura preservada na linha e na entrelinha do rodado do trator para avaliação da densidade do solo; macroporosidade; microporosidade; porosidade total; umidade gravimétrica do solo e resistência à penetração no anel com penetrômetro de bancada (RP anel), nas camadas de 0,00-0,10 e 0,10-0,20 m. Além das referidas posições de amostragem, considerou-se também a da linha de cana para avaliar a resistência mecânica do solo à penetração (RP) com penetrômetro de campo, determinando-se a RP média e máxima, nas camadas de 0,00-0,10; 0,10-0,20; 0,20-0,30; 0,30-0,40 m. O preparo reduzido aumentou a macroporosidade na camada superficial. Não houve efeito do preparo para porosidade total e microporosidade. Na camada (0,00-0,40 m) ocorreu redução da RP média e máxima, do rodado, seguida do entrerrodado e linha de plantio, respectivamente; além de maiores valores destes atributos na camada (0,20-0,40 m) da linha de plantio.

Objetivou-se avaliar os atributos físicos de um Latossolo Vermelho Distroférrico cultivado com cana-planta em função do preparo e época de amostragem. O trabalho foi conduzido na FAECA-UFGD, em um Latossolo Vermelho Distroférrico, onde a área experimental foi dividida em duas subáreas, compostas pelo sistema plantio direto (SPD) e preparo reduzido (PR). Em cada tipo de preparo foram cultivadas oito cultivares de cana-de-açúcar em delineamento inteiramente casualizado, com quatro repetições. Nas unidades experimentais, amostras com estrutura preservada foram coletadas após o preparo do solo (45 DAP) e após os tratos culturais (180 DAP), para determinação da densidade do solo, porosidade total, macroporosidade, microporosidade e resistência mecânica do solo à penetração nas camadas de 0,00-0,10 e 0,10-0,20 m. O SPD apresentou maior densidade e resistência do solo à penetração na camada de 0,00-0,10 m, enquanto os demais atributos físicos não foram influenciados pelo preparo do solo. Houve aumento da densidade do solo, porosidade total, microporosidade e resistência do solo à penetração e diminuição da macroporosidade nas camadas de 0,00-0,10 e 0,10-0,20 m após o tráfego de máquinas para tratos culturais.

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 notillage 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 .

The marked growth of the sugar and alcohol sector has promoted an increase in the fleet of heavy agricultural vehicles to meet the demand for commodities; however, the intense traffic of machines in areas of insufficient soil moisture has resulted in compaction, compromising the productivity of the sugar cane. In order to determine the optimal conditions for resuming the use of tractors under a reduced tillage system, the bearing capacity was evaluated and stress distribution was modelled in a dystroferric Red Latosol cultivated with sugar cane. Soil sampling was carried out during the first ratoon crop at 120 days, using metallic cylinders installed at a depth of 0.05 m in the crop rows and 0.15 m between rows. The samples were submitted to the uniaxial compression test to determine the preconsolidation pressure of the soil. The reduced tillage gave the lowest bearing capacity at the soil surface (0.05 m), while the highest values ​​were found at a depth of 0.15 m. The bearing capacity proved to be an efficient indicator for analysing the structural degradation of the soil by demonstrating the compressibility of the various layers and sampling positions resulting from reduced tillage and the impact of agricultural machines in the field. The prediction model for traction and soil stress distribution that was employed was able to predict the optimal performance of the tractor, and provide stress data that would allow a study of the limiting water content for the traffic of agricultural tyre tractors.