This study aimed to describe the behavior of models for adjusting data of soil penetration resistance for variations in soil moisture and soil bulk density. The study was carried out in Lucas do Rio Verde, MT, Brazil in a typic dystrophic red-yellow Latosol (Oxisol) containing 0.366 kg kg −1 of clay. Soil penetration resistance measurements were conducted in the soil moistures of 0.33 kg kg −1 , 0.28 kg kg −1 , 0.25 kg kg −1 and 0.22 kg kg −1 . Soil penetration resistance behavior due to variations in soil moisture and soil bulk density was assessed by estimating the soil resistance values by non-linear models. There was an increase of the soil penetration resistance values as soil was losing moisture. For the same edaphic condition studied, small differences in the data of soil bulk density affect differently the response of soil resistance as a function of moisture. Both soil bulk density and soil moisture are essential attributes to explain the variatio ns in soil penetration resistance in the field. The good representation of the critical soil bulk density curve as a limiting compression indicator requires the proper choice of the restrictive soil resistance value for each crop.KEY WORDS: soil compaction, pedotransfer functions, cone index. MODELAGEM E CORREÇÃO DA RESISTÊNCIA DO SOLO À PENETRAÇÃO PARA VARIAÇÕES NA UMIDADE E DENSIDADE DO SOLORESUMO: O presente trabalho buscou descrever o comportamento de modelos para ajustes dos dados de resistência do solo à penetração para variações na umidade e na densidade do solo. O trabalho foi realizado no município de Lucas do Rio Verde-MT, em Latossolo Vermelho-Amarelo distrófico típico contendo 0,366 kg kg -1 argila. As determinações da resistência do solo à penetração ocorreram nas umidades de solo de 0,33 kg kg -1 , 0,28 kg kg -1 , 0,25 kg kg -1 , 0,22 kg kg -1 . O comportamento da resistência do solo à penetração, em função de variações na umidade e densidade do solo, foi avaliado pela estimativa nos valores de resistência do solo por modelos não lineares. Houve aumento dos valores de resistência do solo à penetração, à medida que o solo foi perdendo umidade. Para uma mesma condição edáfica estudada, pequenas variações nos dados de densidade do solo afetam diferentemente a resposta da resistência do solo em função da umidade. A densidade do solo é atributo imprescindível para explicar as variações na resistência do solo à penetração em campo, tanto quando a umidade do solo. A boa representação da curva de densidade crítica do solo como indicador de compactação limitante requer a escolha adequada do valor de resistência do solo restritivo para cada cultura. PALAVRAS -CHAVE:compactação do solo, funções de pedotransferência, índice de cone.

Corn grown as second-crop (safrinha) immediately after soybeans contributes to Brazil’s recent sustainable intensification of efforts to land spare and reduce deforestation. Brazil’s Mato Grosso state is very important for corn production with a large number of available hybrids for producers with different characteristics. Evaluating as many hybrids as possible increases the likelihood of identifying those that are more productive. Our experiment used a randomized block design to evaluate 20 corn hybrids for yield and quality in the western Cerrado savannah region of Mato Grosso state. There were significant differences in silage quality and grain yield between hybrids. Silage quality was correlated with higher grain yield. Corn grain yields for 10 higher-yielding hybrids (average = 11,425 kg/hectare) were significantly greater than the two lowest yielding hybrids (6974 and 8207 kg/hectare) and 64% more than the 2020 average in Mato Grosso. Precipitation was not limiting during our experiment but may be in the drier Cerrado area and during other years. Higher silage quality with lower lignin content and higher in vitro digestibility can improve beef productivity as Brazil transitions from extensive grazing to more intensified systems such as pasture supplementation. Increasing corn grain yields in Mato Grosso can hedge against lower crop yields elsewhere.

Soil turning during pre-seeding preparation is meant to loosen and promote physical characteristics responsible for the development of crop roots in soil. In this study, we demonstrate effects of three methods of pre-seeding preparation at two depths of irrigation on carbon dioxide (CO2) efflux as well as the temporal variability in the distribution of soil carbon. This experiment was conducted at the rural cooperative extension research station in Tangará da Serra, Mato Grosso, Brazil, for two wheat production years in 2011 and 2012. The experimental design was randomized in strips, with four repetitions. Wheat was irrigated during the June to early October dry season. The treatments include two methods of soil preparation: traditional preparation with one plowing and two disc harrowings and minimal preparation with one seed bed conditioner pass. A third treatment of direct seeding was also evaluated. Soil CO2 efflux, soil temperature, air-filled soil porosity, and labile carbon were measured. We found soil preparation affects CO2 efflux in irrigated cultivation systems within Brazil’s Cerrado savannah, with conventional tillage having greater CO2 emissions than either reduced tillage or direct seeding. Soil CO2 emissions were lower at 508 mm versus 698 mm irrigation depth, but wheat yields were significantly lower.