O sistema de plantio pode influenciar atributos físicos e químicos do solo, alterando o desenvolvimento das raízes das culturas. O objetivo deste trabalho foi avaliar o efeito do sistema plantio direto (PD) e o do preparo convencional (PC) e o uso de calcário (0 e 2,0 t ha-1) no sistema radicular da cana-de-açúcar. Este estudo foi realizado em Latossolo Vermelho eutroférrico, em experimento de longa duração, iniciado em 1998, após três ciclos de quatro anos com colheita sem queima da palha. Foram realizadas coletas de amostras de solo para avaliação de alguns atributos físicos (densidade, porosidade e resistência à penetração) e de fertilidade do solo. Para a coleta de raízes, foi utilizada sonda amostradora em quatro épocas definidas pelo balanço hídrico da região, sendo a amostragem realizada em seis pontos equidistantes à linha da soqueira, em camadas de 0,20 m até 1,0 m de profundidade. O PD e o uso de calcário resultaram em valores mais elevados dos atributos relacionados à aplicação do calcário, como V% e teores de Ca, apenas na camada superficial. Os valores de densidade e resistência foram mais elevados no PD e na entrelinha. Na linha de plantio, não houve diferença entre os tratamentos. A cana-de-açúcar manteve, em média, cerca de 4,0 t ha-1 de raízes no solo na camada até 1,0 m de profundidade. Houve diferença significativa entre as camadas e as posições de amostragem e, embora as raízes da cana-de-açúcar se concentrem na superfície e próximo da soqueira, 25 a 30 % das raízes estão na entrelinha (0,6 m da soqueira) e 15 a 30 % estão abaixo de 0,60 m, indicando que as raízes da cana-de-açúcar exploram grande volume de solo. A variação na quantidade de raízes foi mais influenciada pela condição hídrica do solo do que pelas práticas de manejo. A maior quantidade de raiz foi determinada no máximo excedente hídrico; e a menor, na época de reposição hídrica do solo. As maiores variações na quantidade de raízes entre épocas foram observadas no PC e sem aplicação de calcário. Os tratamentos PD e com calcário mantiveram a massa radicular com menor variação ao longo das épocas de amostragem. As alterações físicas e químicas do solo por influência do PD e calcário não foram suficientes para alterar significativamente o desenvolvimento do sistema radicular da cana-de-açúcar.

Seeking to provide essential information about sustainable tillage systems, this work aimed to assess the effects of liming and soil cultivation systems on the soil hydrophysical attributes of a long-term cultivated sugarcane field in the tropical region of southeast Brazil. Infiltration tests and soil sampling down to 0.10 m were performed in order to determine saturated soil hydraulic conductivity, soil bulk density, soil total porosity, macroporosity, microporosity, and soil resistance to penetration. The studied areas include no-tillage (NT) and conventional tillage (CT) systems with 0 (CT0 and NT0) and 4 (CT4 and NT4) Mg ha⁻¹ of lime, and an adjoining area with native forest (NF). The data analysis included an analysis of variance followed by the Tukey test to compare different systems, assessment of the Pearson correlation coefficient between variables, and a principal component analysis of the dataset. The lowest bulk density and highest soil total porosity, macroporosity and saturated hydraulic conductivity were found in the NF. The bulk density in CT4 and NT0 was higher than in other systems, indicating the need for amelioration. NT4 is suggested as the most viable system for conservation agriculture in sugarcane fields, combining the benefits of no-tillage and liming to enhance soil hydrophysical functions.

Summary: The root elongation rate represents a biophysical process that can be directly affected by mechanical, water, thermal, and gaseous stresses in the soil to be used as a soil physical quality indicator. The objective of this study was to determine sugarcane root growth parameters under soil physical stress for different root diameter classes in an Oxisol from the Southeast of Brazil. The experimental design was entirely randomized in a factorial scheme 5 × 2 (mechanical × water stress) with three replications. The factor mechanical stress was composed of five compaction levels (1.04; 1.12; 1.19; 1.28; 1.36 Mg m^–3). The factor water stress was composed of two matric potentials (–6 kPa and –33 kPa). Soil samples were collected from the 0.0–0.2 m layer of an Oxisol with a clayey texture. Pre-sprouted sugarcane seedlings were transplanted and conditioned in a growth chamber. Root length, volume, surface area, and diameter were quantified to generate root growth models as a function of physical stresses in the soil. Soil penetration resistance increases from 1.4 to 5 MPa reduced root elongation rate from 3.5 to 1.35 cm day^–1 (–59%) and the average number of roots from 11 to 6 segments (–45%), respectively. The root volume, surface area, and length were reduced because of the increase in the compaction level. Coarse root diameter (1–2 mm) was weakly impacted by mechanical stress, whereas fine root diameter (0.5–1 mm) was more growth limited in compacted soils. The root elongation rate of sugarcane was modelled as a function of mechanical and water stress. Mechanical stress mainly affects the growth of sugarcane roots with small diameter.

Conservation agriculture principles applied to peanut can reduce soil erosion and production costs when cultivated in rotation with sugarcane. Still, the problem with soil compaction is the leading cause of skepticism about the efficacy of this practice. This research aimed to study the effect of three soil management strategies compared with conventional for peanut cv. IAC-OL3, cultivated in rotation with sugarcane using the MEIOSI (method of intercropping occurring simultaneously) system for agronomic practices with additional analysis on changes in soil physics properties. The trial was conducted in 2019-2020 in Planalto municipality (São Paulo, Brazil) under a green-harvested sugarcane field, using a randomized complete block experimental design. The trial consisted of four soil management treatments (conventional tillage, minimum tillage with chisel, strip-tillage, and no-tillage) with five replications. Although no differences were verified in soil bulk density and porosity among treatments, the highest values of soil penetration resistance were observed in no-tillage treatment for all evaluations (before planting, at the beginning of flowering, and before and after harvesting) in comparison with conventional tillage. The difference in soil penetration resistance among the treatments diminished from planting to the end of the cycle. Furthermore, low soil disturbance and maximum covering with straw significantly increased the available water capacity and reduced the incidence and severity of groundnut ringspot virus (GRSV) on peanut plants. Consequently, both minimum-tillage and no-tillage have increased the pod yield on average by 695 and 991 kg ha ^-1 more than strip-tillage and conventional tillage, respectively, without differences in terms of quality and pod losses.

Estimating stability and adaptability parameters of cultivars is a widely used study to access the genotype × environment interaction, in order to identify the best genotypes for each cultivation area. In this study, the adaptability and stability parameters were estimated in eight high-oleic lines and two peanut cultivars in 11 experiments in the State of São Paulo, Brazil, from 2008 to 2013, based on the data of the plots mean productivity (Kg·ha^–1), with the objective of recommending the most productive genotypes in peanut producing regions in the State of São Paulo. The design used for these experiments was the randomized complete blocks, with four replications. Lines L. 599 and L. 551 were the best genotypes regarding overall adaptability and stability in yield, considering the methods of Eberhart and Russell and of Lin and Binns modified by Carneiro. Results produced by both methods were convergent as for the classification of the lines, and the use of one of them would not be detrimental to the recommendation of productive lines associated to production adaptability and stability. The overall adaptability in addition to the stability in the productivity of the lines here evaluated showed outstanding performance in relation to the cultivars IAC Caiapó and Runner IAC 886.