Corn (Zea mays L.) is highly adaptable, but it has difficulties in expressing its productive potential in soils with high aluminum content, since this element is directly related to high acidity in the soil. The objective of this study was to evaluate the nitrogen compounds, proteins and amino acids of two corn cultivars subjected to increasing doses of aluminum. The experiment was carried out in a greenhouse using one of the corn plants from varieties BRS 106 and BRS 4157. The experimental design was entirely randomized, in a factorial design of 5x2, and the factors were composed of five doses of Al 3+ (0; 50; 100; 150 and 200 mmol L-1), with five repetitions. The variables analyzed were the concentration of nitrate, the activity of the nitrate reductase, concentration of ammonium, amino acids and proteins. There was a decrease in nitrate, activity of the Reductase enzyme of the Nitrate and protein in the highest dose of aluminum (200 mmol L-1) for both cultivars. There was an increase in ammonium and amino acids in the leaves of cultivars BRS 106 and BRS 4157. Cultivars BRS 106 and BRS 4157 were affected by the increasing doses of aluminum, but cultivar BRS 106 showed to be more tolerant.

<p>Soil is a major source and also a sink of CO<sub>2</sub>. Agricultural management practices influence soil  carbon sequestration. Identification of CO<sub>2</sub> emission hotspots may be instrumental in implemented strategies for managing carbon cycling in agricultural soils. We used multifractal analysis to assess the spatial variability of both, soil CO<sub>2</sub> emissions and associated soil physico-chemical attributes. The objectives of this study were: i) to characterize patterns of spatial variability of CO<sub>2</sub> emissions and related soil properties using single multifractal spectra, and ii) to compare the scale‐dependent relationship between soil CO<sub>2</sub> emissions and selected soil attributes by joint multifractal analysis. The study site was an experimental field managed as a sylvopastoral system, located in Selviria, South Mato Grosso state, Brazil. The soil was an Oxisol developed over basalt. Soil CO<sub>2 </sub>emission, soil water content and soil temperature were measured at 128 points every meter. In addition<strong>, </strong>soil was sampled at the marked points to analyze clay content, macro and microporosity, air free porosity, magnetic susceptibility, bulk density, and humification index of soil organic matter in absolute values and relative to organic carbon content. The generalized dimension, D<sub>q</sub> versus q, and singularity spectra, f(α) versus α, of the spatial distributions of the 11 variables studied showed various degrees of multifractality. In general, the amplitude of the generalized dimension and singularity spectra was much higher for negative than for positive q order statistical moments. Joint multifractal spectra show a positive relationship between the scaling indices of the spatial distributions of CO<sub>2</sub> and all of the other soil variables studied. However, contour plots were diagonally oriented for higher values of scaling indices and showed no distinct trend for the lower ones. Joint multifractal analysis corroborates different degrees of association between the scaling indices of CO<sub>2</sub> and all of the remaining variables studied. It also showed that CO<sub>2</sub> was stronger correlated at multiple scales than at the observation scale. Therefore, single scale analysis may not be sufficient to fully describe relationships between soil testing methods.Our study suggests that soil factors and processes driven the spatial variability of CO<sub>2</sub> and the associated variables studied may be not very different.</p><p> </p>

Core Ideas The use of soil management at line (alone) reduces the CO2 emission. The higher soil aggregation favorece the higher CO2 emission. The soil management at line (alone) improve the lower soil desegregation. The objective was to determine the influence of partial cultivation of only the crop row on carbon dioxide (CO2) emissions in an Oxisol and Ultisol. The experimental design was a large paired‐plot design with treatments consisting of targeted chiseling to only the planting row to chiseling the whole field. Soil CO2 emissions, soil temperature, and soil moisture were measured daily for 12 d after tillage. In the Oxisol, CO2 emissions were higher on the second day after tillage and then decreased until Day 6. When analyzing the effect of tillage, chiseling in the planting row (CPR) showed, in general, lower CO2 emissions (2.54 µmol m−2 s−1) when compared to chiseling in total area (CTA) (3.32 µmol m−2 s−1), regardless of the day after tillage. However, the linear regression analysis between soil CO2 emissions and soil moisture in the Ultisol was significant for CPR (R2 = 0.79, p < 0.01) and CTA (R2 = 0.58, p < 0.01). Total soil CO2 emissions were higher in the Oxisol for both tillage systems (CPR = 1020.9 kg CO2 ha−1 and CTA = 1336.3 kg CO2 ha−1) than the Ultisol (CPR = 587.0 kg CO2 ha−1 and CTA = 649.3 kg CO2 ha−1). These results indicate that soil tillage by using CPR favors a lower soil CO2 emission to the atmosphere and contributes to a reduction in soil degradation when cultivated with sugarcane (Saccharum officinarum L.).

The objective of this study was to evaluate the influence of minerals in the clay fraction on physical attributes of Yellow Ultisol cultivated with sugarcane and prepared with two different treatments: chiseling across the entire area and chiseling only in planting rows. The samples were collected from four layers of soil at eight months after planting. We assessed the texture of the soil, levels of iron extracted by dithionite-citrate-bicarbonate (DCB) and ammonium acid oxalate (AAO), ratio of kaolinite/(kaolinite + gibbsite), soil bulk density, and soil penetration resistance. The first area showed a higher ratio of kaolinite/(kaolinite + gibbsite) and the second area had greater levels of iron extracted by DCB. Levels of iron extracted by DCB were inversely correlated with soil bulk density and penetration resistance, while the kaolinite/(kaolinite + gibbsite) ratio was directly correlated with soil bulk density and penetration resistance. The area with a greater kaolinite/(kaolinite + gibbsite) ratio had higher values of soil bulk density and soil penetration resistance and the area with higher levels of iron showed lower values of soil bulk density and soil penetration resistance. The mineralogy influenced the soil's physical attributes, while soil preparation treatments did not.