Cícero Célio de Figueiredo

Labile and stable fractions of soil organic matter under management systems and native cerrado

SUMMARY Soil organic matter can be analyzed on the basis of the different fractions. Changes in the levels of organic matter, caused by land use, can be better understood by alterations in the different compartments. The aim of this study was to evaluate the effect of different management systems on the labile and stable organic matter of a dystrophic Red Latosol (Oxisol). The following properties were determined: total organic C and total N (TOC and TN), particulate organic C and particulate N (POC and PN), organic C and N mineral-associated (MOC and NM) and particulate organic C associated with aggregate classes (POCA). Eight treatments were used: seven with soil management systems and one with native Cerrado as a reference. The experiment was designed to study the dynamics of systems of tillage and crop rotation, alternating in time and space. The experimental design was a randomized block design with three replications. The soil samples were collected from five depths: 0–5, 5-10, 10–20, 20–30 and 30–40 cm. Changes in organic C by land use occurred mainly in the fraction of particulate organic matter (> 53 mm). Proper management of grazing promoted increased levels of particulate organic matter by association with larger aggregates (2–8 mm), demonstrating the importance of the formation of this aggregate class for C protection in pasture.

Sistemas de manejo na absorção de nitrogênio pelo milho em um Latossolo Vermelho no Cerrado

The objective of this work was to evaluate the effect of different management systems on nitrogen absorption by corn in an Oxisol in the Cerrado. Total nitrogen (Ntotal), soil and mineral fertilizer derived nitrogen (Ndsolo and Ndfm, respectively), and N-fertilizer recovery efficiency (ERNF) taken by corn were determined. Eight management systems comprised by different implements and crop residues incorporation times were studied. The sampling plan was accomplished by simple random sampling. The soil was the main N source. Under no-till or minimum tillage, corn grains showed greater N content (Ntotal, Ndfm, and Ndsolo), as well as ERNF, than under moldboard plow with crop residues incorporated after harvesting treatment. The disk and moldboards action plows on soil properties as well as crop residues incorporation time, before planting and after harvesting, did not affect the N content in the corn grains (Ntotal and Ndfm), although they presented differences in the absorption dynamics related to N fertilizer broadcasting periods .

Propriedades físico-hídricas em Latossolo do Cerrado sob diferentes sistemas de manejo

The objective of this study was to evaluate the physico-hydric soil properties under different management systems in comparison with the native Cerrado, in Santo Antonio de Goias, Goias State, in areas cultivated since 1993. The evaluated systems in the depths of 0 - 0.10 and 0.10 - 0.20 m were: system S1 (soybean/bean/rice/pearl millet /bean), system S2 (soybean/pearl millet/corn), system S3 (corn + Brachiaria brizantha in integrated crop-livestock system) and system S4 (native cerrado). To compare the results obtained in the several soil management systems, the interval of confidence was used, at a probability level of 5%. The use of area under Brachiaria brizantha pasture for animal grazing caused compaction of the soil in the surface layer, verified through the reduction of the macroporosity, and increase of the microporosity and soil bulk density.

Methods of soil organic carbon determination in Brazilian savannah soils

Several methods exist for determining soil organic carbon, and each one has its own advantages and limitations. Consequently, a comparison of the experimental results obtained when these methods are employed is hampered, causing problems in the comparison of carbon stocks in soils. This study aimed at evaluating the analytical procedures used in the determination of carbon and their relationships with soil mineralogy and texture. Wet combustion methods, including Walkley-Black, Mebius and Colorimetric determination as well as dry combustion methods, such as Elemental and Gravimetric Analysis were used. Quantitative textural and mineralogical (kaolinite, goethite and gibbsite) analyses were also carried out. The wet digestion methods underestimated the concentration of organic carbon, while the gravimetric method overestimated. Soil mineralogy interfered with the determination of carbon, with emphasis on the gravimetric method that was greatly influenced by gibbsite.

Chemical composition of cover plants and its effect on maize yield in no-tillage systems in the Brazilian savanna

Abstract. The use of cover plants is an important agricultural practice in no-tillage systems. Soil cover and nutrient recycling depend on the dynamics of plant residue decomposition. The objective of this study was to evaluate the effect of the chemical composition and decomposition rates of cover plants on maize yield in no-tillage systems in the savannah, central Brazil. Levels of hemicellulose, cellulose, and lignin, along with decomposition rates of the following plant species were determined at flowering and maturation: Urochloa ruziziensis, Cajanus cajan, Canavalia brasiliensis, Crotalaria juncea, Mucuna aterrima, Pennisetum glaucum, Raphanus sativus, Sorghum bicolor, and Triticum aestivum. Spontaneous vegetation growth in the fallow was used as a control. The highest dry matter yields were obtained from Sorghum bicolor, followed by P. glaucum, when harvested at maturation. Canavalia brasiliensis and U. ruziziensis, the species with lowest lignin levels, presented faster decomposition and lower half-life values compared with the residues of C. cajan and S. bicolor. Cover plants with the lowest lignin concentrations, and thus the fastest residue decomposition rates, such as C. brasiliensis, U. ruziziensis, and P. glaucum, resulted in higher maize yields. Urochloa ruziziensis and C. brasiliensis contributed to nutrient recycling due to their faster decomposition, while C. cajan aids in the formation of soil cover due to slower decomposition of its residues.

Intensidade-duração-frequência de chuvas para o Estado de Mato Grosso do Sul

Rain intensity data are necessary to increase security of hydraulic projects. The objective of this study was to determine the rain storm equations and the spatial distribution of rain intensity for the State of Mato Grosso do Sul, Brazil. The equations were obtained by disaggregation of 24 h rain data from 109 pluviometric stations available in the National Water Agency (ANA) data bank. These equations resulted in coefficients of determination above 0,99 for all localities. The adjusted parameters showed high variability, resulting from different rain intensities in different places of the State. The interpolation of data allowed good visualization of the differences, evidencing higher intensities of rains in the central and northern regions and lower intensities in the southeastern and southwestern regions of the State. These results demonstrated the importance of intensity-duration-frequency relationship and its use for studies and hydraulic projects based on data from each place.

Adubo fosfatado revestido com polímero e calagem na produção e parâmetros morfológicos de milho

The low availability of phosphorus in acid soils, such as those of the Cerrado, requires the efficient management of phosphorus fertilization. The use of technologies that increase the efficiency of phosphorus use is an alternative that can be adopted, provided the reality of Brazilian soils is taken into consideration. This work was carried out to evaluate the effect of polymer-coated phosphate fertilizer associated with liming on the production and morphological parameters of corn crops. The study was conducted in the field, in a red-yellow latosol. The experimental design was of randomized blocks arranged in a 2 x 4 factorial, with three replications. The treatments resulted from a combination of two sources of phosphorus (conventional MAP and polymer-coated MAP - Kimcoat ®) at four levels of saturation (27%, 40%, 50% and 60%). The sources of phosphorus displayed differences dependent on the base levels of saturation. The polymer-coated MAP improved the performance of corn, for productivity, total dry-matter yield and plant height, in relation to conventional MAP. The major differences were observed at base saturation levels of 40% and 50%, in which the coated MAP promoted an increase in grain yield of 3.40 and 3.48 t ha-1, respectively, compared to conventional MAP.

Stratification ratio of organic matter pools influenced by management systems in a weathered Oxisol from a tropical agro-ecoregion in Brazil

Enhancement of organic matter plays an essential role in improving soil quality for supporting sustainable food production. Changes in carbon stocks with impacts on emissions of greenhouse gases may result from the stratification of organic matter as a result of soil use. The objective of this study was to evaluate the impact of soil management systems on soil carbon stocks and stratification ratios (SR) of soil organic matter pools. Total organic carbon (TOC), particulate organic carbon (POC), mineral-associated organic carbon, microbial biomass carbon (MBC) and nitrogen, basal respiration, and particulate organic matter nitrogen (PON) were determined. The field experiment comprised several tillage treatments: conventional tillage, no-till with biannual rotation, no-till with biannual rotation combined with a second crop, no-till with annual rotation, and pasture. The labile fractions indicated a high level of variation among management systems. Pasture proved to be an excellent option for the improvement of soil carbon. While the conventional tillage system reduced total carbon stocks of the soil (0–40 cm), no-tillage presented TOC stocks similar to that of native vegetation. Sensitivity of the TOC SR varied from 0.93 to 1.28, a range of 0.35; the range for POC was 1.76 and for MBC 1.64. The results support the hypothesis that the labile fractions (POC, MBC, and PON) are highly sensitive to the dynamics of organic matter in highly weathered soils of tropical regions influenced by different management systems. Reductions to SRs of labile organic matter pools are related to the impacts of agricultural use of Cerrado soils.

Is sewage sludge biochar capable of replacing inorganic fertilizers for corn production? Evidence from a two-year field experiment

ABSTRACT Sewage sludge (SS) is a by-product of wastewater treatment resulting from human and industrial activities. This waste is problematic because it is difficult to manage due to its volume and environmental impacts; therefore, new technologies for treatment are needed to make its final disposal feasible. Such technologies include the pyrolysis process that produces biochar, which can be used for agricultural purposes. The present study reports a two-year field experiment with SS biochar produced under different pyrolysis temperatures and its application to soil in combination with mineral fertilizer to evaluate its effect on soil chemical properties and on corn nutrition and yield. To conduct this evaluation, 15 Mg ha−1 of SS biochar combined or not with mineral fertilizer (NPK) was applied to the soil in the 2015 and 2016 cropping seasons. SS biochar increased soil chemical attributes, especially phosphorus, magnesium, cation exchange capacity and base saturation. Biochar resulted in a greater absorption of nutrients by plants and higher corn yields. However, SS biochar alone was incapable of increasing K uptake by corn. It was concluded that the application of SS biochar can replace mineral fertilizers (nitrogen, phosphorus and micronutrients) for corn production.

Matéria orgânica e infiltração da água em solo sob consórcio milho e forrageiras

Infiltration is a process by which water penetrates through the soil by its surface, and its dynamics can be influenced by several factors, among them, the soil management system adopted. The objective of this work was to estimate water infiltration rate and soil organic matter content in maize and forage intercropping systems. The experiment was conducted in a randomized block design with three replications. Five treatments under no-tillage management were evaluated: 1) Corn (Zea mays L. ), 2) Brachiaria humidicola (Brachiaria humidicola), 3) Corn and Brachiaria humidicola intercropping, 4) Aruana grass (Panicum maximum cv. Aruana), 5) Corn and Aruana grass intercropping. The double ring infiltrometer method was used to determine the basic infiltration rate (VIB). Soil physical properties and soil organic matter were evaluated and correlated with VIB values. Results revealed high VIB values for no-tillage. The highest VIB values were observed in the corn treatment. VIB values decreased with the inclusion of forages. All cultivation systems showed a decrease of organic matter with depth.