Red-Yellow Latosol Research Articles

SOIL DENSITY AND OPTIMUM MOISTURE FOR SOIL COMPACTION IN FIVE SOIL CLASSES IN WESTERN BAHIA STATE

The transformation of natural ecosystems into agricultural environments modifies the soil structure and it may result in its compaction. Therefore, the objective of this work was to determine the optimum moisture for soil compaction (wot) and maximum soil compaction density (Dsmax) in different soil classes in western Bahia State. The samples were collected in five sites covering different soil classes: Orthic Quartzarenic Neosol (RQ), Orthic Ebanic Vertisol (VEo), Haplic Cambisol (CX) and two Red-Yellow Latosol, one already cropped (LVA) and another with native forest (LVA1). Wot and Dsmax were determined according to ABNT NBR 7182 (1986) standards. Data were submitted to a regression analysis and also to the analysis of the principal components (PCA). Wot presented a decreasing order: VEo> LVA> LVA1> CX> RQo, ranging between 8.20 and 15.00% and Dsmax showed the following order RQo> LVA> LVA1> CX> VE, ranging between 1.34 and 1,92 Mg.m-3. The wot was directly proportional to the clay content and the organic carbon and inversely proportional to the soil sand content. For Dsmax, the influence of the clay was inversely proportional whereas in wot, this variable promoted the growth.

Ammonia loss from protected urea in soil under different irrigation depths

This study presents an evaluation of the viability of using protected urea under different irrigation depths to reduce nitrogen losses caused by the volatilization of ammonia (NH3) under the conditions of the Southwestern Amazon. The study was carried out at the Experimental Station of Embrapa Rondônia, in the municipality of Porto Velho, Rondônia State, Brazil. The experiment was conducted in a Red-Yellow Latosol and arranged in a 5 x 6 factorial design consisting of a combination of five treatments (N sources) with six irrigation depths. The sources of N were as follows: 1) urea (45.5% N); 2) urea (44.3% N) + 0.15% copper and 0.4% boron; 3) urea (45% N) + NBPT; 4) urea (43% N) + sulfur (1%); and 5) control (without N). The irrigation depths were 0, 5, 10, 15, 20, and 25 mm. The results showed that, regardless of the use of urease inhibitors, an irrigation depth of 10 mm is suitable for incorporating urea into the soil and stabilizing N losses from NH3 volatilization. NBPT is the most efficient inhibitor under nonirrigated conditions. All N sources promote increases in the concentrations of nitric and ammonia nitrogen in the soil. In the first 15 days after fertilizer application, the highest concentrations of ammonium were in the 0 - 10 cm and 10 - 20 cm soil layers, and NBPT showed the highest ammonium content compared to that of the other sources in the 0 - 10 cm layer. The nitric nitrogen content in the soil was slightly influenced by the irrigation depth in the first 15 days after fertilizer application. However, the ammonia nitrogen content decreased exponentially with the increase in irrigation depth due to the movement of ammonia in the soil.

Leaching of 2,4-d and atrazine herbicides in red-yellow latosol

The intensive use of herbicides has increased the possibility of environmental contamination and the accumulation of pesticide residues in soil and water. This work aimed to evaluate the leaching potential of 2,4-D and atrazine herbicides in red yellow Latosol with a clayey texture. The experimental design was entirely randomized, in factorial 5x3 (five doses of each herbicide for three soil depths). The doses used were 1.25, 2.50, 6.25 and 12.50 L ha-1 for the 2.4-D herbicide and 2.25, 4.50, 11.25 and 22.50 L ha-1 for the atrazine herbicide (plus absolute witnesses). The herbicides were applied in buried pvc tubes to the soil and after accumulated rainfall of 87 mm, cucumber was grown as a bio indicator plant. The plant phytotoxicity, plant height, dry mass accumulation and leaf area where the evaluations were performed at 21 days after the sowing of the cucumber were analyzed. The 2.4-D herbicide didn`t present significant difference between treatments for the plant phytotoxicity variable, however, there was difference between treatments for plant height and dry mass. For leaf area, the difference was observed only for soil depths. Atrazine herbicide also showed no difference between treatments for plant phytotoxicity, but there was a difference between treatments and soil depths for the other variables. Under the conditions evaluated, 2,4-D and atrazine herbicides can leach into clayey soil regardless of the dose used and can reach up to 30 cm depth.

Automation of irrigation by electronic tensiometry based on the arduino hardware platform

This study developed and evaluated an electronic irrigation system controlled by soil water matric potential. The controller uses tensiometers and pressure transducers as a reading mechanism, integrated with an Arduino microcontroller board that drives the solenoid valves and a 1/3 hp single-phase motor. Four electronic tensiometers were installed in plastic containers filled with 6 kg of Red-Yellow Latosol (RYL) with a clayey texture, and another four in plastic containers filled with 7 kg of Regolitic Neosol (RN) with a sandy texture. Irrigation automation components were activated autonomously at the critical potentials of -20, -25, -30, and -35 kPa for RYL, and -10, -15, -20, and -25 kPa for RN, with a 20% variation tolerance. The entire system is able to monitor and control irrigation based on soil water matric potential. Components were deactivated when the soil water potential reached the field capacity of each soil type. Irrigation automation performance was considered satisfactory, as it kept critical potentials within the pre-established thresholds in both soil types. Automation control was set for matric potentials between -10 kPa and -35 kPa in RYL, and between -5 kPa and -25 kPa in RN.

Fertilização organomineral e águas salinas na produção de fitomassa de Capsicum annuum

<p>Um experimento foi executado em casa de vegetação, no período de março a abril de 2018, no município de Crato-CE, com o objetivo de avaliar os efeitos de biofertilizantes (comum e rico quimicamente) em substrato irrigado com diferentes composições de águas salinas sobre a produção de fitomassa de mudas de pimentão amarelo, variedade Sucesso (952). O experimento foi desenvolvido utilizando um material ou substrato dos primeiros 20 cm de um Latossolo Vermelho-Amarelo. O delineamento experimental foi inteiramente casualizado em esquema fatorial 5 x 3, com três repetições, referentes aos valores de condutividade elétrica da água (CEa) de irrigação 0,5; 1,0; 2,0; 3,0 e 4,0 dS m<sup>-1</sup>, no solo sem o insumo orgânico, no solo com biofertilizante comum e, ainda, no solo com biofertilizante rico, totalizando 45 tratamentos, acondicionados em sacos de polietileno preto com capacidade máxima de 3,0 kg. O biofertilizante, depois de diluído na proporção de 3:1, foi aplicado uma única vez a 10% do volume do substrato, dois dias antes da semeadura. A irrigação com águas salinas afetou a morfologia e a qualidade de mudas de pimentão amarelo (cv. Sucesso), mas com menor intensidade nos tratamentos que receberam o insumo orgânico comum e o rico, respectivamente.</p>

Análise empírica da fragilidade ambiental da bacia hidrográfica do rio Duas Bocas, Espírito Santo, Brasil

O estudo teve como propósito analisar a Fragilidade Ambiental Potencial (FAP) e Emergente (FAE) da bacia hidrográfica do rio Duas Bocas, Espírito Santo, por meio da integração das variáveis: declividade, geomorfologia, solos, uso e cobertura da terra e precipitação de 1970, 2008 e 2012. A metodologia dividiu-se em três etapas: a primeira correspondeu a pesquisas bibliográficas e aquisição de dados vetoriais e matriciais. Na segunda etapa foram realizados levantamentos de campo para o reconhecimento da área e validação dos produtos cartográficos in loco. A terceira etapa ficou a cargo dos trabalhos de gabinete com a elaboração dos produtos cartográficos. Com a análise dos resultados contatou-se que a FAP apresentou as classes alta e muito alta na nas porções central e superior da bacia, com presença de Cambissolos Háplicos e Neossolos Litólicos em relevo fortemente dissecado e declividades acima de 30%. Na porção inferior as classes foram baixa e média com presença de Latossolos Vermelho-Amarelo e Gleissolos, em relevo suave ondulado e plano, com declividade entre 0 a 6% e 6% a 12%. A FAE teve uma atenuação na porção superior, devido ao uso da terra (mata nativa), com classes muito baixa e baixa. Já na porção central a classe foi alta e média (exceção 1970), e na inferior classe baixa e média, tendo pastagem como uso e alguns pontos com classe muito baixa, devida a fragmentos de mata nativa, com alta e média em 1970 na planície fluvial. Contudo, a metodologia utilizada mostrou-se satisfatória quanto à fragilidade ambiental.

Mobility of flumioxazin herbicide in a Dystrophic Red Yellow Latosol at Brazilian Southern Amazon

Herbicides are chemicals which can contaminate soil and water, if inadvertently used. In the soil, the herbicide may undergo adsorption and leaching or degradation by physical, chemical and biological processes in addition to being absorbed by the weeds and / or cultivation. The aim of this study was to determine the mobility of flumioxazin in Dystrophic Red Yellow Latosol, in the southern Amazon, using sorghum plant as test under different rainfall indexes. We used PVC pipes, which were filled with soil. The experimental design was completely randomized in a 2x2x5 factorial scheme, consisting of herbicide treatments [with or without flumioxazin (50 g i.a. ha-1)], rain (40 or 80 mm) and soil depths (2.5, 5, 10, 15 and 30 cm). After each rainfall simulation, the tubes were removed and sorghum seeds were placed in the depths 2.5, 5, 10, 15 and 30 cm from the top of the columns. It was observed a higher activity of flumioxazin in the initial 2.5 cm. In all depths where herbicide effect was observed, it was also observed the interruption of sorghum growth, being more intense in the simulations of 80 mm of rainfall. The herbicide presented high adsorptive capacity in Dystrophic Red Yellow Latosol, with mobility up to the first 2.5 cm along the profile.

Multivariate Behavior of Irrigated Sugarcane with Phosphate Fertilizer and Filter Cake Management: Nutritional State, Biometry, and Agroindustrial Performance

Increases in production and final quality of the sugarcane crop require the search for new management and evaluation techniques within the production system, which can range from water and nutritional management, such as the application of water saving irrigation associated with sources (conventional and alternative) and phosphorus doses combined with the use of a sophisticated mathematical method, such as multivariate analysis. It can explain the variations caused by the application of irrigation and the sources and doses of phosphorus throughout the crop cycle. Due to the complex relationships and interactions of the soil-water-plant-atmosphere system, the use of multivariate analysis is able to indicate the best management options to be used. The experiment was carried out in a dystrophic Red Yellow Latosol, medium texture. The experiment consisted of randomized blocks and three replications in a 3 × 4 × 2 factorial design comprising three sources of phosphorus (triple superphosphate, Bayovar natural reactive phosphate, and Araxa natural phosphate) and different doses (0, 90, 180, and 360 kg of P2O5 ha−1) in the presence and absence of filter cake (7.5 Mg ha−1, dry basis). Irrigation with rescue equipment was applied in a single blade of 80 mm. Biometrics, nutritional status, and agroindustrial performance of sugarcane were evaluated. The principal component analysis evidenced that the phosphate fertilization associated with filter cake is responsible for increases in sugarcane biometrics, specially tillers at 6 months (0.589) and final tillering (0.577); nutritional status of iron (0.349), manganese (0.348), boron (0.347), sulfur (0.332), and phosphorus (0.331); and agroindustrial performance of sucrose (0.476), stalk yield (0.470), and total recoverable sugar (0.439). The water saving irrigation potentiated the use of phosphate fertilizer associated with filter cake, increasing the nutritional status of the plants. However, the correlation was irrelevant and or negative for levels of potassium and calcium. In addition, it favored biometrics and agroindustrial performance by expressing a direct and positive correlation with stalk yield, sucrose, and total recoverable sugar, but an inverse correlation between final tillering and plant height, tons of pol per hectare, and total recoverable sugar.

Potassium Fertilization in Sugarcane Ratoon Yield Grown in a Tropical Region

ABSTRACTPotassium (K) is closely associated to the improvement of sugarcane quality, acting in the conversion of reducing sugar (RS) to recoverable sugars (TRS). The present study aimed to evaluate the effect of different levels of K-fertilization on the yield and technological quality of sugarcane ratoons grown under edaphoclimatic conditions in the Brazilian central region. The experiment was carried out using the sugarcane variety CTC-4, in a Distrofic Latosols, medium texture (270 g clay kg−1). The study was arranged in a randomized complete block design, with five treatments (0; 50; 100; 150 and 200 kg K2O ha−1), and five replicates. Potassium content in soil and plant, biometric variables, stalk yield and the technological quality at harvest were evaluated. The 200 kg ha−1 dose increased the K content in 160, 156, 56 and 3% in 0–0.20 and 0.20–0.40 m layers at 180 and 360 days after budding (DAB), respectively, promoting greater absorption of the nutrient by plants (X ̅ = 15.22 g kg−1). The higher potassium absorption reflected in yield gains, with an increasing of 7.9%, compared to the control treatment, yielding 100.37 t ha−1. However, soil K fertilization did not affect the technological quality of the sugarcane ratoon.Abbreviations: K: potassium; RS: reducing sugars; TRS: recoverable sugars; DAB: days after budding; SB: Sum of Bases; CEC: Cation Exchange Capacity; V: Saturation Base; Kcl: potassium chloride; AWC: Available water capacity; PC: Pol percent in sugarcane; Brix: total soluble solids; dRYL: Dystrophic Red Yellow Latosol; eRYA: Eutrophic Red Yellow Argisol.

Estudo da sorção de chumbo em solos intemperizados e em suas diferentes frações

Dentre os processos de acúmulo de metais tóxicos pelo solo, como o chumbo (Pb), o de adsorção é um dos mais notados. No solo, a adsorção refere-se à passagem de um soluto da fase aquosa para a superfície de um adsorvente sólido. Considerando-se que as isotermas de adsorção no solo muitas vezes variam fortemente de solo para solo, são necessários estudos mais detalhados do comportamento de metais em solo brasileiro, para melhor adequação dos modelos às condições climáticas e ambientais brasileiras. Assim, o objetivo é estudar a adsorção de chumbo (Pb) em um Latossolo Vermelho Amarelo (LVA) e um Argissolo Vermelho Amarelo (AVA) e em suas diferentes frações granulométricas. Para determinar a relação entre a quantidade de um composto adsorvido a partir de soluções pelo solos, a várias concentrações, e a quantidade remanescente nessas soluções, são utilizadas isotermas de adsorção que geram resultados quantitativos. Foi também calculado o coeficiente de distribuição (Kd) do metal pelos solos e pelas suas diferentes frações. Neste estudo, em específico, foi possível verificar que a maior adsorção de Pb+2 foi observada pela fração silte + argila dos solos, segundo as isotermas. Quanto à classificação das isotermas, o AVA apresentou isotermas do tipo L e o LVA do tipo H. A partir dos valores de Kd percebe-se que o chumbo apresenta uma alta afinidade pelo LVA e baixa afinidade pelo AVA. Concluindo, que o modelo de Freundlich adequou-se bem aos resultados experimentais de adsorção de chumbo pelos solos.

Spatial Variability of Irrigated Garlic (Allium sativum L.) Production Components

Among the crops that are usually grown under irrigation, one can mention garlic, which is a product with high demand in Brazil and the world, it is highly valued in the cuisine of several countries, and is an aggregated crop with high economic value. In 2018, this work was conducted in Yellow Red Latosol. The objective was to characterize the structure and magnitude of the spatial distribution of garlic production components and to map the productive components to visualize spatial distribution and to evaluate the spatial correlation between garlic bulb yield (BY) and other variables of the crop: total plant mass (TPM), number of leaves (NL), floral tassel length (FTL), leaf length (LL), leaf width (LW), pseudostem diameter (PD), shoot wet mass (SWM), shoot dry mass (SDM), number of cloves per bulb (NCB), clove mass (CM), root dry mass (RDM), and irrigation (IRR). All these traits were sampled in a 90-point grid georeferenced. Data analysis using statistical and geostatistical techniques made it possible to verify that the production components and BY, TPM, NL, FTL, LL, LW, PD, SWM, SDM, CM, and IRR presented special dependence. The spatial correlation between BY and TPM, LW, and CM showed a moderate spatial dependence.

Over-liming in the Construction of the Fertility of Red Yellow Latosol with Different Phosphorus Sources

The availability of P in Cerrado soils is a limiting factor for the satisfactory development of crops. It is known that the efficiency of phosphate fertilization is low and depends on several factors, such as solubility of fertilizers, soil texture, and soil acidity. Thus, the objective of this work was to evaluate the availability of phosphorus as a function of different phosphate sources under the influence of pH, as well as to determine its fertilization efficiency in a red latosol. The experiment was carried out in a greenhouse at Tocantins federal university, in DIC, Brazil was used, in a 3 x 5 + 1 scheme. A red-yellow Latosol was used and three sources of phosphate fertilization were evaluated: Mono-ammonic phosphate - MAP, single superphosphate - SS and Natural phosphate - FN, plus one treatment without fertilization, in five evaluation periods (0, 7, 14, 21 and 28 days). Therefore, the pH in CaCl2 of the soil stabilized between (5.5 – 6.5) in approximately 83 days of incubation with the acidity concealer. The SS and MAP phosphate fertilizers promoted the highest available P contents, with 6.32 and 6.23 mg.d m−3, respectively. The use of FN showed low P levels during the evaluated incubation period, mainly due to its lower solubility.

Estimation of sulfentrazone sorption in isolated application and mixed with glyphosate

The use of herbicides belonging to a single mechanism of action for several consecutive years in the same area may lead to the selection of weed biotypes resistant to herbicides. Weeds resistant to glyphosate have been problem worldwide. As an alternative control, farmers have used glyphosate mixed with sulfentrazone. When two herbicides are mixed, the parameters that govern the behaviour of herbicides in the soil can be altered. In this study, the sorption of sulfentrazone was estimated when applied in isolation with glyphosate formulations. For this, increasing doses of sulfentrazone were applied using Red-Yellow Latosol substrate and washed sand. Each dose of sulfentrazone was applied in a mixture with 1080 g a. e. ha-1 Roundup Ready®, Roundup Ultra® and Zapp Qi®. To evaluate the presence of sulfentrazone in the soil solution, Sorghum bicolor was used as an indicator species. Symptoms of intoxication were evaluated at 7, 14 and 21 days after sowing. At 21 days after sowing, the plants were collected and dried in an oven at 70 ± 10 °C to determine the dry matter. Based on the intoxication of the indicator plants, it was verified that, regardless of the formulation, the presence of glyphosate in the mixture increased the sorption of sulfentrazone in the Red-Yellow Latosol. However, based on dry matter accumulation, sulfentrazone sorption increased because of the mixture with Roundup Ultra®, but decreased due to the presence of Roundup Ready® and Zapp Qi®. Therefore, the application of sulfentrazone in mixture with glyphosate alters the sorptive forces of sulfentrazone in a Red-Yellow Latosol.

Nutrition and physiology of hybrid Eucalyptus urograndis in soil fertilized with sewage sludge

Sewage sludge is a residual pollutant product from the treatment of urban effluent and must be adequately processed before final disposal in order to avoid environmental contamination. The use of sewage sludge in agricultural and forestry areas can improve the physical, chemical and biological properties of soil; it can also be a source of nutrients, increasing crop productivity. Accordingly, this study aimed to evaluate the growth and development of hybrid Eucalyptus urograndis (Eucalyptus grandis x E. urophylla) seedlings cultivated in soil with different doses of sewage sludge. To accomplish this, hybrid E. urograndis seedlings were cultivated for 120 days in pots containing soil (dystrophic Red-Yellow Latosol -LVA) with different doses of sewage sludge (0, 30, 60 or 90 Mg ha-1). The experiment was carried out in a randomized complete block design consisting of four treatments, three replications with four plants per replication, totaling 48 plants. Biometric, biomass and physiological variables (chlorophyll, gaseous exchange, stomatal conductance and transpiration); in addition to macro- and micronutrient contents in leaves and soils of each treatment were evaluated. The treatments with sewage sludge were statistically superior to control treatment for all variables. Therefore, we recommend the application of 60 Mg ha-1 sewage sludge for the growth of hybrid Eucalyptus urograndis seedlings. Conversely, 90 Mg ha-1 sewage sludge inhibited hybrid E. urograndis root growth. Moreover, the use of sewage sludge as organic fertilizer in tropical soils is a viable and sustainable alternative for Eucalyptus cultivation.

Soil Type and Zinc Doses in Agronomic Biofortification of Lettuce Genotypes

The incidence of many malnutrition-related diseases among the populations of developing countries is closely related to low dietary zinc (Zn) intakes. This study evaluated the potential of agronomic biofortification of lettuce genotypes with Zn in different soils. We evaluated the ability to biofortify three lettuce genotypes (‘Grand Rapids’, ‘Regina de Verão’, and ‘Delícia’) in two soils (Red-Yellow Latosol and Dystroferric Red Latosol) using five doses of Zn (0, 5, 10, 20, and 30 mg kg−1). At 55 days after sowing, the plants were harvested. There was an interaction among the soils, genotypes, and Zn doses. Regardless of the soil and genotype, the increase in Zn supply promoted a linear increase in shoot Zn concentration. However, shoot and root dry matter yields were differentially affected by Zn supply according to the genotype and soil type. Overall, the Red-Yellow Latosol provided a higher shoot Zn concentration but also caused greater growth damage, especially in ‘Regina de Verão’ and ‘Delícia’. ‘Grand Rapids’ was biofortified the most in Red-Yellow Latosol.

Immediate Effects of Prescribed Burning on Chemical Properties of the Cerrado Soil

The Cerrado biome increasingly suffers from the environmental impacts of human action. Burning is known as an action used to destroy native vegetation and to clean areas mainly with the purpose of growing soybeans, corn, or raising cattle. In this study we aimed to investigate the influence of low-intensity burning on the chemical composition of a Red-Yellow Latosol in a region characterized as Cerrado sensu stricto. A total of 14 parcels of land were demarcated. In order to analyze the effects of fire on the soil chemical properties, soil samples were collected before and within 24 hours of the burning by means of the same methodology. An increase in organic matter and in the levels of Ca2+, Mg2+, K+, Mn2+, Zn2+, B+, S, as well in the ratios characterizing the soil (CECt, SB, Ca+/T, Ca+/Mg+, V, and Ca+/K+), was observed. Variables that determine the acidity of the soil, such as pH and H + Al, presented changes, although not significant (p > 0.05).

Spatial variability of precompression stress and volumetric water content of a red-yellow latosol (Oxisol)

The intensive agricultural machinery traffic to which soils under coffee crops are exposed may cause significant changes in soil structure. The goals of this study were to: a) characterize the spatial variability of precompression stress (σp) and volumetric water content (θ) of a Red-Yellow Latosol (Oxisol) and determine their spatially dependent structures using ordinary kriging semivariograms; b) using this date to construct a load-bearing capacity (LBC) map for the site, identifying the depth with higher ; and c) use the map as a decision support tool regarding agricultural machinery logistic management in coffee plantations. The research was conducted on an experimental farm of the Agricultural Research Company of Minas Gerais (Epamig), Patrocinio, MG, on a clayey Oxisol. Samples were collected from 2.0 × 1.5 m sampling pits at intersections of a rectangular 40 × 150 m grid, totaling 28 sampling points. The soil samples were collected with metal rings (0.0254 m in height and 0.0630 m in diameter) using an Uhland sampler. Sampling at each pit was at 3 layers: 0.00–0.03 m, 0.10–0.13 m, and 0.25–0.28 m, and seven samples arranged in a matrix form were collected at each layer, totaling 588 samples. The σp and θ showed a spatially dependent structure. The depth of 0.00–0.03 m showed higher LBC, indicating that this depth was more compacted compared to other depths. Based on the σp maps, the tractor and the combine should not traffic into the areas at water content of 0.45 m3 m-3, because the soil has a LBC of 200 kPa. If this condition is not respected, additional compaction will occur. Tractor traffic is permissible when the water content reaches values less than 0.36 m3 m-3, whereas for combine traffic, the water content values must be less than 0.30 m3 m-3.

Structural soil quality related to microbiological parameters in sugarcane.

Sugarcane crop conventional tillage has been replaced by deep soil preparation with few studies about its effect on soil quality and sustainability. The aim of this study was to assess structural volumes ina dystrophic Red-Yellow Latosol subjected to conventional tillage (CT) and deep localized soil tillage (DLST) to verify how the microbiological parameters were affected. The study was conducted in a soil derived from the Caiuá Sandstone formation in Brazil. Four trenches were dug for each soil tillage system to describe the cultural profile and evaluate carbon microbial biomass (CMB) and nitrogen (NMB), basal respiration (BR), and metabolic quotient (qCO2). CT profiles exhibited a predominance of cracked soil volumes, medium-sized and large compact clods with some porosity, and continuous volumes with no cracks and of intermediate porosity. DLST profiles were predominantly free-soil volume with no cohesion and porous in appearance, and compact, cohesive volumes with no porosity visible. The highest levels of CMB and NMB were in the cracked soil under CT. Higher microbial activity indicated by BR and qCO2 were in the free powdery soil under DLST. Soil pulverization caused by DLST could cause serious consequences on soil functionality, boosting erosion, and metabolic stress in the microbiota.

FIRE EFFECTS ON SOIL FUNGI IN A CERRADO VEGETATION AREA ACCORDING TO THE COLLECTION PERIOD

The Cerrado is recognized for its biodiversity, but is currently considered a threatened biome. This study aimed to evaluate the impacts of low-intensity fire on the abundance and richness of fungal communities in a Red Yellow Latosol in Sensu Stricto Cerrado. Five treatments were defined in control and burned plots, which represent the soil collections as a function of the periods after prescribed firing. The fire effects were evaluated in the 0-5 and 15-20 cm layers of soil depth. For statistical analysis, the Shanon-Wiener, Simpson and Berger-Parker indexes were used. A significant reduction of 33.3% was observed (ANOVA; Dunnett Test p> 0,05) in total abundance (UFC.g-1), in the superficial layer and in the deeper soil profile (15-20 cm) of the burned plots when compared to the control plots. However, it was observed a fungi recolonization at 2 months after burning. A total of 21 fungi genera were found, and more diversity was observed in the burned plots compared to non-burned. The maximum Shanon-Wiener index was H´=0,85 in the 15-20 cm depth for the burned plots. For the dominance index, a maximum value of 70% was observed for the Aspergillus genus (in the treatment before burning for the 15-20 cm depth). The fluctuations in the diversity of fungi after burning were not affected by the fire, but by the rainfall indexes in the treatments after burning. The equity was uniform and showed differences in the numerical richness in burned plots and control. Rainfall has a great impact on the fungal recovery speed.

The release of macronutrients from second crop corn straw and their behaviour in a red-yellow latosol

Crop residues left on the soil function as a nutrient reservoir and as a ground cover in agricultural systems. The aim of the present study is to assess the chemical alterations in the soil after the decomposition of different amounts of straw from corn as second crop. The climate of the region is classified as hot tropical and the soil is categorized as Red-Yellow Latosol (Typic hapludox) in the cerrado-amazon ecotone. The experiment was set up in randomized blocks in September 2013 after harvesting the second crop corn, comprised of corn straw rates (0, 14.18 and 42.54 t ha-1) with six repetitions. The content of macronutrients, H+Al, pH and base saturation in the soil profile were assessed. The straw rates were added to litter bags and stored on the soil, where they were kept for 154 days throughout the rainy period. Subsequently, the soil characteristics were assessed in layers 0 to 0.05, 0.05 to 0.10, 0.10 to 0.15, 0.15 to 0.20 and 0.20 to 0.40 m. The Ca+2 and Mg+2 elements were only released by the straw on the first 0.05 m of soil. However, K circulated in the soil profile reaching depth of 0.40 m. There was reduction in K+ saturation in treatments without straw. No alterations were observed in the other nutrients and studied attributes. According to the results, it is important to distribute the cultural remains of maize homogeneously in the area during harvesting to avoid the appreciation of soil fertility spots, especially of K.