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Land uses may shift soil biota community composition, and soil chemical traits. Our aims were to assess if the land uses may influence the soil biota community composition and soil chemical traits; if there are differences into soil biota biomass as influenced by land uses; and what are the plant-soil feedback among the land uses, soil biota, and soil chemical traits. We have collected soil samples and extracted soil biota individuals from four different land uses (e.g., natural ecosystem, conventional farming system, agroecological farming system, and fruticulture). Our results have revealed that land uses have influenced soil biota abundance (from 59.0 to 210.12 ind. trap− 1 in the natural ecosystem and fruticulture system, respectively), richness (from 6.5 to 10.5 in the fruticulture system, and natural ecosystem, respectively), diversity (from 1.01 to 1.75 in the conventional farming system, and natural ecosystem, respectively), dominance (from 0.52 to 0.71 in the natural ecosystem, and conventional farming system, respectively), and its biomass. The studied land uses have decreased the soil organic carbon when compared with the natural ecosystem (5.75 g kg− 1). SOC, soil pH, Olsen's available P, Mg2+, K+, and Na+ were the main factors contributing to the variance of the samples accounting for 78% of the data variance. The results of our study highlight the importance of considering land uses as key factors influencing soil biota community and soil chemical traits. Thus, long-term experiments considering land uses (e.g., conventional farming system, fruticulture, and agroecological farming system) may exploit negative effects of land uses on soil biota abundance on the one hand, while positive effects on soil chemical traits on the other hand. [ABSTRACT FROM AUTHOR]

With the expansion of organic agriculture, research is needed to indicate economically and ecologically viable fertilizer options, especially in semiarid regions, with low soil organic matter and nitrogen content. In the Brazilian semiarid region, vermicomposts are widely used by farmers and are scientifically investigated; however, there is no information for millicompost, a new type of organic compound that has shown very promising results in other regions. Thus, this study aimed to analyze the decomposition rate, nutrient release, and microstructure evaluation of vermicomposts from different sources and of millicompost produced from plant residues, with the application of mineral nitrogen-urea and organo-mineral fertilizer in the Brazilian semiarid region. The experimental design was a randomized block in a 4 × 3 factorial scheme, with four replicates; four organic composts (millicompost, commercial vermicompost, vermicompost from bovine manure, vermicompost from goat manure); and three types of fertilization (without fertilizer, with mineral-urea and organo-mineral fertilizer). The organic composts were decomposed using litterbags at the soil surface. The variable's decomposition rate and the nutrient release were evaluated at six-time intervals (0, 30, 60, 90, 120, and 150 days), and microstructure was evaluated at the beginning and the end of the experiment, with scanning electron microscopy (SEM). The highest decomposition was verified for commercial vermicompost rich in macro and micronutrients and with lower P contents. The lignin:N ratio and the initial P content were more important in the permanence of the organic compost in the field than the C:N ratio. Regardless of the organic composts, the use of urea as a mineral fertilizer stimulated decomposition more than the organo-mineral fertilizer. The initial composition of the nutrients was decisive in the dynamics of nutrient release, mass loss, and decomposition of C. There was no pattern in the release order of macronutrients. However, for the micronutrients, the release order was Cu > Fe > Mn, in all treatments. Microstructure analysis is a visual analysis where differences are detected through microphotographs and the biggest difference occurred with millicompost, which showed elongated fibers and fiber bundles, forming a relatively open structure characteristic of the presence of fulvic acid. However, the addition of organo-mineral fertilizer formed agglomerates in compacted micro-portions, helping the mineralization of C and N. [ABSTRACT FROM AUTHOR]

Modern times have required studies that take into account the main soil features, aligning the use of land with the protection of more sensitive environments. From this perspective, this study aimed to perform a morphological description and determine the physical and chemical attributes for soil classification in the community of Poção, located in the municipality of Martins/RN, by highlighting the more sensitive attributes in the differentiation of environments through multivariate analysis. Nine soil profiles were identified to perform the morphological description and collect samples for physical and chemical analyses. The study updates the soil classes found in the study area: Acrisols, Planosols, and Cambisols, with the relief being the main factor responsible for the difference between soil attributes. The influence of organic matter on the soil attributes highlights the importance of its maintenance. Aluminum and the clay fraction are responsible for the distinction of the Acrisol class, whereas silt, potassium sodium, total organic carbon, the electrical conductivity of the saturation extract, and the cation exchange capacity allow the differentiation of Fluvisols. [ABSTRACT FROM AUTHOR]

Studies on soils and their interrelationships with land use in the context of the semi-arid region of Brazil are still scarce, even though they have the potential to assist in understanding the use and management of soil and agricultural crops. From this perspective, this study investigated four land uses in different locations of the Apodi Plateau, an elevated area in semi-arid region of northeastern Brazil. The different soils were analyzed for their resistance to root penetration, water infiltration, inorganic fractions, soil density, total porosity, potential of hydrogen, electrical conductivity, total organic carbon, potential acidity, and sum of bases. The soil resistance to root penetration and water infiltration were determined in the field. The results obtained were interpreted using multivariate and geostatistical analysis. The resistance data were subjected to the Shapiro–Wilk test at 5% of probability and expressed in maps, whereas infiltration data curves were constructed to estimate the amount of infiltrated water at the different time intervals. The textural classification was an important factor for the analysis of soil resistance to root penetration (Q) and the infiltration rate, being evidenced in the cluster analysis and allowing the formation of two groups, one for the surface layers of the areas and another for the subsurface layers, with the inorganic sand and clay fractions standing out with the greatest dissimilarity. The establishment of conservation practices for soil management is suggested to correct the pore space problems and the degradation of agroecosystems in areas with soils whose conditions are similar to the ones of this study. [ABSTRACT FROM AUTHOR]

Mineralogical studies are incipient and necessary in the Apodi Plateau, Brazil. This study aimed to evaluate the interrelationship between the mineralogy of the clay fraction and its structural and chemical attributes and to differentiate two important pedo-environments in the semi-arid region of northeastern Brazil (Ferralsol and Cambisols of the Apodi Plateau-RN) using the multivariate technique. We evaluated the interrelationships between mineralogy and the structural and chemical attributes of the soil and differentiated between agroenvironments. We collected soil samples from six profiles in diagnostic horizons of the Ferralsols and Cambisols. In the mineralogical analysis of the clay fraction, X-Ray Diffraction was used to identify mineral peaks of clay and iron oxides. The physical and chemical properties of the soils were determined. The multivariate statistical technique was applied to process the data. The clay minerals identified were hematite, goethite, kaolinite, and illite. The principal component analysis allowed for the separation of environments according to soil density, Fed and Mg2+ for developed soils, and potassium, weighted average diameter, microporosity, total organic carbon, sodium, the sum of bases, calcium, total porosity, aeration, potential acidity, and Feo discriminated developing soils. This study revealed that the clay fraction influenced the structural attributes of the soil according to the degree of soil development. Two profiles presented atypical situations: High contents of crystallized iron in Cambisols and illite peaks in Ferralsolos. These mineralogical results are not commonly found in the literature, highlighting the potential for further studies. The answers concerning the mineralogy of semiarid soils in Brazil and the world show similarity. [ABSTRACT FROM AUTHOR]

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Emitter clogging is the major problem of drip irrigation systems operating with wastewater. The objective of this study was to evaluate the alteration of the flow rate variation coefficient (FVC) and to identify the biological agents that cause obstruction in drip units operating with swine effluent and public water supply. The experiment was set up in a split-plot scheme, with the times of application of swine effluent and public water supply in the main plots and dripper types in the secondary parcels, evaluating times of FVC in the tertiary parcels, using a completely randomized design (CRD) with three repetitions. The FVC of the drip subunits was calculated on every 40 hours as well as the microscopic analysis of the biological agents of clogging, until 160 h. At the end of the tests, biofilm samples were collected in each drip unit to identify the groups of predominant bacteria. The results indicated that the FVC was effective in detecting the clogging of the emitters, evidencing that the construction characteristics and the times of application of swine effluent and of the public water supply interfere in this process. Microscopic analyzes of the biofilm indicated that the main biological agents that caused obstruction were algae, bacteria, fungi and protozoa. [ABSTRACT FROM AUTHOR]

Copyright of Revista Brasileira de Agricultura Irrigada - RBAI is the property of Revista Brasileira de Agricultura Irrigada - RBAI and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Caatinga is the property of Revista Caatinga and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)