ABSTRACT: This study addresses the need to understand the presence of functional microorganisms in tropical soils, providing valuable information for conservation and sustainable management. The main objective is to analyze the variability of functional microorganisms at different soil depths and their correlations with physicochemical parameters. To this end, soil samples were collected from 15 random points in a reserved forest and analyzed for physicochemical and microbiological properties at two depths (10 and 20 cm). The following functional microorganisms were quantified: viable aerobes, lactobacilli, actinomycetes, fungi, and nitrogen-fixing bacteria using specific protocols. The non-parametric Wilcoxon test was used to determine differences between depths, and the Pearson correlation coefficient (|ρ| ≥ 0.8) was used to analyze correlations between physicochemical parameters and microorganisms. The results suggest that the abundance of viable aerobic microorganisms, Lactobacillus, Actinomycetes, and Fungi decreases with soil depth, while nitrogen-fixing bacteria show no significant differences. The decrease in abundance is related to factors such as nutrient and oxygen availability and microenvironmental conditions. There is a strong positive correlation between the amount of viable aerobic microorganisms and Lactobacillus with phosphorus content, and a negative correlation between Actinomycetes and clay content. Actinomycetes prefer sandy soils, while Fungi thrive in soils rich in organic matter. The negative correlation between Fungi and Actinomycetes suggests competition for limited resources and possible chemical interactions, such as the production of antibiotic compounds by Actinomycetes. This study demonstrates that a detailed understanding of soil microbiota can offer new opportunities to improve agricultural practices, especially in terms of soil fertility management and environmental sustainability.

RESUMEN: Este estudio aborda la necesidad de entender la presencia microorganismos funcionales en suelos tropicales, proporcionando información valiosa para la conservación y manejo sostenible. Tiene como principal objetivo analizar la variabilidad de microorganismos funcionales en diferentes profundidades del suelo y las correlaciones con los parámetros fisicoquímicos. Para ello se recolectaron muestras de suelo de 15 puntos aleatorios en un bosque reservado y se analizaron propiedades fisicoquímicas y microbiológicas a dos profundidades (10 y 20 cm). Se cuantificaron los siguientes microorganismos funcionales: aerobios viables, lactobacilos, actinomicetos, hongos y bacterias fijadoras de nitrógeno utilizando protocolos específicos. Se empleó la prueba no paramétrica de Wilcoxon para determinar diferencias entre profundidades y el coeficiente de correlación de Pearson (|ρ| ≥ 0,8) para analizar correlaciones entre parámetros fisicoquímicos y microorganismos. Los resultados sugieren que la abundancia de microorganismos aerobios viables, Lactobacillus, Actinomicetos y Fungi disminuye con la profundidad del suelo, mientras que las bacterias fijadoras de nitrógeno no muestran diferencias significativas. La disminución de la abundancia se relaciona con factores como la disponibilidad de nutrientes y oxígeno y las condiciones microambientales. Existe una correlación positiva fuerte entre la cantidad de microorganismos aerobios viables y Lactobacillus con el contenido de fósforo, y una correlación negativa entre Actinomicetos y el contenido de Arcilla. Los Actinomicetos prefieren suelos arenosos, mientras que los Fungi prosperan en suelos ricos en materia orgánica. La correlación negativa entre Fungi y Actinomicetos sugiere competencia por recursos limitados y posibles interacciones químicas, como la producción de compuestos antibióticos por parte de los Actinomicetos. Este estudio demuestra que la comprensión detallada de la microbiota del suelo puede ofrecer nuevas oportunidades para mejorar las prácticas agrícolas, especialmente en términos de gestión de la fertilidad del suelo y sostenibilidad ambiental.

ABSTRACT The method of applying fertiliser to the soil affects grain productivity. The aim of this study was to determine the dynamics of phosphorus, potassium and sulphur in the arable layer of the soil during the third year of agricultural production, as a function of the method of application. The study took place in the district of Diamantino, Mato Grosso, in an area of soybean-maize succession under minimum tillage. Five treatments were tested in a randomised block design: no phosphorus or potassium (P0-K0); broadcast phosphorus and in-furrow potassium (Pb-Kf); in-furrow phosphorus and potassium (Pf-Kf); in-furrow phosphorus and broadcast potassium (Pf-Kb); broadcast phosphorus and potassium (Pb-Kb). When the soybeans reached physiological maturity, soil samples were collected from the 0-0.05, 0.05-0.10, 0.10-0.15 and 0.15-0.20 m layers for analysis of the pH, and P, K, S and organic matter content. The soil attributes were submitted to analysis of variance and Tukey’s test at 5%, and the nutrient dynamics in the soil profile were analysed by regression. The in-furrow application of phosphorus (Pf-Kb and Pf-Kf) improved P availability in the 0-0.05 m layer by 69.12% and 46.54% compared to the Pb-Kb treatment, by 73.93% and 50.71% compared to the Pb-Kf treatment, and by 136.77% and 105.16% compared to the P0-K0 treatment. The in-furrow application of phosphate fertiliser proved to be more effective in terms of phosphorus availability in the soil. The residual effect of broadcasting phosphate fertiliser on phosphorus availability in the soil can be seen from the third year of production onwards.

ABSTRACT Phosphorous is a limiting nutrient in sugarcane cultivated in Argisols in the Northeast of Brazil, and understanding its availability in the soil, as well as determining sufficiency ranges in the plants is essential when recommending levels of phosphorus fertiliser. The aim of this study was to: (i) Define classes for interpreting P availability in Argisols of the Northeast using the Mehlich-1 and Anion Exchange Resin (AER) extractors; (ii) Evaluate P extraction by the same extractors; and (iii) Correlate the P content of the soil with the P content of the plants, and establish sufficiency ranges in the plants. Three field trials were carried out in a sandy (PVAd1), medium (PAdx) and clayey (PVAd2) Argisol, applying the following amounts of P: 0, 40, 80, 120, 160 and 200 kg ha-1 P2O5. The AER extracted more P than did Mehlich-1 from each of the soils. The P content of the classes for interpreting P availability determined by the AER were higher than those determined by Mehlich-1. AER was the best extractor to represent P availability in the Argisol with the clayey texture (PVAd2), and Mehlich-1 in the Argisol with the sandy texture (PVAd1). The ranges of P sufficiency in the leaves of the sugarcane varied between soils, with values of 0.66-0.73 g kg-1 in PVAd1, 0.59-0.69 g kg-1 in PVAd2 and 0.34-0.47 g kg-1 in PAdx. As such, the texture of Argisols cultivated with sugarcane in the Northeast of Brazil should be a criterion for choosing the P extractor used in assessing its availability.

Summary: The development and productivity of agricultural crops is directly related to the nutritional supply they receive. The hypothesis of this trial is that the concentration of ions measured in the soil solution allows evaluating the ef ficiency of the nutritional management and its ef fect on the crop - the concentration of ions are conditioned by the mineral supply and the ion exchange processes of the soil. Thus, the objective of the experiment is to measure the ef fect of the continuous application of four nutrient solution concentrations on the concentration of ions in the soil solution and the tomato crop response under greenhouse conditions. The trial was established in calcareous soil under a complete randomized block design with three replications, with indeterminate tomato plants. The treatments were four concentrations of a Steiner solution modified for tomato cultivation: (1) 50, (2) 75, (3) 100 and (4) 125% applied continuously by fertigation. In each treatment the soil solution was extracted, and the concentration of NO3 -, K+ and Ca+2 ions, pH and electrical conductivity were measured for 18 weeks at the same time the crop response was measured. The concentration of the nutrient solution applied constantly to the tomato crop has a direct relationship with the availability of nutrients. The nutrient solution at 125% generated better growth, physiology, commercial quality and agronomic yield. Calcium was the only element that was detected in suf ficient levels in the soil solution from a concentration of 50% in the nutrient solution because of its high original availability in the soil.

Resumen: El desarrollo y productividad de los cultivos agrícolas está directamente relacionado con el suministro nutricional que estos reciben. La hipótesis de esta investigación es que la concentración de iones medidos en la solución del suelo, permite evaluar la eficiencia del manejo nutricional y su efecto sobre el cultivo, así, la concentración de iones está condicionada por el aporte mineral y los procesos de intercambio iónico del suelo. El objetivo de ésta investigación, fue medir el efecto de la aplicación continua de cuatro concentraciones de solución nutritiva sobre la concentración de iones en la solución del suelo y la respuesta en el cultivo de tomate bajo invernadero. El ensayo se estableció en suelo calcáreo bajo un diseño de bloques completos al azar con tres repeticiones, con plantas de tomate indeterminado. Los tratamientos fueron cuatro concentraciones con diferente proporción de la solución Steiner modificada para el cultivo de tomate: 1) 50, 2) 75, 3) 100 y 4) 125%, que fueron aplicadas de forma continua por fertirriego. En cada tratamiento se extrajo la solución del suelo y se midió la concentración de los iones NO3 -, K+ y Ca+2, el pH y la conductividad eléctrica durante 18 semanas. Al mismo tiempo, se midió la respuesta en el cultivo. La concentración de la solución nutritiva, aplicada de forma constante al cultivo de tomate, presenta una relación directa con la disponibilidad de nutrientes. La solución nutritiva al 125% generó mejor crecimiento, fisiología, calidad comercial y rendimiento agronómico. El calcio fue el único elemento que se detectó en niveles suficientes en la solución del suelo a partir de una concentración de 50% en la solución nutritiva, debido a su alta disponibilidad original del suelo.

Abstract Introduction: Hatay cuisine has an important place in Turkey and world cuisine. It consists of meat dishes, stuffed vegetables, vegetable dishes, jams, pickles, pilafs, soups, appetizers and salads, herbs collected from nature, desserts, pastries, dairy products and dry foods. The culinary processes differing in cultures alter nutrient value of foods. Food preparation and processing operations affect contents and bioavailability of micronutrients in traditional dishes. Several studies have been carried out to investigate the influence of traditional food preparation and processing methods in vitamins and minerals. In this study, nutrient retention in popular dishes of Hatay cuisine was analyzed. Material and methods: Google Trends is an open access tool that allows to determine the popularity of search terms. In the current study, the most common dishes searched in the last 12 months by individiuals living in Hatay province were selected. Şıhılmahşi, tepsi kebabı, tuzlu yoğurt çorbası, humus and künefe were the most searched on the web. We used the Nutrient Retention Factor Table of the United States Department of Agriculture (USDA), and the nutrient content of the Turkish traditional dishes described above was calculated after cooking of Hatay cuisine. Results: the highest loss of micronutrients has been found in vitamin B6, folate, vitamin B12 and thiamine. In şıhılmahşi, the highest loss was in folate, with 40 %. In tepsi kebabı, the highest loss appeared in vitamin B6, with 50 %. In tuzlu yoğurt soup, 70 % loss of B12 was reported. In humus, the highest loss was in folate at the level of 40 %. In künefe, the most loss occurred in folate with 30 %. Conclusion: specific cooking, preparation and preservation practices of traditional dishes that are compatible with local experience can be encouraged as an alternative or adjunct to other methods of increasing the availability of micronutrients in foods.

Resumen Introducción: la cocina Hatay tiene un lugar importante en Turquía y en la cocina mundial. Se compone de platos de carne, verduras rellenas, platos de verduras, mermeladas, encurtidos, pilafs, sopas, aperitivos y ensaladas, hierbas recolectadas de la naturaleza, postres, repostería, productos lácteos y alimentos secos. Los procesos culinarios que difieren en las culturas alteran el valor nutritivo de los alimentos. Las operaciones de preparación y procesamiento de los alimentos afectan el contenido y la biodisponibilidad de los micronutrientes en los platos tradicionales. Se han llevado a cabo varios estudios para investigar la influencia de los métodos tradicionales de preparación y procesamiento de alimentos en las vitaminas y los minerales. En este estudio se analizó la retención de nutrientes en platos populares de la cocina Hatay. Material y métodos: Google Trends es una herramienta de libre acceso que permite determinar la popularidad de los términos de búsqueda. En el estudio actual, se seleccionaron los platos más comunes buscados en los últimos 12 meses por personas que viven en la provincia de Hatay. Şıhilmehşi, kebab en bandeja, sopa de yogur salada, hummus y künefe fueron los más buscados en la web. Usamos la tabla de factores de retención de nutrientes del Departamento de Agricultura de Estados Unidos (USDA, por sus siglas en inglés) y el contenido de nutrientes de los platos tradicionales turcos descritos anteriormente se calculó después de cocinar la cocina Hatay. Resultados: las mayores pérdidas de micronutrientes se han encontrado en vitamina B6, folato, vitamina B12 y tiamina. En Şıhilmehşi, la pérdida más alta fue de folato, con un 40 %. En el kebab en bandeja la mayor pérdida se presentó en vitamina B6, con un 50 %. En la sopa de yogur salada, se informó una pérdida del 70 % de B12. En hummus, la mayor pérdida fue en folato, a un nivel del 40 %. En künefe, la mayor pérdida se presentó en folato, con un 30 %. Conclusión: se pueden fomentar prácticas específicas de cocción, preparación y conservación de platos tradicionales que sean compatibles con la experiencia local como alternativa o complemento de otros métodos para aumentar la disponibilidad de micronutrientes en los alimentos.

ABSTRACT Zinc (Zn) is an essential nutrient for plants, and there is limited information on its availability in Paraguayan soils. The objective of the research was to evaluate and classify the availability of Zn in soils of the Eastern region of Paraguay. For this, a database was generated with the results of soil analyses from the FCA-UNA, CIHB-IPTA and FUCAI-UCA laboratories. The concentration of available Zn in soils was classified as "high" (>1.2 mg kg-1); “medium” (0.5 - 1.2 mg kg-1) and “low” (<0.5 mg kg-1), generating a Zn availability map at the district level. The availability of Zn was evaluated at the district and departmental levels, as well as with descriptive statistics parameters. Considering the average Zn levels at the district level, of the 234 districts that make up the Eastern region of Paraguay, 74% of the districts (174 districts) presented a "high" level, 6% a "medium" level (15 districts) and 3% “low” level of Zn (6 districts). Considering the total number of soil samples analyzed (11,395 samples), 79% (9,038 samples) presented "high" levels of Zn, 12% (1,316 samples) presented "medium" levels of Zn, and only 9% (1,041 samples) presented “low” levels of Zn. The national average, considering the 11,395 soil samples, was 6.5 mg kg-1 of Zn, therefore, in 79% of the soils analyzed in the Eastern region there are Zn levels above the critical level of Zn for agricultural activities, forage and forestry production.

RESUMEN El Zinc (Zn) es un nutriente esencial para las plantas, existe limitada información de su disponibilidad en los suelos de Paraguay. El objetivo de la investigación consistió en evaluar y clasificar la disponibilidad de Zn en suelos de la región Oriental del Paraguay. Para ello fue generada una base de datos con los resultados de análisis de suelo de los laboratorios de la FCA-UNA, CIHB-IPTA y FUCAI-UCA. Se clasificó la concentración de Zn disponible de los suelos en nivel “alto” (>1,2 mg kg-1); “medio” (0,5 - 1,2 mg kg-1) y “bajo” (<0,5 mg kg-1), generándose un mapa de disponibilidad de Zn a nivel distrital. Se evaluó la disponibilidad de Zn a nivel distrital, departamental, así como, con parámetros de estadística descriptiva. Considerando la media de los niveles de Zn a nivel de distrito, de los 234 distritos que conforman la región Oriental del Paraguay, en el 74% de los distritos (174 distritos) presentaron nivel “alto”, 6% nivel “medio” (15 distritos) y el 3% nivel “bajo” de Zn (6 distritos). Considerando el número total de muestras de suelo analizadas (11.395 muestras), el 79% (9.038 muestras) presentaron niveles “alto” de Zn, el 12% (1.316 muestras) presentaron niveles “medio” de Zn, y solo el 9% (1.041 muestras) presentaron niveles “bajo” de Zn. La media nacional considerando las 11.395 muestras de suelo fue de 6,5 mg kg-1 de Zn, por lo tanto, en 79% de los suelos analizados de la región Oriental hay niveles de Zn superior al nivel crítico de Zn para las actividades agrícolas, de forrajes y forestales de producción.

ABSTRACT Phosphorus (P) is an essential nutrient for growth and yield of sweet potatoes; in sandy soils, sweet potato yield and quality may be limited by application of low P doses, mainly in degraded areas. The objective of this work was to evaluate the effect of P doses on yield and quality of sweet potato root tubers grown in tropical sandy soils with different initial P availabilities: 23.2 mg dm-3 (high P - crop rotation) and 3.7 mg dm-3 (low P - post degraded pasture). Two experiments were carried out in a randomized block design, with four replicates. The treatments consisted of P doses (0, 22, 44, 88, and 176 kg ha-1) applied to the planting bed. Tuber yield, number and mean weight of tubers, P concentration in leaves and tubers, exported P, as well as the percentage of starch, reducing sugars, total sugars, and sucrose in the tubers were evaluated. P concentration in the soil was evaluated at the end of the experiment. In the area with high P availability (> 20 mg dm-3 - resin), increasing P doses did not increase root tuber yield and decreased root starch concentrations. In the area with low P availability (< 3.7 mg dm-3 - resin), root tuber yield and starch concentration peaked when applying 68 and 33 kg ha-1 of P, respectively. In areas after degraded pasture, with low initial soil P concentration, P fertilization for sweet potato crops should be carried out with a P dose of 68 kg ha-1. In areas with crop rotation and adequate soil P concentration, P fertilization should be carried out to replace the amount of P exported by the harvested root tubers to avoid decreases in soil fertility.

RESUMO O fósforo (P) é um nutriente essencial para o crescimento e produtividade da batata-doce, e em solos arenosos, a produtividade e a qualidade da batata-doce podem ser limitadas pela baixa dose de P aplicada, principalmente em áreas degradadas. O objetivo deste trabalho foi avaliar o efeito de doses de fósforo na produtividade e qualidade das raízes tuberosas de batata-doce cultivadas em solos arenosos tropicais com diferentes disponibilidades iniciais de P; 23,2 mg dm-3 (P alto - rotação de culturas) e 3,7 mg dm-3 (P baixo - pós pastagem degradada). Dois experimentos foram conduzidos em blocos casualizados, com quatro repetições. Os tratamentos consistiram de doses de P (0, 22, 44, 88 e 176 kg ha-1) aplicadas no sulco de plantio. Foram avaliadas a produtividade, número e peso médio de tubérculos, teor de P nas folhas e nos tubérculos, exportação de P, além da porcentagem de amido, açúcar redutor, açúcar total e sacarose nos tubérculos. No final do estudo foi avaliado o teor de P no solo. Em área com alta disponibilidade de P (> 20 mg dm-3 - resina), o aumento das doses de P não aumenta a produtividade de tubérculos e diminui as concentrações de amido nas raízes. Em área com baixa disponibilidade de P (< 3,7 mg dm-3 - resina), a produtividade de tubérculos e a concentração de amido atingiram o máximo ao aplicar 68 e 33 kg ha-1 de P, respectivamente. Cultivo de batata-doce em área após pastagem degradada com baixo teor inicial de P no solo, a adubação fosfatada deve ser realizada na dose de 68 kg ha-1 de P. Em área com rotação de culturas e teor adequado de P no solo, a adubação fosfatada deve ser realizada para repor a quantidade de P exportada pelas raízes tuberosas colhidas para evitar a perda da fertilidade do solo.

ABSTRACT Water supply quality, nutrient availability in irrigation solutions, and discharge water or effluents must be monitored for protected cultivation to achieve sustainable management of food production. This study aimed to evaluate whether effluent solution from mini-tomato-protected crops can be recycled in an irrigation system based on plant nutritional demands. The experiment was carried out on a farm with mini-tomato protected-cropping. Water supply, as well as nutrient and effluent solutions, were analyzed in the experiment. Water supply was within the Brazilian limits established by CONAMA, except for nitrite, phosphorus, and sulfide. The effluent solution showed significant concentrations of macro- and micronutrients, highlighting phosphorus (220 to 395 mg L-1). The replacement of nutrient solution in the central fertigation tank, excess of elements applied in the nutrient solution, and accumulation of effluent solution in the disposal tank kept the effluent solution enriched when compared to the nutrient solution initially applied. Water quality monitoring showed that effluent solution can be reused in the irrigation system based on its physicochemical parameters and mini-tomato tomato nutritional demands. The analyses also allowed us to detect control points to achieve food production sustainability.

ABSTRACT Nitrogen (N) is the third nutrient more absorbed by okra. Therefore, an adequate supply of this element is essential for okra growth through the accumulation of dry matter in the leaves, stem, root and fruit. The objective was to evaluate the influence of N doses on growth, photoassimilates partition and yield of okra. The experiment was carried out in a Red-Yellow Argisol. A randomized complete block design with four replicates was used. The treatments consisted of N doses applied as topdressing (0, 60, 120, 240, 360 kg/ha). Samples of plants were held at 60, 75, 90, 105, 120, 135, 150 and 165 DAS for determination of the plant’s dry weight. The plant showed slow growth until 70 days, and after that time, intensified its growth until the end of the cycle. Total dry mass and absolute plant growth rate increased with increasing N availability, reaching the maximum marketable fruit yield of 10,665 kg/ha with 346 kg/ha N. The growth and partition of photoassimilates among the organs of the okra plant ‘Santa Cruz’ are altered with increasing nitrogen availability applied in topdressing.

RESUMO O nitrogênio (N) é o terceiro nutriente mais absorvido pelo quiabo. Portanto, o suprimento adequado deste elemento é essencial para o crescimento do quiabeiro por meio do acúmulo de massa seca nas folhas, caule, raízes e frutos. O objetivo deste trabalho foi avaliar a influência do nitrogênio no crescimento, na partição de fotoassimilados e na produtividade do quiabeiro. O experimento foi realizado em Argissolo Vermelho-Amarelo. Utilizou-se o delineamento em blocos ao acaso com quatro repetições. Os tratamentos foram constituídos de doses de N aplicadas em cobertura (0, 60, 120, 240 e 360 kg/ha). As amostragens de plantas foram realizadas aos 60, 75, 90, 105, 120, 135, 150 e 165 dias para determinação da massa seca da planta. A planta apresentou um crescimento lento até 70 dias, e após esse tempo, intensificou o seu crescimento até o final do ciclo. A massa seca total e a taxa de crescimento absoluto das plantas aumentaram com o aumento da disponibilidade de N, alcançando a máxima produtividade de frutos comercializáveis de 10.665 kg/ha com a dose 346 kg/ha de N. O crescimento e a partição de fotoassimilados entre os órgãos da planta do quiabo ‘Santa Cruz’ são alterados com o aumento da disponibilidade de nitrogênio aplicado em cobertura.

ABSTRACT Soil nutrient availability and interpretations of nutrient contents are based on the results obtained from specific extraction methods used in routine testing laboratories. The development of new extraction methods and new extractants with better accuracy is particularly important to determine the correct fertilizer rates to be applied. For this purpose, this study aims to synthesize, characterize and evaluate the predictive capacity of cellulose acetate film containing calcinated layered double hydroxide (CAF-LDH-c), as a new extractant and a new method of P extraction in soils. Different analyses techniques were used to characterize the CAF-LDH-c sample, including X-ray diffraction, attenuated total reflectance Fourier transform infrared spectroscopy, and scanning electronic microscopy. Soils were collected from twelve areas with different management and initial availability of P. The soils were subjected to six rates of P and were cultivated with plants. The predictive capacity of CAF-LDH-c, as a new extractant of P in different soils, was evaluated and compared to Mehlich-1 (M-1), Mehlich-3 (M-3), and Mixed Exchange Resin (MER) extractants. Chemical analyses performed on CAF-LDH-c showed that LDH in powder form was incorporated into the cellulose acetate film. There was a linear relation between P uptake by plants and extractable soil P in the soil by CAF-LDH-c, M-1, M-3, and MER extractants. The significant correlations between extracted P in the soil and P uptake by plants for CAF-LDH-c showed the efficacy of the new extractor and the newly proposed method for different types of soils. The results from the present study confirm the possibility of using CAF-LDH-c extractant as a new methodology to evaluate the availability of P in the soil for plant cultivation.

Resumo Objetivo Os processos de ciclagem em áreas úmidas são altamente dinâmicos e envolvem interações complexas entre processos hidrológicos, transformações biogeoquímicas e comunidades microbianas. Esta revisão avaliou as interações entre os elementos no contexto dos ciclos biogeoquímicos e as possíveis rotas em que a matéria orgânica é processada em solos alagados. Métodos Nessa revisão foram abordados os processos de entrada e ciclagem de matéria orgânica em solos inundados. Utilizamos um levantamento bibliográfico não sistemático para indicar as possíveis rotas biogeoquímicas de processamento da matéria orgânica em solos alagados. Resultados Exploramos processos hidrológicos, disponibilidade de oxigênio, rotas biogeoquímicas do processo de matéria orgânica e as entradas e exportações de matéria orgânica em solos alagados de áreas úmidas. Conclusões A degradação anaeróbica dos recursos orgânicos ocorre predominantemente em solos submersos. Em condições de manutenção das taxas naturais de produção primária e adução de detritos alóctones, o armazenamento de detritos orgânicos em solos alagados prevalece sobre a mineralização. A importância da hidrologia para a exportação de carbono orgânico é evidente. Nas áreas úmidas, a exportação de matéria orgânica está predominantemente associada à matéria orgânica dissolvida e a produção de metano. hidrológicos microbianas inundados oxigênio submersos alóctones mineralização evidente metano

Abstract Aim Cycling processes in wetlands are highly dynamic and involve complex interactions between hydrological processes, biogeochemical transformations, and microbial communities. This review attempts to assess the interactions between elements within biogeochemical cycles and the possible routes in which organic matter is processed in waterlogged soils. Methods The input and cycling of organic matter in flooded soils were approached in this review. We used a non-systematic literature survey to indicate the possible biogeochemical routes of organic matter processing in waterlogged soils. Results We explore hydrological processes, oxygen availability, biogeochemical routes of the organic matter process, and the inputs and exports of organic matter in flooded soils from wetlands. Conclusions The anaerobic degradation of organic resources predominantly occurs within submerged soils. Under conditions of maintenance of natural rates of primary production and allochthonous detritus input, storing organic detritus in flooded soils prevails over mineralization. The importance of hydrology for the export of organic carbon is evident. In wetlands, the export of organic matter is predominantly associated with dissolved organic matter and methane production. transformations communities nonsystematic non systematic availability process mineralization evident

ABSTRACT The naturally fragile sandy soils of the Pampa Biome (PB) may be degraded with the introduction of poorly managed agricultural crops. Anthropic use can markedly decrease vegetation cover on sandy soils, leaving them more exposed to erosive agents. Decreases in organic matter content, biodiversity, and nutrient availability, increased soil compaction, and decreased water availability are also some of the impacts caused on PB soils by implementing poorly managed agricultural crops. In Rio Grande do Sul, in areas with sandier soils, the intense replacement of PB with commercial crops that has occurred in recent years (2000-2020) may be starting a disastrous cycle of degradation of these soils. However, it is not yet known how much these soils are degraded by recent anthropic use. There are no local scientific publications dedicated to the diagnosis of the degradation of these soils by anthropic use. Therefore, the need for this study was based on the objective of evaluating the physical and hydraulic properties of sandy PB soils with the insertion of agricultural crops. The study was conducted on three different soils, where soil samples were collected under three systems of use (extensive cattle raising on native grassland, eucalyptus afforestation, and soybean crop). Our results show that it can take more than nine years for soybean and ten years for eucalyptus land-use change to indicate some level of degradation in soil physical and hydraulic properties after replacing PB with these cultivated crops.

ABSTRACT Ammonia volatilisation causes major nitrogen losses from the soil and applied urea which results in low urea-N usage efficiency. Incubation experiment and pot experiment were conducted to assess the effect of enriched rice straw biochar on ammonia volatilisation, soil pH, exchangeable ammonium, available nitrate, and rice plant growth in comparison to the urea without additives under waterlogged conditions. During the incubation study, urea was amended with different rates of enriched rice straw biochar (5, 10, 15, and 20 t ·ha-1). Urea amended with biochar at 5 to 10 t·ha-1 had successfully minimized ammonia loss compared to urea without biochar. Besides, application rate of 5 to 10 t·ha-1 of biochar also preserved more ammonium ions (65.37% and 66.54%, respectively), while at the same time, the retention of nitrate ions was 50.9% and 45.3% over urea without biochar. Similarly, 5 to 10 t·ha-1 of enriched rice straw biochar increased soil N level and improved rice plant growth significantly in pot experiment. Precisely, incorporation of enriched rice straw biochar at rate of 5 and 10 t·ha-1 offers wide variety benefits to soil amendments and rice plant nutrient uptake. Hence, the findings suggest that urea amended with enriched rice straw biochar altered the nutrients level in soil by improving rice plant growth.

Abstract Estuaries are important features for global biogeochemical understanding, due to their highly coupled interaction between sediment and water. In those places, the land-sea transect sometimes has a gradient of physical and chemical characteristics, influencing the availability of nutrients and consequently primary production. This study aimed to observe the benthic aerobic respiration and sediment-water nutrient fluxes in a freshwater to marine transect in the Cananéia-Iguape Estuarine-Lagoon Complex (CIELC) on the southeastern Brazilian Coast. This area contains the most pristine mangrove at the limit between tropical and subtropical zones, providing an ideal observatory for ecological research programs. Intact sediment cores were incubated in laboratory to determine fluxes of O2, TCO2, and dissolved nutrients. Three different sites with different salinities were sampled during the four seasons of the year. Sediment characteristics of the sites were compared, showing higher organic matter in the lowest saline (LS) site and higher phytopigments in the highest saline (HS) site, as expected. Benthic aerobic respiration, O2 and CO2 fluxes, ranged from −0.4 to −3.2 mmol m−2h−1 and 0.1 to 1.5 mmol m−2h−1, respectively, and exhibited statistically significant variations between seasons and in a salinity gradient. Dissolved inorganic nitrogen and silicate, ranging from −228.7 to 544.8 μmol m−2h−1 and −205.8 to 4,173.5 μmol m−2h−1, respectively, were generally released from the sediment, whereas phosphate ranged from −25.2 to 29.6 μmol m−2h−1 with more variation in time and space. The LS site was characterized as a nitrogen sink and a silicate and phosphate releaser, and the HS site was characterized as a nitrogen producer and a phosphorus consumer. However, seasonal and spatial variations were observed, and the interaction between space and time factors was always highly significant, indicating that the metabolic behavior of the benthic compartment depends on both trophic and physicochemical conditions.

ABSTRACT Cover crops, isolated or mixed, provide several benefits to agricultural systems, such as nutrient cycling and weed control. The present study aimed to determine the biomass production and nutrient accumulation of a cover crop mix and its effects on weed suppression (biomass production), in the off-season, in a no-tillage area in the Cerrado region. The experimental design was in randomized blocks with six treatments and eight replications. Treatments comprised five cover crop mixes plus the control treatment (fallow). Mixes of cover crops, cultivated between grain harvests in a no-tillage system in the Cerrado region, efficiently reduced weed shoot biomass in the three evaluation periods, 30, 70, and 210 days after sowing. Additionally, it is concluded that the mixes 5 (Black oats, Buckwheat, Millet, Piatã grass, and Crotalaria ochroleuca) and 4 (C. spectabilis, Buckwheat, Pearl millet, and Crotalaria breviflora) are the best among those evaluated for Cerrado conditions because they produce more biomass in the offseason, due to the greater availability of nutrients to the soil, in addition to providing less biomass of weeds compared to fallow.

RESUMO As plantas de cobertura, isoladas ou em mix, proporcionam diversos benefícios aos sistemas agrícolas, como ciclagem de nutrientes e controle de plantas daninhas. O presente estudo teve como objetivo determinar a produção de biomassa e o acúmulo de nutrientes de mixes de plantas de cobertura e seus efeitos na supressão de plantas daninhas (produção de biomassa), na entressafra, em uma área de plantio direto na região do Cerrado. O delineamento experimental foi em blocos casualizados com seis tratamentos e oito repetições. Os tratamentos consistiram em cinco mix de plantas de cobertura mais o tratamento controle (pousio). Os mixes de plantas de cobertura, cultivadas na entressafra de grãos em sistema plantio direto na região do Cerrado, reduziram eficientemente a biomassa da parte aérea das plantas daninhas nos três períodos de avaliação, 30, 70 e 210 dias após a semeadura. Adicionalmente, conclui-se que os mixes 5 (Aveia preta, Trigo mourisco, Milheto, Capim Piatã e Crotalaria ochroleuca) e 4 (C. spectabilis, Trigo mourisco, Milheto e Crotalaria breviflora) são os melhores dentre os avaliados para condições de Cerrado, pois produzem mais biomassa na entressafra, devido à maior disponibilidade de nutrientes ao solo, além de proporcionarem menor biomassa de plantas daninhas em comparação ao pousio.