Resumen: Las Reservas Ecológicas, son la base primordial para la subsistencia de la biodiversidad, desempeñan funciones cruciales para el mantenimiento de los ecosistemas, especialmente, en la preservación de los servicios ecosistémicos de regulación del clima y suministro de agua. Determinar la capacidad de acumulación del COS en tres ecosistemas de la Reserva Ecológica Arenillas (REAR) y la influencia que tienen con los factores de profundidad y el tipo de suelo, fue el objetivo de la investigación. Se partió de la hipótesis que dichos factores ejercen un efecto sobre las propiedades físicas-químicas del suelo, provocando la variabilidad del carbono. Se establecieron 14 unidades de muestreo para los tres ecosistemas; 1) Intervenido, 2) Bosque deciduo y 3) Bosque arbustal deciduo, se extrajo de cada unidad dos muestras de suelo a profundidades de (0-10 y 10-30 cm), dando un total de 28 muestras. Los resultados revelaron diferencias significativas entre los tres tipos de ecosistemas, permitiendo afirmar que, en la REAR, el contenido de COS es mayor en el ecosistema de Bosque deciduo, que en los denominados Bosque arbustal deciduo y la zona Intervenida. Así mismo, los suelos del tipo Alfisol y Entisol en el Bosque deciduo presentaron la mayor capacidad de almacenamiento de COS, siendo la capa superficial la de mayor acumulación en los tres ecosistemas. Se concluyó que las bajas precipitaciones, el aumento de la temperatura y la esporádica vegetación producida por actividades antrópicas, afectan el almacenamiento de COS, limitando la prestación de servicios ecosistémicos relacionados con la captura de carbono edáfico.

Abstract: Ecological Reserves are the primary basis for the subsistence of biodiversity, they play crucial roles in the maintenance of ecosystems, especially in the preservation of ecosystem services of climate regulation and water supply. The objective of the research was to determine the accumulation capacity of COS in three ecosystems of the Arenillas Ecological Reserve (REAR) and the influence of depth factors and soil type. It was hypothesized that these factors exert an effect on the physical-chemical properties of the soil, causing carbon variability. Fourteen sampling units were established for the three ecosystems; 1) Intervened, 2) Deciduous Forest and 3) Deciduous shrub forest, two soil samples were extracted from each unit at depths of (0-10 and 10-30 cm), giving a total of 28 samples. The results revealed significant differences between the three types of ecosystems, allowing us to affirm that, in the REAR, the COS content is higher in the deciduous forest ecosystem than in the deciduous shrub forest and the Intermediate zone. Likewise, Alfisol and Entisol soils in the deciduous forest had the highest COS storage capacity, being the surface layer the one with the highest accumulation in the three ecosystems. It was concluded that low precipitation, increased temperature and sporadic vegetation produced by anthropic activities affect COS storage, limiting the provision of ecosystem services related to soil carbon sequestration.

Resumen La cuenca baja del río Acre se ubica en una zona de deforestación con la implementación de pastizales para ganado vacuno en suelos susceptibles a la erosión y clima ecuatorial. La existencia de mataderos y ganado vacuno en el municipio de Boca do Acre, en el estado de Amazonas, es uno de los problemas vinculados a la deforestación en la Amazonía brasileña. Ante este escenario, se presentó una estimación de las pérdidas de suelo con la aplicación de la Ecuación Universal en un sistema de información geográfica. En la metodología, se desarrolló una base de datos con información vectorizada para extraer las áreas de tipos de suelo y cobertura del suelo, incluyendo el análisis espacial de pendientes extraído del modelo digital de elevación. Como resultado del análisis de las áreas por geoprocesamiento y vectorización, se obtuvieron los cálculos de las parcelas de erosión a través de tablas con los parámetros adoptados por los referentes científicos. Se encontró que el 60% de la pérdida de suelo ocurre en el área agrícola en el 11% del territorio de la cuenca, siendo predominantemente en áreas de asentamientos rurales en el estado de Acre. Como resultado de la estimación, la pérdida de suelo en la cuenca baja del río Acre fue de 386.422 t/ha/año, con una producción de 46 millones de toneladas de sedimentos por año.

Abstract The Lower Acre River Basin is located in an area of deforestation with the implementation of pastures for beef cattle ranching in soils susceptible to erosion and equatorial climate. The existence of slaughterhouses and beef cattle in the municipality of Boca do Acre, in the state of Amazonas, is one of the problems linked to deforestation in the Brazilian Amazon. Given this scenario, an estimate of soil losses was presented with the application of the Universal Equation in a geographic information system. In the methodology, a database was elaborated with vectorized information for the extraction of the areas of the types of soils and land cover, including the spatial analysis of slopes extracted from the digital elevation model. Due to the analysis of the areas by geoprocessing occurring by vectorization, the calculations of the erosion plots were obtained through tables with the parameters adopted by the scientific references. It was found that 60% of the soil loss occurs in the area of agriculture in 11% of the territory of the watershed, being predominantly in areas of rural settlements of the state of Acre. As a result of the estimate, soil loss in the Lower Acre River Basin was 386,422 t/ha/year, with a production of 46 million tons of sediment per year.

Resumo A Bacia do Baixo Rio Acre está localizada em uma área de desflorestamento com implantação de pastagens para pecuária de corte em solos suscetíveis à erosão e clima equatorial. A existência de abatedouros e pecuária de corte implantada no município de Boca do Acre, no Amazonas, é um dos problemas vinculados ao desmatamento da Amazônia Brasileira. Diante desse cenário, foi apresentada uma estimativa de perdas de solo com aplicação da Equação Universal em sistema de informação geográfica. Na metodologia, foi elaborado um banco de dados com informações vetorizadas para extração das áreas dos tipos de solos e cobertura da terra, incluindo a análise espacial de declividades extraídas do modelo digital de elevação. Em decorrência da análise das áreas pelo geoprocessamento ocorrer pela vetorização, foram obtidos os cálculos das parcelas de erosão através de tabelas com os parâmetros adotados pelas referências científicas. Foi constatado que 60% da perda de solo ocorrem na área de agricultura em 11% do território da bacia hidrográfica, sendo predominantemente em áreas de assentamentos rurais do estado do Acre. Como resultado da estimativa, a perda de solos na Bacia do Baixo Rio Acre foi de 386.422 t/ha/ano, com uma produção de 46 milhões de toneladas de sedimentos por ano.

Summary: The state of Chiapas presents degradation processes of dif ferent kinds, as a consequence of the current established agricultural model. It is estimated that, in the near future, the surface of the state of Chiapas will present more than 55% degradation, generating changes in the physical, chemical and biological properties of the soil, af fecting the quality of life of human beings, mainly due to scarcity of food. The objective of this research was to evaluate the quality of the soils in three municipalities of the central depression of Chiapas, Mexico. The analysis were interpreted taking NOM-021-SEMARNAT-2000 as a reference and were classified according to the world reference base (WRB), version 2014. For the evaluation of soil quality, the sustainable use of land subindex (SUSS). 144 soil samples corresponding to 21 profiles were analyzed. Of the 21 profiles studied, 17 present poor soil qualities, two a sensitive quality, one acceptable quality and one with good quality. Only two soil groups presented good fertility and are classified as Vertisols and Phaeozems, which present good quality and capacity to maintain sustainable agricultural production in this region.

Resumen: El estado de Chiapas presenta procesos de degradación de diferente índole, como consecuencia del actual modelo agrícola establecido. Se estima que, en el futuro cercano, la superficie del estado de Chiapas presente más de 55% de degradación, generando modificaciones en las propiedades físicas, químicas y biológicas del suelo; afectando la calidad de vida de los seres humanos, principalmente por escasez de alimentos. El objetivo de esta investigación fue evaluar la calidad de los suelos en tres municipios de la depresión central de Chiapas, México. Los análisis se interpretaron tomando como referencia la NOM-021-SEMARNAT-2000 y se clasificaron de acuerdo con la world reference base (WRB), versión 2014, para la evaluación de calidad del suelo se utilizó el subíndice de uso sustentable del suelo (SUSS). Se analizaron 144 muestras de suelo correspondientes a 21 perfiles. De los 21 perfiles estudiados, 17 presentan calidad de suelo pobre, dos calidades sensibles, uno calidad aceptable y uno con calidad buena. Solo dos Grupos de suelo presentaron buena fertilidad y son clasificados como Vertisols y Phaeozems, los cuales presentan buena calidad y capacidad para mantener producción agrícola sostenible en esta región.

Summary: Excessive use of chlorpyrifos affects the quality of agricultural soils causing negative effects on the safety of harvested food. The behavior of chlorpyrifos residues depends on soil properties, especially organic matter. Our aim in this research was to determine the effect of the application of vermicompost on the residual and dissipation of chlorpyrifos in an entisol soil of semi-arid climate with variations in its edaphic fertility. Four treatments were studied. T1: 7.5% vermicompost (V) and 92.5% soil (S); T2: 5% V and 95% S; T3: 2.5% V and 97.5% S; T4: 0% V and 100% S. The treatments were subjected to a seven-day incubation period. Subsequently, a dose of chlorpyrifos of 1.5 mg kg-1 as active ingredient was applied once for each treatment. A completely randomized design was used with three replicates for each treatment, forming 12 experimental units. The analytical determination of chlorpyrifos was carried out by high performance liquid chromatography (HPLC). The evaluations were carried out 1.7, 14, 28, 42, 70 and 98 days after the application of chlorpyrifos. The results showed that the incorporation of vermicompost to the soil at increasing levels promoted a decrease in the residual concentration of chlorpyrifos and facilitated its gradual dissipation. The chlorpyrifos dissipation curves correspond to a first order logarithmic equation where the effects of the treatments caused greater dissipation of chlorpyrifos as the evaluation period elapsed. At 98 days of evaluation, T1 registered lower residuality (0.786 m kg-1), higher daily dissipation rate (0.008) and lower half-life of chlorpyrifos (86.64 days). At the end of the research period, edaphic levels of P, K, EC and CEC increased while OM, N and pH decreased after vermicompost application.

Resumen: El uso excesivo de clorpirifos afecta la calidad de los suelos agrícolas provocando efectos negativos en la inocuidad de los alimentos cosechados. El comportamiento de los residuos de clorpirifos depende de las propiedades edáficas especialmente la materia orgánica. El objetivo de la investigación fue determinar el efecto de la aplicación de vermicompost en la residualidad y disipación de clorpirifos en un suelo entisol de clima semiárido con variaciones en su fertilidad edáfica. Se estudiaron cuatro tratamientos. T1: 7.5% vermicompost (V) y 92.5% suelo (S); T2: 5% V y 95% S; T3: 2.5% V y 97.5% S; T4: 0% V y 100% S. Los tratamientos fueron sometidos a un periodo de incubación de siete días. Posteriormente, se aplicó una dosis de clorpirifos de 1.5 mg kg-1 como ingrediente activo en una sola oportunidad por cada tratamiento. Se utilizó un diseño completamente al azar con tres repeticiones por cada tratamiento conformando 12 unidades experimentales. La determinación analítica de clorpirifos se efectuó por cromatografía líquida de alta resolución (HPLC). Las evaluaciones se realizaron a 1,7, 14, 28, 42, 70 y 98 días de la aplicación de clorpirifos. Los resultados demostraron que la incorporación de vermicompost al suelo en niveles crecientes promovió la disminución de la concentración residual de clorpirifos y facilitó su disipación de manera gradual. Las curvas de disipación de clorpirifos corresponden a una ecuación logarítmica de primer orden donde los efectos de los tratamientos ocasionaron mayor disipación de clorpirifos conforme transcurrió el periodo de evaluación. A 98 días de evaluación el T1 registró menor residualidad (0.786 m kg-1), mayor tasa de disipación diaria (0.008) y menor vida media de clorpirifos (86.64 días). Al final del periodo de investigación, los niveles edáficos de P, K, CE y CIC se incrementaron mientras que la MO, N y pH descendieron luego de la aplicación de vermicompost.

Abstract Introduction. Climate change adaptation measures require informed decision-making. However, small-scale agriculture shows low rates of technology adoption due to cost and lack of connectivity. Objective. To evaluate three low-cost prototypes of small-scale agriculture devices for soil moisture measurement in different soil textures, as well as to determine the respective calibration equations, and the effects of electrical conductivity and temperature on moisture measurement. Materials and methods. Three measurement and recording prototypes for soil moisture were evaluated in soils with variations in clay/sand content and electrical conductivity in productive plots at Zamorano University in Honduras and a demonstration farm in Popayán, Colombia during the first quarter of 2022. Commercial sensors were used as a reference to compare the performance of the prototypes through regression analysis of hourly sensor readings over 90 days. Electrical conductivity (dS/m) and temperature variables were collected to determine their influence on moisture reading accuracy. Results. The soil moisture measurement devices showed better performance in soils with lower sand content. The measurement from the devices overestimated moisture readings by 0.19 to 0.52 percentage points for each additional degree of soil temperature. Additionally, for each additional dS/m of electrical conductivity, the reading needed adjustment by 8 to 55 percentage points. Conclusions. Prototype A was the most accurate device, while prototype B was the most precise compared to commercial sensors. Soil moisture devices performed best in soils with lower sand content. The three models evaluated performed best in loam soil with a medium clay content.

Resumen Introducción. Las medidas de adaptación al cambio climático requieren de la toma de decisiones informadas. Sin embargo, la agricultura de pequeña escala muestra bajas tasas de adopción de tecnologías por su costo y falta de conectividad. Objetivo. Evaluar tres prototipos de dispositivos para agricultura de pequeña escala y de bajo costo para medir humedad de suelo en diferentes texturas, así como determinar las respectivas ecuaciones de calibración y los efectos de conductividad eléctrica y temperatura en la medida de humedad. Materiales y métodos. Se evaluaron tres prototipos de dispositivos de medición y registro de humedad de suelo, en suelos con diferencial en contenido de arcilla/arena y conductividad eléctrica en parcelas productivas de la Universidad Zamorano, en Honduras; y Finca demostrativa en Popayán, Colombia, durante el primer trimestre del 2022. Se tomaron como referencia sensores comerciales para la comparación del desempeño de los prototipos, mediante análisis de regresión de las lecturas por hora de los sensores durante 90 días. Se recolectaron las variables de conductividad eléctrica (dS/m) y temperatura para determinar la influencia en la precisión de la lectura de humedad. Resultados. Los dispositivos de medición y registro de humedad presentaron un mejor desempeño en suelos con menor contenido de arena. La medición de los dispositivos sobrestimó entre 0,19 y 0,52 puntos porcentuales la lectura de humedad por cada grado adicional de temperatura del suelo, y que por cada dS/m adicional de conductividad eléctrica la lectura se debe ajustar entre 8 y 55 puntos porcentuales. Conclusiones. El prototipo A fue el dispositivo más exacto, mientras que el prototipo B fue el más preciso, con respecto a los sensores comerciales. Los dispositivos de humedad presentaron un mejor desempeño en suelos con menor contenido de arena. Los tres modelos evaluados obtuvieron el mejor desempeño en suelo franco con contenido medio de arcilla.

Abstract Introduction. The soil and climatic conditions of Ecuador are ideal for rice cultivation, yields are higher than the world average, but agronomic management leads to an increase of cadmium in the soil, which can reach the grain by translocation, which affects its safety. Objetive. To evaluate the absorption of cadmium through the omission of macronutrients technique in six soils of Ecuador and its effect on the vegetative development of rice crops. Materials and methods. The trial was carried out at the Pichilingue Tropical Experimental Station of the National Institute of Agricultural Research, Ecuador, during 2018. Nine treatments were studied: 1) Without fertilization and without Cd (control 1), 2) without fertilization and with Cd (Control 2), 3) Complete fertilization and six omission treatments of one nutrient at a time, a completely randomized block design of experiments, divided plots and three repetitions was used. The variables evaluated were those related to the production of dry matter in the root and aerial part. For the comparison between means, the Tukey test was used (p<0.05). Results. Nutrients omissions (N and P) led to reduced Cd absorption, which decreased dry matter production, particularly in very acidic or alkaline soils such as in Sucumbíos (pH 4) and Guayas (pH 7, 9), respectively. Conclusions. The absorption of cadmium in rice plants was reduced to a greater extent with the omission of the macronutrients N and P, mainly in the soils of Sucumbíos, Los Ríos, El Oro and Manabí, the nutrient omission technique also affecting the production of dry matter and yields, also observing that a pH below 5 or higher than 7.9 affects the absorption of cadmium in the soils studied.

Resumen Introducción. Las condiciones edafoclimáticas del Ecuador son ideales para el cultivo del arroz, los rendimientos son mayores al promedio mundial, pero su manejo agronómico conlleva a un aumento de cadmio en el suelo, que puede llegar al grano por translocación, lo cual afectan su inocuidad. Objetivo. Evaluar la absorción de cadmio mediante la técnica de omisión de macronutrientes en seis suelos del Ecuador y su efecto sobre el desarrollo vegetativo del cultivo de arroz. Materiales y métodos. El ensayo se realizó en la Estación Experimental Tropical Pichilingue del Instituto Nacional de Investigaciones Agropecuarias, Ecuador, durante el año 2018. Se estudiaron nueve tratamientos 1) Sin fertilización y sin Cd (testigo 1), 2) sin fertilización y con Cd (Testigo 2), 3) Fertilización completa y seis tratamientos de omisión de un nutriente a la vez, se usó un diseño de experimentos de bloques completamente al azar, parcelas divididas y tres repeticiones. Las variables evaluadas fueron las relacionadas a la producción de materia seca en raíz y parte aérea. Para la comparación entre medias, se utilizó la prueba de Tukey (p<0,05). Resultados. Las omisiones de los nutrientes (N y P) llevaron a la reducción de la absorción del Cd, que disminuyó la producción de materia seca, en particular en los suelos muy ácidos o alcalinos como en Sucumbíos (pH 4) y Guayas (pH 7,9), respectivamente. Conclusiones. La absorción de cadmio en plantas de arroz se redujo en mayor medida con la omisión de los macronutrientes N y P, principalmente en los suelos de Sucumbíos, Los Ríos, El Oro y Manabí, afectando también la omisión de nutrientes a la producción de materia seca y los rendimientos, observándose además que un pH por debajo de 5 o superior a 7,9 afecta la absorción de cadmio en los suelos estudiados

Resumen La carretera Puyo-Tena es propensa a deslizamientos de tierra debido a la geodinámica, geomorfología y materiales geológicos de la zona (afloramientos y estratos inestables). En los últimos años, este problema ha provocado de forma persistente la inutilización parcial o total de la carretera en numerosas ocasiones. El objetivo de la investigación fue generar un modelo cartográfico de susceptibilidad a deslizamientos a partir de variables como la pendiente, las formaciones geológicas, la cobertura y uso de la tierra, así como las distancias a fallas, carretera y ríos. El grado de incidencia de deslizamientos se estimó como la combinación lineal de las variables ponderadas mediante el proceso de jerarquía analítica. La importancia de este método semicuantitativo radica en su capacidad para desagregar un problema de decisión complejo en un modelo de decisión más simple y coherente. El modelo cartográfico resultante se reclasificó en cinco categorías de susceptibilidad: muy baja, baja, moderada, alta y muy alta. Los resultados mostraron que 17 km de los 80 km de la carretera Puyo-Tena tienen una alta probabilidad a deslizamientos, lo que equivale a 21,25% de la carretera. Además, dentro de este porcentaje, se determinó que existen quince regiones con alta probabilidad de deslizamientos debido a su ubicación en zonas con fuertes pendientes, litología porosa y permeable, gran cantidad de ríos y suelos agrícolas. Para la verificación del modelo se utilizó el área bajo la curva (en inglés AUC) de la característica operativa del receptor (en inglés ROC). Los resultados de la verificación mostraron que el modelo cartográfico para el área de estudio tiene un valor de precisión de 83,7%. El modelo cartográfico de susceptibilidad a deslizamientos permitirá tomar las decisiones pertinentes para mitigar eventos potenciales que puedan poner en peligro a transportistas, bienes materiales y residentes de la zona.

Abstract The Puyo-Tena roadway is prone to landslides due to the geodynamics, geomorphology, and geological materials of the area (unstable outcrops and strata). In recent years, this problem has persistently caused the road to be partially or completely disabled on numerous occasions. The objective of the research was to generate a cartographic model of landslides susceptibility based on variables such as slope, geological formations, land cover and land use, as well as distances to faults, road, and rivers. The degree of landslides incidence was estimated as the linear combination of the weighted variables using the analytic hierarchy process. The importance of this semi-quantitative method lies in its ability to break down a complex decision problem into a simpler and more coherent decision model. The resulting cartographic model was classified into five susceptibility categories: very low, low, moderate, high, and very high. The results showed that 17 km out of the 80 km of the Puyo-Tena roadway have a high probability of landslides, which is equivalent to 21.25% of the road. Furthermore, within this percentage, it was determined that there are fifteen regions with a high probability of landslides due to their location in areas with steep slopes, porous and permeable lithology, a large number of rivers, and agricultural soils. The area under the curve (AUC) of the receiver operating characteristic (ROC) was used for model verification. The verification results showed that the cartographic model for the study area has an accuracy value of 83.7%. The cartographic model of landslide susceptibility will enable relevant decisions to be made to mitigate potential hazards that may endanger transporters, material goods, and residents of the area.

ABSTRACT Lowland rice in Santa Catarina (SC), Brazil, is grown as a sole crop, which has aggravated problems with weeds. In this context, the objective of this study was to evaluate the efficacy of weed management systems in soybean crops to decrease weed infestation in lowland rice production areas, using pre- and post-emergence herbicides. The experiment was conducted in Turvo, SC, from August 2021 to April 2022. A randomized block design with four replications was used, in a 6 × 5 factorial arrangement. The factors consisted of six pre-emergence herbicides treatments (S-metolachlor, diclosulam, sulfentrazone, sulfentrazone + diuron, pyroxasulfone + flumioxazin, and a control without herbicide), and five post-emergence herbicide treatments: control without herbicide, glyphosate at two rates (930 and 1,550 g a.e. ha-1), applied alone or in combination with clethodim. The herbicide sulfentrazone caused persistent phytotoxicity and resulted in the lowest soybean grain yield. The herbicide S-metolachlor was ineffective in controlling weed species, except barnyard grass, even when combined with post-emergence application. The poor control of these weed species does not result in significant interference, causing no significant decreases in grain yield of soybean crops grown in floodplain soils. The use of S-metolachlor, diclosulam, and pyroxasulfone + flumioxazin, combined with post-emergence application of glyphosate (930 g a.e. ha-1), resulted in highly effective control of barnyard grass, inhibiting weed seed production. Only the combination of glyphosate (1,550 g a.e. ha-1) with clethodim can suppress barnyard grass seed production without using pre-emergence herbicides. SC , (SC) Brazil crop weeds context areas pre postemergence post emergence Turvo 202 2022 used arrangement preemergence Smetolachlor, Smetolachlor S metolachlor, metolachlor (S-metolachlor diclosulam diuron flumioxazin herbicide) 930 (93 1550 1 550 1,55 ae e a.e ha1, ha1 ha interference soils (1,55 ha-1 (SC 20 93 (9 155 55 1,5 (1,5 ha- 2 9 ( 15 1, (1, (1

RESUMO O arroz irrigado em Santa Catarina é cultivado em monocultivo, o que tem agravado os problemas com plantas daninhas. Deste modo, o objetivo deste estudo foi avaliar a eficiência de sistemas de manejo de plantas daninhas na cultura da soja sobre a redução da infestação de plantas daninhas em uma área de produção de arroz irrigado, utilizando para isso herbicidas em pré e/ou pós-emergência da soja. O experimento foi conduzido no município de Turvo - SC no período de agosto de 2021 a abril de 2022. Utilizou-se o delineamento de blocos casualizados com tratamentos organizados em esquema fatorial 6 × 5, com quatro repetições. O fator A constou de seis tratamentos aplicados em pré-emergência, os herbicidas utilizados foram: S-metolachlor, diclosulam, sulfentrazone, sulfentrazone + diuron, pyroxasulfone + flumioxazin, além de uma testemunha sem herbicida. Já o fator B constou de cinco tratamentos aplicados em pós-emergência: testemunha sem herbicida, gyphosate em duas doses (930 e 1550 g e.a. ha-1), aplicadas de forma isoladas ou em associação com clethodim. O herbicida S-metolachlor foi ineficiente para o controle de outras plantas daninhas, mesmo quando combinado com a aplicação em pós-emergência. O controle deficiente destas espécies não resulta em significativa interferência, não causando decréscimo na produtividade de grãos da soja, em ambientes de terras baixas. O uso dos herbicidas S-metolachlor, diclosulam e pyroxasulfone + flumioxazin, combinados com a aplicação em pós-emergência de glyphosate (930 g e.a. ha-1) resultou em controle eficiente de capim-arroz e inibiu a produção de sementes. Apenas a associação de glyphosate (1550 g e.a. ha-1) com clethodim suprimiu a produção de sementes de capim-arroz, sem a aplicação de herbicidas em pré-emergência. monocultivo modo eou pósemergência pós emergência 202 2022 Utilizouse Utilizou se 5 repetições préemergência, préemergência emergência, pré-emergência foram Smetolachlor, Smetolachlor S metolachlor, metolachlor diuron flumioxazin 930 (93 155 ea e.a ha1, ha1 ha 1 , pósemergência. emergência. interferência baixas ha-1 capimarroz capim (155 capimarroz, arroz, préemergência. 20 93 (9 15 ha- (15 2 9 ( (1

Verlorenvlei is a globally important RAMSAR wetland on the arid west coast of South Africa. A prolonged drought between 2016 and 2021 and increasing competition for water from the agricultural sector resulted in extremely low water levels. We used historical aerial and satellite imagery from 1942 and rainfall and water level data for the past 50 years, to assess habitat changes within the estuarine functional zone of the Verlorenvlei Estuarine Lake. Prior to the drought, lake water levels and water surface area remained stable (1113 ± 27 ha (SE)). Since then, there has been a 64% decrease in open water area, exposing 193 ha of sandbanks, of which 190.9 ha were hyper-sulfidic pyrite-rich. The water in the lower lake was hypersaline (>100), and in the middle, it was acidic (pH<3). The low water level plus sediment and nutrient input from surrounding agriculture resulted in a localised increase in reeds. Additional pressures, such as fires, have reduced the above-ground biomass of reeds and sedges, potentially altering surface morphology and reducing stored carbon. Despite flooding and filling up in June 2023, the lake remained in an acidic state (3.9-4.3). Similar low-lake level, hypersaline and acidic conditions are predicted to become more common under future climate change scenarios where aridity and extreme weather events are anticipated. Inflow of fresh water into the estuary and control of farming practices are required to keep the Verlorenvlei in a functional state, with long-term monitoring necessary to assess the ecological condition in response to restoration actions. SIGNIFICANCE: We assessed the habitat changes in Verlorenvlei, an estuarine lake on the arid west coast of South Africa. Estuarine lakes are scarce, and an extended drought greatly reduced the water surface area, exposing hyper-sulfidic pyrite-rich soils, leading to lake acidification and a negative response from biota. Competition for water from agribusiness and the burning of reeds are added pressures. Subsequent heavy rains have been slow to buffer lake acidity, and the impacts thereof serve as a warning for the management of similar ecosystems and their ecological water requirements, especially under climate change where extreme weather conditions, increased aridity and competition for water are realities.

Resumen El estado de Yucatán, conocido por sus suelos poco profundos de Leptosol plantea desafíos a la agricultura. Por lo tanto, este estudio se centró en examinar los atributos ecofisiológicos que influyen en los determinantes del crecimiento y rendimiento de seis genotipos de maíz. El estudio evaluó características vegetativas, tasas de crecimiento, distribución de materia seca, rendimiento de grano e índice de cosecha. Todos los genotipos de maíz mostraron madurez temprana, una característica favorable bajo las condiciones de clima de Yucatán. La mayoría de los genotipos exhibieron una tasa de crecimiento y un contenido de materia seca superiores en comparación con el genotipo nativo Elotillo. El tallo y el grano fueron identificados como los órganos primarios de acumulación de materia seca con 36% y 22%, respectivamente. El mayor rendimiento de grano se observó en los híbridos Impacto y DK-390. Este estudio proporcionó información valiosa para los agricultores al seleccionar genotipos de maíz adecuados en Yucatán, aunque se recomienda realizar evaluaciones adicionales con diferentes genotipos y condiciones de manejo.

Abstract The state of Yucatan, known for its shallow Leptosol soils poses challenges to agriculture. Therefore, this study focused on examining ecophysiological attributes influencing the growth and yield determinants of six maize genotypes. The study assessed vegetative characteristics, growth rates, dry matter allocation, grain yield, and harvest index. All maize genotypes exhibited early maturity, a favorable trait under the climate conditions of Yucatan. Most genotypes exhibited superior growth rate and dry matter content when compared to the landrace Elotillo. Stem and grain were identified as the primary organs for dry matter accumulation, with 36% and 22% respectively. The highest grain yield was noted in hybrids Impacto and DK-390. This study provided valuable information for farmers in selecting suitable maize genotypes in Yucatan, although additional evaluations of different genotypes and management conditions are recommended.

ABSTRACT: Buckwheat is known for its aptitude as green manure, as it increases soil’s physical and chemical properties at the same time it has none or very few fertilization requirements besides a fast canopy closure and has no ravagers or natural enemies documented in Brazil. This crop has the potential to fill an empty period known as the “Autumn gap” in Southern Brazil, which is characterized by the low or no forage offer at all, justified by the fact its forage has the same quality as that of a grass forage, besides, its grains, highly nutritious, can also be consumed by humans, ruminants, or non-ruminants. This review aims to provide relevant information about recent buckwheat research to make it a viable alternative for the Autumn gap. ABSTRACT manure soils soil s Brazil gap all grains nutritious humans ruminants nonruminants. nonruminants non ruminants. non-ruminants

RESUMO: O trigo mourisco é conhecido por sua aptidão como adubo verde, melhorando as propriedades físicas e químicas do solo ao mesmo tempo que possui nenhuma ou baixíssimas requisições de fertilização, além de rápido fechamento de dossel e de não possuir pragas nem outros inimigos naturais documentados no Brasil. Essa cultura tem o potencial de cultivo para preencher o período de tempo conhecido como “vazio outonal” no Sul do Brasil, período caracterizado pela baixa ou nenhuma oferta de forragem. O valor nutritivo é bom, além de seus grãos, altamente nutritivos, também poderem ser consumidos por humanos, ruminantes e não-ruminantes. Essa revisão visa fornecer informações relevantes da pesquisa sobre o trigo mourisco nos últimos anos objetivando o incentivo a viabilização dessa cultura como alternativa no vazio outonal no sul do Brasil. RESUMO verde fertilização Brasil forragem bom grãos nutritivos humanos nãoruminantes. nãoruminantes ruminantes. não-ruminantes

Irrigation is required to supplement rainfall to enhance the productivity of chickpea in South Africa (SA). However, the dependence on irrigation can be problematic for SA and other countries with limited natural water resources and variable rainfall. Even though access to irrigation water has been identified as one of the challenges faced when planting chickpea in the winter season in SA, irrigation management strategies for chickpea grown on soils differing in texture have not gained considerable research attention. Hence, this study aimed to assess the effects of irrigation levels on dry matter production of chickpea grown on two soils differing in soil texture under greenhouse conditions. The experiment was arranged as a 3 × 2 factorial in a completely randomized design, with 3 irrigation levels (25%, 50% and 75% of the water-holding capacity of soil (WHC)) and 2 soils differing in soil textural class (Loamy sand (LS) soil and sandy loam (SL) soil), replicated thrice. Irrigation level, soil texture and their interaction significantly affected shoot biomass (SBM) and total plant biomass (TBM). Generally, SBM, TBM and root biomass decreased correspondingly with the reduction in irrigation. The 25% WHC significantly reduced the SBM by up to 60% and TBM by up to 56% compared to the 50% and 75% WHC. The SBM and TBM were higher in SL soil than in LS soil. A significantly higher root/shoot ratio (0.45) in the LS soil than in the SL soil (0.16) indicated that the conditions of LS soil encouraged plants to allocate higher proportions of biomass into roots, possibly due to increased competition for soil resources. In conclusion, maintaining soil moisture at 50% WHC ensures better chickpea dry matter production in SL soil.

ABSTRACT Degraded peat has a high potential for use in agricultural production, especially food crops. The water table, which impacts the production of greenhouse gases (GHGs), is the main problem concerning peat utilization. The study aimed to determine the production of greenhouse gases at various peat water levels. The study was conducted in a laboratory setting utilizing the soil column of undisturbed peat soil. The factorial experiment was arranged in randomized block design, with three replicates, with the first factor was peat cropping use: Maize (Zea mays L.), pineapple (Ananas comosus (L.) Merr.), and scrubs. The second factor was water level (0, 10, 20, 30 cm depth). Variables measured were GHG flux (CO2 and CH4), pH, redox potential, total C content, and ash content. The peat cropping use interacted significantly with the peat water level on the potential for CH4 and CO2 production and the value of global warming potential. Water table depth significantly increased CO2 flux and global warming potential (GWP) in all three peat cropping uses. The lowest GWP at a 0 cm peat water level was 944 (pineapple use), 961 (maize use), and 1097 mg CO2e m-2 d-1 (scrub use). Peat for pineapple cultivation produces the lowest CO2 production and GWP compared to maize cultivation and scrubs. The negative relationship between redox potential and GWP is significant in peat for scrub. The relationship between pH and GWP is significant in peat for pineapple and scrub.

ABSTRACT Finding sustainable methods for utilizing biosolids, also known as municipal sewage sludge (SS), presents a pressing challenge in modern waste management practices. Therefore, this study aimed to evaluate the impact of SS amendment on growth, biochemical, proximate, and heavy metal bioaccumulation parameters of berseem clover (Trifolium alexandrinum L.) fodder crop under field conditions. Trifolium alexandrinum was cultivated using different rates of SS mixing (i.e., T0: 0% as control with no SS application, T1: 5%, and T2: 10%). The results obtained showed a significant (p < 0.05) increment in growth, biochemical, and proximate parameters of T. alexandrinum with an increasing SS mixing rate. The highest productivity of T. alexandrinum fodder (1.92 kg m-2 fw) was observed in the T2 treatment as compared to the control treatment. The heavy metal analysis of shoot and root parts of T. alexandrinum showed that the contents (mg kg-1) of eight elements (Cd 0.02-0.13, Co 0.04-0.08, Cu 5.94-0.05, Cr 0.43-1.68, Fe 7.08-15.93, Ni 0.89-2.90, Mn 1.62-5.38, and Zn 3.30-7.04) increased significantly (p < 0.05) with SS mixing rate. The bioaccumulation factor (BAF) was below 1 except for Cu and Zn exhibiting their rapid uptake by plants from SS-treated soils. However, dietary intake modeling (DIM < 1) and health risk index (HRI < 1) studies showed that the levels of heavy metals did not exceed the permissible limits in any SS treatment. Overall, SS amendment has a positive impact on the growth, biochemical, proximate, and heavy metal characteristics of T. alexandrinum. Therefore, this study suggested a strategy for low-cost soil fertilization and fodder crop production which could sustainably benefit waste recycling.

ABSTRACT Sugarcane-duck symbiosis (SDS) is an ecological breeding production method wherein meat ducks are released in sugarcane (Saccharum officinarum L.) fields during the middle and late stages of sugarcane growth. The effects of SDS on sugarcane rhizobacterial diversity remain poorly understood. We conducted field experiments with sugarcane monoculture (SC) and SDS and performed genetic analyses on the rhizobacterial communities based on 16S rRNA across different growth stages of sugarcane. The effects of soil physicochemical factors on the bacterial community structure were analyzed via redundancy analysis. We found that soil organic matter (SOM), total N (TN), nitrate N (NN), and ammonium N (AN) contents of sugarcane rhizosphere soils increased during different growth periods in SDS. During the perennial root stages, the Shannon-, Ace-, and Chao1 indices increased, whereas the available P (AP) content decreased. The soil pH was more balanced and its effect on the soil bacterial community was insignificant. The dominant sugarcane rhizosphere flora were Actinobacteria, Proteobacteria, Chloroflexi, Acidobacteria, Firmicutes, norank_f__norank_o__Gaiellales, Sphingomonas, norank_f__Roseiflexaceae, Bacillus, and norank_f__Xanthobacteraceae, but with significant inter-annual variations. Redundancy analysis showed that SOM, TN, NN, AN, AP, catalase (CAT) and invertase (INV) activity were closely associated with the diversity of the soil bacterial communities, and TN and INV activity were the main drivers of sugarcane rhizobacterial communities in the SDS groups. In conclusion, SDS improves the fertilizer supply capacity and soil quality of sugarcane soils by regulating major soil nutrient content, available nutrients, and microbial diversity. This study provides a theoretical basis for scientifically managing SDS and the screening of biocontrol bacteria.