Abstract The objective of this work was to evaluate different pastures types on carbon footprint (CF). The cattle in the Piedmont zone, Cumaral, Meta, Colombia are principally Brahman, the pastures are formed with the tropical forage grasses Brachiaria decumbens for improved pastures (IP) and degraded pastures of B. brizantha (DP), also, various silvopastoral systems (SPSs) depending of planting trees on pasture at the same time and in the same space were evaluated. GHG emissions per kg of live weight (LW) were estimated to be reduced from 9.14, and 7.17 to 4.4 kgCO2eq.kgLW-1 in SPSs, and IP to DP, respectively. In all systems the largest GHG emission were enteric fermentation CH4, manure management N2O, feed animal management CO2. Soil C sequestration rates ranged from 2.46 to -1.72 tCO2.ha-1.yr-1 in DP to SPSs, respectively, IP account for -1.35tCO2eq.ha-1yr-1. CF were neutralized from 8.12 to -11.6 kg CO2eq.kg LW-1 in DP to IP. The beef production system with the lowest CF studied were that based on SPSs, mainly B. decumbens associated with Acacia mangium, accounting -60 kg CO2eq.kgLW-1. In our study, all other SPSs had a very large impact on negative CF, due to differences in C stored in biomass that would account for GHG neutralization of -15.3, -21.8, -24.31, -20.42 kg CO2eq.kgLW-1 in SPSs of B. decumbens + Gliricidia sepium, B. decumbens + Mangifera indica, B. decumbens + G. angustifolia and B. decumbens + citrus cinensis, respectively. It is possible to neutralize CF in beef cattle production through several SPSs in Piedmont’s case study.

ABSTRACT Actinobacteria of the genus Streptomyces are part of the soil microbiota from rice-growing areas and along with other microorganisms, such as Trichoderma spp., combine to act as natural enemies against the destructive soil-borne pathogen Rhizoctonia solani, causal agent of rice sheath blight disease. In this study, seven actinobacteria of the genus Streptomyces and three fungi of the genera Trichoderma and Purpureocillium were isolated from soils cultivated with rice using the serial dilution method. Streptomyces spp. M2A2 was selected for its ability to significantly reduce the in vitro growth of R. solani by 52% after 96 h by antibiosis in dual culture, while in the control treatment the mycelial growth was 100%. Furthermore, biocontrol efficacy of treated plants of the susceptible cultivar Fedearroz 68 with actinobacteria was confirmed and the onset of symptoms were delayed up to 14 days, compared to the control treatment. Rice plants treated with Streptomyces spp. M2A2 showed lesions of R. solani reaching 0.7% of the plant height, the effectiveness of this treatment was similar to the difenoconazole treatment, whereas in the control treatment, the lesions covered 34% of the plant height. When compared to the antagonist fungus Trichoderma spp. M2H1, Streptomyces spp. M2A2 presented a better performance of biological control. The results clearly demonstrated that Streptomyces spp. M2A2 isolate from soils of rice growing areas has biocontrol efficiency against R. solani and therefore can be a promising biocontrol agent.

HIGHLIGHTS Brachiaria decumbens pasture associated with kudzu Pueraria phaseloides legume represents an alternative for higher arbuscular mycorrhizal fungi (AMF). Higher lime doses presented high rates of AMF and improved soil chemical properties (SCP). Higher lime doses were the most influential technological factor than the type of pasture and the N, P, K fertilizer sources on AMF.

Abstract In agroforestry systems (SAF), accurate measurement of the textural degree allows infering about the importance of otherphysical properties of the soils with functions in their ecosystem regulations in a season of low precipitation. The objective of this study was to evaluate the texture by the pipette and Bouyoucos methods in an Oxisol from Piedemonte Llanero in the dry season, in different uses and soil management: monoculture of Guanábana Annona muricata L. (MG) and monoculture of banana Musa paradisiaca (MP) with intensive agriculture, conventional and reduced tillage, respectively; compared to the agroforestry system (SAF) of cocoa Theobroma cacao L. associated with yopo Anadenanthera peregrina L. and acacia Acacia mangium Willd. (SAFC) and SAF of coffee Coffea arabica L. associated with banana M. paradisiaca (SAFCF) with zero tillage and conservation practices. The experiment was installed in an unrestricted random design (DIA) in a factorial arrangement (2 textural methods x 4 land uses) in 4 replications. The data from the evaluations were subjected to analysis of variance, and the means were compared by the Tukey test at 5% probability. It was observed that the sand and clay fractions were influenced by the land uses and the determination methods and their interaction, while the silt fraction only by the analytical method. In agroforestry systems, when evaluating the texture by Bouyoucos, the finest fraction of the soil corresponding to clay and silt is underestimated, and the sand fraction is overestimated. Being associated with loamy-sandy soils, hence the pipette method was more efficient in specifying these fractions, and they were associated with loamy soils, with a better textural balance, contributing to better regulation of the physicochemical properties in the SAFs.

Resumen En los sistemas agroforestales (SAF), una medición precisa del grado textural permite inferir la importancia de otras propiedades físicas de los suelos con funciones en sus regulaciones ecosistémicas en épocas de baja precipitación. El objetivo de este estudio fue evaluar la textura por los métodos de pipeta y Bouyoucos en un oxisol de Piedemonte Llanero en época seca, en diferentes usos y manejo de suelos: monocultivo de guanábana Annona muricata L. (MG) y monocultivo de plátano Musa paradisiaca (MP) con agricultura intensiva, labranza convencional y reducida, respectivamente, comparados con sistema agroforestal (SAF) de cacao Theobroma cacao L. asociado con yopo Anadenanthera peregrina L. y acacia Acacia mangium Willd. (SAFC) y SAF de café Coffea arabica L. asociado con plátano M. paradisiaca (SAFCF) con cero labranza y prácticas de conservación. El experimento fue instalado en un diseño irrestrictamente al azar (DIA) en arreglo factorial (2 métodos texturales x 4 usos del suelo) en 4 repeticiones. Los datos de las evaluaciones fueron sometidos a análisis de variancia y las medias fueron comparadas por el test de Tukey al 5% de probabilidad. Se observó que las fracciones arena y arcilla estuvieron influenciadas por los usos del suelo y los métodos de determinación y su interacción, en tanto que la fracción limo solo por el método analítico. En los sistemas agro-forestales, al evaluarse la textura por Bouyoucos se subestima la fracción más fina del suelo correspondiente a arcilla y limo, y sobreestima la fracción gruesa, y están asociados con suelos franco-arenosos. De ahí que el método de pipeta fue más eficiente al precisar estas fracciones y se asociaron con suelos francos, con un mejor balance textural, contribuyendo a una mejor regulación de las propiedades fisicoquímicas en los SAF.

RESUMEN El presente estudio fue realizado en Villanueva, departamento del Casanare, Oriente de Colombia. Se evaluó el impacto de tres sistemas de labranza: T1: Labranza reducida (desbrozadora, un pase de cincel vibratorio, un pase de rastra y siembra), T2: siembra directa y T3: labranza de conservación (desbrozadora, un pase de cincel vibratorio, siembra con 30% de cobertura) sobre algunas variables físicas, químicas y biológicas del suelo, como la densidad aparente (Da), porosidad (ɲ), porcentaje de materia orgánica del suelo (%MOS) y unidades formadoras de colonias de hongos y bacterias UFCs. Se utilizó un Diseño de Bloques Completamente al Azar con tres tratamientos y cinco repeticiones para 15 unidades experimentales, evaluados en dos épocas: uno antes de la preparación y el otro después de dos meses de siembra de maíz. Se realizó Análisis de Varianza y la Prueba De Comparación de Medias de Tukey (p≤0,05). La Da fue más alta en T1 (1,52g/cm3) en el primer muestreo. Con el T3 se alcanzó una Da más baja en ambas épocas (1,27g/cm3). La porosidad fue mayor con el T3 sin diferencias entre muestreos. La siembra directa ocasionó un mayor porcentaje de MOS durante el último muestreo. La labranza de conservación presentó mayores UFCs de hongos y bacterias con respecto a los otros dos sistemas de labranza.

ABSTRACT Based on the negative effects of conventional tillage in Inceptisoil at Villanueva, department of Casanare, Oriente of Colombia, the present investigation evaluated the impact of three tillage systems: T1: Reduced tillage (brushcutter, vibratory chisel, harrowing and sowing), T2: direct sowing and T3: conservation tillage (brushcutter, vibratory chisel, sowing with 30% crop residues) on some physical, chemical and biological soil variables, such as bulk density (Da), porosity (ɲ), percentage of soil organic matter (%SOM) and colony forming units of fungi and bacteria CFUs. A completely randomized block design was used with three treatments and five repetitions for 15 experimental units, evaluated in two periods: M1: before preparation and M2: after two months of corn sowing. Analysis of variance and Tukey's mean comparison test (p≤0.05) was performed. The Da was higher in T1 (1.52g/cm3) in M1. The T3 got the lower Da in both seasons (1.27g/cm3) and a greater porosity without differences between samplings. The T2 produced the higher percentage of SOM in M2. T3 showed higher CFUs of fungi and bacteria with respect to T1 and T2. Conservation tillage must be taken into account for a better soils management.

En un Andisol Typic dystrandept del Altiplano de Pasto (2800 m.s.n.m., 12.6°C, 820 mm/ao y 900 h de luz solar), Colombia, se evaluaron algunas variables de crecimiento, contenido de nutrientes y producción de uvilla (Physalis peruviana) como respuesta a la fertilización con N, P y K. Los tratamientos consistieron en la aplicación de urea (46% N) como fuente de N, superfosfato triple-SPT (46% de P2O5) como fuente de P y cloruro de potasio-KCl (60% K2O) como fuente de K, en dosis iguales para cada fuente, de 80, 150 y 300 kg/ha/ao aplicados en dos épocas al momento del trasplante y 30 días después, antes de la floración. Los resultados mostraron diferencias en fuentes y dosis (P < 0.01) en todas las variables analizadas. Las dosis de 300 kg/ha de urea, 150 kg/ha de SPT y 300 kg/ha de KCl favorecieron la mayor altura de planta, la materia seca y la absorción de NPK (P < 0.05). La absorción de N fue mayor que la de K y éste a su vez que la de P en todas las interacciones evaluadas (P < 0.05). La aplicación de 300 kg/ha de cada uno de los fertilizantes ocasiono incremento del rendimiento de P. peruviana. Por otra parte, fueron encontrados efectos positivos en la absorción NPK en relación con los rendimientos de Physalis peruviana con 300 kg/ha de urea, 150 kg/ha de SPT y 300 kg/ha de KCl (P < 0.05), por tanto se recomiendan estas dosis de fertilizantes.

In a Typic dystrandept Andisol of Pasto Altiplano (2,800 meters above sea level, 12.6°C, 820 mm/year and 900 hours of sunlight), were evaluated some variables of growth, nutrition and production of Physalis peruviana by effect of N, P and K fertilization. The treatments consisted of the application of urea (46% N) as a source of N, superphosphate Triple-SPT (46% P2O5) as a source of P, Potassium Chloride-KCl (60% K2O) as a source of K, in similar doses for each source, 80, 150 and 300 kg/ha/year applied in two times at transplant and 30 days later, before flowering. The results showed differences in sources and doses (P < 0.01) in all variables analyzed. The dose of 300 kg/ha of Urea, 150 kg/ha of SPT and 300 kg/ha of KCl resulted in the highest values of plant height, dry matter and NPK absorbed (P < 0.05). N absorbed was greater than K absorbed and this in turn to P absorbed in all interactions tested (P < 0.05). All sources evaluated at 300 kg/ha led to higher yields of Physalis peruviana (P < 0.05). On the other hand, positive effects were found in the absorbed NPK in relation with yields of Physalis peruviana with 300 kg/ha of urea, 150 kg/ha of SPT and 300 kg/ha of KCl (P<0.05), therefore these doses of fertilizers are recommended.