Nelson Walter Osorio

Se evaluó el impacto de los sistemas agrícolas sintrópico y convencional sobre las propiedades físicas y químicas del suelo y la producción de Coffea arabica L. var. Castillo, en dos zonas cafeteras de Colombia con condiciones edafoclimáticas similares, comparando sistemas sintrópicos con diferente tiempo de implementación (un año y más de diez años) y sistemas convencionales como referencia. El sistema sintrópico de largo plazo presentó mejoras significativas en la calidad del suelo, reflejadas en mayor contenido de materia orgánica total, nutrientes esenciales, pH más favorable y mejores propiedades físicas. Sin embargo, la mayor productividad se registró en el sistema convencional de largo plazo, evidenciando que las mejoras en las propiedades fiscas y químicas del suelo no se traduce de manera inmediata en mayores rendimientos. En conjunto, los resultados indican que el manejo sintrópico prolongado favorece la funcionalidad del suelo, mientras que la respuesta productiva depende del tiempo de implementación y del diseño del sistema.

Coffee crop demands phosphorus (P) during the nursery stage and vegetative growth. These requirements are commonly satisfied by applying a high dose of soluble phosphatic fertilizers, which increases production costs and causes environmental concerns. The Colombian coffee zone has a great diversity of soils with variable mineral composition and organic matter (OM) content. These conditions exhibit a long-term stability, concomitantly govern soil P availability and, hence, a standard recommendation for P fertilization may cause nutritional imbalance in the soil solution. To accurately estimate soil P-availability in Colombian coffee soils, a P-fixation (PF)-based approach using sorption isotherms technique was evaluated in five Andisols and four Inceptisols. Changes in the soil solution P concentration were monitored over time. Results showed that PF value was overestimated (> 68 %) during 36 h of equilibration; after this period, the system stabilized, providing reliable PF values. The relation between PF and applied P was assessed at a concentration of 0.2 mg L-1 (P0.2), level considered adequate in the soil solution to support maximal crop yields in different cultivated plants, was achieved by applications between 104 and 773 mg kg-1 of P in Andisols, and between 0 and 349 mg kg-1 of P in Inceptisols. OM content (OM: 7.7%), presence of non-crystalline materials, texture, and mineralogy explained the PF across soils. These finding suggest that a PF-based approach could serve as a valuable tool for developing site-specific P fertilization strategies and useful for establishing future P coffee fertilization in Colombia.

Inadequate grassland management has resulted in the degradation of extensive areas, loss of productivity and sustainability of many of them, reflecting a common reality among livestock farmers in Colombia. Therefore, at the Paysandú Agricultural Station of the Universidad Nacional de Colombia, located in the Santa Elena township of the city of Medellín, a study was carried out to determine a soil quality index (SQI) by evaluating the physical and chemical indicators that were most related to the deterioration and dry matter production of kikuyu grass (Cenchrus clandestinus). A minimum data set (MDS) was established for the most sensitive indicators, selected by principal component analysis (PCA), and a nonlinear scoring function was used to obtain the SQI. Statistical differences were found between all the treatments in relation to dry matter production (P total porosity TP > macropores MAC > micropores MIC > penetration resistance PR > effective cation exchange capacity ECEC > pH. As a result, the following formula was obtained: SQI = (0.225×BD) + (0.224×TP) + (0.220×MAC) + (0.218×MIC) + (0.113×PR) + (0.0879×ECEC) + (0.0877×pH). This index should be tested in kikuyu grass-dominated pastures located in the Colombian high tropics. The baseline is critical at values > 0.58 Mg m-3 for BD and > 2.25 MPa for PR. In addition, the optimum pH range for kikuyu grass development was between 5.4 and 6.4.

Annual crops and pastures in monoculture frequently have negative effects on ecosystem services due to soil and biodiversity losses. Silvopastoral systems (SSP) have been proposed as an alternative for livestock production systems; however, there are few studies that demonstrate their benefits on soil health. For that reason, this study was established to evaluate the effect of different land uses on soil health measured through chemical indicators. For this purpose, the following land uses managed for at least 19 years were evaluated: (i) intensive maize (Zea mays) production, (ii) a guinea (Megathyrsus maximus) and angleton (Dichantium aristatum) mixed pasture, (iii) SSP with grasses and shrubs of totumo (Cresentia cujete) and leucaena (Leucaena leucocephala), (iv) a multistrata SSP with the same grasses and shrubs plus tree fodder species: (Cassia grandis, Albizia saman and Guazuma ulmifolia); and (v) a secondary forest used as a reference. The evaluations were made in contrasting seasons (dry and rainy), in soils of the Middle Sinú river valley (Colombia), with a drainage gradient. In general, the soils of the SPS presented the highest values for MOS, total N, Mg, B, N-NO₃ and CICE, the grass alone pasture presented the highest values in micronutrients: Mn, Fe, Cu, Zn and S and NH₄, and lower values for pH, P and NO₃, and the highest for Al; whereas, intermediate values for all chemical indicators were obtained in the secondary forest. In contrast, soils cultivated with corn presented the poorest chemical indicators. It is concluded that SSP improve the chemical indicators of soil health as compared to the grass alone pasture and corn monoculture.

In recent years, Colombia have become globally as one the major producer of Hass avocado. Contributions of all nutrients are made in the fertilization plans, but it is not known if the additions made have been adequate and opportune. Thus, the objective of this study was to determine the effects of site and year of productions on the removal of nutrients during the harvest stage of different tissues of the Avocado fruit cv. Hass in two farms (El-Sinaí and La-Escondida) located in the high-Andean tropical zone of Colombia in three years of production (2018-2020). For this purpose, fruit samples were taken at the harvest stage of highly productive trees from two sites in Colombia (i) El-Sinaí (Anserma, Caldas; altitude 2,000 m, average annual temperature and precipitation 18.65°C and 1,837 mm) and (ii) La-Escondida (Rionegro, Antioquia; altitude 2,200 m, average annual temperature and precipitation 16.84°C and 2,091 mm). The fruit tissues (peel, pulp, seed-coat and seed) were subjected to elemental composition analysis. Significant (P N > Ca > P >Mg > S and they may be used as a reference for elaboration of fertilization programs in the regions studied, particularly in terms of the doses and ratios of nutrients. Also, the nutrient concentration in the different fruit tissues may be used as a reference of fruit nutritional status of productive trees for farmers interested in monitoring and improving nutritional of low-yield trees.

La explotación de oro aluvial ocasiona problemas en el suelo como, por ejemplo, erosión, contaminación y pérdida de la vegetación. Una de las estrategias biotecnológicas actualmente utilizadas para disminuir los impactos de esta práctica es la restauración mediante el uso de microorganismos benéficos, caracterizados por incrementar la disponibilidad de nutrientes necesarios para el crecimiento de las plantas. Este trabajo tuvo como objetivo mejorar el crecimiento y la adaptación de Leucaena leucocephala en suelos degradados por minería aurífera de aluvión del municipio de Istmina, Chocó-Colombia, mediante la inoculación con Azospirillum brasilense, Mortierella sp. y Rhizoglomus fasciculatum. Se realizó la inoculación simple y combinada de los microorganismos en bolsas que contenían plántulas de 15 días de desarrollo bajo condiciones de invernadero. Las variables estudiadas fueron altura, masa seca aérea, masa seca radical, fósforo foliar y colonización micorrizal. Los resultados mostraron que se dio una promoción significativa (P<0.05) en la masa seca aérea y radical, y en la concentración de P foliar con las inoculaciones individuales y duales de R. fasciculatum con A. brasilense y Mortierella sp. con A. brasilense, con respecto al control. La triple inoculación no presentó mejores resultados que los alcanzados con las inoculaciones duales. Estos resultados demuestran que la inoculación de estos microorganismos de manera individual y/o combinada ejerce un efecto benéfico en la nutrición y en el crecimiento de Leucaena, por lo que se recomienda esta práctica para incrementar su desarrollo y establecimiento en programas de restauración de suelos afectados por minería aurífera de aluvión.

La importancia de las propiedades físicas del suelo influye de manera apreciable en su funcionamiento, calidad del agua, control climático, ciclo de los nutrientes y biodiversidad, entre otros. Estas proporcionan más funciones ecosistémicas que solamente el aporte nutricional para la producción agrícola. Actualmente, el suelo está sometido a presión de manejo para la producción de alimentos, energía y materia prima y esto ha llevado a su deterioro físico y degradación. Este trabajo tiene como objetivo evaluar los efectos de la densidad aparente y el tamaño de agregados de suelo de sistemas silvopastoriles (SSP) (proveniente de pasturas del bosque seco tropical) sobre el crecimiento del pasto guinea (Megathyrsus maximus) cv. Mombasa. Para tal fin, se realizaron dos experimentos separados bajo condiciones de invernadero, estableciendo valores crecientes a cada variable a través de ejercer fuerzas mecánicas (densidad aparente: 0.93-1.80 Mg m-3) y tamizado (tamaño medio de agregados: 0.125-7.15 mm) y luego se sembraron semillas del pasto y se dejaron crecer por 30 días. Se encontraron dos modelos funcionales que relacionan la biomasa de las raíces del pasto con el valor de la densidad aparente y con el tamaño medio de agregados del suelo. Se concluye que para ambas variables se detectan modelos de regresión cuadrática, es decir, de punto óptimo; siendo estos valores óptimos para la densidad aparente de 1.0 Mg m-3 y de tamaño de agregados de 1.5-2.0 mm. Estos parámetros podrían ser utilizados como indicadores físicos en el diagnóstico de la salud del suelo y de utilidad en el establecimiento de pasturas de la región del Valle del Rio Sinú.

Soil phosphorus (P) availability is a limiting factor for coffee seedling growth. Usually, large amounts of P fertilizers are required, generating nutritional imbalance, increasing production costs, and raising environmental concerns in water pollution. The use of arbuscular mycorrhizal fungi (AMF) can enhance plant P uptake and growth and reduce the dose of P fertilizers. A greenhouse experiment was conducted in a substrate containing Paleudult soil and quartz sand, with low level of soluble P (1 mg kg-1), to establish the effect of AMF inoculation with Rhizoglomus fasciculatum on coffee (Coffea arabica L. cv. Colombia) seedlings growth and P uptake under three levels of P in soil solution (0.002, 0.02, and 0.2 mg L-1). AMF colonization was significantly reduced when contents of P in solution increased. Shoot dry weight and P foliar concentration were increased by the AMF inoculation when soil P in solution was 0.02 mg L-1; these effects were lower at 0.2 mg L-1 and null at 0.002 mg L-1 P. Results showed that AMF inoculation can play an important role in the growth of coffee seedlings as long as the content P in soil solution maintains intermediate level. At the lowest P level, the response of coffee seedlings to AMF inoculation was ineffective, while at the highest level, AMF application was unnecessary for coffee growth.

El aguacate ha sido plantado y consumido desde hace más de nueve mil años sobre la Tierra, sin embargo, solo hacia finales del siglo XX se dio un aumento sostenido de su cultivo y producción, que sobrepasó, en 2018, los 5,6 millones de toneladas. Además ha adquirido una gran valor en la dieta humana para su consumo en fresco debido a sus calidades nutricionales y organolépticas. No obstante, la composición y las cualidades nutricionales de los frutos son muy variables, pues dependen del clima, el suelo, la temperatura, la humedad, la cantidad de lluvia durante el desarrollo del fruto y las prácticas de manejo del cultivo, además de las diferencias genotípicas entre cultivares. Dado que Colombia aún no cuenta con toda la información técnica necesaria para acompañar el incremento de nuevas áreas de cultivo y salvaguardar las actuales, este manual compendia una cantidad importante de temas clave para su cultivo.

Tropical soils are characterized by acidity and poor plant nutrient availability, limiting their agricultural productivity. These soils are commonly amended with lime, but its low solubility impairs its effectiveness to enhance soil fertility. The use of gypsum has gained attention among farmers due to its higher solubility and mobility in the soil, local accessibility, and low price. Therefore, this study was conducted to determine the effects of Agricultural Gypsum (AG) addition on ten Colombian acid soils that had poor fertility and contrasting their physical and chemical characteristics. Surface (0-20 cm) soil samples were air-dried, sieved (<2 mm), and transferred into plastic vases, 40 g (dry base) per vase. Increasing rates of gypsum were added by duplicate: 0.0, 0.25, 0.5, 1.0, 2.0, 4.0, 8.0, and 16.0 g kg-1. Then, the soils were incubated for two weeks and watered to maintain 50% of their maximum water holding capacity. Soil pH, Al+3, Ca+2, Mg+2, K+, S-SO4-2, and P-H2PO4-2 were measured using standard methods. The results showed that AG addition significantly (P<0.05) increased soil exchangeable Ca+2-K+, Ca+2 saturation, S-SO4-2 concentration, and exchangeable Al+3, particularly with doses above 4.0 g kg-1. In contrast, soil Al+3 saturation, P-H2PO4-2 and pH significantly decreased as the AG doses increased, while soil exchangeable Mg+2 levels were not significantly affected. The use of gypsum incubation tests could be promissory for its effects on soil amelioration associated mainly to increase soil exchangeable Ca2+ and S-SO 42- and to decrease Al3+ saturation.