La evaluación del efecto de la aplicación de abono orgánico y soluciones salinas sobre los atributos biológicos de suelos de Quibor estado Lara, Venezuela, uno bajo manejo convencional (CV) y otro bajo manejo conservacionista (CS), se realizó mediante un ensayo de invernadero. Se utilizaron tres dosis de materia orgánica (MO): 0, 15 y 30 Mg ha-1 y cuatro soluciones de riego (SR): testigo con agua (T), sulfato de calcio (SC), cloruro de sodio (CN) y la mezcla de sulfato de calcio con cloruro de sodio (ME) con tres muestreos en el tiempo, a los 32, 75 y 120 días después del trasplante (DDT). Se determinaron los atributos biológicos, respiración basal (C-CO2), carbono de la biomasa microbiana (CBm) y cociente metabólico (qCO2). El estudio demostró que C-CO2 en CV fue afectada de manera independiente por la MO y SR, aumentando significativamente con la MO aplicada (261 μg C-CO2 g-1 suelo 10 día-1), y disminuyendo con CN (214 μg C-CO2 g-1 suelo 10 día-1); el qCO2 afectado por la interacción del tiempo con las SR fue mayor con agua de chorro a los 32 DDT (421 mg C-CO2 g-1 CBm día-1) y a los 120 DDT fue mayor con CN (683 mg C-CO2 g-1 CBm día-1). El CBm en CV y todos los atributos biológicos en CS fueron afectados por la interacción dosis de MO y SR, esta interacción a su vez fue inf luenciada por el tiempo. El C-CO2 y CBm fueron mayores en CS con respecto a CV.

Mineral deficiencies in soil-plant-animal relations are linked to chemical properties and reproductive problems in grazing animals. The objective of this study was to determine the dynamics of K, Ca, and Mg in the green leaf biomass of two types of introduced forages, Brachiaria dyctioneura (Bd) and Centrosema macrocarpum (Cm), compared to the natural vegetation of the neotropical savannah (NS) in an agricultural ecosystem. The three types of vegetation, associated with the corn crop, served as livestock feed during the dry season. The soil’s nutrient content (0-15 cm depth), the production and nutritional dynamics of green leaf biomass, and leaf/stem relationships in the fields during the grazing period were determined. In the corn crop-livestock agroecosystem, K decreased (%) in concentration as the grazing period progressed, presenting the following trend: Bd>Cm>NS. The dynamics of Ca and Mg in green leaf biomass increased slightly (p<0.05) by the end of the grazing period for Bd and Cm, in contrast to a significant decrease in the natural vegetation of the savannah. The concentration of K in the soil did not reveal significant differences between ground cover and NS plants, and the soils under Cm evidenced the highest percentage of Ca. A higher percentage of Mg was observed in the soil planted with Cm. For the three types of vegetation, an improvement was observed in the nutritional quality of the forage and soil and in the yield (kg/ha). These findings are valuable contributions within the context of production in savannas and to forage quality for livestock.

2016-12-23T18:47:23

Conventional agricultural in the Venezuelan Llanos has generated gradual soil degradation. Therefore, conservationist agriculture has been proposed. According to several works, this type of management favors soil macrofauna. To test this hypothesis, the response of soil macrofauna to the establishment of conservationist maize crops, associated with Brachiaria dictyoneura (Bd) and Centrosema macrocarpum (Cm), was evaluated. The samples of soil and soil macrofauna were taken per vegetation cover at different climatic season over 2 years and 10 months. For this period and under the conditions studied, the results partially refute the hypothesis; on the one hand, they showed that the soil macrofauna of a natural savanna (NS) is the most diverse and equitable (N1 = 4.5 ± 2.8), followed by the cultivation of maize associated with Cm (N1 = 3.2 ± 1.9) and the least diverse with Bd (N1 = 2.6 ± 2.1). Additionally, some taxonomic groups apparently did not tolerate soil intervention, while Termitidae was favored. On the other hand, the temporal variation of the soil macrofauna did not differ between vegetation covers (F: 1.18; p = 0.37). This variation could be due to the decrease in TP (r = −0.55) and increased BD (r = 0.56).