Efficacy, sustainability and diffusion potential of rock dust for soil remediation in Chontales, Nicaragua

Abstract: To produce enough food for a growing population, soil remediation is crucial unless more forests are to be cleared to make way for agriculture land. Finely ground rocks have been proposed as a soil amendment for highly weathered soils. In Chontales, Nicaragua most of the forest has been converted to cattle pasture. In fertile soils, crop agriculture is more lucrative per unit of area than cattle grazing, but the low nutrient content of Chontales soils makes it uneconomic. The purpose of the study was to examine whether incorporation of rock dust is a sustainable way to increase the fertility in Chontales and thus can be part of a strategy that encourages farmers to adopt crop agriculture as an alternative to animal husbandry. A field experiment was conducted in which basaltic rock dust and compost was applied to soil for cultivation of common beans. Three sustainability parameters were analyzed and the diffusion potential of the proposed technology was assessed. The experiment failed to confirm the positive result obtained in previous studies on yield in similar soils and no correlation between pest resistance and rock dust applications was found. The failure to produce a confident result on yield was partly due to a leaf hoppers invasion and harm caused by intruding calves into the experiment site. Rock dust was found to be typically free of toxic agents and little environmental damage is associated with the practice, provided that the source of extraction is close to the application site. The relative disadvantage in terms of social prestige and incompatibility with the current cattle oriented production system were found to be the main obstacles for diffusion of the technique in Chontales.