Improving Productivity of Small Farmers by Bio-Rational Soil Management: II. The Case of Horticultural Crops

Abstract

Production of horticultural crops in the Andean region of Bolivia is low as a result of various abiotic and biotic soil constraints, and the recourse to pesticides and fertilizers is frequently too expensive. Agricultural soils in this region of Bolivia are generally characterized by a low fertility with low content of organic matter and yields of most crops are limited. Therefore, it was proposed a recycling of organic waste into compost and the use of natural microbial soil inhabitants, - AMF and PGPR - to reduce chemical–dependence of small-scale agriculturists Several field trials located in Cochabamba department (Bolivia) with different horticultural crops were conducted. After four years. farmers are able to prepare with post-harvest organic residues and animal manures their own compost for its field incorporation at planting time (7-10 t/ ha). Several native isolates of PGPR and AMF were identified (B. amyloliquefaciens & G. intraradices, respectively). However with a commercial B. subtilis product (BZF 24WP), which later on was locally multiplied and formulated, and a Bolivian commercial mycorrhiza of G. fasciculatum (DESAmic), a biofertilizer was formulated and evaluated in several trials with different horticultural and orchard crops in farmer fields showed both plant growth promoting effect (horticultural and orchard crops:42.0 to 98.0 %). It was also observed a suppressive/inhibitory soil borne diseases effect. Therefore, it was also showed that micro-scale composting production based on organic waste from rural post-harvest residues in combination with animal manures, represent an alternative to chemical fertilizers