Use of Biochemical Properties and Root Density As Indicators of Compost Quality and Effect of Organic Amendments On Table Grape In Limari Valley, Chile.

Pisco is a distillate from the muscatel grape fermentation. It is the national drink in Chile and in Peru and its production and export is important in the economy of these countries. One of the main environmental problems of the Pisco industry is the generation of large amounts of residues, during a short period of time during the year, associated to summer and fall seasons (March to May). Average grape yield, for Muscatel variety, are close to 45 to 50 ton/ha, 30% of which (12 to 15 ton/ha) will be residues. Organic waste from the distillation process of grape includes bunch raquises, skin and seeds obtained from grape stripping operations; these wastes have high content of lignin and cellulose, nitrogen, and potassium. A co-composting system was proposed to recycle organic wastes into vineyards crops, using as main raw material grape pomace and bunch raquises together with goat manure and other available organic materials. Compost was processed during 120 days, and completed maturation in 240 days.   Several chemical and biochemical indicators were measured, including concentration of humic and fulvic substances, and some hydrolytic enzymes as ureases, phosphatases, and β-glucosidase. It was determined that  mixtures using grape pomace, horse manure, and other ligneous material, showed better results. Fungi and yeast  showed  high correlation  with amylolitic activity ( 0.76, p<0.04), and the biodegraded products showed good organic matter properties (pH 6.97-8.66; %HA 3.62- 19.1; %FA 1.54-6.38), and statistical differences in ureases, phosphatases and β-glucosidase activities. In pots the application of compost resulted in stimulation of root system in table grape var. Thompson seedless, with an average root density of 1500 g/L, with significant differences (p<0.011) compared with humic acids applications (<600 g/l), and complete chemical fertilization (<500g/l). At the same time, the activity of β-glucosidase in soil, showed significant differences (p<0.0001) among treatments (compost :40 µg p-nitrophenol/g h^-1 ; humic acids: <20 µg p-nitrophenol/g h^-1 and chemical fertilization (<25 µg p-nitrophenol/g h^-1 ). The results suggest using β-  glucosidase as biochemical indicator for compost quality and its effect as organic  amendment.