Use of Organic Amendments In Table Grape Var. Thompson Seedless: Effect On Root System and Soil Quality Indicators.

Table grape (Vitis vinifera L.), Thompson seedless variety is one of the most important export crops in Chile. The application of different organic matter sources as soil amendment and also as organic substrate, is a common practice intended to decrease plant decay and stimulate root development. In order to evaluate the effect of the application of organic amendments on some soil quality indicators and agronomic variables in table grape cultivated in an Inceptisol soil, different treatments including compost from grape pomace, humic acids extract, a commercial microbial inoculant, and chemical NPK fertilization, were evaluated.  Organic materials were applied in four C rates: Compost, 0, 125, 250 y 500 g C/pot; liquid humus, 0, 25, 50 and 100 g C/pot; Compost and liquid humus at their maximum C rates were also evaluated in absence of chemical fertilization. Results showed a stronger root development in plants receiving compost and inoculant application, as compared to control treatments, probably by presence of promoting rhizobacteria and the continuous mineralization of organic matter that increased nutrient availability for the plant; this was evidenced by the increase of the enzymatic activities, β-glucosidase, acid phosphatase, and alkaline phosphatase in all treatments receiving compost; this activity is stimulated in presence of organic matter in different mineralization stages as in compost,  increasing the water soluble C and available N and P. On the other hand, the application of liquid humus produced a larger increment in WSC per carbon unit applied compared to compost, meaning that the former would be more efficient than the latter to provide C for soil microorganisms.