Quality of Organic Fertilizers Used in Greenhouses in Quibor Depression, Venezuela

Abstract

Quíbor depression is the main zone for agricultural production in Venezuela, where, during the last years, production systems under coverage have been introduced, together with the use of non-certi ed organic fertilizers. The objective of this research was to evaluate the quality of organic fertilizers used in production systems in greenhouses in Quibor, Venezuela. A completely randomized experimental design was used and eleven (11) organic fertilizers (four solid and seven liquids) were evaluated for three times. Solid fertilizers were collected in the upper, lower and middle part of the battery, while liquids were taken directly from the storage tanks. For characterizing fertilizers the TMECC protocol was used, organic matter was determined by nitrogen calcination at 450°C in Kjeldahl and macronutrients (potassium and calcium) and micronutrients (copper, manganese, iron and zinc), in 1/20 (v/v) material aqueous extract and quanti ed by atomic absorption. Results show that vermicompost manure and compost had the highest values of macronutrients, whereas for liquid fertilizers Macro®, was the one showing the highest concentration of nitrogen, humus1 the highest values of Ca and Mg, while in Micro® humus2 the highest contents of manganese, iron, copper and zinc were found. All solid fertilizers had low levels of micronutrients.