Caracterización química, según granulometría, de dos vermicompost derivados de estiércol bovino puro y mezclado con residuos de fruto de la palma aceitera Chemical characterization according to grain size of two vermicompost produced from pure and mixed bovine dung with fruit remains of the oil palm industry

With the purpose of evaluating the effect of the food provided to earthworms (Eisenia spp), for the elaboration of vermicompost and the effect of grain size on its chemical characteristics. Vermicompost used was produced from either bovine dung (VE) or mixtures of this with fruit remains of the oil palm industry (BDOP). These vermicompost were sieved through a 5 mm sieve to obtain three grain size: fine (≤ 5mm), thick (> 5<10 mm), and mixed (vermicompost that was not sieved). A factorial experiment 2x3 was used, under a completely randomized design. The factors evaluated were type of food at two levels (VE, BDOP); and thick, fine and mixed grain size to obtain 6 treatments with 4 replications for a total of 24 observations. The chemical variables evaluated on these treatments were: Nitrogen, Phosphorus, Potassium, pH, CE, Ashes, C/N Ratio, CIC, Magnesium, Calcium, Organic matter, total organic Carbon, total humus extracts, humus acid carbon, fulvic acid carbon (FAC), humification index (HI), Evolution Index (EI), Polymerization Index. For all the variables, significant differences (P<0.001) were observed, in the interaction between the factors (food x grain size ), for the type of food were differences except for FAC, HIand EI. The grain size only registered significant differences for CTHE, FAC, IE and IP variables. As the food of the worm influences in most of the chemical characteristics, these analyses must be repeated whenever a cycle of production of biofertilizing.