Eficiência de bactérias diazotróficas na produção de fertilizante microbiano para pimentão em solo com e sem herbicida

Abstract

The sweet pepper culture is very prominent with a socioeconomic impact in the national and international market, and the rapid return on investment presents an important position among the most consumed vegetables in Brazil, with a great demand in relation to soil fertility. A more affordable alternative to conventional fertilizers is the use of biofertilizers of phosphate and potassium rocks plus elemental sulfur inoculated with oxidizing bacteria (Acidithiobacillus), with the addition of organic matter enriched in N by diazotrophic bacteria. The objective of the work is to produce microbial fertilizers, with diazotrophic bacteria selected for N enrichment in order to improve the productivity and characteristics of the pepper in soil with and without addition of herbicide. Two experiments were carried out, the first in a greenhouse conducted in a 4x6x3 factorial scheme, in a completely randomized design, with three replications. Four proportions of organic materials were used: 100% of filter cake; 75% filter cake + 25% earthworm humus; 75% filter cake + 25% earthworm humus and 100% biological fertilizer, inoculated with NFB 10001, NFB 10003, NFB 10020, NFB 10022, NFB 10023 and without inoculation for three incubation periods 15; 30 and 45 days, in order to select diazotrophic bacteria. After this experiment, the NFB 10001 diazotrophic bacterium was selected for the inoculation of the biological fertilizer used in the second experiment, which proved to be efficient in N enrichment. The second experiment was conducted in the field, conducted in a 5x2 factorial scheme, in a randomized complete block design, with 4 replicates. Five fertilization treatments were used: with biological fertilizer at the recommended dose; biological fertilizer with addition of the fungus Cunninghamella elegans at the recommended dose and twice the recommended dose; conventional fertilizer at the recommended dose, and control with earthworm humus (12 t ha-1), with and without herbicide. Plant and soil analyzes and soil biological analyzes (basal respiration, microbial biomass carbon, metabolic coefficient and microbial coefficient) were performed at the end of the experiment. The organic fertilizer with the addition of Cunninghamella elegans (PNPK) was as efficient as the soluble fertilizer (FNPK), for productivity, number of fruits, diameter and length of fruits, and thickness of fruit peel, with productivity being the most sensitive variable to detect changes caused by the addition of herbicide to the soil.