Caracterização de compostos líquidos provenientes de compostagem e sua aplicação em culturas agrícolas

Abstract

The agricultural sector has great economic importance for Brazil. However, it generates a large amount of solid organic waste. Composting appears as a relevant alternative for the disposal of these residues, and the liquid compost generated during this process is a product of high nutritional value, which can be used with biofertilizer in agricultural crops. Thus, this work aimed to characterize liquid compounds generated by three different composting piles and evaluate their application in the production of sugarcane seedlings, in the cultivation of seed potatoes and in the cultivation of bean plants. Three composting piles were set up containing agricultural and agroindustrial residues, with sugarcane residues in all of them. At 90 days, during the last turnover, the liquid compound for each pile was collected and sent to environmental analysis laboratories for chemical and microbiological characterization. Then, seedlings of two varieties of sugar cane were produced using the pre-sprouted seedling production method where the one bud was immersed in liquid compounds diluted in 0, 10, 20, and 30% for 15 hours before being planted. Shoot height, root length, neck diameter, chlorophyll and fresh and dry shoot and root mass were evaluated. In addition, seed potatoes were planted which were also immersed in the liquid compounds, in the same dilutions and time of the cane, where senescence, chlorophyll, dry mass of the aerial part, fresh mass and tuber dryness and productivity were evaluated. Besides that, beans were grown in pots and the seeds were immersed in liquid compounds in doses of 0, 5, 10, 15, 20 and 30% for 15 hours prior to planting. The beans evaluations were related to the time to reach the stages of development, number and weight of pods and grains, diameter of the stem and height of the plant. The three liquid compounds contain significant doses of macro and micronutrients, in addition to ideal pH values, making it possible to use them as a biofertilizer for plant fertilization. All liquid compounds are free of contaminants and can be conditioned to agricultural use without damage to health. The most suitable liquid compound and dose to achieve the best results from sugarcane seedlings vary according to the variety used and the target variable. Liquid compound 3 is the most suitable for the cultivation of seed potatoes under the conditions tested, with the 30% dose having the best productivity rates for this crop. All doses and liquid compounds tested for the bean culture are effective to obtain higher values of number and weight of grains.