Addition of Charcoal Waste to Earthworm Humus Promotes Better Results in the Production of Papaya Seedlings

Aimed at improving the physical and chemical attributes of the substrates for seedling production, several agro-industrial wastes have been used. One of the waste with a potential of substrate incorporation is the charcoal waste. The objective of this study was to evaluate the effect of increasing doses of charcoal waste (CW) on the production of papaya seedlings (Carica papaya L.). The experimental design was a randomized block design, as an experimental model. The treatments were composed of 5 (five) concentrations of CW added to earthworm humus based on volume, and the following treatments were evaluated: T1: 100% earthworm humus + 0% CW (control); T2: 97.5% humus + 2.5% CW; T3: 92.5% humus + 7.5% CW; T4: 85% humus + 15% CW and T5: 70% humus + 30% CW. Each of the 5 (five) treatments had 4 (four) replicates (blocks). The evaluations consisted of plant height measurement, collection diameter, root length, dry mass of leaves and roots, and Dickson quality index. Regression models were adjusted (P <0.05) to treatments with increasing levels of CW. CW doses around 10% promoted better results of collection diameter, root length and root dry mass. For the other variables, CW doses around 13% promoted the best results. It is believed that the addition of CW promoted significant improvements in earthworm humus; however, high doses promoted an elevation of pH at levels considered critical for the availability of some nutrients for the crop. In general, the best values ​​obtained for the analysed variables were those in which about 9.25% to 14.25% of the CW addition to the humus used.