The objective of this study was to analyze the composition of the ashes generated in the boiler of a slaughterhouse that slaughter ninety thousand chickens per day and to evaluate the possibility of using the ashes as a conditioner and soil fertilizer. The research was conducted in the largest slaughterhouse and birds of Espírito Santo. The ashes were collected directly from the boiler after cooling, a one hundred and fifty gram sample was separated and sent to a soil chemical analysis laboratory. The following parameters were evaluated: hydrogen potential (pH), phosphorus (P), potassium (K), sodium (Na), calcium (Ca), magnesium (Mg), aluminum (Al), cation exchange capacity at pH 7 (T), base saturation index (V), effective cation exchange capacity (t), exchangeable base sum (SB), aluminum saturation index (m), nitrogen (n) and total or potential acidity (H + Al). The results of the ash characterization showed the presence of beneficial nutrients such as potassium, phosphorus, magnesium and calcium, but the calcium content was considered low, medium magnesium and good for cultivation, high potassium and phosphorus. Regarding the possibility of using natural ash as an aid in soil improvement, the results showed that the concentrations are in disagreement with the recommended. The pH value obtained was considered high 9.78, above the recommended for use as a conditioner in soil fertilization, which would be a more neutral pH around 5.5 to 6.0. However, most Brazilian agricultural soils have medium to high acidity, which results in low crop yield. Thus, the use of ashes can be considered in specific cases of known very acidic soils. However, annual soil analyzes should be performed to monitor the evolution of the behavior of these nutrients, as well as the pH in the areas used for deposition of this material. These reviews are a good suggestion for future long-term research.