Ranked among of the principal production systems of the world, pastures account for around 70% of arable land [1] , and are regarded as very important in several temperate and tropical zones [2] . Brazil, possesses nearly 200 million of hectares of edaphoclimatic conditions and native and cultivated pastures [3] , mainly the Brachiaria grasses.

Genus Brachiaria has contributed significantly to Brazil, as it enabled cattle ranching on the acidic and poorly fertility, and the basis of the cultivated pastures in the country [4] .

The arable areas frequently show soils with quality disparity, revealing nutritional deficits that arise from intense and constant cultivation. Therefore, the soil fertility is normally corrected by applying chemical fertilizers, obtained from non-renewable sources, and which in turn affect the production costs. Hence, certain measures and alternatives need to be established to maintain the systems on a long-term basis and wood ash is one such alternative source [5] .

Considering this, cattle ranchers require alternative and cheaper means of soil fertilization, without adversely affecting either the environment or grazing animals. Wood ash appears to rank high among the suitable options for agricultural crops, as it offers a vital means of recovering some of the nutrients lost through soil leaching and crop utilization. Wood ash is composed of a series of elements essential for plants and, as it is alkaline, it changes the soil pH, which is an important criterion for its implementation in agriculture [6] .

As a good option, reusing wood ash can minimize commercial fertilizer requirements, which in turn will reduce soil acidification and raise the calcium reserves [7] . Utilization of plant waste in agriculture is a good practice that has increased production and alleviated issues of solid waste disposal. From this perspective, using the ash as a fertilizer can prove to be a sustainable alternative supply of P to the agricultural systems [8] . As it is versatile in nature, wood ash can be utilized along with liquid waste, to boost its nutrient supply [9] .

Brazil has the enormous potential for generating energy through thermochemical conversion, produces enormous quantities of waste (ash) that must ultimately be disposed. One of the ways could be their application to pastures used for grazing, and for the recovery of degraded areas. However, scientific proof is necessary for the correct application of the wood ash [10] .

The aim of this study was to assess the productive and phytometric characteristics of Brachiaria brizantha (cv. BRS Piatã) in response to the application of wood ash rates to the Brazilian Oxisol.

The experiment was conducted in a greenhouse at the Federal University of Mato Grosso, Campus of Rondonópolis-MT, Brazil, using the forage grass, genus Brachiaria brizantha cv. BRS Piatã.

The soil was first collected at a depth of 0.00 - 0.20 m from a region supporting Cerrado vegetation, classified as Oxisol [11] . The chemical and granulometric analysis of the soil was done according to and the results are seen in Table 1 [12] .