Use of Biochar in Brazilian Land-Use Systems: The Current State of Knowledge.

Biochar as a soil amendment in land-use systems has attained prominence recently; numerous studies in different parts of the world have reported a variety of beneficial effects of biochar. Considering that several soil constraints limit agricultural production in Brazil and that biochar occurs naturally in the Brazilian Amazon (locally known as “Terra Preta de Indio” or “black earth”), its use seems to be particularly relevant to Brazil. This literature review assesses the current state of knowledge on the subject in the country. Results of a total of 14 experiments of that nature from Brazil, published in 15 papers, were selected for the review. In 10 nursery experiments, eight had positive influence on two vegetable crops (lettuce and eggplant) and six forestry (tree) species; however, in six experiments, biochar at higher rates of application had negative influence. In the five field experiments reviewed, biochar had positive influence only on rice (Oryza sativa), with increase in yield, SOC and water holding capacity. Although biochar also increased SOC in other experiment, its potential to increase overall SOC is doubtful because of its faster decomposition rate compared to native SOC described in one experiment. Some experiments included use of additional sources of nutrients along with biochar, so that the effect of biochar per se cannot be established. The review indicates that biochar could potentially be beneficial in Brazilian land-use systems especially for seedling production and for drought-sensitive plants, but more detailed investigations are needed before solid conclusions can be drawn.