Wheat growth and yield responses to biochar addition under Mediterranean climate conditions

The effects of the addition of a slow pyrolysis biochar (produced from olive-tree prunings) to a vertisol were studied in a field experiment during one wheat (Triticum durum L.) growing season. The biochar addition did not significantly affect soil parameters such as pH, dissolved organic C and N, ammonium, nitrate or microbial biomass N. By contrast, biochar addition decreased soil compaction and increased the soil water-retention capacity and nutrient content (total N and the available contents of P, K, Mg, Cu and Zn). These favourable changes led to an increase in fine root proliferation (increasing specific root length and reducing root tissue density) and promoted crop development. As a result, the plants in biochar-treated plots showed higher relative growth and net assimilation rates, aboveground biomass and yield than those in control plots. Neither grain quality nor nutrient content were significantly affected by biochar addition. Our results suggest that the use of biochar as a soil amendment in agricultural soils can improve soil physical properties and increase fertility, favouring crop development under semiarid Mediterranean conditions.