Effects of Biomass Ashes on Plant Nutrition in Tropical and Temperate Regions

The drastic rise of prices for commercial fertilizers is one of the main obstacles to increase the productivity in crop production, mainly in poor countries. The search for alternatives therefore becomes very important. The reutilization of residues from bionergy processes for plant nutrition is an important concern to save fertilizers and to implement nutrient cycling in agriculture. For this study ashes derived from bioenergy production were investigated. The effect of sugar cane ash (SCA) on lettuce and cucumber was investigated in Cuba and the effects of ashes from wood (WA), poultry litter (PLA), and rape meal (RMA) on ryegrass and oil radish were investigated in Germany. Special attention was given to phosphorus (P) availability. Positive yield effects and an increased plant P uptake were found when ashes were applied (mainly SCA and RMA). Investigation regarding the effect of PLA on soil P pools showed that the ash application may also result in an increase of readily available P contents in soil. Furthermore, an increased plant uptake of potassium was found. The results indicate that ashes derived from the energetic use of biomass may provide a suitable source for plant nutrition.