Co-Recycling of fly ash and poultry manure in nutrient-deficient sandy soil

This experiment was aimed at studying the effects of adding coal fly ash and poultry manure to a sandy soil on the yields and elemental uptake of Brassica parachinensis and B. chinensis. Three rates of fly ash (0, 3 and 12% w/w) and three rates of poultry manure (0, 2.5 and 5.0% w/w) were mixed separately and in combinations (3% ash + 2.5% manure, 12% ash + 2.5% manure, 3% ash + 5% manure, 12% ash + 5% manure) with the sandy soil. Manure applications were effective in increasing crop yields for both species as compared with the control (sandy soil alone) or fertilizer treatment. Highest yields were recorded with the highest manure treatment. Addition of 12% ash + 2.5 or 5% manure decreased crop yields of B. chinensis but not those of B. parachinensis. Mean tissue concentrations of Zn and Mn were significantly lower (p < 0.05) with increase in ash application rate for both crops while Mo concentration was consistently higher. The changes in metal availability were possibly due to the high alkalinity of the soil after ash addition. The lower electrical conductivity and pH of the soil following cropping indicates the high leachability of elements in sandy soil. Therefore, continuous fertilization is essential if continuous cropping is carried out.