Coal fly ash and lime stabilized biosolids as an ameliorant for boron deficient acidic soils

Previous studies have shown that a combination of coal fly ash (10% w/w) and lime (1% w/w) amendment was effective in stabilizing biosolids (ACS) by killing the pathogens and reducing heavy metal availability, and the product contained a high B content. It was, therefore, the aim of the present study to evaluate the suitability of the ACS as a B fertilizer for a degraded acid soil with B deficiency in South China. An acid and B deficient loamy soil was amended with the ACS at application rates of 6.4, 12.7, 25.5, 63.7 and 127.4 mg ha⁻¹, which were then compared to the same soil receiving an equivalent B fertilizer application rates of 0.9, 1.4, 2.2, 4.5 and 8.4 kg ha⁻¹, respectively. Soil hot water soluble B content and pH increased significantly with an increase in the amendment rate of the ACS mixture. Soil amended with the ACS mixture had a significantly higher dry weight yield for both cucumber and corn than the control and its counterparts of soil with B fertilizer. The highest yield was obtained in the treatment with 5% ACS mixture amendment. Boron concentrations in plant tissues increased according to the application rates of the ACS mixture and B fertilizer. Cucumber was more sensitive than corn to both B deficiency and toxicity as indicated by the insignificant effect of B fertilizer application on dry weight yields of corn. The experimental results demonstrated that the ACS mixture at an application rate of ≤ 63.7 mg ha⁻¹ could act as a B fertilizer supplement for the acid loamy soil.