Abstract
The use of biochar as an agricultural soil improvement was tested in acid sulfate and sandy soils from Malaysia, cropped with rice and corn. Malaysia has an abundance of waste rice husks that could be used to produce biochar. Rice husk biochar was produced in a gasifier at a local mill in Kelantan as well as in the laboratory using a controlled, specially designed, top lift up draft system (Belonio unit). Rice husk biochar was applied once to both soils at two doses (2% and 5%), in a pot set up that was carried out for two cropping seasons. Positive and significant crop yield effects were observed for both soils, biochars and crops. The yield effects varied with biochar type and dosage, with soil type and over the cropping seasons. The yield increases observed for the sandy soil were tentatively attributed to significant increases in plant-available water contents (from 4%–5% to 7%–8%). The yield effects in the acid sulfate soil were likely a consequence of a combination of (i) alleviation of plant root stress by aluminum (Ca/Al molar ratios significantly increased, from around 1 to 3–5) and (ii) increases in CEC. The agricultural benefits of rice husk biochar application to Malaysian soils holds promise for its future use.
Highlights
Biochar is produced by pyrolyzing biomass, ideally from organic waste products which have no further commercial purpose, into stable biochars
In this study the changes in cation exchange capacity (CEC) caused by the amendment of rice husk biochars were significant for both biochars, both crops and both cropping seasons
The positive effect of rice husk biochar amendment to sandy and acid sulfate soils in this study may indicate that the positive chemical and physical effects created by the biochar amendment affect the biology of the system offering a habitat for the microorganisms
Summary
Biochar is produced by pyrolyzing biomass, ideally from organic waste products which have no further commercial purpose, into stable biochars. Panhwar et al [11] studied the effects of biochar and organic matter amendments on rice grown on acid sulfate soil from Kelantan. For biochars produced form rice husk, previous studies have reported low concentration of PTEs [14] that do not exceed guideline values set by the UK for the use of sewage sludge application to soil [15]. In Thailand, Oka [17] reported the positive effects of 10 t/ha rice husk biochar application on nitrogen fixation rates, growth and yield of soy bean planted in a low fertile sandy soil. The amelioration effects of adding rice husk biochar to two problematic soils from Kelantan, namely sandy spodosols and acid sulfate soils over two cropping season was investigated in greenhouse pot trials. The study is among the first to probe the possible use of gasifier rice husk biochar in Malaysia, a readily and cheaply available biomass waste material from rice mills that promotes positive waste management strategies
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