Positive and negative effects of biochar from coconut husks, orange bagasse and pine wood chips on maize (Zea mays L.) growth and nutrition

Transformation of organic waste into biochar for land application is a relatively new green technology management tool. Land-applied biochars can improve soil quality and plant growth. The aim of our study was to investigate the effects of biochars derived from coconut husk, orange bagasse and pine wood chips at different rates of application (0, 5, 10, 20 and 60 t ha− 1), on the biomass, nitrogen (N) and phosphorus (P) status of maize (Zea mays L) cultivated in a sandy soil, under greenhouse conditions. The treatments were arranged in a completely randomized block design with four replications. The effects of biochar addition on plant dry biomass and nutrition were dependent upon the biochar type and application rate. Soil treated with coconut husk biochar at an equivalent rate of 30 t ha− 1 resulted in a 90% increase in maize biomass and plant N and P concentrations of 0.88 and 0.12%, respectively. Orange bagasse biochar applied at a similar rate had no effect on plant biomass, and resulted in plant N and P concentrations of 0.85 and 0.15%, respectively. Application of pine wood chip biochar to soil did not affect plant biomass or nutrition. Even though soil total N increased with an increasing application rate of orange bagasse biochar, N leaching may not have posed a problem since KCl extractable N decreased. However, the associated increase in soil pH may result in potentially greater N losses over time. Thus, the increase in plant biomass and nutrition indicates the superiority of the coconut husk biochar as soil amendment; yet, the application of orange bagasse biochar needs more investigation.