Effects of Enriched Biochars Containing Magnetic Iron Nanoparticles on Mycorrhizal Colonisation,Plant Growth,Nutrient Uptake and Soil Quality Improvement

At present, there is little commercial sale of biochar, since farmers find they can not gain a return on their investment in this amendment in the first few years after its application, because of the high cost associated with large application rates. To overcome this constraint, development of artificially aged enriched biochar-mineral complexes(BMCs), having a higher mineral content, surface functionality, exchangeable cations, high concentration of magnetic iron(Fe) nanoparticles, and higher water-extractable organic compounds has been undertaken by a combined team of researchers and a commercial company. Two biochars produced under different pyrolysis conditions were activated with a phosphoric acid treatment. A mixture of clay, chicken litter, and minerals were added to the biochar, and then this composite was torrefied at either 180 or 220?C. In this study a pot experiment was carried out in glasshouse conditions to determine the effects of four different BMCs, with different formulations applied at rates of 100 and 200 kg ha-1, on the mycorrhizal colonisation, wheat growth and nutrient uptake, and soil quality improvement. It was found that the phosphorus(P) and nitrogen uptake in wheat shoots were significantly greater for a low application rate of BMCs(100 kg ha-1). The present formulation of BMC was effective in enhancing growth of wheat at low application rate(100 kg ha-1). The increase in growth appeared due to an increase in P uptake in the plants that could be partly attributed to an increase in mycorrhizal colonisation and partly due to the properties of the BMC.

Influences of Biochar and Biochar-Mineral Complex on Mycorrhizal Colonisation and Nutrition of Wheat and Sorghum

The high price of synthetic fertilisers and the price barrier for biochar as a soil amendment have encouraged the exploration of using biochar in fertiliser replacement formulations. Biochars coupled with fertilisers can be applied at lower application rates to achieve benefits in plant growth and nutrition, as well as soil biological fertility. It is necessary to evaluate the use of biochar as a fertiliser substitute. Therefore, this study investigated the comparative influences of biochars, including Acacia saligna （AS）, Simcoa jarrah （S J） and Wundowie jarrah （W J）, mineral fertiliser with microbes （MF ＋ M）, biochar-mineral complex （BMC） and their combination on mycorrhizal colonisation, growth and nutrition of wheat in a glasshouse experiment and sorghum in field conditions. BMC ＋ MF ＋ M treatment produced higher mycorrhizal colonisation than MF ＋ M alone, indicating that BMC had a significant role in increasing mycorrhizal colonisation. SJ （treated with acetic acid） and MF ＋ M treatments, as well as AS ＋ MF ＋ M application, showed similar effects on mycorrhizal colonisation, but lower colonisation than the BMC ＋ MF ＋ M treatment. Ovcrall~ the BMC ＋ MF ＋ M treatment supported the maximum shoot, root and total plant dry weight followed by AS ＋ MF ＋ M and WJ ＋ MF ＋ M. The MF ＋ M treatment had the maximum shoot N and K concentrations, while BMC ＋ MF ＋ M application had the maximum shoot P concentration. AS ＋ MF -4- M and WJ ＋ MF ＋ M treatments supported the maximum N uptake by wheat shoots, while BMC ＋ MF ＋ M supported the maximum P uptake. The results showed that biochars and BMCs could increase mycorrhizal colonisation, plant growth and nutrient uptake of wheat, particularly N, P, K, S and Zn. The field experiment confirmed that BMC application at a rate of 300 kg ha-1 could increase the yield of irrigated sorghum on a loam soil and provide better applied P use efficiency compared to a water-soluble fertiliser alone. These results indicated that biochar-based fertilisers might increase the resilience and sustainability of dryland cropping in environments such as in Western Australia and warrant further field evaluation.