Effects of Different Feedstock Type and Carbonization Temperature of Biochar on Oat Growth and Nitrogen Uptake in Coapplication with Compost

Abstract

We aimed to verify whether (i) biochar-compost application improves plant growth when compared with compost application alone and (ii) a diversity of biochar caused by feedstock type and carbonization temperature affects the extent of plant growth. We prepared six types of biochar from larch (Larix kaempferi Sarg.) and dairy manure at 300 °C, 450 °C, and 600 °C for 1 h. Compost was applied as control, and each biochar was co-applied with compost to oat plants (Avena sativa L.). The total nitrogen input of all the seven treatments was adjusted to the same level to assess their effects on plant nitrogen uptake and nitrogen content. Compared with the control, biomass production increased from 13.1 to 34.0% with the wood biochar application and from 39.7 to 64.2% with manure biochar application because of more mineralization of compost and nitrogen fixation through rhizobacteria and/or diazotrophic endophytes. The diversity of biochar caused a difference in the extent of oat growth, and feedstock type of biochar was a more dominant factor than carbonization temperature. Due to the favorable chemical properties of manure biochar like high pH and more labile-C and -N content, the manure biochar application increased average biomass production by 26.0% compared with the wood biochar application. The carbonization temperature had no significant impact on oat growth, but the optimal temperature was indicated as approximately 450 °C. Biochar diversity causes a difference in plant growth in biochar-compost application, and the selection of appropriate biochar, such as manure biochar at 450 °C, would be a guideline for achieving a robust crop production system.