Using Biochar As a Soil Amendment for Radish Production in Middle Tennessee.

Biochar is defined as a solid material obtained from thermochemical conversion of biomass in an oxygen-limited environment. It can be found in nature as a result of wildfires or chemically manufactured through the process of pyrolysis. Biochar can be used for a wide range of applications, including increasing soil carbon sequestration, improving nutrient use efficiency, mitigation of greenhouse gas emissions, etc. The purpose of this research is to assess the efficacy and effectiveness of using biochar as a soil amendment for radish (Raphanus sativus L.) production by evaluating soil chemical and biological properties as well as plant growth conditions affected by different biochar amendment rates and fertilization regimes in the middle Tennessee region. This research was conducted on an outdoor testing bench of the Middle Tennessee State University Greenhouse Unit, Murfreesboro, Tennessee from October 1^st to November 17^th, 2015 (48 days) and repeated from June 15^th to August 9^th 2016 (56 days). This 2-yr experiment was a Completely Randomized Design (CRD) with factorial arrangement and three replications. The treatments consisted of the combinations of four biochar amendment rates and two N fertilizer sources. Biochar was amended at rates of 0, 5, 20, and 40 Mg ha^-1 (control, low, medium, and high). Fertilizer were applied at zero (control), 122 kg ha^-1 of urea (56 kg N ha^-1) and 4.8 Mg ha^-1 of aged dairy cattle manure (56-60 kg N ha^-1) determined by local vegetable scientists. Medium-level biochar amendment with low N fertilization rate provided the greatest above-ground biomass yield (1206 kg ha^-1).  Biochar treatments can help retain higher soil pH level and soil microbial activity particularly at low N fertilization rates (P < 0.1).  Urea fertilizer provided the greatest effect on increasing leaf chlorophyll concentration indicated by higher SPAD values (P < 0.05).