Effects of Peanut Shell and Mixed Wood Biochars on Soil N Supply Rates and Pearl Millet (Pennisetum americanum) Yield.

ASA, CSSA, and SSSA-Annual Meeting

November 15 -18, 2015

Minneapolis, MN

 Effects of peanut shell and mixed wood biochars on soil N supply rates and pearl millet (Pennisetum americanum) yield

 Andre Diatta, John Fike, Wonae Fike, Gabriel Pent, Martin Battaglia

Dept of Crop and Soil Environmental Sciences

Virginia Tech

Abstract

The value of biochar for enhancing crop productivity by improving soil nitrogen availability and simultaneously reducing leaching losses and decreased fertilizer inputs seems promising. In this research, the effects of peanut shell and mixed wood biochars on plant-available nitrogen (ammonium and nitrate) supply and millet yield were studied under fertilized conditions. In this field experiment, treatments consisted of a combination of the two biochar sources at three rates (0, 10, and 20 Mg ha−1) and three N application levels (0, 50, and 100 kg N ha−1) with three replicates in a completely randomized design. Ion-exchange membranes were used to assess temporal changes in plant-available N concentrations at 2-week intervals over 12 weeks. Increases were not observed in plant-available N (NH4 + + NO3 −) supply between the control (336.50 µg N cm−1) and biochar treatments. Total soil carbon in response to 10 and 20 Mg ha−1 char application rates was increased over the control by 8.61 and 14.67 mg g−1 with peanut shell char and by 7.60 and 13.22 mg g−1 with mixed wood char. Total soil N significantly increased over the control (1.63 mg g−1) only with increasing peanut shell application levels by 8.61% and 12.3% 1.85 mg g−1 for 10 and 20 Mg ha−1 rates, respectively. Both biochar sources increased millet yields over the control (4.34 Mg ha−1); yield increased with increasing peanut shell char application rate (35% and 53% increase with 10 and 20 Mg ha−1 rates, respectively) but did not differ between mixed wood char application rates (mean = 33%). Late season estimates of leaf chlorophyll content reflected a similar pattern of response to biochar application. These results suggested biochar amendments resulted in the formation of a carbon sink and in the accumulation of N in soil to some extent. Biochar addition also had a positive effect on leaf chlorophyll content and crop productivity improvement in Unison-Braddock soils.