Dr. Bijesh Maharjan
Dr. Richard B. Ferguson
Date of this Version
Panday, D. 2020. Effects of Char on Nitrogen Management in Agricultural Soils of Semi-arid Western Nebraska. Ph.D. Dissertation. University of Nebraska-Lincoln.
Soils in western Nebraska are characterized by low soil organic C due to semi-arid environment in the region and further aggravated by disruption of soil aggregates and rapid C decomposition from intensive tillage, erosion, and frequent droughts. Proper management of soil C may improve soil properties, reduce N losses, and subsequently improve crop yields in this low C soil and low moisture condition. This dissertation focuses on C-rich coal char (henceforth “char”) as a potential strategy to overcome the existing problem of low C in semi-arid region. Char is an industrial by-product, resulting from inefficient coal burning during sugar beet processing in western Nebraska. It contains around 30 g kg-1 total C by dry weight as well as other essential plant mineral nutrients. Laboratory results showed that addition of char reduced ammonia (NH3) volatilization likely from increased ammonium (NH4-N)sorption and retention due to its high surface area (82.1 m2 g−1) and high cation exchange capacity (CEC, 46.9 cmol kg−1). Char also reduced soil pH in fertilized soil, thereby, contributing towards reduction of NH3 loss. In field experiment, maize yield increased following char application which can be potentially due to increased micronutrient uptake and increased soil organic C. In field and lab experiments, char had a minimal positive effect on soil chemical properties. Char is a promising soil amendment particularly in high pH and low C soil. However, it might take longer before measurable enhancement on soil properties can be observed following char application. There were no adverse effects of adding char, alone or in combination with other amendments, on crop yields. However, possible adverse effects of pesticide sorption and potential trace metal accumulation in soil, crop tissue, or grains on char addition need to be considered before using char on agricultural lands.
Advisor: Bijesh Maharjan