Scaling understanding of biochar aging impacts on soil water and crop yields

Abstract

This dissertation was made possible through the support and input of many people and funding from multiple sources. I would like to thank my major professor, David Laird, for giving me the opportunity to conduct this research, for challenging me, and always striving to make me a better scientist, writer, and communicator. Many thanks to my committee members, Rick Cruse, Sotirios Archontoulis, Robert Horton, and Jerry Hatfield, for their guidance, insight, and continuous encouragement throughout the course of my PhD. Also, thank you to my colleagues, the faculty, and staff in the Department of Agronomy for providing me with the resources and support I needed to advance in my degree and for making my time at ISU a great experience. Special thanks to members of my lab, in particular, Samuel Rathke, Rivka Fidel, Santanu Bakshi, and Chumki Banki for their assistance with and input in various aspects of my research. To the many friends I have made in Iowa-Thank you! It is impossible to mention all those who have contributed to my success and have been a part of my 'Iowa experience', but some people include:

Agricultural Waste-Based Biochar for Agronomic Applications

“…The highly porous structure of biochar improves soil physical properties and interstitial spaces within the biochar-soil matrix and allows the reorganization of pore size distribution, which enhances the soil's water retention capacity [24,69]. Biochar has a hydrophilic surface because of the presence of oxygen-containing functional groups on its surfaces [105], which enables water to infiltrate into its intrapores [106]. An increase in the number of oxygen-containing functional groups on the biochar surfaces induces an enhancement ofthe biochar's hydrophilicity [105].…”

“…Biochar has a hydrophilic surface because of the presence of oxygen-containing functional groups on its surfaces [105], which enables water to infiltrate into its intrapores [106]. An increase in the number of oxygen-containing functional groups on the biochar surfaces induces an enhancement ofthe biochar's hydrophilicity [105]. Another consideration that must be examined during biochar amendment is its effect on plant-available water content.…”

Biochar hydrological characteristics in related to branch wood properties

“…A water drop penetration time (WDPT) test was conducted to evaluate the degree of hydrophobicity (HP), according to Aller (2017). A 50-mL container was filled with solid biochar, then placed in a weighing boat in an oven at 50 °C for two weeks.…”

“…Hydrophobicity is a result of aliphatic surface functional groups (Kinney et al 2012;Aller 2017;Weber and Quicker 2018). The highest degree of hydrophobicity (extremely hydrophobic) was observed in A. gerrardii biochar, especially that pyrolyzed at the lowest temperature, followed by E. camaldulensis and T. aphylla.…”

Biochar ageing improves soil properties, growth and yield of red radish (Raphanus sativus) in a Haplic Cambisol

“…Biochar can be aged naturally or artificially through oxidation, hydration, leaching, hydrolysis, freeze-thaw, wetting and drying cycles, mineralisation, and adsorption of dissolved organic matter onto biochar surfaces [ 16 ]. Natural ageing usually happens in the field over several years, decades or centuries, while artificial ageing is done in the laboratory using chemicals like hydrogen peroxide (H 2 O 2 ), sulphuric acid (H 2 SO 4 ), and HNO 3 [ 16 , 17 ].…”