The runoff of nitrogen (N) and phosphorus (P) from agricultural lands is responsible for 40% of the impaired lake/river area in the U.S.. Loss of N and P from agricultural lands applied with conventional fertilizers not only wastes the state billions of dollars every year, but also results in negative agronomic and environmental consequences including decreased crop profitability, water impairment, and potential impacts on climate change. In this project, we developed a novel carbonaceous bio-soil amendment (CSA) from biomass (renewable) resources to retain nutrients and act as a controlled-release form of N and P. The substrate is bio-char made by pyrolysis of biomass materials, such as crop residue and agricultural waste materials, at moderate temperature and under limited oxygen supply. The CSA was produced optimally binding phosphate, ammonium and metal cations (i.e., magnesium (Mg) or calcium (Ca)) on the surface of bio-char. Consistent with our hypotheses, we found that nano-crystallites of struvite (MgNH₄PO₄) and calcium ammonium phosphate (CaNH₄PO₄) precipitates are deposited on surfaces and in pores of char; and 2) such precipitates were sparingly soluble and acted as controlled-release supplies of N and P. The results of this project may promote innovation and result in the development of the next-generation soil conditioner–fertilizer compost by sustainably utilizing the biomass materials that are abundant in the Midwest.

Theses and Dissertations

Mallula, S.; 2022 (expected). Effect of Biochar on the Loss of Nutrients from Soil. Dissertation (in preparation) to the University of North Dakota

Presentations:

Mallula, Z., and Xiao, F. 2020. Effect of Biochar and Other Soil Amendments on the Loss of Nutrients from Soil. ND EPSCoR Annual State Conference, April 2020. The conference was unfortunately cancelled due to COVID-19 concerns.

Achievements and Awards: 

We developed a new carbonaceous bio-soil amendment (CSA) as both a controlled-release fertilizer and a beneficial soil amendment/conditioner to improve the fertilizer use efficiency and soil structure and fertility. The substrate of this amendment is bio-char, an engineered form of char made from pyrolysis of agricultural, forestry, or urban biomass materials under zero or low oxygen supply and at moderate temperature. During thermal treatment, the cellulose, hemicellulose, and lignin components of the feedstock undergo thermal loss, and the solid becomes increasingly polyaromatic, (defective) micro-graphitic, and nanoporous depending on the heating rate, final temperature, final temperature duration, and surrounding atmosphere. Our results show that natural chars generated during historical wildfires, land clearing, and crop residue burning were able to hold moisture and provide surface for beneficial microbial colonies. Consistent with our hypotheses, we found that Mg- or Ca-impregnation led to precipitation of PO₄–P and NH₄–N as struvite (MgNH₄PO₄) or calcium ammonium phosphate (CaNH₄PO₄) on surfaces and in pores of bio-char, which acts as a slow-release fertilizer.