Biochar bound urea boosts plant growth and reduces nitrogen leaching

Authors

Wei Shi, Nanjing Agricultural University
Yanyan Ju, Nanjing Agricultural University
Rongjun Bian, Nanjing Agricultural University
Lianqing Li, Nanjing Agricultural University
Stephen D. Joseph, University of Wollongong, Nanjing Agricultural University, University of New South WalesFollow
David R. G Mitchell, University of WollongongFollow
Paul R. Munroe, University of New South Wales
Sarasadat Taherymoosavi, University of New South Wales
Genxing Pan, Nanjing Agricultural University

RIS ID

139956

Publication Details

Shi, W., Ju, Y., Bian, R., Li, L., Joseph, S., Mitchell, D. R. G., Munroe, P., Taherymoosavi, S. & Pan, G. (2020). Biochar bound urea boosts plant growth and reduces nitrogen leaching. Science of the Total Environment, 701 134424-1-134424-9.

Abstract

Over use of N fertilizers, most commonly as urea, had been seriously concerned as a major source of radiative N (Nr) for severe environment impacts through leaching, volatilization, and N2O emission from fertilized croplands. It had been well known that biochar could enhance N retention and use efficiency by crops in amended croplands. In this study, a granular biochar-mineral urea composite (Bio-MUC) was obtained by blending urea with green waste biochar supplemented with clay minerals of bentonite and sepiolite. This Bio-MUC material was firstly characterized by microscopic analyses with FTIR, SEM-EDS and STEM, subsequently tested for N leaching in water in column experiment and for N supply for maize in pot culture, compared to conventional urea fertilizer (UF). Microscopic analyses indicated binding of urea N to particle surfaces of biochar and clay minerals in the Bio-MUC composite. In the leaching experiment over 30 days, cumulative N release as NH4+-N and of dissolved organic carbon (DOC) was significantly smaller by >70% and by 8% from the Bio-MUC than from UF. In pot culture with maize growing for 50 days, total fresh shoot was enhanced by 14% but fresh root by 25% under Bio-MUC compared to UF. This study suggested that N in the Bio-MUC was shown slow releasing in water but maize growth promoting in soil, relative to conventional urea. Such effect could be related mainly to N retention by binding to biochar/mineral surfaces and partly by carbon bonds of urea to biochar in the Bio-MUC. Therefore, biochar from agro-wastes could be used for blending urea as combined organo/mineral urea to replace mineral urea so as to reduce N use and impacts on global Nr. Of course, how such biochar combined urea would impact N process in soil-plant systems deserve further field studies.