Journal article

Publication year: 2016

Pages: 1196-1204

Journal: Journal of Environmental Quality

Volume number: 45

Issue number: 4

ISSN: 0047-2425

eISSN: 1537-2537

DOI Link: https://doi.org/10.2134/jeq2015.10.0529

Publisher: Wiley

Abstract: 
Biochar (BC) has been shown to increase the potential for N retention in agricultural soils. However, the form of N retained and its strength of retention are poorly understood. Here, we examined if the N retained could be readily extractable by standard methods and if the amount of N retained varied with BC field ageing. We investigated soil and field-aged BC (BCaged) particles of a field experiment (sandy soil amended with BC at 0, 15, and 30 t ha(-1)) under two watering regimes (irrigated and rain-fed). Throughout the study, greater nitrate than ammonium retention was observed with BC addition in topsoil (0-15 cm). Subsoil (15-30 cm) nitrate concentrations were reduced in BC treatments, indicating reduced nitrate leaching (standard 2 mol L-1 KCl method). The mineral-N release of picked BCaged particles was examined with different methods: standard 2 mol L-1 KCl extraction; repeated (10x) extraction in 2 mol L-1 KCl at 22 +/- 2 degrees C and 80 degrees C (M-0); electro-ultrafiltration (M-1); repeated water + KCl long-term shaking (M-2); and M-2 plus one repeated shaking at 80 degrees C (M-3). Nitrate amounts captured by BCaged particles were several-fold greater than those in the BC-amended soil. Compared with M-0, standard 2 mol L-1 KCl or electro-ultrafiltration extractions retrieved only 13 and 30% of the total extractable nitrates, respectively. Our results suggest that "nitrate capture" by BC may reduce nitrate leaching in the field and that the inefficiency of standard extraction methods deserves closer research attention to decipher mechanisms for reactive N management.

Harvard Citation style: Haider, G., Steffens, D., Müller, C. and Kammann, C. (2016) Standard Extraction Methods May Underestimate Nitrate Stocks Captured by Field-Aged Biochar, Journal of Environmental Quality, 45(4), pp. 1196-1204. https://doi.org/10.2134/jeq2015.10.0529

APA Citation style: Haider, G., Steffens, D., Müller, C., & Kammann, C. (2016). Standard Extraction Methods May Underestimate Nitrate Stocks Captured by Field-Aged Biochar. Journal of Environmental Quality. 45(4), 1196-1204. https://doi.org/10.2134/jeq2015.10.0529