Towards predicting biochar impacts on plant-available soil nitrogen content

• DOI: 10.1007/s42773-022-00137-2
• Publication Date: 2022-02-17T07:02:44Z
• Authors: Claire L. Phillips; Kylie M. Meyer; Manuel Garcia-Jar...; Clara S. Weidman; Catherine E. Stewart; Thomas Wanzek; Michael A. Grusak; Donald W. Watts; Jeff Novak; Kristin M. Trippe
• Keywords: Nitrogen Cycle; Amendment; Soil carbon; Slash-and-char

Abstract Biochars can improve soil health but have been widely shown to reduce plant-available nitrogen (N) owing their high carbon (C) content, which stimulates microbial N-immobilization. However, because biochars contain large amounts of C that are not microbially available, total elemental C:N ratio does correspond well with impacts on N. We hypothesized N would relate biochar mineralizable-C (C min ) and ratios the mineralizable component could provide a means for predicting conditions net N-mineralization or -immobilization. conducted two laboratory experiments, first measuring from respiration isotopically labeled barley manufactured at 300, 500, 750 °C, second characterizing by proxy measurements ten six feedstocks several temperatures. For both soils were incubated 2% mass determine N-mineralization. Contrary expectation, all increased relative unamended soils. Also unexpected, higher temperature (500 700 °C) less stimulated more decomposition than 350 °C biochar. across diverse production methods, none characteristics correlated The finding improved adds complexity range responses be expected in response amendment. Because limited ability predict properties, users should monitor manage fertility.