Biochar and Nitrogen Fertilizer Alters Soil Nitrogen Dynamics and Greenhouse Gas Fluxes from Two Temperate Soils
- Jiyong Zhenga,
- Catherine E. Stewart *b and
- M. Francesca Cotrufoc
- a State Key Lab. of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A & F Univ., 26 Xinong Rd, Yangling, Shaanxi, China, 712100M
b USDA–ARS, Soil-Plant-Nutrient Research Unit, Suite 100, 2150 Centre Ave., Bldg. D, Fort Collins, CO 80526-8119
c Dep. of Soil and Crop Science and Natural Resource Ecology Lab., Colorado State Univ., Fort Collins, CO 80523-1499. Trade and company names are provided for the benefit of the reader and do not imply endorsement or preferential treatment of the product by the authors or the USDA. Assigned to Associate Editor Kurt Spokas
Biochar (BC) application to agricultural soils could potentially sequester recalcitrant C, increase N retention, increase water holding capacity, and decrease greenhouse gas (GHG) emissions. Biochar addition to soils can alter soil N cycling and in some cases decrease extractable mineral N (NO3− and NH4+) and N2O emissions. These benefits are not uniformly observed across varying soil types, N fertilization, and BC properties. To determine the effects of BC addition on N retention and GHG flux, we added two sizes (>250 and <250 µm) of oak-derived BC (10% w/w) to two soils (aridic Argiustoll and aquic Haplustoll) with and without N fertilizer and measured extractable NO3− and NH4+ and GHG efflux (N2O, CO2, and CH4) in a 123-d laboratory incubation. Biochar had no effect on NO3−, NH4+, or N2O in the unfertilized treatments of either soil. Biochar decreased cumulative extractable NO3− in N fertilized treatments by 8% but had mixed effects on NH4+. Greenhouse gas efflux differed substantially between the two soils, but generally with N fertilizer BC addition decreased N2O 3 to 60%, increased CO2 10 to 21%, and increased CH4 emissions 5 to 72%. Soil pH and total treatment N (soil + fertilizer + BC) predicted soil N2O flux well across these two different soils. Expressed as CO2 equivalents, BC significantly reduced GHG emissions only in the N-fertilized silt loam by decreasing N2O flux. In unfertilized soils, CO2 was the dominant GHG component, and the direction of the flux was mediated by positive or negative BC effects on soil CO2 flux. On the basis of our data, the use of BC appears to be an effective management strategy to reduce N leaching and GHG emissions, particularly in neutral to acidic soils with high N content.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © 2012. . Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.