Solution Center for Nutrient Management
Solution Center for Nutrient Management
Solution Center for Nutrient Management
University of California
Solution Center for Nutrient Management

Nutrient Management Research Database

General Information

Research Title

An estimation of annual nitrous oxide emissions and soil quality following the amendment of high temperature walnut shell biochar and compost to a small scale vegetable crop rotation

Research Specifications

Crop: Lettuce, Peppers, Swiss Chard
Soil Type:
County, State: Yolo, California
Year: 2013

Authors

Emma C. Suddick and Johan Six

Summary/Abstract from Original Source

Agricultural soils are responsible for emitting large quantities of nitrous oxide (N2O). The controlled incomplete thermal decomposition of agricultural wastes to produce biochar, once amended to soils, have been hypothesized to increase crop yield, improve soil quality and reduce N2O emissions. To estimate crop yields, soil quality parameters and N2O emissions following the incorporation of a high temperature (900 °C) walnut shell (HTWS) biochar into soil, a one year field campaign with four treatments (control (CONT), biochar (B), compost (COM), and biochar + compost (B + C)) was conducted in a small scale vegetable rotation system in Northern California. Crop yields from five crops (lettuce, winter cover crop, lettuce, bell pepper and Swiss chard) were determined; there were no significant differences in yield between treatments. Biochar amended soils had significant increases in % total carbon (C) and the retention of potassium (K) and calcium (Ca). Annual cumulative N2O fluxes were not significantly different between the four treatments with emissions ranging from 0.91 to 1.12 kg N2O–N ha− 1 yr− 1. Distinct peaks of N2O occurred upon the application of N fertilizers and the greatest mean emissions, ranging from 67.04 to 151.41 g N2O–N ha− 1 day− 1, were observed following the incorporation of the winter cover crop. In conclusion, HTWS biochar application to soils had a pronounced effect on the retention of exchangeable cations such as K and Ca compared to un-amended soils and composted soils, which in turn could reduce leaching of these plant available cations and could thus improve soils with poor nutrient retention. However, HTWS biochar additions to soil had neither a positive or negative effect on crop yield nor cumulative annual emissions of N2O.

 

Research Highlights

Design and Methods

  • High temperature walnut shell biochar was applied either with or without compost in a vegetable system.
  • N2O emissions were monitored over the course of a full season.
  • Soil N levels were also monitored.

Results

  • Over the course of a year, neither the biochar nor biochar+compost reduced N2O emissions.
  • The biochar only treatment increased soil carbon storage along with increasing available Ca and K.

Additional Information

Tags (links to other subject matter in database)

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