The effects of straw or straw-derived gasification biochar applications on soil quality and crop productivity: A farm case study.
Thermal gasification of straw is a highly efficient technology that produces bioenergy and gasification biochar that can be used as a soil amendment, thereby returning non-renewable nutrients and stable carbon, and securing soil quality and crop productivity. A Danish on-farm field study investigated the impact of traditional straw incorporation vs. straw removal for thermal gasification bioenergy production and the application of straw gasification biochar (GB) on soil quality and crop production. Two rates of GB were applied over three successive years in which the field was cropped with winter wheat (Triticum aestivum L.), winter oilseed rape (Brassica napus L.) and winter wheat, respectively, to assess the potential effects on the soil carbon pool, soil microorganisms, earthworms, soil chemical properties and crop yields. The application of GB did not increase the soil organic carbon content significantly and had no effect on crop yields. The application of straw and GB had a positive effect on the populations of bacteria and protists, but no effect on earthworms. The high rate of GB increased soil exchangeable potassium content and soil pH indicating its potassium bioavailability and liming properties. These results suggest, that recycling GB into agricultural soils has the potential to be developed into a system combining bioenergy generation from agricultural residues and crop production, while maintaining soil quality. However, future studies should be undertaken to assess its long-term effects and to identify the optimum balance between straw removal and biochar application rate.
University of Copenhagen, Department of Plant & Environmental Sciences, Thorvaldsensvej 40, 1821 Frederiksberg, Denmark.
Veronika
V
Hansen
University of Copenhagen, Department of Plant & Environmental Sciences, Thorvaldsensvej 40, 1821 Frederiksberg, Denmark.
Dorette
D
Müller-Stöver
Aarhus University, Department of Environmental Science - Environmental Microbiology & Biotechnology, Frederiksborgvej 399, 4000 Roskilde, Denmark.
Valentina
V
Imparato
Aarhus University, Department of Bioscience - Soil Fauna Ecology and Ecotoxicology, Vejlsoevej 25, Silkeborg, Denmark.
Paul Henning
PH
Krogh
University of Copenhagen, Department of Plant & Environmental Sciences, Thorvaldsensvej 40, 1821 Frederiksberg, Denmark.
Lars Stoumann
LS
Jensen
Bregentved Estate, Koldinghus Allé 1, 4690 Haslev, Denmark.
Anders
A
Dolmer
Roskilde University, Department of People and Technology, Universitetsvej 1, 4000 Roskilde, Denmark. Electronic address: hnie@ruc.dk.
Henrik
H
Hauggaard-Nielsen
D000383:Agriculture / Q000379:methods; D000818:Animals; D001682:Biological Availability; D001937:Brassica / Q000254:growth & development; D002244:Carbon / Q000378:metabolism; D057965:Carbon Sequestration; D002606:Charcoal / Q000737:chemistry*; D000072480:Farms; D009835:Oligochaeta; D018520:Plant Shoots / Q000737:chemistry; D011188:Potassium / Q000493:pharmacokinetics; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D014908:Triticum / Q000254:growth & development*
D012987:Soil; C540010:biochar; D002606:Charcoal; D002244:Carbon; D011188:Potassium
Biochar; Carbon sequestration; Earthworms; Soil chemical properties; Soil quality