Submitted to: Agronomy Society of America, Crop Science Society of America, Soil Science Society of America Meeting
Publication Type: Abstract Only
Publication Acceptance Date: April 1, 2008
Publication Date: N/A
Technical Abstract: Management practices are needed to reduce soil CO2 emission and increase C sequestration under dryland cropping system. The effects of tillage, cropping sequence, and N fertilization were evaluated on soil surface CO2 flux, soil total C content at 0- to 120-cm depth, and soil temperature and water content at 0- to 15-cm from April to October, 2006 and 2007 in eastern Montana. Tillage and cropping sequences were no-tilled continuous malt barley (NTCB), no-tilled pea-malt barley (NTP-B), no-tilled fallow-malt barley (NTF-B) and conventional-tilled fallow-malt barley (CTF-B) with split plot application of two N rates (0 and 80 kg N ha-1) to barley. Tillage and cropping sequence did not influence CO2 flux in the second phase of the cropping sequence. In 2006, CO2 flux was greater with 80 than with 0 kg N ha-1 in NTCB, NTF-B, and CTF-B in June and August following substantial rain. In 2007, CO2 flux was greater with 80 than with 0 kg N ha-1 in NTP-B and CTF-B in June and July but was greater with 0 than with 80 kg N ha-1 in NTCB and NTF-B in July following rain. Soil temperature varied with treatments. Averaged across measurement dates, CO2 flux was greater in NTCB and NTP-B with 80 kg N ha-1 than in NTF-B with 0 and 80 kg N ha-1. Soil temperature was greater in CTF-B with 0 kg N ha-1 than in NTP-B and CTF-B with 80 kg N ha-1 in 2006. Soil water content was greater in CTF-B with 0 kg N ha-1 than in other treatments. Soil total C was not influenced by treatments. Although NTF-B reduced CO2 emission, continuous cropping with N fertilization increased the emission probably by increasing root respiration due to increased biomass production.