|Olk, Daniel - Dan|
|ANDERS, MERLE - University Of Arkansas|
Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 5/20/2014
Publication Date: N/A
Technical Abstract: Rice is commonly grown in the U.S. under continual flood from early vegetative growth until shortly before harvest. Wetting and drying cycles offer potential savings in water use. In a three-year field study, wetting/drying cycles improved water use efficiency (kg grain m-3 water applied) by 22 to 43%. They also suppressed in-season greenhouse gas emissions by 38 to 90% depending on crop rotation (continuous rice or rice-soybean) and duration of drying cycles (vegetative growth only or full-season). Methane emissions fell by 43 to 94%, and NOx emissions rose only slightly due to careful timing and rate of N fertilizer inputs. Grain yield decreased by 5% with season-long wetting/drying cycles compared to the flood control. For continuous rice, yield did not decrease with wetting/drying only during vegetative growth, probably due to a late-season increase in available soil N as measured in 15N microplots. This flush evolved during the 3 years of the study, possibly reflecting the gradual accumulation of higher quality soil organic matter. Details will be provided on the biochemical composition of the soil organic matter, including phenol levels which have been associated with inhibition of soil N cycling. Combinations of crop rotation and wetting/drying cycles offer growers a range of options to meet their desired balance of grain yield, water savings, and suppression of greenhouse gas emissions. Some combinations will be further evaluated across wider regions of rice production.