|JOHNSON, FRANK - University Of Missouri|
|MOTAVALLI, PETER - University Of Missouri|
|SCHARF, PETER - University Of Missouri|
Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 5/29/2019
Publication Date: 11/11/2019
Citation: Johnson, F.E., Motavalli, P.P., Veum, K.S., Scharf, P.C., Lerch, R.N. 2019. Measuring potential soil N2O rates using the dentrification enzyme activity (DEA) protocol on Missouri claypan soils [Abstract]. ASA-CSSA-SSSA Annual Meeting. November 10-13, 2019. San Antonio, Texas. Paper No. 1164.
Technical Abstract: Denitrification in agricultural soils is responsible for a majority of human caused nitrous oxide (N2O) production which has a global warming potential 300 times that of carbon dioxide. The objective of this research is to assess the spatial dependence of soil N2O flux rates from claypan soils. The underlying hypothesis for this research was that denitrification is a major loss pathway of N fertilizer in claypan soils, and is influenced by soil properties that vary with landscape position. Surface soil samples (0-10 cm) were collected from two claypan fields, located in Central Missouri, under different agricultural management systems. Samples were collected on a 90-m grid within each field (with the exception of one field, where some samples were obtained near the edge of the field near the drainage way). At each sample location, 5-10 sub-samples were collected using a hand-held soil probe within ~0.3 m circumference of the grid location and composited. Denitrification was measured using the denitrification enzyme activity (DEA) protocol. Semivariograms will be generated to assess spatial dependence of potential N2O flux across the fields. If significant spatial dependence exists, kriging will be used to generate potential N2O flux maps of each field. Lower landscape positions are anticipated to have higher flux rates due to accumulation of soil C from long-term sediment deposition; however, the high smectitic clay content of upland soils may also provide conditions suitable for high N2O flux rates. This research will provide pertinent data related to spatial dependence of denitrification in restrictive layer soils and it’s potential importance to the N budget in these crop management systems.