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Abstract
Nkongolo, N.V., K. Schmidt, R.M. Paro, N.O. Hoilett, S. J.
Adisa and S.S. Johnson.
2008. Improved
quantification of CO2, CH4, and N2O fluxes
from soil in agricultural fields in central Missouri. JEMREST 5:00-00
As it is the case for soil chemical and
physical properties, greenhouse gas fluxes also exhibit tremendous variability
across the field. However, because of the cost involved with collecting
numerous samples, measurements of fluxes across agricultural fields are often
limited to few points. The average value of point measurements is later used
to predict the total flux for the sampled area or the entire field. This
approach may result in an over or underestimation of the total flux. The
objective of this study was to assess how geographic information systems and
map analysis could improve the estimation of N2O, CH4
and CO2 fluxes from soil in agricultural fields in central Missouri. The study
was conducted in a corn, pasture and soybean fields at Lincoln University's
farms. The approach consisted in sampling N2O, CH4 and
CO2 fluxes, fitting a variogram model to fluxes data with GS+,
predicting fluxes at un-sampled locations by kriging or inverse distance
weighing when the data fitted into a model. Fluxes maps were thereafter
produced and their zones were classified
with Multispec 3.2. After classification, an improved total field flux
(ITFF) for each of N2O, CH4 and CO2 was
calculated by a summation of all zones multiplied by their corresponding flux
values. This improved total field flux was compared to the total flux (TF)
calculated using the field average flux value, for each greenhouse gas.
Results showed that ITFF for N2O, CH4 and CO2
fluxes calculated using a combination geostatistics, geographic information
systems and maps analysis was higher as compared to that calculated using the
field average flux (TF). Our approach seems to provide in an improved
quantification of greenhouse flux. The approach can be extended to other soil
and environmental parameters.
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