Impact of soil surface characteristics on soil water content variability in agricultural fields.
Manns, H.R., Berg, A.A., Bullock, P.R., and McNairn, H. (2014). "Impact of soil surface characteristics on soil water content variability in agricultural fields.", Hydrological Processes, 28(14), pp. 4340-4351. doi : 10.1002/hyp.10216 Access to full text
The accuracy of soil water content (WC) interpretation from satellites and its application in hydrological modelling is dependent on our understanding of the effects of field-scale surface soil properties on soil WC variability. Soil texture, surface roughness and surface residue were evaluated for their influence on soil WC variability with data obtained from satellite ground verification sampling near Carman, Manitoba, within a 28 km2 area. Over the course of five selected dates from 23 April to 18 May 2008, soil WC and other physical variables were obtained in 38 agricultural fields covering three distinct soil textural classifications. Within each field, at each of 16 sampling locations, four individual soil WC measurements were taken, including sampling points with and without the influence of crop residue left on the soil surface. A principal component analysis and multiple linear regression both identified soil texture as the primary physical process controlling variability in soil WC and coefficient of variation (CV) among fields during the campaign. Residue cover was also a significant factor representing a second principal component that explained 37% of variability in average soil WC and contributed to 31% of variability in CV. Whereas soil texture predominated in soil WC and CV on most sampling dates, residue cover was of equal significance as texture in dry soils. This study identified specific effects of tillage and residue management contributing to field-scale soil WC variability that could contribute significant improvements to interpretation of remotely sensed soil WC and subsequent scaling efforts over agricultural regions.
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