Submitted to: International Agrophysics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/30/2019
Publication Date: 5/22/2019
Citation: Griffith, B.J., Daughtry, C.S., Russ, A.L., Dulaney, W.P., Gish, T.J., Pachepsky, Y.A. 2019. Effect of shallow subsurface flow pathway networks on corn yield spatial variation under different weather and nutrient management. International Agrophysics. 33:271-276.
Interpretive Summary: Field variability of crop yields is caused mostly by differences in soil conditions. Both soil water and nutrient contents can be affected by shallow ground water that allow crops to withstand droughts. Shallow ground water is typically found above the shallow layer of fine-textured, predominantly clayey material, which prevents infiltration of water to larger depths. The surface of such layer is not ideally smooth and flat; thus, subsurface flow pathway networks happen not as a sheet-like layer, but rather via a network of subsurface streams. The objective of this work was to estimate and compare effects of subsurface flow pathway networks on spatial variation in corn fields, with different nutrient management, in years of different water availability. The novel method of geographic weighted regression showed the strong dependence between corn yields and distance to the subsurface flow pathways. Results of this work will be used by researchers and practitioners involved in evaluation and design of site-specific crop management.
Technical Abstract: Understanding spatial pattern of crop variability factors appears to be necessary to use resources efficiently and to improve the resilience of the farm enterprise. Ground water availability can be a major spatially variable factor of crop yields. It was demonstrated that in soils with the infiltration-restricting layer, temporary ground water can be organized in the network of channels that conduct water laterally in wet periods and become water storage and water subsidy sources for plants in dry periods. The objective of this work was to quantify the relationships between the distances to the subsurface flow pathway network (SFPN) and corn yield for different weather conditions and nutrient management. Corn yield was monitored across two fields at the USDA-ARS OPE3 experimental site in Maryland, one of which was fertilized with bovine manure and the other with standard chemical fertilizer. Data were collected during dry, normal, and above normal years in terms of the amount of precipitation from planting to physiological maturity. The SFPN was delineated using the hydrologic ArcGIS algorithms from data on topography of the infiltration-restricting layer found mostly at depths between one and three meters. The geographically weighted regression was used to evaluate the strength of the relationship between distances to the SFPN segments and corn yields. Adjusted determination coefficients of regressions were in the range from 0.485 to 0.655. Decrease of the adjusted determination coefficients from a dry to normal year and an increase from the normal to wet year was found at both the chemical fertilizer and manure application fields. Factoring the SFPN influence into crop management can be an important component of precision farming strategies.