LAUSR

*Corresponding author e-mail: [email protected] © 2019 Institute of Agrophysics, Polish Academy of Sciences A b s t r a c t. Ground water availability can be a major spatially variable factor of crop yields. In soils with the infiltration-restricting layer, 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 and corn yield for different weather conditions and nutrient management. Corn yield was monitored across the manured and chemically fertilized fields at the USDA-ARS OPE3 experimental site in Maryland. Data were collected during dry, normal, and above normal years in terms of the amount of precipitation from planting to physiological maturity. The subsurface flow pathway network was delineated using ArcGIS from data on topography of the infiltration-restricting layer found mostly at depths between one and three meters. The geographically weighted regression was used. Adjusted determination coefficients of regressions ranged 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. Factoring the subsurface flow pathway network influence into crop management can be an important component of precision farming strategies. K e y w o r d s: subsurface flow pathways, ground penetrating radar, geographic weighted regression, corn yield