Hydropedological processes and their implications for nitrogen availability to corn

Abstract

Hydropedological processes affect soil water and nutrient transport and cycling. This study evaluated the impact of hydropedological properties on soil N availability and corn ( Zea mays L.) growth in three areas within the same field representing distinguishing but typical mid-Atlantic (USA) landforms. These areas included: a depressional area (Site A), a steep (14%) slope area (Site B), and a flood plain area with 1% slope (Site C); different soil types (Hagerstown, Opequon, and Melvin series, respectively); and varying hydrological features (soil water content, matric potential, and subsurface flow) in a Ridge and Valley agricultural landscape. A small-plot replicated study was conducted in each of these three areas, including four blocks of two N treatments (NH 4NO 3) applied to corn at planting (0 and 150 kg N ha − 1 ). Soil and above-ground plant biomass samples were collected during the growing season and grain yield was determined at harvest. Site A had the greatest mean grain yield (fertilized: 8.5 Mg ha − 1 ; control: 4.5 Mg ha − 1 ) and above-ground plant biomass (at physiological maturity or PM, fertilized: 11.7 Mg ha − 1 ; control: 7.1 Mg ha − 1 ), probably due to the fine-textured (> 19% clay) and low saturated hydraulic conductivity (Ksat < 0.3 cm min − 1 ) soil with good water and N holding capacity. In contrast, Site B had the smallest grain yield (fertilized: 6.9 Mg ha − 1 ; control: 3.5 Mg ha − 1 ), which corresponded to the smallest inorganic soil N content due to its thin Ap1 (10 cm) and Ap2 (21 cm) horizons, greater Ap1 horizon Ksat (1.61 cm min − 1 ), and shallow lateral subsurface flow at the steep soil–bedrock interface (0.4 m below the surface). Despite the greater inorganic soil N content at Site C, the above-ground plant biomass (at PM, fertilized: 7.0 Mg ha − 1 ; control: 6.2 Mg ha − 1 ) and grain yield (fertilized: 7.1 Mg ha − 1 ; control: 4.5 Mg ha − 1 ) were less than observed at Site A and probably resulted from the low soil water content during the growing season, which also corresponded to greater solar radiation (564 kw h m − 2 ), coarser texture (> 20% sand), and deep subsurface lateral convergent flow (0.7 m below the surface). Understanding these types of relationships between corn response to N fertilizer and hydropedological features will improve N management decisions for corn production.