|Zhu, Qing - Pennsylvania State University|
|Lin, Henry - Pennsylvania State University|
|Sripada, Ravi - Monsanto Corporation|
Submitted to: Geoderma
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/6/2009
Publication Date: 10/28/2009
Citation: Zhu, Q., Schmidt, J.P., Lin, H., Sripada, R. 2009. Hydropedological processes and their implications for nitrogen availability to corn. Geoderma. 154(1-2):111-122.
Interpretive Summary: Nitrogen availability for corn and N demand by corn can vary across a field, and understanding the causal factors of this variability will be essential to improving N fertilizer use efficiency for corn production. We evaluated soil N availability and corn growth response in three areas of a field that could be distinguished based on hydrology and pedology (hydropedology) differences within a mid-Atlantic landscape. These three areas represented: 1) a depression (Site A), 2) a steep (14%) slope (Site B), and 3) a floodplain (Site C). Two levels of N fertilizer (zero and 150 kg N per ha) were applied to each area, which were distinguishable by soil type, soil water content, matric potential, saturated hydraulic conductivity, and subsurface flow. From a N management perspective, the hydropedological characteristics at Site A would probably be the easiest to manage. These soils retained adequate soil water and maintained relatively high levels of soil nitrate throughout the growing season. By contrast, the soils at Site B were thin and susceptible to leaching and subsurface lateral flow losses of N, though soil water content appeared to be adequate throughout the growing season. This landscape feature would probably benefit from multiple N applications during the growing season or from a slow release N fertilizer applied once. Nitrogen management at Site C could be improved with an in-season N application that is adjusted based on anticipation of a wetter or drier growing season. These soils were susceptible to the dry weather. If drier growing conditions limit crop growth, the N fertilizer applications might be reduced to correspond with the lower likelihood of response to N fertilizer. Nitrogen application decisions that account for the interactions of soil properties, hydrology, and topography should help achieve the economic and environmental objectives of sustainable N management.
Technical 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 (NH4NO3) applied to corn at planting (0 and 150 kg N per ha). Soil and above-ground biomass samples were collected during the growing season and grain yield determined at harvest. Site A had the greatest grain yield and above-ground biomass, probably due to the fine textured (greater than19% clay) and low saturated hydraulic conductivity (Ksat is less than 0.3 cm per min) soil with good water and N holding capacity. In contrast, Site B had the least grain yield, which corresponded with the least inorganic soil N content due to its thin Ap1 (10 cm) and Ap2 (21 cm) horizons, greater Ap1 horizon Ksat (1.6 cm per min), 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 biomass and grain yield were less than observed at Site A and probably resulted from the low soil water content during the growing season, which corresponded with greater solar radiation (564 kw h per m2), coarser texture (greater than 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.