Agricultural Nitrogen Budget for a Long-Term Row Crop Production System in the Midwest USA

Abstract

In the Midwestern United States, subsurface drainage (commonly known as tile drains) systems have been extensively used for sustaining agricultural production. However, the tile drains have raised concerns of facilitating the transport of agricultural chemicals from the fields to receiving waters. Data from a long-term field experiment in the Little Vermilion River (LVR) watershed of east-central Illinois, USA, shows that the tile drain systems have contributed to increased nitrate N (NO3-N) to the receiving water body, Georgetown Lake Reservoir, over time. We conducted more than 10 years of research on fate and transport of NO3-N in tile drain water, surface runoff and soil N. Corn (Zea mays L.) and soybean (Glycine max L.) were planted in rotation for this watershed. We evaluated N balance (inputs and outputs) and transfer (runoff and leaching) components from three sites with both surface and subsurface flow stations within this watershed, and N budgets for individual sites were developed. Nitrogen fertilizer application (average 192 kg ha−1 y−1) and soil N mineralization (average 88 kg ha−1 y−1) were the major N inputs for corn and soybean, respectively in this watershed. Plant N uptake was the major N output for both crops during this entire study period. Annual N uptake for the LVR watershed ranged from +39 to +148 (average +93) kg ha−1 and −63 to +5 (average −32) kg ha−1, respectively, for corn and soybeans. This data indicates that most of the soil mineralized N was used during soybean production years, while corn production years added extra N in the soil. Surface runoff from the watershed was negligible, however, subsurface leaching through tile drains removed about 18% of the total rainfall. Average NO3-N concentrations of leaching water at sites A (15 mg L−1) and B (16.5 mg L−1) exceeded maximum contaminant level (MCL; 10 mg L−1) throughout the experiment. However, NO3-N concentrations from site E (6.9 mg L−1) never exceeded MCL possibly because 15–22% lower N was received at this site. We estimated that the average corn grain yield would need to be 28% higher to remove the additional N from this watershed. Our study suggests that N application schemes of the LVR watershed need to be reevaluated for better N management, optimum crop production, and overall environmental sustainability.

Soil mineral nitrogen content and grain yield with enhanced efficiency fertilizers in maize

“…This study was conducted on silt loam soil in different fields each year that were previously cropped with soybean in a standard maize–soybean–maize–soybean rotation. The same fertilizer‐N rate was used all years of the study, corresponding to a commonly recommended rate applied in three major areas in the United States (Dattamudi et al., 2020; Scharf et al., 2005). Therefore, observed differences in crop yields may be attributed to differences in weather conditions, with in‐season precipitation likely as a primary factor (2009: 654 mm; 2010: 569 mm; 2011: 372 mm).…”

Corn Yield Increase Under Constant Fertilizer Did Not Reduce Nitrate Export

“…Logically, more nitrogen exported as grain will leave less behind in fields for export into vulnerable aquatic ecosystems and groundwater resources (Gentry et al, 2009). Thus, increasing yields without equivalently increasing inputs is one way proposed to increase crop N-use efficiency (NUE Crop ) (Sinclair andVadez, 2002, as cited in Asibi et al, 2019;Lu et al, 2019;Dattamudi et al, 2020) and the related measure of partial factor productivity (PFP). These indices characterize how much grain is generated per unit of fertilizer applied, i.e., the return on fertilizer.…”