Do Synergistic Relationships between Nitrogen and Water Influence the Ability of Corn to Use Nitrogen Derived from Fertilizer and Soil?

Abstract

A gronomy J our n al • Volume 10 0 , I s sue 3 • 2 0 0 8 551 ABSTRACT To improve site-specifi c N recommendations a more complete understanding of the mechanisms responsible for synergistic relationships between N and water is needed. Th e objective of this research was to determine the infl uence of soil water regime on the ability of corn (Zea mays L.) to use N derived from fertilizer and soil. A randomized split-block experiment was conducted in 2002, 2003, and 2004. Soil at the site was a Brandt silty clay loam (fi ne-silty, mixed, superactive frigid Calcic Hapludoll). Blocks were split into moderate (natural rainfall) and high (natural + supplemental irrigation) water regimes. Nitrogen rates were 0, 56, 112, and 168 kg urea-N ha -1 that was surface applied. Water, soil N, and N fertilizer use effi ciencies were determined. Plant utilization of soil N was determined by mass balance in the unfertilized control plots and by using the δ 15 N approach in fertilized plots. Findings showed that: (i) plants responded to N and water simultaneously; (ii) N fertilizer increased water use effi ciency (170 kg vs. 223 kg grain cm -1 in 0 and 112 kg N ha -1 treatments, respectively); and (iii) water increased the ability of corn to use N derived from soil (67.7 and 61.6% effi cient in high and moderate water regimes, respectively, P = 0.002) and fertilizer (48 and 44% effi cient in high and moderate water regimes, respectively, P = 0.10). Higher N use effi ciency in the high water regime was attributed to two interrelated factors. First, total growth and evapotranspiration (ET) were higher in the high than the moderate water regime. Second, N transport to the root increased with water transpired. For precision farming, results indicate that: (i) the amount of N fertilizer needed to produce a kg of grain is related to the yield loss due to water stress; and (ii) the rate constant used in yield goal equations can be replaced with a variable.

Testing Day's Conjecture that More Nitrogen Decreases Crop Yield Skewness

“…To the extent that conservation tillage promotes soil water storage, one might expect an effect on yield skewness in water-constrained cropping areas. Data on irrigation effects are also available (e.g., Eck 1984; Kim et al 2008), where one would expect that an increase in availability of irrigation water will act to make yield skewness less positive or more negative. …”

Corn Response to Nitrogen Timing and Rate under Strip Tillage and Low-Yield Environment in Southeastern Coastal Plains

“…This is in agreement with reports that mid-season water deficits would override the effect of N, even in a short duration (Strachan et al, 2002) and dry conditions during a growing season could result in low corn yield (Viswakumar et al, 2008;Haghighi et al, 2010), especially drought during silking period. Kim et al (2008) also noted that the amount of N fertilizer needed to produce a unit of grain yield is related to the yield loss due to water stress. They observed higher N use efficiency in the high than moderate water regime.…”

A Rapid Method for Measuring Feces Ammonia‐Nitrogen and Carbon Dioxide‐Carbon Emissions and Decomposition Rate Constants

“…Dried fecal material contained 18.2 g total N kg -1 and 38.5 g total C kg -1 , which was determined on a ratio mass spectrometer after combustion at 1000°C. The δ 13 C value was -28.62 ‰, which indicated that the excreted materials were primarily derived from C 3 plants (Kim et al, 2008). Inorganic N was extracted from fresh fecal materials with 1M KCl and analyzed on a spectrometer to determine fecal NH 4 -N, which averaged 370 mg NH 4 -N (kg dry fecal material) -1 (Kim et al, 2008).…”