Spatial and Temporal Variation of Soil Nitrogen Parameters Related to Soil Texture and Corn Yield

Abstract

The spatial variability of soil properties that affect the soil N budget and corn (Zea mays L.) grain yield were studied for 2 yr in south‐central Texas to better assess the potential for variable‐rate N fertilization. Residual soil NO3–N with depth and soil N mineralization (Nmin) potential and their relationships with soil total N, soil organic C, and clay content were characterized. Residual soil NO3–N to 60‐cm depth was more related to corn yield than NO3–N at shallower depths. Residual soil NO3–N showed temporal variation with spatial structure existing for NO3–N in the first year when NO3–N concentrations were high, but this variation was absent in the second year when NO3–N concentrations were low. The opposite trend was observed for soil Nmin. Soil total N exhibited temporal persistence. Soil Nmin showed significant correlations with soil clay content in both years. Temporal persistence of soil texture and variation in spatial structure for N parameters would likely result in different strategies for soil N management zones in 2002 vs. 2003. This experiment demonstrated the potential importance of soil texture for modifying fertilizer N recommendations. Texture generally is more easily determined than soil N parameters at the scale and intensity necessary for site‐specific N management.

Responsive in-season nitrogen management for cereals

“…Another major factor contributing to low NUE in current strategies has been uniform application rates of fertilizer N to spatially variable landscapes, even though numerous field studies have indicated economic and environmental justification for spatially variable N applications in many agricultural landscapes (Mamo et al, 2003;Hurley et al, 2004;Koch et al, 2004;Scharf et al, 2005;Shahandeh et al, 2005;Lambert et al, 2006;Hong et al, 2007). Uniform applications within fields discount the fact that N supplies from the soil, crop N uptake, and response to N are not the same spatially (Inman et al, 2005).…”

Solute dynamics and the Ontario nitrogen index: II. Nitrate leaching

“…Soil texture also influences N dynamics and crop uptake as a result of its influence on soil physical properties such as K sat on water availability and biological activity (e.g., denitrification, mineralization, and immobilization). Shahandeh et al (2005) found that soil clay content was negatively correlated with corn yield; however, clay content was also found to be positively related to N mineralization and soil organic carbon levels. Hence, the relationship between clay content, N mineralization, and crop growth can be very complicated.…”

“…1-5), it appears that some of the applied N must have been immobilized and then mineralized during the subsequent growing season for us to observe an N response to fall fertilizer N application. Shahandeh et al (2005) reported that corn yield in south central Texas was related more strongly to the amount of residual soil NO 3 − -N over the entire primary rooting depth (top 60 cm) than to NO 3 − -N amounts at shallower depths. In this study, N uptake by corn (fall 2008) likely responded to the combined effects of residual N left over from the previous year's N addition (fall 2007), background soil N resulting from the mineralization of soil organic N, and recently applied N that was immobilized and then remineralized during the following growing season.…”

“…Although soil profile distributions of NO 3 − -N are well known to vary substantially in space and time (e.g., Eghball et al 2003;Shahandeh et al 2005;Gehl et al 2006;Hong et al 2007), field-based information on the impacts of climate, seasons, and soil hydraulic properties (e.g., K sat ) remains extremely limited. However, it is precisely the impacts of climate, seasons, and soil hydraulic properties that are required to assess N indexes and to develop effective strategies for minimizing surface and ground water contamination by agricultural NO 3 − -N. The overall objectives of this study were to (1) characterize downward movement of NO 3 − through the profiles of five soils over a 1-yr period (four seasons) in the cool, humid regions of Southern Ontario and (2) assess the Ontario N Index by determining relationships among soil hydraulic properties (K sat ), Cl tracer movement, and N transport.…”

Optical crop sensor for variable-rate nitrogen fertilization in corn: II - indices of fertilizer efficiency and corn yield

“…The main causes for the low efficiency of corn N fertilization are: high losses by N-NH 3 volatilization (Lara Cabezas et al, 1997b;Cantarella et al, 2008), N-NO 3 -leaching (Sangoi et al, 2003;Ceretta et al, 2005), lack of synchrony between crop demand and N availability (Amado et al, 2002;Aita & Giacomini, 2008), inter-annual variability in the crop response to N fertilization (Fiorin et al, 2007;Ciampitti & Garcia, 2008), and spatial variability of soil organic matter (SOM) and N mineralization potential (Shahandeh et al, 2005;Gregoret et al, 2006;Solie et al, 1999;Casa et al, 2011;Portz et al, 2012). All these factors influence N fertilization, making an increase in fertilizer use efficiency a complex challenge.…”