Spatial and Temporal Variation of Soil Nitrogen Parameters Related to Soil Texture and Corn Yield
2005
Shahandeh, H. | Wright, A. L. | Hons, F. M. | Lascano, R. J.
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.
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