 under construction
Site-Specific Nitrogen Fertilizer
An increasing number
of farmers are considering the use of site-specific nitrogen (N)
applications to maize (Zea mays L.) as a way of maximizing yield
potential while minimizing fertilizer cost. The objective of this 3-yr
experiment was to evaluate the spatial structure of yield response and
develop a method for predicting site-specific N requirements. Four
experimental N rates (50, 110, 160, or 220 kg ha-1), two tillage
systems (chisel till and zone-till) and two crop rotations (maize-maize and
maize-soybean (Glycine max L.)) were superimposed over a 12 ha field
in central New York State with a complex of Honeoye-Lima, Kendaia, and Lima
soils ranging from moderately-well to poorly-drained soils. Pre-sidedress
soil nitrate tests (PSNT) showed significant spatial structure but were
poorly correlated with crop N response, indicating that N fertilizer
recommendations based on PSNT results cannot simply be applied in a
site-specific management approach. Tillage treatments did not have
significant effects on the spatial structure of yield and were generally
comparable in N response. Spatial Yield response analysis showed limited
regionalization of both yield and profit response to N, suggesting that
site-specific application of nitrogen is impractical. The greatest source of
variability in N requirements was observed in the annual effects of weather,
specifically early season temperature and precipitation. Optimal N rate
varied from 110 kg ha-1 for the dry years 1999 and 2000 to 220 kg
ha-1 for 1998, with a warm wet spring. Annual variations in
optimum N rate were not well correlated with annual yield differences and
yield potential itself does not appear to be a strong predictor of N needs.
Publications
- Katsvairo, T, W.J. Cox, and H.M. van Es. 2003. Spatial
growth and soil responses of two corn hybrids to two N levels. Agronomy
Journal (accepted for publication).
- Zaitchik, B., H.M. van Es, and P.A. Sullivan. 2003.
Variability and scale in the application of a physical slope stability
model for landslide evaluation in Honduras. Soil Science Society of
America Journal (in print). (view
article)
- Karunatilake, U. and H.M. van Es. 2002. Temporal and
spatial changes in soil structure from tillage and rainfall after
alfalfa-corn conversion in a clay loam soil. Soil and Tillage Research
67:135-146. (view article)
- Katsvairo T.W., W.J. Cox and H.M van Es. 2002. Tillage
and rotation effects on soil physical characteristics. Agron. J. 94:
299-304.. (view)
- van Es, H.M., C.B. Ogden, R.L. Hill, R.R. Schindelbeck,
and T. Tsegaye. 1999. Integrated assessment of space, time, and
management-related variability of soil hydraulic properties. Soil Sci.
Soc. Am J. 63:1599-1607.
- Ogden, C.B., H.M. van Es, R.J. Wagenet, and T.S.
Steenhuis. 1999. Spatial temporal variability of flow in clay soil
macropores under no till and plow till. J. Environm. Qual. 1264-1273.
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- Collection of field
- data using a
- backpack dGPS reciever
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