Winter wheat is commonly grown in rotation with leguminous and non-leguminous
crops in the Willamette Valley. For agronomic, economic, and
environmental reasons it is important to understand the influence of previous crops on
availability of N and other nutrients.
Objectives of this study were: (1) to evaluate the effects of long-term rotations on
winter wheat response to N fertilizer, and (2) to evaluate the use of Plant Root
Simulator���(PRS) probes for measuring soil N mineralization and N availability to
winter wheat.
Field experiments were conducted over three growing seasons in plots of
`Stephens' soft white winter wheat at Hyslop farm. Plots receiving 0, 50, 100, 150 and
200 kg N ha����� at Feekes GS 4 were sampled to determine above ground N uptake, grain
yield, and grain protein. In spring 1998, PRS probes were placed in 0 kg N ha����� plots and
removed at one-week or two-week intervals. In autumn 1998, probes were placed in
unfertilized plots and removed at 1-week, 4-week, and 8-week intervals. Probes
measured the availability of NH������-N, NO������-N, K���, Ca�����, Mg�����, and P0��������-P.
Grain yield and N uptake were greater for wheat following clover as compared to
following oats. Three-year average fertilizer equivalent values calculated from N uptake
and grain yield data were 44.5 kg N h����� and 49.0 kg N h�����, respectively. The similarity
of these independent measurements suggest that differences in N availability were the
primary reason for the rotation effect.
PRS probes also detected rotational differences in N availability. Average N
recovered by probes sampled at 1-week intervals indicated that there was 63% as much
NO������-N available to wheat following oat as compared to clover. Wheat recovered 64% as
much N following oats as compared to clover. This suggests that PRS probes are an
effective method for predicting relative amounts of plant available N. PRS probes also
detected rotational differences in plant available potassium.
Agronomic responses are useful for assessing the availability of nutrients that are
limiting plant growth. PRS probes, on the other hand, are effective for assessing the
availability of both limiting and non-limiting nutrients. / Graduation date: 2000
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/33586 |
| Date | 13 July 1999 |
| Creators | Salisbury, Steven Earl |
| Contributors | Christensen, Neil W. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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