|
Table 2: Grain performance of non-wheat crops. |
||||||||
|
|
|
2004 |
|
1996-2004 Average |
||||
|
Crop |
|
Yield |
Protein |
Oil |
|
Yield |
Protein |
Oil |
|
|
|
lb/a |
% |
% |
|
lb/a |
% |
% |
|
|
|
|
|
|
|
|
|
|
|
Grain Lentil |
|
1488 |
23.2 |
-- |
|
1116 |
N.A. |
-- |
|
Field Pea |
|
3071 |
18.5 |
-- |
|
1579 |
N.A. |
-- |
|
Safflower |
|
848 |
-- |
32.1 |
|
672 |
-- |
31.9 |
This year, as in six of the previous eight years, applying insufficient N to continuous wheat resulted in decreased yields. Applying excessive N to wheat following green manure did not significantly increase (LSD=5%) wheat yield this year or any of the previous twenty-four cases (i.e., three legume species × eight years) during the previous eight years. The finding that insufficient N usually reduced yield and that excess N seldom increased yield supports the validity of fertilizer recommendations based on soil testing.
|
Table 3: HRSW performance in the WREC Annual Legume Study |
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|
|
N |
2004 |
|
1996-2004 Average |
|||
|
Previous Crop |
Treatment |
N |
Yield |
Protein |
|
Yield |
Protein |
|
|
|
lb/a |
bu/a |
% |
|
bu/a |
% |
|
|
|
|
|
|
|
|
|
|
Wheat |
Recommended |
60 |
51.8 |
14.7 |
|
32.7 |
15.3 |
|
Wheat |
Insufficient |
0 |
31.7 |
10.9 |
|
24.2 |
12.4 |
|
Fallow |
Recommended |
60 |
53.6 |
16.6 |
|
38.7 |
15.9 |
|
Safflower |
Recommended |
30 |
51.2 |
14.0 |
|
30.4 |
16.1 |
|
|
|
|
|
|
|
|
|
|
Forage Lentil |
Recommended |
0 |
41.5 |
13.5 |
|
30.8 |
16.1 |
|
Green Manure [F.L.] |
Recommended |
0 |
53.7 |
16.0 |
|
38.5 |
15.9 |
|
Green Manure [F.L.] |
Excessive |
60 |
52.2 |
16.9 |
|
38.7 |
16.6 |
|
|
|
|
|
|
|
|
|
|
Grain Lentil |
Recommended |
0 |
39.9 |
14.7 |
|
30.4 |
16.3 |
|
Green Manure [G.L.] |
Recommended |
0 |
55.1 |
15.1 |
|
39.3 |
15.4 |
|
Green Manure [G.L.] |
Excessive |
60 |
56.6 |
16.7 |
|
39.1 |
16.6 |
|
|
|
|
|
|
|
|
|
|
Field Pea |
Recommended |
30 |
47.7 |
14.5 |
|
34.0 |
15.7 |
|
Green Manure [F.P.] |
Recommended |
0 |
50.0 |
15.8 |
|
37.9 |
15.8 |
|
Green Manure [F.P.] |
Excessive |
60 |
50.7 |
16.7 |
|
38.8 |
16.5 |
|
|
|
|
|
|
|
|
|
|
Average |
|
|
48.9 |
15.1 |
|
34.9 |
15.7 |
|
LSD (5%) |
|
|
8.9 |
1.2 |
|
|
|
The overall average wheat protein content was less this year than the 9-year average (Table 3). For individual treatments, the protein content was less than the corresponding 9-yr average, except in the treatments where the wheat received excess nitrogen fertilizer.
Applying insufficient N to continuous wheat reduced wheat grain protein this year and in seven of the previous eight years. Applying excessive N to wheat following green manure significantly increased wheat grain protein in only one case this year (the grain lentil green manure), and in fourteen of twenty‑four cases (i.e., three legume species × eight years) during the previous eight years. This suggests that although protein content is maximized at a greater N rate than is yield, applying more N than recommended inconsistently increases protein content and may not be economically beneficial.
This study is being continued to determine if the observed trends continue and if long-term benefits such as improvement in soil quality are obtained. An economic analysis of the results to date has been performed.
|
|