|
Table 2: Grain yields of non-wheat crops. |
|||||||
|
|
|
|
2003 |
|
1996-2003 Avg |
||
|
|
Crop |
|
Yield |
Oil |
|
Yield |
Oil |
|
|
|
|
lb/a |
% |
|
lb/a |
% |
|
|
|
|
|
|
|
|
|
|
|
Grain Lentil |
|
1670 |
-- |
|
1070 |
-- |
|
|
Field Pea |
|
1440 |
-- |
|
1393 |
-- |
|
|
Safflower |
|
1064 |
30.3 |
|
650 |
31.9 |
This year, applying insufficient N to continuous wheat resulted in increased yields. In six of the previous seven years, applying insufficient N to continuous wheat 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-one cases (i.e., three legume species × seven years) during the previous seven 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 |
|||||||
|
|
N |
2003 |
|
1996-2003 Average |
|||
|
Previous Crop |
Treatment |
N |
Yield |
Protein |
|
Yield |
Protein |
|
|
|
lb/a |
bu/a |
% |
|
bu/a |
% |
|
|
|
|
|
|
|
|
|
|
Wheat |
Recommended |
60 |
30.0 |
17.0 |
|
30.4 |
15.4 |
|
Wheat |
Insufficient |
0 |
34.8 |
14.7 |
|
23.2 |
12.6 |
|
Fallow |
Recommended |
0 |
37.1 |
17.1 |
|
36.9 |
15.8 |
|
Safflower |
Recommended |
60 |
30.8 |
18.4 |
|
27.8 |
16.4 |
|
|
|
|
|
|
|
|
|
|
Forage Lentil |
Recommended |
60 |
30.6 |
18.2 |
|
29.5 |
16.5 |
|
Green Manure [F.L.] |
Recommended |
0 |
35.8 |
17.4 |
|
36.6 |
15.9 |
|
Green Manure [F.L.] |
Excessive |
60 |
37.6 |
17.7 |
|
37.1 |
16.5 |
|
|
|
|
|
|
|
|
|
|
Grain Lentil |
Recommended |
60 |
30.5 |
17.8 |
|
29.2 |
16.5 |
|
Green Manure [G.L.] |
Recommended |
0 |
37.0 |
16.4 |
|
37.4 |
15.4 |
|
Green Manure [G.L.] |
Excessive |
60 |
35.6 |
17.8 |
|
36.9 |
16.5 |
|
|
|
|
|
|
|
|
|
|
Field Pea |
Recommended |
60 |
35.7 |
17.2 |
|
32.3 |
15.9 |
|
Green Manure [F.P.] |
Recommended |
0 |
35.3 |
17.0 |
|
36.4 |
15.8 |
|
Green Manure [F.P.] |
Excessive |
60 |
34.9 |
17.7 |
|
37.3 |
16.5 |
|
|
|
|
|
|
|
|
|
|
Average |
|
|
34.3 |
16.3 |
|
33.1 |
15.8 |
|
LSD (5%) |
|
|
4.5 |
0.6 |
|
|
|
Wheat protein content for all treatments was greater this year than the corresponding 8-year average (Table 3). Protein content of the continuous wheat with insufficient N was lower than any other treatment.
Applying insufficient N to continuous wheat reduced wheat grain protein this
year and in six of the seven previous years. Applying excessive N to
wheat following green manure significantly increased wheat grain protein in two
of three cases (i.e., grain lentil and field pea) this year as well as in twelve
of twenty‑one cases (i.e., three legume species × seven years) during the
previous seven 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.