Oakes Irrigation Research
Site
Carrington Research Extension Center * North Dakota State University
P.O. Box 531, Oakes, ND 58474-0531, Voice: (701) 742-2189, FAX: (701)
742-2700, email: rgreenla@ndsuext.nodak.edu
Richard Greenland
High winds, which occur frequently in the spring time in North Dakota, blow soil particles from the finely prepared onion seedbed across the ground, causing extensive damage to newly emerged onion plants. One way of stopping the destruction is by planting a cover crop. In this study a cover crop of barley was drilled just before the onions were planted. Onions were planted either perpendicular to or parallel with the rows of barley. The barley was then killed with Fusilade at different heights and data collected to determine the effect of the cover crop on onion production.
Table 52. Number and yield of onions in the onion cover crop study.
MATERIALS AND METHODS
| Soil: | Maddock sandy loam; pH=7.5; 2.7% organic matter; soil-P and soil-K were very high; soil-S was low. |
| Previous crops: | 1996 - potato; 1995 - carrots; 1994 - sweet corn. |
| Seedbed preparation: | Disked on April 24. Multiweeded (field cultivated) on April 24 to incorporate fertilizer and smooth the seedbed. |
| Planting: | Drilled barley cover crop on April 25 (1 bu/acre, 6-inch rows). Direct seeded 'Santos' onions on April 25 with a Stanhay vegetable planter at a population of about 200,000 seeds/acre. Planted in paired rows (3" apart), with the paired rows on 16" centers. |
| Plots: | Plots were 6 ft wide by 17 ft long. The study had 4 reps. |
| Fertilizer: | On April 23, broadcast 14 lbs N/acre and 70 lbs P2O5/acre as 10-50-0, 16 lbs N/acre and 19 lbs S/acre as 21-0-0-24, and 94 lbs K20/acre as 0-0-60. Sprayed 50 lbs N/acre as 28-0-0 on April 24. Fertigated 52 lbs N/acre as 28-0-0 on July 11. |
| Irrigation: | Overhead sprinkler irrigation as needed. |
| Pest control: | Weeds were controlled with Prowl (1.5 pt/acre on May 27), Fusilade + Penetrate II (12 oz/acre + 1 pt/25 gal on June 4), and Buctril + Goal (1.5 pt + 0.6 pt/acre on June 13). Sprayed Bravo (1.5 pt/acre on August 5) and Dithane (2.2 qt/acre on August 20) to control purple blotch. No insect control needed. |
| Harvest: | Pulled onions on Sept 17. Onions were allowed to dry in the field until Oct 7, when they were bagged. The tops were removed and onions graded on Oct 28, 29, and 30. |
Results from this years study differed from results of the past two years. Planting the barley cover crop parallel to the onions did not increase onion yield compared to planting barley perpendicular to the onions, as happened in previous years. Also, this year the cover crop did not reduce yields until it grew to over 9 inches tall before we killed it. In previous years we had to kill it when it was 6 to 7 inches tall to avoid yield reductions.
Return to top of onion cover crop study
Table 52. Number and yield of onions in the onion cover crop study.
Barley |
Number of bulbs (given by bulb size) |
Yield (given by bulb size) | |||||||
| >3" | 2¼ to 3" | >2¼" | total | >3" | 2¼ to 3" | >2¼" | total | ||
| ----------------- 1000s per acre --------------- | ---------------- cwt per acre -------------- | ||||||||
| Height when sprayed | |||||||||
| 4 inches | 36.7a† | 31.1 a | 67.7 a | 86.1 a | 244 a | 105 a | 348 a | 395 a | |
| 6.5 inches | 31.1 a | 31.7 a | 62.7 a | 84.0 a | 203 a | 106 a | 308 a | 361 a | |
| 9 inches | 29.9 a | 34.5 a | 64.4 a | 88.5 a | 190 a | 118 a | 309 a | 357 a | |
| 12 inches | 5.9 b | 13.1 b | 19.0 b | 50.1 b | 33 b | 42 b | 75 b | 114 b | |
| Planting direction‡ | |||||||||
| perpendicular | 26.5 | 28.5 | 55.0 | 76.4 | 169 | 96 | 265 | 308 | |
| parallel | 25.2 | 26.7 | 51.9 | 77.9 | 166 | 89 | 255 | 305 | |
| C.V.(%) | 34 | 28 | 25 | 18 | 36 | 29 | 27 | 24 | |
†Values in the same column followed by the same letter are
not significantly different at the 0.05 level. There were no significant
differences in any column for perpendicular vs. parallel.
‡Planting direction with respect to onion rows.
Return to top of onion cover crop study
Go to Oakes Irrigation Research Site Cover Crop Studies page
Go to Oakes Irrigation Research Site 1997 annual report