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
PUMPKIN COVER CROP AND LIVING MULCH STUDY
Richard Greenland
Table 80. Number of pumpkins and yield response to a barley cover crop and living mulches
Pumpkins are planted in wide rows, leaving large areas of bare ground between rows. In current pumpkin production, the between-row area is usually cultivated early in the season, before the pumpkin plants begin to run, to control weeds. This exposes the soil to erosion and also reduces soil organic matter. Later in the season hand weeding is used to control weeds. After harvest of pumpkins, little residue is left to protect the soil and it is usually too late in the season for cover crop establishment. Cover crops and living mulches planted between the pumpkin rows could prevent soil erosion and increase soil organic matter, but if they compete too much with the pumpkins then pumpkin yield could be reduced. In this study a barley cover crop was planted in early spring, leaving unplanted strips, 3.5 ft wide, for planting pumpkins in mid- to late-May. When the barley headed, it was flailed and a living mulch (hairy vetch, rye, soybean, and/or corn) was planted between the pumpkin rows. Data on height, stand, and vigor of pumpkin, living mulches, and weeds were collected to determine competitiveness of the living mulches. Total dry matter was measured at the end of the season. Our objective was to find a cover crop/living mulch combination that protects the soil, helps control weeds, but doesn’t compete with the pumpkins enough to reduce pumpkin yield.
MATERIALS AND METHODS
Soil: |
Maddock sandy loam; pH=6.9; 1.9% organic matter; soil-P and soil-K were very high; soil-S was low. |
Previous crops: |
2002 - field corn and popcorn; 2001 - cabbage, onion, potato and pumpkin; 2000 - potato, tomato, pepper and sweetcorn. |
Seedbed preparation: |
Disked twice on Apr 11. Multiweeded (field cultivated) twice; once April 11 and once May 23. |
Planting: |
‘Gold Gem’ pumpkin seeds were planted 1 ft apart in rows 8 ft apart on May 23. On June 20 thinned to an in-row spacing of one plant every 3 ft. |
Plots: |
Plots were 20 ft long by 16 ft (two rows) wide. |
Fertilizer: |
On April 9, broadcast 11 lbs N/acre and 52 lbs P205 as 11-52-0, 30 lbs K2O as 0-0-60 and 18 lbs N/acre and 20 lbs S/acre as 21-0-0-24. On April 14 sprayed 50 lbs N/acre as 32-0-0. Fertigated 50 lbs N/acre as 28-0-0 on June 26. Side dressed 30 lbs N/acre as urea on July 24. |
Irrigation: |
Overhead sprinkler irrigation as needed. |
Pest control: |
Weeds were controlled by hand weeding the three foot strip (where the pumpkins were planted) on all plots and by weed control treatments given in Table 79. Sprayed Asana (8 oz/acre on July 8, July 17, July 25 and August 22) and Ambush (8 oz/acre on August 6) to control cucumber beetles. |
| Harvest: | Hand harvested October 3 to 9. |
Dry matter determination: |
In October, after all harvesting was done, an area of 4 ft by 1' 4" (about 1/2 square meter) was randomly selected from each plot. All the above ground plants or plant parts were removed from that area and dried at 105 to 110 F for a minimum of 24 hours, then weighed to find the above ground dry matter. |
The pumpkin variety we used this year, Gold Gem, was not as vigorous as the pumpkin varieties used in previous years, so the living mulches grew more. The number and yield of marketable pumpkins were the same for all treatments. The total number of pumpkins in the check plots was greater than for the cover crop/mulch treatment plots, but the check plots also had more rotten and unmarketable pumpkins. The barley cover crop and the living mulches, except rye, increased end of season dry matter and helped protect the soil. Hairy vetch grew much more vigorously this year than in the previous two years of this study. Rye did not grow well in any of the three years of the study.
Herbicide treated plots and plots that were flailed high had more pumpkins and higher yields than the plots that were cultivated or that were flailed low. Lambsquarters control was slightly better with herbicides, and pigweed control was slightly better with cultivation.
Sweetcorn was planted in 2003 on the 2002 pumpkin cover crop study area. Weed control was slightly better where no cover crops or living mulches were planted the previous year, but yield of sweetcorn was not affected by the cover crop treatments.
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Table 79. Treatments applied to the Oakes Irrigation Research Site 2003 pumpkin cover crop/living mulch study.
Cover crop/living mulch treatments1
No barley cover crop nor living mulch (check)
Barley cover crop; no living mulch
Barley cover crop; hairy vetch
Barley cover crop; rye
Barley cover crop; hairy vetch + rye
Barley cover crop; soybean
Barley cover crop; soybean + corn
Barley cover crop; corn
Weed control treatments
Herbicide - Buctril (1 pt/acre on May 22 before planting pumpkin) and Poast + Dash (1.5 + 1 pt/acre on June 20 three days before flailing barley). The 3.5-ft strips were not cultivated.
No herbicide - The 3.5 ft strips were cultivated just before planting pumpkins.
Note: The 3.5-ft wide strip the pumpkins were planted in was hand weeded in all plots. The area between the pumpkin rows was not weeded except for the check (no barley, no living mulch) plots.
Barley flail height treatments2
High - flailed at 1 ft high
Low - flailed at less than 1 inch high
1Barley was planted with a drill (6-inch row spacing) on April 14 in strips 5 ft wide, leaving 3.5-ft wide bare strips for planting pumpkins. Living mulches were no-till planted on June 27 and June 28 with a Monosem specialty planter in 18-inch rows into the barley cover crop that had been flailed. A trash whipper was used ahead of the planter units to move the barley away from the planted row. Where two living mulches were planted, they were planted in alternating rows.
2Barley was flailed on June 23. This was just after barley headed, when the pumpkins began to run, and before planting the living mulches.
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Table 80. Number of pumpkins and yield response to a barley cover crop and living mulches in the Oakes Irrigation Research Site 2003 pumpkin cover crop/living mulch study.
Treatment |
Number of pumpkins |
Pumpkin yield |
Fruit size |
|||||
marketable |
not marketable1 |
rotten |
total |
marketable |
not marketable1 |
total |
||
|
------------------- number per acre ------------------ |
--------- tons per acre ------------ |
lbs/fruit |
|||||
Cover crop, living mulch |
||||||||
No barley, no mulch |
850 |
610 a |
570 c |
2270 a |
7.3 |
5.0 a |
13.5 a |
17.3 |
Barley, no mulch |
1240 |
320 c |
250 ab |
1930 b |
8.7 |
2.1 c |
11.4 ab |
13.9 |
Barley, hairy vetch |
940 |
420 ac |
200 a |
1700 bc |
7.1 |
2.5 c |
10.4 bc |
15.7 |
Barley, rye |
930 |
570 ab |
250 ab |
1890 bc |
6.8 |
3.8 ab |
11.3 ab |
14.5 |
Barley, hairy vetch + rye |
1160 |
320 c |
250 ab |
1940 b |
8.0 |
2.3 c |
11.4 ab |
14.0 |
Barley, soybean |
1010 |
380 bc |
470 bc |
1980 ab |
7.1 |
2.2 c |
9.9 bc |
14.2 |
Barley, soybean + corn |
880 |
350 c |
280 ab |
1630 c |
5.6 |
1.9 c |
8.0 c |
12.4 |
Barley, corn |
930 |
410 bc |
300 ab |
1770 bc |
6.0 |
2.6 bc |
9.3 bc |
12.6 |
|
||||||||
Probability |
0.07 |
0.04 |
0.03 |
0.006 |
0.22 |
0.0009 |
0.007 |
0.09 |
|
||||||||
Herbicide treated |
||||||||
No |
900 b |
440 |
330 |
1800 b |
6.4 |
2.8 |
9.8 b |
14.1 |
Yes |
1080 a |
400 |
320 |
1980 a |
7.8 |
2.8 |
11.5 a |
14.5 |
|
||||||||
Probability |
0.04 |
0.38 |
0.79 |
0.04 |
0.052 |
0.94 |
0.015 |
0.44 |
C.V. (%) |
37 |
61 |
77 |
22 |
37 |
61 |
23 |
17 |
|
||||||||
Barley flail height |
||||||||
High |
1160 a |
390 |
240 |
1940 a |
8.0 a |
2.4 |
11.1 a |
13.8 |
Low |
870 b |
390 |
330 |
1740 b |
6.1 b |
2.6 |
9.4 b |
14.0 |
|
||||||||
Probability |
0.009 |
0.99 |
0.07 |
0.02 |
0.007 |
0.63 |
0.015 |
0.63 |
C.V. (%) |
28 |
61 |
71 |
21 |
30 |
64 |
23 |
20 |
1Not marketable were those pumpkins that had disease spots, small rotten spots, major blemishes, or very odd shapes.
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Table 81. Pumpkin stand, injury and height, living mulch vigor and height, weed control, and end of season dry matter as affected by cover crop and living mulches in the Oakes Irrigation Research Site 2003 pumpkin cover crop/living mulch study.
Treatment |
Early Stand1 |
Pumpkin injury2 |
Living mulch vigor3 |
Redroot pigweed control3 |
Lambs- quarters control3 |
Hairy nightshade control3 |
Pumpkin height4 |
Living mulch height4 |
Final dry matter5 |
|
1000s/A |
---------------------------- 0 to 106 --------------------------- |
------ inches ----- |
tons/A |
|||||
Cover crop/living mulch |
|||||||||
No barley, no mulch |
2.0 |
0.0 |
0.0 |
8.9 |
8.8 |
9.6 |
21.0 |
0.0 |
1.1 |
Barley, no mulch |
1.8 |
2.4 |
0.0 |
8.5 |
7.7 |
8.7 |
20.1 |
0.0 |
2.5 |
Barley, hairy vetch |
1.8 |
2.4 |
6.3 |
8.8 |
8.9 |
8.8 |
18.3 |
9.1 |
4.2 |
Barley, rye |
2.1 |
2.1 |
2.1 |
8.9 |
8.6 |
8.9 |
18.2 |
3.9 |
1.5 |
Barley, hairy vetch+rye |
1.8 |
2.3 |
4.2 |
8.4 |
8.8 |
8.9 |
18.8 |
9.4 |
3.8 |
Barley, soybean |
1.9 |
1.9 |
6.3 |
8.9 |
8.1 |
9.1 |
20.2 |
12.3 |
3.5 |
Barley, soybean + corn |
2.1 |
2.2 |
6.1 |
9.2 |
8.6 |
8.9 |
19.9 |
15.2 |
4.2 |
Barley, corn |
1.8 |
2.0 |
6.9 |
8.9 |
8.3 |
9.1 |
20.6 |
20.1 |
3.9 |
|
|||||||||
Probability |
0.07 |
<.0001 |
<.0001 |
0.13 |
0.013 |
0.02 |
0.012 |
<.0001 |
<.0001 |
LSD (0.05) |
— |
0.8 |
0.4 |
— |
0.7 |
0.5 |
1.7 |
1.5 |
0.9 |
|
|||||||||
Herbicide treated |
|||||||||
No |
1.9 |
2.1 |
3.9 |
9.1 |
7.7 |
8.9 |
19.4 |
8.8 |
3.2 |
Yes |
2.0 |
1.7 |
4.1 |
8.5 |
9.3 |
9.1 |
19.8 |
8.8 |
3.0 |
|
|||||||||
Probability |
0.28 |
0.09 |
0.04 |
0.02 |
0.013 |
0.41 |
0.4 |
1 |
0.58 |
C.V. (%) |
14 |
38 |
15 |
9 |
9 |
6 |
10 |
22 |
29.0 |
|
|||||||||
Barley flail height |
|||||||||
High |
1.9 |
2.4 |
4.7 |
9.1 |
8.5 |
9.0 |
19.4 |
10.0 |
3.5 |
Low |
1.9 |
2.0 |
4.5 |
8.5 |
8.4 |
8.8 |
19.4 |
10.0 |
3.3 |
|
|||||||||
Probability |
0.54 |
0.004 |
0.17 |
0.02 |
0.59 |
0.2 |
0.85 |
0.89 |
0.17 |
C.V. (%) |
12 |
37 |
13 |
6 |
9 |
6 |
10 |
15 |
27 |
1Pumpkin plants/17 ft of row before thinning. Plants later thinned to 6 plants/17 ft of row.
2Pumpkin injury measured on July 24. Injury was mostly mechanical injury from tractor and implements while planting living mulch.
3Measurements taken on July 24.
4Measurements taken on Aug 1.
5End of season dry matter.
6Ratings 0 = no injury, zero vigor, or no weed control, 10 = complete death of crop, complete control of weed, very vigorous mulch.
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Table 82. Effects of cover crops/living mulches used in pumpkins in 2002 on weed growth and sweetcorn in 2003.
Treatment |
Weed ratings |
Sweetcorn |
|||||
Rrpw1 |
Colq1 |
Hns1 |
FT1 |
ears |
yield |
ear size |
|
|
-------------------------- 0 to 102 ------------------------- |
1000s/A |
tons/A |
lbs/ear |
|||
Cover crop/living mulch |
|||||||
No barley, no mulch |
9.9 |
8.5 a |
9.8 |
8.9 a |
22.8 |
10.1 |
0.9 |
Barley, no mulch |
10.0 |
7.4 c |
9.8 |
7.4 bc |
23.6 |
10.3 |
0.9 |
Barley, hairy vetch |
9.9 |
7.6 c |
9.8 |
7.0 bc |
22.7 |
10.0 |
0.9 |
Barley, rye |
9.9 |
7.6 c |
9.6 |
6.5 c |
22.5 |
9.9 |
0.9 |
Barley, hairy vetch + rye |
9.8 |
7.8 bc |
9.5 |
6.9 bc |
24.2 |
10.9 |
0.9 |
Barley, soybean |
9.9 |
7.5 c |
9.9 |
6.8 bc |
23.4 |
10.8 |
0.9 |
Barley, soybean + corn |
9.9 |
8.2 ab |
9.9 |
8.1 ab |
23.8 |
10.5 |
0.9 |
Barley, corn |
9.9 |
7.4 c |
9.6 |
7.2 bc |
21.6 |
9.8 |
0.9 |
Probability |
0.63 |
0.0006 |
0.19 |
0.02 |
0.55 |
0.15 |
0.57 |
|
|||||||
Herbicide treated |
|||||||
No |
9.9 |
7.6 |
9.8 |
6.8 b |
23.7 |
10.6 |
0.9 |
Yes |
9.9 |
7.9 |
9.7 |
7.9 a |
22.5 |
10.0 |
0.9 |
|
|||||||
Probability |
0.39 |
0.5 |
0.76 |
0.014 |
0.56 |
0.58 |
0.67 |
C.V. (%) |
3 |
12 |
6 |
12 |
17 |
17 |
6 |
|
|||||||
Barley flail height |
|||||||
High |
10.0 |
7.2 b |
9.7 |
7.0 |
22.5 |
10.0 |
0.9 |
Low |
9.8 |
8.1 a |
9.8 |
7.3 |
23.7 |
10.6 |
0.9 |
|
|||||||
Probability |
0.19 |
0.002 |
0.76 |
0.45 |
0.15 |
0.31 |
0.83 |
C.V. (%) |
3 |
8 |
5 |
10 |
12 |
10 |
6 |
1Weed identification: Rrpw - redroot pigweed; Colq - common lambsquarters; Hns - hairy nightshade; FT - yellow and green foxtail.
2Ratings: 0 is no effect (no weed control or no crop injury); 10 is complete weed or crop kill.
3Values in the same column and section followed by the same letter are not significantly different at the 0.05 level. If no letters in column, then there were no statistically significant differences between values in that column.
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