Research
Cover Crop results for 2001
A Hairy Vetch/Rye Cover
Crop for Weed Control and
Fertilization in Muskmelons
Chemical fertilizers and
herbicides are used frequently in muskmelon plantings in Iowa. We investigated the use of a hairy
vetch/rye cover crop as an organic nitrogen source and as a living mulch to
control weeds. We conducted the
experiment at the ISU Horticulture Farm and at the Muscatine Island Research
Station. The cover crop was planted
in the fall prior to the summer muskmelon season, and was killed by rolling with
a cultipacker after flowering. A
slit was made in the mulch using a chisel tooth, and transplants were
inserted. For conventional mulch
treatments, soil was treated with a pre-emergence herbicide and transplants were
planted into black plastic mulch.
Plants receiving conventional fertilizer treatments were side-dressed
with inorganic nitrogen at vining.
Weeds were counted and characterized during the season, and yield data
were collected. Due to planting
error, the vetch stand in Ames was very thin, and the rye stand was very
thick. The low legume population in
the cover crop and the high grass population likely reduced the amount of
nitrogen present in the plots before planting. We chose to apply nitrogen to all of the
plots at Ames and simply look at the weed suppressive abilities of the cover
crop. Therefore, we tested only
treatments 2 and 4 in our study at Ames.
We measured yield and estimated disease pressure for each plot by
weighing weeds from sampled regions of each plot at the beginning and end of the
growing season. At Ames, the weed
pressure grew so heavy that we had to hand weed plots to prevent a dramatic
increase in the weed seed bank. We
measured the hours required to weed these plots.
Treatment
1: Hairy vetch/rye cover crop + application
of chemical nitrogen
Treatment
2: Hairy vetch/rye cover crop
Treatment
3: Conventional black plastic mulch +
application of chemical nitrogen
Treatment
4: Conventional black plastic
mulch
We found no differences
in yield among the treatments at either location. There were some trends that suggest the
cover crop may very slightly reduce yields, however further years' data are
necessary to truly know how the mulch affects yield. We saw differences in weed pressure for
each treatment, however. The weed
pressure at Muscatine was pretty low throughout the season, and in general, the
living mulched plots had more weed pressure than did the plastic mulched plots
(Table 1). At Ames, there were no
differences in weed weight between the two treatments, however the plots with
the rye living mulch took an average of 94.02 hours to weed, while the plastic
mulched plots took only 38.9 hours (P<0.0001). Overall, the hairy vetch/rye living
mulch at Muscatine seemed to suppress weeds effectively, and the rye mulch at
Ames did not. We will repeat this
experiment next year and will be able to draw firmer conclusions with more
data.
Weed weights for samples
taken at Muscatine before planting and in the
middle of the season.
|
Treatment
|
1st Sample Weed Weight
(grams)
|
2nd Sample Weed Weight
(grams)
|
|
1
|
1.5
|
7.2 A
|
|
2
|
4.2
|
8.2 A
|
|
3
|
1.7
|
2.0 B
|
|
4
|
0.5
|
1.2 B
|
|
LSD (a=0.05)
|
4.9
|
6.5
|