POTATO INVESTIGATIONS LABORATORY
Mimeo Report 60-3 September 25, 1959
POTATO-COVER CROP ROTATION
Donald L. IMhre
Overproduction associated with low prices in some years and low production per
acre other years are important reasons for lack of profit by potato growers in the
Hastings area. One solution to this problem is to plant rye or some other soil-
improving crop instead of potatoes every second or third year. This practice
would reduce total production by decreasing acreage planted to potatoes, which also
could have a favorable effect on the market price for the crop. At the same time
it would increase the yield per acre, and possibly improve the quality of the
Results at the Potato Investigations Laboratory as given in Table 1 show that
one crop of rye increased yields an average of 34.9 and 12.8 percent in the first
and second potato crops following rye grown on Leon fine sand.
Table 1.- Effect of One Crop of Rye on the Three Following Crops of Potatoes.
Potato Potato Potato Yield, Size A, Cwt./A Difference in Yield due to Rye
Crop Variety Potatoes, 1956 Rye, 1956 Cwt./A Percent
Sebago 149.9 211.0 61.1 40.
1957 Red Pontiac 195.1 251.7 56.6 29.0
Average 172.5 23 5 3
Sebago 175.5 214.1 38.6 22.0
1958 Red Pontiac 279.5 289.5 10.0 .6
Average 227.5 251. 2713 127
Sebago 132.4 122.2 -10.2 -7.7
1959 Red Pontiac 195.8 204.1 8.3 4.2
Average 1i4.1 163.2 1.0 -1.8
The Abruzzi rye crop was planted at the rate of one bushel per acre on Nov. 7,
1955, fertilized with 200 pounds of nitrate of soda-potash on Feb. 6, 1956 and
incorporated into the soil May 7, 1956. Sesbania or a sorghum was grown during
the summer and fall months before and after the rye crop, which is the usual
practice when potatoes are grown instead of rye. This increase in potato yields
following rye was probably due to the improved tilth of the soil which occurred
when certain organic acids from the rye cover crop aggregated the soil and
stabilized the aggregates. Such an improvement in physical condition of the soil
would enable air and water to enter and leave the soil more freely.
These promising results suggested that it would be of interest to calculate
the potential net returns from a three-year rotational system and from existing
continuous potato operations as practiced at present. This comparison is shown
in Table 2. An increase in yield of only 20 percent in the first year and 10
percent the second year would result in an average annual net return for the
three years of $10.60 compared to $6.00 per acre for the continuous potato
In summary, a three-year rotational system, including one crop of winter rye
followed by two winter crops of potatoes, shows promise of being profitable in the
Hastings area and warrants consideration by growers, especially on soils which are
old and less productive at present. The rye crop exerted a beneficial effect which
was very pronounced in the first potato crop, and was apparent to a lesser extent
in the second potato crop. Under some conditions it might prove profitable to
alternate rye and potatoes in a two-year rotational system. Further studies on
the value of a winter cover crop, such as rye, oats or a legume, will be made on
land which has been in continuous potato production for over 40 years and on new
land which has just been cleared.
It is tentatively recommended that Florida Black, Abruzzi, or Gator rye be
broadcast at the rate of one bushel per acre in October or November. The land
should receive about 300 pounds of 6-8-8 fertilizer before planting. The rye crop
should be sidedressed in February with about 100 pounds of ammonium nitrate, or
it equivalent per acre.
Table 2.- Comparison of Theoretical Net Returns for Three Years of Continuous
Potatoes and Two Years of Potatoes in Rotation with Rye.
Net Return, Dollars per Acre*'
Year in Continuous Increase in Yield Due to Rye
Rotation Potatoes 20% First Year 30O First Year
1___0% Second Year 15% Second Year
First 6.00 -60.00** -60.00**
Second 6.00 59.20 85.80
Third 6.00 32.60 45.90
Total 18T00 31.80 71.70
Average 6.00 10.60 23.90
*Based on following values: yield of US lA potatoes, 140 cwt. per acre;
market price, $3.00 per cwt.; growing costs, $260.00 per acre; harvesting
costs, $1.10 per cwt. The net returns were determined by subtracting the
growing and harvesting costs from the gross returns.
**Includes the following costs per acre: $30.00 land rent and $30.00 for
seed, fertilizer, labor and other expenses for growing rye.
Myhre, D. L. Rye in rotation with potatoes looks promising. Fla. Agri. Exp. Sta.
Sunshine State Agri. Res. Rept. 4, No. 4. 1959.