F (3 0b M POTATO INVESTIGATIONS LABORATORY
Mimeo Report 62-5* October 6, 1961
ROTATION CROPS IN POTATO PRODUCTION
D. R. Hensel
The high fixed cost of potato production makes it essential to maintain high
yields. The fixed costs are the same on low yielding areas as on the high yielding
areas, therefore, one must obtain the highest yield possible. One solution of this
problem would be to grow potatoes in a rotation. Special soil improvement crops
grown periodically in a rotation with potatoes have shown that they successfully
improve the yield of potatoes which follow in the rotation.
Results of the rotation experiment conducted at the Potato Investigations
Laboratory are presented in Table 1. The results show that one year of either r';e
or oats gave large increases in potatoes the following year. The land where rye or
oats was planted the season before yielded 47 cwt./A more potatoes. Lupine and
volunteer growth did not do well enough to be used as a common practice. Besides
adding organic matter to the soil, the rye and oats crops probably improve the
physical condition of the soil which might increase soil aeration and make the soil
more favorable for water to enter and percolate through it.
Table 1.- Effect of one year Special Cropping in a Potato Rotation on New Land.
Potato Yield Increase in A's compared to
Treatment Size A in Cwt./A continuous potatoes
Continuous potatoes 268.2 -
Lupine 290.6 22.5 8.4
Oats 315.3 47.0 17.5
Rye 314.9 46.8 17.4
Volunteer growth 281.3 13.1 4.9
Rye, oats, and lupine were planted in the first part of November. The crops
were knocked down, and beds were listed into 15 row beds and planted to sart for the
summer cover crop as soon as the potatoes were harvested. The rye, oats, and lupine
received 200 lbs./A of 6-8-8 at planting time. The rye and oats were sidedressed
with an additional 40 pounds nitrogen per acre.
To determine if the rotation is profitable some calculations must be made.
From previous work reported at the Potato Laboratory, the lasting effect of the
rotation is about 2 years. Increase in yield of potatoes the second year is about
one-half of the first. In computing the profits, $260 per acre was used as the
fixed cost of potato production. The variable cost of harvesting and marketing
potatoes was $1.10 per cwt. No cost was charged to production of rye or oats since
it was assumed that they could be harvested for grain and produce enough income to
meet production costs.
Besides the cost of production, harvesting, and marketing, the price of
potatoes and the fertility level of the land must be considered. For land which the
fertility level is less than 200 cwt./A and the price is less than $3Q00 pr cwt., it
would be profitable to use a rotation. If the farm in question is m@ltaining an
average yield of 250 cwt./A, then the use of a rotation would be prostabe if the
price of potatoes is below $2.50 per cwt. The factors influencing t L';use of- ',
rotation are not only the present potential of the soil but the price ~yer a three'' -,
year period. Secondary effects of the rotation would cause less pota6, to be
planted which would help reduce the problem of over production. The ru
would give the operator more time to devote to his other potatoes and st'l
more profitable operation.
*Revision of Mimeo Report 60-3; 200 copies