POTATO INVESTIGATIONS LABORATORY
Hastings, Florida ,-.
Mimeo Report 59-4 October 1, 1958
LAND LEVELING FOR DRAINAGE AND IRRIGATION OF POTATOES1
Donald L. Myhre
Smooth lan4 is a prerequisite for successful and efficient drainage and irri-
gation by the water furrow method as used in the Hastings area. The importance and
value of land leveling for increased potato production has become increasingly ap-
parent during the past four or five years. Experiments conducted at the Potato In-
vestigations Laboratory show that yields of U.S. 1A and 1B Sebago tubers can be in-
creased to at least 300 hundred-pounds per acre on old cultivated land. This high
production was obtained by breaking the organic hardpan under Leon "white caps",
leveling the land to a uniform slope, maintaining adequate but not excessive soil
moisture throughout the growing season, controlling insects and diseases, employing
good cultural practices, using about 2,500 pounds per acre of both seed and 6-8-8
fertilizer and growing a good summer cover crop. A good leveling job results in
better water control for irrigation and drainage, more uniform stand of plants,
increased potato yields and a reduction in labor costs.
In general, the leveling operation should consist of pushing the top 4 to 10
inches of good dark soil aside, cutting off the ridges, filling in the low spots,
replacing the top soil and obtaining a uniform irrigation slope of about 2 to 4
inches in a distance of 100 feet. Removal and replacement of top soil is generally
not feasible if the cuts or fills are less than 2 inches.
Soil Survey.- A soil survey should be made before doing any land leveling so
that the work can be done according to a good plan which best suits the needs of
the land as a part of the complete farm plan. Technicians of the Soil Conservation
Service are available to help with the survey, the plan, the staking, and to check
the work after it has been completed. A soil survey is desirable in order to de-
termine the nature of the surface soil and subsoil and the location of the clay
and hardpan. Cuts should not be made to expose clay. Field experience has shown
that water control is much more satisfactory if the clay subsoil is at least 18
inches below the top of the ground.
Soil surveys are usually made for either a land smoothing job or a land
leveling Job. Land smoothing consists of cutting off the ridges and filling in
the low spots without taking into consideration the general slope of the field.
Land leveling is a more complete method of land preparation and consists of grad-
ing the entire field to a specified slope.
Land Leveling Equipment.- Most leveling jobs in the Hastings area are done at
present with a heavy track-tractor equipped with a bulldozer blade or a rubber-
tired carryall scraper machine or pan. The bulldozer is used for pushing aside
topsoil, breaking the hardpan under Leon "white caps", cutting ridges and spreading
soil in low spots not more than 200 feet away. The carryall machine will cut to
grade and spread soil evenly and is ecomical for carrying soil long distances.
Roto-haulers are very good except where deep cuts are necessary. Smaller wheeled
scrapers pulled by farm tractors are used for leveling land on some farms but
they require more time to get the job done.
1Revision of Mimeo Report 58-4
The final land leveling is completed with a landplane or leveler. It has an
adjustable blade near the center of its frame. The longer machines give a smoother
finishing job. Wooden drags or floats can be used also to help smooth the surface.
Releveling every year or two with a landplane or leveler smooths out small surface
irregularities caused by settling of soil in fills or by tillage implements near
turnrows of field.
Grade of Field.- The grade or slope of the field depends on the original
topography and the surface drainage of the field. A level field with no slope
would be best for irrigation but hazardous for drainage after heavy rains. In
general, the grade should be 2 to 3 inches per 100 feet, but should not be over 4
inches because of potential soil erosion by heavy rains. A cross slope of not more
than about 1 inch per 100 feet is convenient, especially for irrigation because less
water control structures are needed in the water supply ditch.
Cost of Leveling.- The cost per acre of leveling land depends on a number of
factors, the principal ones being the cubic yards of soil moved, the type of equip-
ment used and the skill of the operator. The cost per operating hour for a track-
tractor equipped with a bulldozer blade or pulling a pan ranges from $8 to $20, de-
pending on the size of the tractor. The cost of leveling fields in the Hastings
area ranges from $50 to $125 per acre, while the cost per cubic yard of cut varies
from $0.18 to $0.25, depending on the contractor. A portion of this cost will be
shared by the government if the leveling job meets certain specifications under the
Agricultural Conservation Program.
Value of Land Leveling.- The effects of breaking hardpan and leveling land on
yield anid qualT of potatoes were determined in an experiment in 1956, 1957, and
1958. The brownish organic hardpan under the Leon soil was broken up with a bull-
dozer blade and mixed thoroughly with the dark and light sandy topsoil in the area
in 1955. This hard impervious layer was 2 to 12 inches thick and about 18 inches
below the surface. The area was leveled to provide a uniform slope of about 0.3
foot per 100 feet. The leveled area and an adjacent, undisturbed, nonleveled area
were limed with 1 ton per acre of dolomite. Potatoes were planted in both areas in
each of the last three years, using 2,500 pounds per acre of both seed and 6-8-8
In 1956 the total yield in the leveled area was 338 and in the nonleveled 315
hundred-pounds per acre. The potato tubers grown in the leveled area were of better
quality than those grown in the nonleveled area which produced some tubers with
scurf, "growth cracks" and corky ringspot. The net income was $172 per acre more
in the leveled area than in the nonleveled area, which was more than enough to pay
for the cost of leveling. About one-half of this increased net 'income was was due
to the improved quality of the potato crop and the other one-half to the increased
total yield of 23 sacks per acre in the leveled area. In 1958, yield of the third
crop of Sebago potatoes after breaking the organic hardpan and leveling the land
was 13 percent higher than in the undistrubed area. These results show that break-
ing the organic hardpan in soils where it occurs and leveling the land surface is
very profitable for potato growers.
1Myhre, D. L. Effects of breaking hardpan and deep plowing on potato yields.
Fla. Soil and Crop Sci. Soc. Proc. 17. 1957. (In press)
Myhre, D. L. Land leveling pays for potatoes. Sunshine State Agr. Res. Rpt. 2: 8-9.