POTATO INVESTIGATIONS LABORATORY
Mimeo Report 58-4 October 1, 1957
LAND LEVELING FOR DRAINAGE AND IRRIGATION OF POTATOES1,2
Donald L. Myhre
Smooth land is a prerequisite to successful and efficient drainage and irri-
gation by the water furrow method in the Hastings section. The importance and
value of land leveling for increased potato production has become increasingly
apparent during the last two or three years. Experiments conducted at the Potato
Investigations Laboratory indicate that Sebago potato yields on old sandy land in
the Hastings section can be doubled to at least 300 one-hundred pound racks per
acre by breaking the organic hardpan under Leon "white caps", lev3J.i'g the land to
a uniform slope, maintaining a high soil moisture content throughout ne.st of the
growing season, controlling insects and diseases, employing good c'lt ,'ral 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 distribution of the
irrigation water from the water furrows, 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.
Soil Survey.- A soil survey should be made before doing any land leveling so
that thie w-rk can be done according to a good plan which best suits the needs of
the land. 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 com-
pleted. A soil survey is desirable in order to determine 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 unch more satis-
factory 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 level-
ing job. Land smoothing consists of cutting off the ridges and filling in the low
spots without -tkirg into consideration the general slope of the field. Land
leveling is a more complete method of land preparation and consists of grading the
entire field to a specified slope.
1Revision of Mimeo Report 57-2.
2Data in process of publication in Soil Sci. Soc. of Fla.
Land leveling Equipment.- Most leveling jobs in the Hastings section are done
at present with a heavy track-tractor equipped with a bulldozer blade or a rubber-
tired carryall scraper machine. 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 economical for carrying soil long distances. 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.
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.
Relevcli:.g very year or two with a landplane or leveler is recommended for smooth-
ing out 6all surface irregularities caused by settling of soil in fills or by
tillage irp.Lrments near turnrows of field.
Grace of F.eld.- The grade or slope of the field depends on the original
topography ~'ri. "surface drainage of the field. A level field with no slope
would bs cost fcr irrigation but hazardous for drainage after heavy rains. In
general, the grade should not be over 4 inches fall in a distance of 100 feet.
A few fields in the Hastings section have been laid out with very good results on
grades of less than 1 inch per 100 foot.
Cost of Leveling.- The cost per acre of leveling land depends on a number of
factors, 7:io prinxpil 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 carryall ranges from about $8
to $15, depending on the size of tractor. The cost of leveling fields in the
Hastings area ranges from about $50 to $150 per acre.
Value of Land Leveling.- The effects of breaking hardpan and leveling land on
yield and quality of potatoes were determined in an experiment in 1956. The brown-
ish organic hardpan under the Leon soil was broken up with a bulldozer blade and
mixed thoroughly with the dark and light sandy topsoil in the area. 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, using 2,500 pounds
per acre of both seed and 6-8-8 fertilizer. Some plots were sidedressed 1, 2, or
3 times with 500 pounds per acre of 6-8-8. Artesian water was maintained in irri-
gation furrows adjacent to the plots from time of planting until just before harvest.
The potatoes were harvested on May 9, 1956, 108 days after planting. The total
yield in the leveled area was 338 and in the nonleveled 315 one-hundred pound sacks
per acre. The potato tubers grown in the leveled area were of better quality than
those grown in the nonlevelod 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 nonlovelod area. About one-half of this increased not income was
due to the improved quality of the potato crop and the other one-half to the in-
creased total yield of 23 sacks per acre in the leveled area.