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III. Developments in Planting Equipment

III. Developments in Planting Equipment

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from pull-behind units to flexible, high-speed, tractor-mounted units,

greater interchangeability of parts, and improved adjustments and controls that permit more precise operation at higher speeds.



The factor of precision is becoming increasingly important. Uniformity

in the depth of seed placement is essential if uniform germination is to

be achieved. Uniformity of plant spacing, while not a critical factor from

the standpoint of crop yield, is important in mechanical harvesting to

assure an even flow of crop material into the harvester. The effectiveness

of mechanical thinners is also dependent upon uniform planting, just as

high-speed mechanical, flame and chemical weed-control practices depend on such uniformity of plant position.

There has been a significant trend toward the use of bigger multiple

planting units. Four- and six-row units (Fig. 4 ) are rapidly replacing

FIG.4. A six-row planter equipped to apply liquid fertilizer and granular insect

and weed-control chemicals. (Courtesy of the International Harvester Co. )

two-row equipment. Where land smoothing and conditioning is practiced

this trend has been most rapid. Similar trends are occurring in grain drills,

both through use of additional furrow openers and through the use of

multiple units operating on one hitch. This increased use of multiple

planting units has created several related machine-design problems.

When planting is done in multiple units the cultivation equipment must



be designed on the same basis to insure proper alignment. Equipment

for side dressing, weed and insect control sprays, and other follow-up

management practices must be adapted to the same multiples as the

planters. With the increased length to which the tool carriers must be

extended to accommodate these multiple units a problem in suspension

develops. Provision must be made to carry heavy seed and fertilizer

hoppers without causing changes in the depth adjustment of the planter

as the weight changes with dispersal of their contents. In four- and

particularly six-row equipment, provision should be made for individual

suspension of the planting units to permit them to follow irregularities

in the contours without affecting the planting depths. Provision for folding

or otherwise retracting these long tool carriers is essential to provide for

roadability and to facilitate passing through gates and into storage sheds.

Precision placement of seed in the planting furrow has been the goal

of agronomists and engineers alike. During recent years the intensive

cotton mechanization research program has focused major attention on

cotton-planting equipment. Studies to determine the relative importance

of various planting techniques and spacings have been reported by Corley

et al. ( 1955),Hudspeth and Jones ( 1954), Miller ( 1955a,b), and Colwick

(1955). The importance of using hill-drop cotton planters on heavy soils

is stressed by Miller (1955a,b). His studies showed that, where several

seeds germinated close together, they could, by combined effort, emerge

under more serious crusting conditions than would be possible under

single-drop plantings. Closer spacing, three to five plants per foot, gives

better vegetative growth control, grass and weed control through shading

and improves harvester efficiency. Autry and Schroeder (1953) have

made detailed studies of the design factors for hill-drop planters resulting

in new concepts on cell shape, plate speed, plate-to-ground speed ratio

and in tube design. The simple matter of shortening the tube length has

resulted in more accurate seed drop and placement, according to

Porterfield et aZ. (1954). There has been a complete redesign of the

planter shoe and seed-covering devices to achieve precise control of

seed depth and depth of seed cover. The development of the seed press

wheel has been traced by Miller (1955a). While this device was first

used as early as 1925, it did not come into prominent use until the steel

rim was replaced by the zero-pressure, hollow rubber tire in the early

1950's. Its use and application is described by Tavernetti and Miller

( 1954) ( see Fig. 5).

The seed press wheel principle is becoming more important on a

number of other planters where seed germination is critically dependent

upon intimate seed-soil contact. This contact permits quicker moisture



pick-up giving earlier germination and emergence. This permits shallower

planting and helps to combat crusting problems.

Interchangeable hoppers, agitators, plates, and speed-control gears

have made the modern planter extremely versatile; one basic planter

meets all of the farmer’s needs. Each design improvement-sometimes insi@cant when viewed alone-has contributed to the present-day planter

capable of accurate and reliable seed placement at speeds of over 4

miles per hour. Taken in total, this is a major break-through in improving

farm operation efficiency.

FIG.5. Detail of planter-shoe equipped with soft rubber-tired seed press wheel.

( Courtesy of the International Harvester Co. )

The application of fertilizer as a part of the planting operation has

become a universal practice. Here, as with planters, the progress in

development has been the result of many minor steps. The engineering

problems in fertilizer placement have been summarized by Walker

(1957). He pointed out that on early models, placement of the fertilizer

has been haphazard; the split boot roughly divided the application into

two bands that were approximately level and theoretically to the side of

the seed. As agronomists unraveled the feeding habits of seedlings and

plants, the importance of precise fertilizer placement was established.

Special fertilizer-disk openers, equipped with tapered prelubricated roller

bearings, now give a positive furrow for fertilizer placement at any depth

or distance relative to the seed that may be desired.

Nearly all planters can be modified to use either dry or liquid

fertilizer. Positive valves are designed to open and close automatically as

the planter is raised and lowered from the carrying and planting positions.

The fertilizer hoppers have changed. On early planters the fertilizer



hopper’s capacity was about equal to the capacity of the seed hopper.

Higher rates of application, longer rows and higher speeds gradually

forced redesign; hoppers of one and two hundred-pound capacity thus

becoming common. Their sharp angular designs are being replaced by

smooth one-piece construction. Glass-fiber reinforced plastic hoppers

are rapidly replacing metal units. This is a major development in meeting

the corrosion problem, Plastic coating of other portions of the fertilizerplacement equipment and use of reinforced cast plastic components, while

still in the research and development stage, promise further advances.

(Fig. 6 ) .

FIG.6. Multiple row planter equipped with large plastic hoppers for dry-fertilizer

application and special hoppers for adding other soil treatment materials. (Courtesy

of the International Harvester Co.)

The introduction of many new forms of fertilizer has forced other

developments. Merrill (1956) and Guelle (1954) have provided a general

review of these developments. The safe and accurate transfer and

metering of materials such as anhydrous ammonia has necessitated the

development of a whole array of transfer systems, metering devices, and

injection equipment. Hedman and Turner (1954) reported on the early

developments in direct-injection metering systems, variable orifices, and

on the use of the ratometer to indicate rate of flow for anhydrous ammonia. After several additional years of research, Hansen (1958) made an

exhaustive report on the engineering principles involved in handling

liquid materials. The multiple-discharge hose-type fertilizer pump, described by Gantt (1956) and Gantt et al. (1956), was made possible by

the introduction of improved bearing designs and the development of

plastic hose material that could stand up against constant flexing.

Devices and schemes for actual placement of fertilizer in the soil

with minimum waste and loss continues to be a challenge, A unique

suggestion has been made by Arya and Pickard (1958). They suggest



direct injection in which the kinetic energy of the material is substituted

for the tractor energy now used to force the injection knives through

the soil. This is an example of how far reaching the application of sound

engineering principles may be in the design of agricultural machinery.

In the continuing trend toward unitized operations the applications

of insecticides, fungicides, nematicides, and herbicides are rapidly being

combined with the planting operation. An array of tanks, pumps, valves,

sprays, and injectors are being added to planting units. While each item

added requires additional power, it does reduce the number of trips

over a field and thus reduces labor output.


Equipment for planting and fertilizing those crops commonly grown

in narrow-spaced rows or drills has been modernized in the same way

that row planters have been changed, Seed-metering devices have been

improved to give positive seed spacing. Both single and double-disk

openers, equipped with dust-tight prelubricated bearings, cut through

trash and clods to give precise depth placement. Fertilizer, formerly

loosely broadcast on the surface, is now drilled into the soil at an exact

distance to the side and at a predetermined depth below the seed. Carefully designed covering blades have replaced the chain-type covers, and

press wheels firm the soil around the seed. Both the grain and fertilizer

hoppers have been enlarged, treated to prevent corrosion, and equipped

with positive-action agitators.

There is a strong trend toward the use of tractor-mounted drill equipment. Buhr (1955) notes that a mounted drill can plant a daily acreage

equivalent to that of a 25 per cent larger drill towed on wheels. This

increased production is due to faster field travel, more rapid turns on

headlands, easier loading since the drill can be readily backed up to a

truck, and smoother fields due to self-elimination of tractor wheel tracks.

Each small change has had a significant bearing on the improvement

of farm efficiency. More rapid and timely planting with improved percentages of germination is vital in modern farm operations.

Aside from these general machine changes there have been some

significant changes in the uses being made of drill equipment. The interseeding of legumes and grasses in corn at the last cultivation, as

reported by Van Doren and Hays (1958) has been an important conservation and crop-management development. When interseeding is

practiced the corn rows are generally spaced 60 to 80 inches apart to

reduce shading and moisture competition for the interseeded crop. Since

moisture may be limited at time of seeding, it is important that the soil

be firmly packed around the seed. Two machines that have been found



successful are a conventional grain drill with packer wheels attached

and the cultipacker seeder. Drills have been modified by removing one

or two openers to permit straddling the corn rows or by cutting off part

of the machine to reduce the drill width. Specifically designed drills for

interseeding are appearing on the market. Johnson (1955) and Peterson

( 1955) describe many of the machine modifications in detail (Fig. 7).

FIG.7. Interseeding alfalfa in corn up to 40 inches in height. Fenders protect

corn plants. Fertilizer is applied in bands directly in front of tubes delivering legume

seeds to the soil surface. Legume seed is broadcast directly in the corn row. Pressure

on packer wheels may be adjusted to suit soil conditions. A mounted grain drill may

be modified to provide a similar unit. (Courtesy of the Allis Chalmers Manufacturing Company.)

The seeding of small grains in permanent pasture to provide supplementary winter grazing has become another important new management practice, particularly in the South. This practice resulted in the

development of a number of multiple-use drills designed to operate in

heavy pasture sods where conventional drills would have been unable

to provide an adequate seed furrow and proper fertilization and seed

coverage. Early studies on the design of the machines are reported by



Jones et al. (1951), Dudley and Wise (1953), and Howell and Jones

(1954). Particular attention has been given to the development of this

machine by Hulburt (1956), Wagner and Hulburt (1953), and U. S.

Dept. Agr. ( 1956a).

With growing use of rough, cloddy, and trashy fallows for wind and

water-erosion protection throughout the West, new drills have been

developed to operate under these severe conditions. Many of these machines are essentially standard drills that have been made heavier and

equipped with larger disk openers, One unique machine that has been

developed at several western locations is the blade-type drill. A hollow

horizontal blade (similar to a blade weeder) is drawn through the soil

at planting depth, a moving chain conveys the seed down a tube and

meters it out along the trailing edge of the blade. Krall (1951) reports

that while many refinements are needed to improve uniformity of seed

metering and to reduce seed damage, this drill operates very well under

extreme trash conditions (over 2000 pounds per acre) where conventional drills will clog.


The use of aircraft for seeding and fertilizing rough hilly areas and

wet areas has advanced tremendously in recent years. The first rice seeding by plane was reported in California in 1929, when it was necessary

to replant areas that had already been flooded. Most of the rice acreage

in this country is now seeded by plane, Southwell (1951) describes the

use of planes for seeding burned and cut-over pasture and range land

that is too rough for conventional drills. Pelleted seed has been found

effective in this work.

Much attention has been given to the development of special planes

for this work. High payload capacity with maximum maneuverability is

a major objective. Weick (1952) and Anonymous (1956a) trace the

development of specialized airplane equipment both here and in England. With further refinements in seed-pelleting techniques and in improved equipment, this type of seeding and fertilization will gain in

importance. The spreading of over 450,000 tons of fertilizer on approximately 4 million acres by plane during 1957-1958 in New Zealand

(Anonymous, 1958) is an important indication of this trend.

A comprehensive discussion of planting and fertilizer-placement

equipment would be too extensive for this report. Each specialty crop

has certain planter requirements that result in the development of special equipment. For example, Futral and Allen (1951) describe a special high-speed peanut planter that uses a perforated belt with sized

holes to pick up, convey, and then “throw” the seeds to the ground. The



development of graded and later monosperm sugar beet seeds required

the design of special planting equipment in this industry. Burgesser

(1950)points out that the use of coated and pelleted seeds will require

a complete new study of planter design to assure proper metering, placement, and covering. Descriptions of these special planter developments

can best be found in the literature pertaining to the individual crop

under study.

IV. Developments in Cultivating Equipment

Cultivation of crops generally refers to those tillage operations that

are carried out after the seed has been planted. Weed control is the

major objective of cultivation but in some areas, particularly where irrigation is practiced, it is intended to loosen the soil, thus improving

infiltration. While the actual cultivators themselves have changed little,

the ways in which they are mounted, powered, adjusted, and managed

have been modified. The chemical and flame control of weeds have

further modified the entire cultivation program.



It is pointed out by Bainer et al. (1955) that nearly all present-day

cultivators are tractor mounted. The tricycle-type tractor with high clearance and adjustable rear-wheel tread has become the primary base for

cultivating equipment. Small tractors with rear-mounted engines to provide maximum visibility have been adopted to carry cultivators for

vegetable crops where extremely close and precise tillage is required.

Some improvements have been made in the methods of mounting

cultivators on the tractor frame. While front-mounted units are preferred

because of better visibility and more responsive control from steering,

rear-mounted units still have certain advantages. Quick coupling on the

drawbar links and the fact that they may be set to partially remove the

compaction effects of the tractor wheels, are important considerations.

There is still serious need for simplification in mountings and in adjustment. This becomes more important as the number of row units increases

to four-, six-, and even eight-row outfits. Quick interchange is desired

for the many different cultivator tooth designs.

The advances in metallurgy and in heat treatment have made possible the development of cultivator teeth that have much longer life

through resistance to shock and abrasion. Williamson (1955)points out

that sweeps of thin, broad-angle, low-crown design provide excellent

weed cutting with a minimum of soil throwing even at high speeds. Only



3/16 inch thick, they are self-sharpening and can be used without other

care until worn out.

Hydraulic controls have replaced nearly all of the mechanical lift

equipment. Double-acting cylinders permit positive penetration under

hard-ground conditions. In some instances the units on each side of the

tractor can be lifted or lowered independently. This provides a great

advantage when cultivating along grass waterways, variable-width contour strips, and terraces. In tractors equipped with both front- and rearmounted units, delayed-action valves are being used to permit the rear

gang to stay in the soil until they have moved forward to the field edge,

where the front gang was raised.

There have been many modifications in plant-shield design. Rotary

shields and floating self-adjusting stationary shields permit much closer

operation to the row. To improve this further, one company has developed an electronic control mechanism that automatically senses the

position of the cultivator in relation to the plant and then transmits this

to an automatic power-steering mechanism. This system virtually eliminates the hazards of human error in guiding the tractor in close-cultivation work.

The rotary hoe, and a number of its modifications, has been in use

for many years, Recent improvements in design and construction has

placed new emphasis upon its use. A major design change has been the

sectional and individual suspension of the spiders in place of the single,

rigid axle mounting. This has resulted in maximum flexibility, allowing

the unit to conform to surface irregularities, and thus doing away with

the problem of excessive depth of penetration on high spots and weeds

left in depressions. Rea (1954) has shown that excellent results can be

obtained with such equipment at speeds up to 18 miles per hour. R. W.

Wilson (1956b) has also shown that this equipment has considerable

promise in early cultivation of tobacco.

Sectional units consisting of three or four rotary-hoe wheels have

been mounted on conventional planters directly over the crop row in

order to break crusts and dislodge small weeds that could not be reached

with conventional cultivating attachments. Rotary cultivating units, in

which the row middles are stirred by units driven from the power takeoff that have various-shaped knives and blades mounted parallel to the

axis of rotation, have been developed for cultivating special crops. The

degree of soil pulverization can be controlled by adjusting the relative

speed of rotation to the rate of forward travel.

There is continued effort to find better ways of controlling weed

growth in the row where it is difficult to reach without injuring the crop.

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III. Developments in Planting Equipment

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