One company is manufacturing a broadcast spreader with three hoppers so that nitrogen, phosphorus, and potassium are applied separately and the ratios can be varied. With the three-hopper broadcaster, a saving in cost of fertilizer should be expected by buying fertilizer materials in bulk quantities in concentrated form. Bulk truck spreaders have come into common use for applying complete fertilizers a method that requires less handling of the fertilizer materials and reduces costs of application. Compaction of soils under such large concentrated loads, however, is considered a potential problem in some areas. The use of fertilizer in liquid form may be found to be extremely efficient as far as ease of handling is concerned; a minimum of muscular exertion is needed when suitable equipment is provided for this fairly new form of fertilizer.

BETTER PROVISION has been made for cleaning equipment because much of the corrosion is caused by the fertilizer that remains in the machine after use. Many machines now have easily removable bottoms, agitators, and metering mechanisms. Some have hoppers that are removable or can be inverted for removing the residue of fertilizer and cleaning. Some are equipped with corrosion-proof plastic hoppers that are reinforced with fiberglass.

Many fertilizer distributors have positive metering devices that can dispense damp and lumpy fertilizers. Improved gage settings assist in making calibrations more accurately and with greater ease. Agitator parts are stronger, and the controls of fertilizer flow are being made sturdier and are adapted to manual and automatic operation.

Fertilizers of higher analysis have brought about a need for machines that apply them more uniformly and more accurately with respect to the seed or plant.

IMPROVEMENT IN THE PHYSICAL condition of solid fertilizers is reflected in the production of more granulated fertilizers, which cake and harden less during storage and can be distributed more easily and uniformly in the field. These free-flowing granular fertilizers continue to flow in many machines after the agitator or metering mechanism has stopped, however, and the hopper opening has to be closed in order to stop the flow of fertilizer. On many machines this is accomplished by closing the bottom of the hopper with the metering plate as the drive is thrown out of gear.

Another method is to have a second plate under the hopper; the plate closes the openings automatically when the drive is disengaged. This arrangement does not disturb the setting of the metering plate when operating in the field which is often quite important, as resetting an orifice-type opening is very sensitive, particularly at relatively low application rates of fertilization.

TO APPLY LIQUID fertilizers, new machines have come into use. Anhydrous ammonia requires equipment to withstand high pressures and soil depositors to place the material at least 6 inches deep. One high-pressure liquid applicator has rotating shafts in front of the knife-blade openers to open the soil for deposition. The device reduces draft and tends to disturb the soil less so as to have less chance of losing the nitrogen gas.

The mixed liquid fertilizers that contain nitrogen, phosphorus, and potassium may be applied on the surface without loss of plant food. They are more adaptable to close-growing crops when applications are delayed. They can be applied with field sprayers, particularly on pastures and small grains. The development of metering pumps and their use with dribble tubes has improved the ease of obtaining a uniform flow in the broadcast or row application.

The high-pressure metering piston pump has been adapted for low-pressure and nonpressure solutions. A metering hose pump, invented in the late 1930's, was further developed for its adaptation to the nitrogen fertilizer solutions and mixed liquid fertilizers. The refinement of the hose pump was accomplished by research engineers in cooperative research with the North Carolina Agricultural Experiment Station and the Agricultural Research Service of the Department of Agriculture. Through this cooperative research and subsequent field testing, this metering hose pump was made practical for farm use. The metering pump is now being made commercially for use on farms.

Compressors driven by tractor power takeoff are arranged on tractors to maintain constant tank pressure for low-pressure solutions which provides a simple and effective arrangement on many commercial liquid fertilizer applicators. However, the system requires steady forward travel in the field to maintain a uniform application, which is also a requirement of the gravity-flow systems and pump systems of the power takeoff type.

THE RESULTS of research in the application of fertilizer for most efficient use of nutrients has complicated the equipment requirements in some cases. An example in the complication of equipment is in the band seeding of hay lands and pasture crops. Crops in various sections respond differently to fertilizers, and machines have had to be designed with greater flexibility to meet the varied requirements. Attachments have been put on conventional corn planters so that the plant food can be placed to one side and below the seed; the placement can be adjusted conveniently by the operator.

Some planters also have a high and low position for fertilizer bands so that large amounts can be placed deeply and smaller amounts can be put at a more shallow depth as starters. One machine with such a dual-level arrangement has been made to plant row crops in either prepared seedbeds or in sod or stubble land.

Equipment is available for applying fertilizer to the lower soil zones at the time that the subsoiling operations are undertaken.

Several grassland machines have been put on the market for seeding and applying fertilizers on pastures or rough land without destroying the existing crop. Various arrangements of depositors to put seed and fertilizer at different depths are found on the different sod grassland drills and some may be adjusted to vary the amounts of soil left between seed and fertilizer.

The greater response to fertilizer and more efficient use of seeds for pasture and hay land by the band seeding method has brought demands for new machines to do band seeding. The heavy-duty grassland drills may be used for band seeding in prepared seedbeds, but other means are available through conversion kits for fertilizer-grain drills. Some machines for band seeding use the packer wheels of a corrugated land roller for press wheels. They plant the seed in rows, and the fertilizer is placed in bands below the seed.

PROBLEMS HAVE ARISEN in the wake of these changes. A great need is storage facilities on farms for liquid fertilizers and dry fertilizers in bulk. The future of some of the machines mentioned may depend on the solutions to the storage problems. There also has been a need for a single machine that dispenses granulated and pulverized fertilizers in a more satisfactory manner. Corrosion of metal parts has always beer, a problem with fertilizers, and in some instances it has been greatly intensified with some of the new materials in both dry and liquid fertilizers.