As is well-known, in recent years irrigation of meadows, pastures and other fields using self-propelled irrigators, which typically comprise a long radial arm rotating about a center post on a plurality of wheels has become common, particularly in the flatter parts of the United States. Most of the irrigators of which the present inventor are aware are designed to be operated using heavy watering for a period of some hours moving fairly fast around a field, sometimes making four or more revolutions per 24 hour period. After this heavy watering is completed, the irrigator may not be used again for a period of a week or more. Heavy watering requires extremely high water pressures and delivery rates. Typically, high pressures are used to spray the irrigation water far from the pipe carrying the water from the central post to the various regions of the field. Use of high water pressures requires that the piping and accompanying irrigator structure must be very heavily constructed normally 10 to 15 feet above the ground, and hence expensive to build and to operate. Furthermore, spraying of the water under high pressures, as in the prior art, means that the water is very finely dispersed in the air, whence it is very much more subject to evaporation, especially in the hot dry climate of the Southwest, than if it were more gently dispersed, e.g. in the form of droplets or trickles falling from a pipe nearer the ground.
Accordingly, it is an object of the invention to provide a moving irrigator system in which the water is not sprayed in the air, but instead is dripped or trickled gently onto the earth from a slowly moving radial arm, so as to reduce losses due to evaporation in the air and therefore to require smaller volumes of water for irrigation.
It is also an object of the invention to provide an irrigator which will disperse an amount of water on to the ground comparable to the prior art practices, but which will move the arm at a slower pace, continuously or near continuously. In this way, a very light irrigation is provided regularly, for example, daily. This will provide adequate moisture for the crop being grown, and will not have the disadvantages that the crop will become too dry before irrigation is begun again, as is typically the case with present irrigators.
Thus, by dispersing controlled amounts of water from the arm to the ground, each individual square foot of land receives an equal amount of water as the radial arm passes around the field.
Those skilled in the art of raising animals for market, particularly beef cattle, will realize that the tendency of the animals is to concentrate in one part of a pasture until the food supply in that area has been totally consumed, or the plants have been destroyed by the animals laying on them. Frequently, the animals will eat so heavily that the plants themselves will be destroyed. Therefore, even if they then move onto another area of the pasture, the area where they have been will not recover adequately; and their tendency is to return to the area and consume whatever new growth there is, further damaging the plant life. The prior art has addressed this problem by dividing pastures into a number of different, smaller areas and driving the animals from one to another from time to time. However, even this is not as efficient as would be desirable, because there will always tend to be some parts of each individual portion of the pasture where the animals will tend to confine their heaviest grazing, make trails, lay down repeatedly, and establish manure areas. Accordingly, the prior art has recognized the utility of providing a movable fence which can be used, in effect, to define a movable pasture. See, for example, U.S. Pat. No. 4,341,181 to Fair, which shows a corral which follows a track. However, the device shown in the Fair patent requires that an operator lay out a track for its movement, which is inefficient of manpower. The art requires an automatic apparatus defining a pasture which keeps the animals moving in a prescribed pattern which will ensure relatively even grazing, which does not require an operator to be present, and which will provide an undisturbed regrowth period before an area is again grazed.
It is accordingly an object of the invention to provide an apparatus for ensuring that cattle graze a pasture uniformly and substantially continuously such that maximum utilization is made of the pasture, which does not require an operator's continued or frequent presence, and which provides a regrowth period without animal traffic.
Provision of uniform grazing according to the invention also solves another problem recognized by the prior art, that of disposition of manure. Uniform grazing ensures that the disposition of manure over a field is substantially even. By the time the animals return to a particular area of the pasture enough time will have passed that the manure will have substantially decomposed and become useful fertilizer as well, a further aid in obtaining maximum productivity from the land.
As mentioned above, prior art automatic irrigation systems have tended to be constructed very heavily due to the large amounts of water at relatively high pressures which they must disperse.
It is an object of the present invention to provide an automatic irrigation system which is not required to disperse high volumes of water at high pressure and which can, therefore, be built inexpensively and utilized at low cost.
It is a further object of the invention to combine such an irrigation system with a system for automatic management of the movement of a herd through a pasture, as described above, such that maximum economy can be realized simultaneously with maximum efficiency of use of energy, water, and land.
It is therefore the ultimate object of the invention to provide a combination herd management and irrigation apparatus which will be simple and relatively inexpensive to construct, which will be durable in operation, which will cause a herd of grazing cattle to move progressively through a defined path in a pasture so that the same areas of the pasture are not revisited before the plant life has had time to regrow, and wherein irrigation is performed in the most efficient possible manner, all so as to ensure maximum efficiency of use of energy, of water, and of land. Desirably, the apparatus should permit either function, irrigation and livestock herding, to be performed without the other.