Improved water distribution in the operation of pivot move agricultural irrigation sprinkler systems

Claim 1

In a method of distributing a source of water under pressure onto a field made up of soil having the capability of receiving water without appreciable surface run-off at a relatively high average application rate when relatively dry and at a relatively low application rate when relatively saturated with water with the use of a pivot move agricultural irrigation system including elongated conduit means for receiving a source of water under pressure at one end and conveying the water under pressure in a generally horizontal direction toward the opposite end thereof, a series of step-by-step rotary sprinkler heads spaced longitudinally along said conduit means in communicating relation therewith for distributing water under pressure within said conduit means incrementally onto the field in step-by-step rotary fashion within overlapping individual pattern areas defining a predetermined sprinkler head pattern area having first and second portions disposed on opposite sides of said conduit means, and means for supporting said conduit means above and generally parallel with the surface of the field and for effecting an arcuate movement of said conduit means about an axis adjacent said one end thereof in a direction toward said first pattern area portion along a predetermined circular path in the field while said conduit means is communicated with a source of water under pressure to distribute the same onto the field through said series of sprinkler heads within a predetermined system pattern area substantially greater than said predetermined sprinkler head pattern area by progressively moving the position of said predetermined sprinkler head pattern area within said predetermined system pattern area in said direction, the improvement which comprises the steps of operating at least a plurality of said series of sprinkler heads adjacent the opposite end portion of said conduit means so as to distribute the water under pressure within the longitudinally adjacent portion of said conduit means to the first pattern area portion covered thereby with an average application rate which is higher than the average application rate in said second portion covered thereby by a ratio of the order of between 1.3 to 1 and 4.0 to 1 and varying the application rate within the first pattern area portion covered thereby such that the distribution pattern increases rapidly adjacent the leading portion of the sprinkler head pattern area covered to an extent sufficient to insure that the maximum accumulated application rate is applied to the soil while in a relatively dry condition, thus minimizing the creation of appreciable surface run-off.