Center pivot irrigation system having apparatus for irrigating corners

In a center pivot irrigation system having a main pipeline sprinkler rotatable about a center for supplying a generally circular area with irrigating fluid, and having an auxiliary nozzle rotatably carried by the main pipeline sprinkler for irrigating corner regions, the improvement comprising means responsive to irrigating fluid pressure in the main pipeline sprinkler for operating the auxiliary nozzle to discharge irrigating fluid therethrough upon the occurrence of the conditions that

• (1) the main pipeline sprinkler is substantially non-rotating;
• (2) the main pipeline sprinkler has substantially ceased discharging irrigating fluid;
• and
• (3) pressure in the main pipeline sprinkler has increased to a selected value, indicative that the main pipeline sprinkler has substantially ceased discharging the irrigating fluid.

In a center pivot irrigation system having a main pipeline sprinkler rotatable about a center for irrigating a generally circular area with irrigating fluid, and having an auxiliary nozzle rotatably carried by the main pipeline sprinkler for irrigating corner regions, the improved method of operating the system comprising the steps of

• (a) substantially stopping rotation of the main pipeline sprinkler;
• (b) substantially stopping discharge of the irrigating fluid from the main pipeline sprinkler when its rotation has stopped;
• (c) detecting the pressure of the irrigating fluid in the main pipeline sprinkler;
• (d) enabling operation of the auxiliary nozzle when the irrigating fluid pressure in the main pipeline sprinkler has increased to a selected value indicating that said step of substantially stopping discharge has been effected;
• and
• (e) irrigating from the auxiliary nozzle upon the completion of steps a-d.

A center pivot irrigation system adapted to provide corner irrigation comprising:

• (a) a main pipeline sprinkler rotatable about a center and having a plurality of main fluid discharge nozzles spaced therealong for controllably providing fluid to a central, generally circular area;
• (b) a drive mechanism for rotating the main pipeline sprinkler at a substantially constant first rate for irrigating areas corresponding to non-corner orientations, and at an intermittent rate for irrigating areas corresponding to corner orientations, the intermittent rate defined in part by a zero rate period during which the main pipeline sprinkler is substantially at rest;
• (c) an auxiliary sprinkler, including at least one rotatably mounted auxiliary nozzle disposed substantially at the end of the main pipeline sprinkler, for irrigating said corner areas substantially only during said zero rate periods;
• and
• (d) fail-safe means for disabling the operation of the auxiliary sprinkler and resuming operation of the main pipeline sprinkler upon malfunction of the auxiliary sprinkler.