MSU is working with local producers to increasing efficiency of the irrigation systems by improving scheduling and system uniformity thus increasing the product yield per unit of water used. Approximatley 80% of irriagtion water used is applied with center pivots.
An MSU report "Field Evaluation of Center Pivot Sprinkler Irrigation Systems In Michigan" is now available. Recomenations from the report is provided below.
1) Evaluation test should always be done in open area and catch cans should be far from the canopy of the crop as shown in Figures 4 and 6.
2) Following ASAE S436.1standard it is suggested to run systems when winds are low, preferably less than 5 mph and no greater than 11 mph.
3) Regular system maintenance is necessary including repair, adjustment or modification to keep the system operated efficiently. If CUs are periodically measured (at least annually) system repairs and adjustments can be scheduled when coefficients fall below the desired values. This will save operation costs and conserve water.
4) Water pressure should be tested at the sprinkler outlet to ensure that each sprinkler operates at the design pressure especially sprinkler(s) which give low or high volume caught in catch cups, which affects the overall DU and CU.
5) Low uniformities in the center pivot system have compounding negative effects when nitrogen is applied. Therefore, any major leaks and poor end gun performance need to be fixed or adjusted to insure the highest uniformity possible.
System Improvement for a Uniform Distribution
6) Location of the pivot according to the field topography and time of operating end gun should be considered.
7) The depth applied, timer setting and time of revolution should be set according to the manufacturer information book, otherwise consultation from the manufacturer is necessary.
8) Regular measuring system flow rate by accurate and modern flow meter is advised. As a water management tool this helps reduce water costs, prevent over irrigation and reduces leaching of chemicals and fertilizers into the ground.
9) Using available new technology can improve system performance.
10) Using rotating spray sprinklers is advised. Rotating spray types provides the widest throw distance, is closest to matching infiltration rates of the soil and reduces water surface runoff.
11) Drop down nozzles proved to distribute water evenly. This type of sprays would be recommended where the nozzles do not enter the crop canopy because water distribution is severely decreased once this occurs.
12) Operating of the pressure regulation for all sprays should be checked and replaced when needed.
The University of Nebraska-Lincoln has recently completed a Center Pivot Water Conservation Project. The web site for this project provids a wealth of information on center pivots.