DEVELOPING OF CENTER PIVOT IRRIGATION SYSTEM FOR CHEMICALS SPRAYING

Abstract

A simple pivot attached sprayer system (PASS) was designed tlu•ough National Agricultural Research "NARP" Project titled Improving tl1e Efficiency and Environmental Benefits of Fertigation/Chemigation on Field and Vegetable Crops with Sprinkler and Micro lnigation No. A 006. lt installed on a single­ tower center pivot inigation system. The spray boom was 40-m lengfu and 25 mm dia. The sprinkler risers were 8-mm dia. A variable space design is used. Three sizes ofthe micro sprinkler, spinner-type (0.81, 0.94 and 1.16 mm dia.) were selected. The spacing between sprinklers was vatied from 2.4 to 4.1 m. At 138 kPa sprinkler pressure and 900 liter I Feddan application rate, the PASS inlet pressure head was 20.6 m, and fue power requirement (without agitation) was 0.03 kW. A centrifugal pump (0.94 kW) has been used which had additional capacity and pressure (8.3 m3/lrr,4 bar) for hydraulic agitation atJd future applications that need more power requirements. At (69, 103, 138 and 172 kPa) sprinkler operating pressure, fue PASS average droplet size, along spray boom, was less fuatJ 400 J.lll1 and it might be classified as medium spray. The uniformity of the application profile was acceptable except near fue pivot point where the results indicated tl1at there was a need to change the size and spacing of the micro sprinklers near the pivot point to get less flow rate and more amounts of overlap to coincide with the travel velocity at fue region near fue pivot. The deposition distribution of fue PASS (qualitative examination) at 138 kPa sprinkler operating pressure and (75 and 100 em) height over the Faba bean canopy (the average length of 2 Faba been was 130 em and the plant density was 30 plants/m ) showed that the 75 em height of spray boom gave higher amount of deposits on the upper and lower surface and higher intensity ratio (in the order of 5.65: I) than I 00 em height of the spray boom.