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<br />THE ZIMMERMAN FARM <br /> <br />The Colorado Water Conservation Board has completed the second <br />year's operation of a trickle irrigation demonstration on the Zimmerman <br />farm. The irrigation system is much the same as described in our <br />previous report to th~,Four Corners Regional Commission, who sponsored <br />part of the installation in 1973. <br /> <br />Two changes were incorporated in the system. One, a second 2 HP <br />pump was installed to overcome the head loss from the addition of a <br />water meter. Secondly, a 3-inch PVC syphon was installed to increase <br />the supply volume from the 2-inch pollyethelyne line used in the 1973 <br />season. (Note: The PVC was found to be too porous for use as a syphon <br />and was eventually replaced by a 3-inch suction hose.) <br /> <br />The system was operated daily to replace the water used by the trees. <br />Two tensiometers were placed one foot away from emitters and they were <br />kept just below the 20% saturation point. Line pressures were maintained <br />at 15 psi except for the upper side of the orchard, which was kept at <br />near 20 psi to compensate for line drainage. The upper end of the orchard <br />did not produce as well as expected in 1973, and because of the poorer <br />soil, it was decided to increase the water applied to that area by 10%. <br />Total water applied to the orchard was 1.3 AFjAC. <br /> <br />For the 1973 season the fertilizer had been' appl'ied by the operator <br />in the Fall of 1972. In 1974 we began to look at,the nutritional needs <br />of the plant by having a leaf analysis performed at the C.S.U. Austin <br />Station. ,The results showed that there was a deficiency in the uptake of <br />nitrogen. <br /> <br />N <br /> <br />P <br /> <br />K <br /> <br />Fe <br /> <br />Mn <br /> <br />Zn <br /> <br />Upper <br /> <br />2.03 <br /> <br />.080 <br /> <br />1.00 <br /> <br />56 <br /> <br />11 <br /> <br />16 <br /> <br />Lower <br /> <br />1.77 <br /> <br />.135 <br /> <br />1. 38 <br /> <br />55 <br /> <br />24 <br /> <br />18 <br /> <br />In the Fall of 1973, one half pound of nitrogen per tree was applied <br />through the system. We were at the point of adding another one half <br />pound of nitrogen per tree in the Spring of 1974 when the leaf samples <br />showed the nitrogen uptake of the trees to be in excess of the normal <br />amount. <br /> <br /> N P K Fe Mn Zn <br />Upper 4.70 .336 2.05 82 15 45 <br />Lower 4.76 .360 2.38 83 20 49 <br /> 1708 <br />