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Fluid Journal : Winter 2015
5 The Fluid Journal Winter 2015 Trials for the in-season applications were expanded to three pivots. Each pivot covered 120 acres and included treatments of 3-18-18 applied by aircraft. Applications of 6-24-6 were through center pivots and each was compared to the grower standard practice (GSP) where no additional Figure 1. Phosphorus recovery from in-season applications of NPK fluid fertilizer to irrigated alfalfa. Figure 2. Potassium uptake and recovery from in-season applications of NPK fluid fertilizer to irrigated alfalfa. nutrients were applied. Liquid NPK's were applied when the crop had a regrowth of 6 to 8 inches. Rates included 3, 5, and 5 gallons per acre for each of the respective cuttings. Each pivot was harvested with commercial swathers. Trucks were weighed with hay quality samples removed for quality analysis. In total there were about 600 trucks weighed and sampled, providing a very good evaluation of treatment responses. The main objective of the Simplot alfalfa is for it to be used as livestock feed. All was green-chopped with a moisture content of 65 percent. The 2013 trials indicated a very positive response to in- season NPK applications. Improvements in nutrient content of P and K were both remarkable (Figures 1 and 2). It is interesting to note the changes in tissue concentration and removal from relatively low applications for both P and K. Three times as much removal of these nutrients was observed compared to the application totals. While not shown in this article, there was an improvement in relative forage quality and it could be attributed directly to increased nutrient uptake as a result of these in-season low salt NPK fluid fertilizers being applied. Yields up Yield improvements were positive for both the 3-18-18 and the 6-24- 6. However, the applications applied through the center pivot tended to be higher. Improvements of yields were impressive with 6-24-6 providing over a 3 ton (@ 65% moisture) improvement over the grower standard practice of 20.5 tons compared to 23.3. Improvements with these types of applications for both years have encouraged the Cooperating Farm Managers to incorporate these applications into many of their alfalfa fields for the future. Observes Kent Frisch: "If we can consistently see these types of responses and the materials can improve our alfalfa production benefits-to-cost by at least 2:1, our alfalfa production will be seeing more of these applications." Our goals The J.R. Simplot Company continues to improve on nutrient management as it applies to both new products as well as a better understanding of how to use the nutrients we have. It should also be noted that improvements in Relative Feed Quality were also positively influenced and especially with the 3-18-18 applications. This may have been related to the higher concentration of tissue K that resulted from this particular NPK low- salt foliar application. The positive nature