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Fluid Journal : Spring 2011
8 The Fluid Journal Spring 2011 acrerateof50lbsN,40lbsP,100lbs K, 20 lbs S, plus 1 lb B. The treatments totaled seven: 1. Check 2. 0-N, PKSB 3. N, 0-P, KSB 4. NP, 0-K, SB 5. NPK, 0-S, B 6. NPKS, 0-B 7. NPKSB We fertilized the research plots on April 14, 2008, a couple of days before the rest of the field received a fertilizer custom applied by Interior Seed and Fertilizer Ltd.'s floater applicator. We flagged the experimental site so it was not fertilized when the rest of the field was completed. We took forage yield samples off the research plots twice, one at the end of June before the rancher did a silage cut on the field and the other in the middle of September just before cattle were allowed to graze the field. The two-cut total forage yield results are shown in Table 2. The Table clearly shows there was a response to N. All other nutrients did not show as clear a response compared to the complete blend or the no-fertilizer treatment. Final analysis After the study was complete, we sent a Dr. Jensen is Northern Great Plains Director for the International Plant Nutrition Institute, Norcross, GA. Figure 1. Forage growth response to fertilizer on right compared to the zero-fertilizer plot on the left one month after application. Table 1. Soil test result of selected measurements and rating of nutrient availability, sampled fall 2006. Measurement pH % organic matter EC (salinity) N P KSB ----------------lb/A--------------- ppm Analysis result 7.2 5.4 0.5 14 23230632 Soil level rating normal normal non-saline deficient marginal adequate Table 2. Two-cut total forage yields from fertilizer response trial, 1998. Treatment Nutrient applied Yield-tons/A 7 NPKSB 4.40 4 NP, 0-K, SB 4.18 6 NPKS, 0-B 4.13 3 N, 0-P, KSB 3.98 5 NPK, 0-S, B 3.93 2 O-N, PKSB 3.72 1 Check 2.93 final report to the customer. In that report, we could definitely conclude that there was a response to fertilizer. We felt we had "showed him" there was benefit from using fertilizer (see example in Figure 1). When we considered the regular 40 lbsN,30lbsP,40lbsK,and15lbsS/A application he used, there was excellent response to N. We suggested that he consider continuing the PKS applications just to maintain their availability for future crops. We recommended from our research that he not add B but that he should continue to monitor his soil by having soil samples analyzed regularly. We wouldn't recommend running this type of trial for every customer who questioned whether or not they are getting a response to fertilizer. Costs. I did a rough comparison of the cost of conducting this trial compared to just relying on regular soil testing to basically come up with the same recommendation. A soil sampling, soil analysis, and recommendation performed by a retail fertilizer dealer probably costs around $300, if you consider retail staff time involved, equipment, and laboratory analysis charges. The field trial we conducted cost close to $3,000 when all my time, Interior Seed and Fertilizer's time, and a research technician's time was taken into account, plus travel costs taking research equipment to the ranch. So, in this case, it cost ten times as much to conduct a "show me" field demonstration. Fortunately, there has been past investment in regional fertilizer trials in most agricultural regions that we can refer to in order to estimate the yield response for most crops from added nutrients. Based on this, I would conclude that the soil testing and recommendation system we have available to us is very cost effective. "We showed him the benefit of using fertilizer." "We conclude our recommendation system is cost effective."
Early Spring 2011