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Fluid Journal : Fluid Journal 1996-1998
2 Fluid Journal Winter 1997 Figure 3. Average corn yields in a five-year comparison study of strip versus broadcast, Barber, Purdue University. Figure 2. Corn yield response to strip versus broadcast of a 4-10- 10 fluid fertilizer, Wanatah, IN, Barber, Purdue University. Lbs/A of 4-10-10 Check 120 124 128 132 136 140 144 Yield - bu/A 500 1,000 Placement method Broadcast 120 122 124 126 128 130 Yield Soil Test 132 Yield - bu/A Soil Test Reading Strip Broadcast Strip 20 24 28 32 36 40 44 with a large volume of soil to reasonably supply all roots. Where plants are younger and uptake is faster, an even higher concentration near roots may stimulate additional growth. React with soil The only reason to band apply phosphate or potassium rather than broadcast and mix with the plow layer is that either can be fixed into unavailable forms by reaction with the soil. When broadcasting, these nutrients are essentially contacting all of the soil. By applying as a band, less fertilizer soil contact occurs and less fixation occurs. An additional benefit of some localization is to provide a higher fertility level when plants are young. Though soil fixation is reduced by banding, it also results in these two fertilizers being mixed with only two or three percent of the soil. Hence, too few roots are contacted for the fertilizers to be effective. An intermediate placement between these two extremes that has proved more effective, and is the focus of our research, is something we call strip placement. Bumps yields In order to get fertilizer mixed with only 10 to 20 percent of the soil in our experiments, strips of fertilizer three to four inches wide were applied at 28- to 30-inch intervals on the surface of the soil before fall plowing. During plowing, the strips were mixed with a portion of the soil. It was not a uniform mix and degree of mixing depended on conditions during plowing. Strip treatments were compared with broadcast applications. Our approach was to develop ways of applying fluids in the least quantities required to attain high yields. The smallest amount this could be, without mining the soil, waste replace exactly what was removed by the crop harvested. Location of one of the experiments we'll cite in this report was Wanatah in northern Indiana. Soil was a sandy loam. Fertilizer source selected to investigate the influence of placement was a 4-10-10 fluid. As can be seen in Figure 2, strip placement was superior to broadcast. At another site where we conducted experiments for five years, average yields reported were as shown in Figure 3. At this site, soils were also sampled. Test results showed that strip treatments produced the highest average soil test. The results of our fertilizer experiments have supported the general principles already discussed. Using an intermediate degree of mixing, accomplished via strip treatments, has proven the more efficient placement. Fertilizer reaches a greater proportion of the root system and is not tied up as much by the soil as occurs with broadcast applications. The use of strip treatments, versus the extremes of banding and broadcasting, is definitely worth considering in the pursuit of getting greater yield responses from applied fluids. Timing of fertilizer application is very important for the nitrogen part of fluid fertilizers. Timing is not as important for phosphate and potassium, whereas placement is more important. Placement is not nearly as important for nitrogen because it can move through the soil and be available to the plant as long as it is in moist soil and not on the dry surface. Dr. Barber is professor emeritus at Purdue University.
Fluid Journal 1993-1995
Fluid Journal 1999-2001