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Fluid Journal : Fluid Journal 1999-2001
Summer 1999 significant (data not shown). In addition, split N applications or the interactions between tillage, method, and split N application had minimal effects on growth or nutrient uptake at the three measured growth stages. Placement. The highly significant and uniformly consistent response to fertilizer treatments was due to placement method and to fertilization in general. Dry matter accumulation from the nine-leaf to soft dough stage of growth suggested that the plants grew slowly at first and then more rapidly to soft dough (data not shown). At the nine-leaf stage, knife placement of the NPK suspension resulted in greater dry matter than either surface placement or the check. This difference became more pronounced during the season. Growth rates with surface placement methods did not appear to reach a maximum until 88 days after planting (Figure 3). However, knife placement appeared to result in maximum growth rate by 74 days after planting. Figure 2. Grain sorghum yield component responses to suspension fertilizer application methods, Sweeney, Kansas State University. 1,800 1,700 1,600 1,500 1,400 1,300 1,200 1,100 Check Broadcast Dribble Knife Check Broadcast Dribble Knife 70,000 65,000 60,000 55,000 50,000 45,000 40,000 35,000 Kernels/head Kernels/head Stand--heads/A Heads/A Figure 1. Grain sorghum yield response to tillage and suspension fertilizer application methods, two-year average, Sweeney, Kansas State University. 100 90 80 70 60 50 40 Check Broadcast Dribble Knife Yield-bu/A Reduced-till Ridge-till No-till Figure 3. Rate of sorghum dry matter accumulation in response to NPK suspension application methods, Sweeney, Kansas State University. 240 200 160 120 80 ! ! ! 9-Leaf Boot Soft Dough 3240485664728088 Days after Planting Knife Dribble Broadcast Check Growth Rate (dry matter), lbs/A/day
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