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Fluid Journal : Fluid Journal 1993-1995
1 Fluid Journal Winter 1994 by Drs. D.D. Francis, J.W. Doran, R.D. Lohry Nitrific ation Inhibitor in Fl uid Star Nitrific ation Inhibitor in Fl uid Star Nitrific ation Inhibitor in Fluid Star Nitrific ation Inhibitor in Fluid Star Nitrific ation Inhibitor in Fluid Starters ters ters ters ters Improves Corn N Uptak Improves Corn N Uptak Improves Corn N Uptak Improves Corn N Uptak Improves Corn N Uptake ee ee Nebraska research also shows increased microbial immobilization of N. Summary: Efficient use of starter fertil- izer N by young corn plants is depen- dent upon keeping N positionally avail- able. Nitrate-N can be readily leached out of the rooting zone of permeable soils before it can be used by young plants, although it may be recovered later by older plants. For soils used in this study, nitrifica-tion of NH4 (ammonium), fol- lowed by leaching, lowered corn N up- take more than microbial immobiliza- tion. A nitrification inhibitor (dicyandi- amide or DCD in this study) signifi- cantly increased corn N uptake and mi- crobial immobilization of ammonium. This is probably due to DCD maintain- ing more starter N in the ammonium form, which in turn maintains positional availability of starter N for young corn plants. Under moderate leaching condi- tions, it may be advantageous to add a nitrification inhibitor to starters to en- sure that N remains positionally avail- able to young corn plants. he question of which form of N (ammonium or nitrate) to supply to corn plants at specific growth stages is an interesting one. A theoretical advantage of NH4-N is that energy would not have to be expend-ed in reducing NO3-N for assimilation in the developing plant. NH4-N is also more likely to enhance uptake of P in young corn plants. Disadvantages of NH4-N in starters T Figure 1. Percent uptake by corn of tagged N applied in a starter, Janude sandy loam and Hord silt loam, Francis, et al. , Unversity of Nebraska. % Uptake of Tagged N 80 70 60 50 40 30 20 10 Tagged Nitrate Tagged Ammonium Growth Stage V3 V8 V3 V8 V3 V8 * DCD Added Year 2 Year 1 Figure 2. Percent of tagged N recovered in top 12 inches of soil at V3 sampling date, Janude sandy loam and Hord silt loam, Francis, et al., Unversity of Nebraska. % Tagged N 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 Tagged Nitrate Tagged Ammonium Tagged Nitrate Tagged Ammonium Tagged Nitrate* Tagged Ammonium* 0-2 inches 2-5 inches 5-12 inches * DCD Added Soil Depth Year 2 Year 1
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