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  • Jan23Mon

    Early Available Phosphate & Critical Field Corn Growth Stages

    Field Notes January 23, 2017 Joe Pflum, Northeast US Sales Agronomist
    Filed Under:
    Starters, Agronomy, Field Notes

    Early Available Phosphate

    • Cold, wet soils release Phosphorus very slowly, even when soil tests indicate adequate amounts
    • The concentration of the orthophosphate in solution is important for potential diffusion
    • Placement of nutrients with the seed develops zones of higher orthophosphate concentration allowing greater uptake
    • Plants can only absorb phosphate in its Ortho form
    • Orthophosphate is immediately available for crop to use at germination
    • Absorption of nutrient ions is greatest near the actively growing tip of each root. Corn seedlings have a high demand for phosphorus
    • The concentration of phosphorus has to reach 0.5% in five-leaf corn, or the yield potential of that plant is reduced
    • To meet this P requirement, small roots need a concentrated source of P close to the seed

    Critical Field Corn Growth Stages

    Growth Stage
    Days after Emergence Growth Event Importance
    V3 9-12 Seminal roots, ear shoots Seedling vigor seen, ears established
    V5 14-21 Ear shoots complete Number of kernel rows established
    V6 25-30 Nodal root system established.  Rapid Growth Phase. Plants ability to take up nutrients is established
    V-14 50-60 Number of ovules determined Number of kernels per row determined
    R-1 63-70 Pollen shed begins.  Brace roots established.  Maximum root mass achieved. Kernel fertilization.  Develop ear weight. Kernel fill.