Concentrations of N and P in Young Corn Plants, as Affected by Various Growth‐limiting Factors1

Abstract

AbstractYields and concentrations of N and P were studied in young corn (Zea mays L.) plants as a basis for correct interpretation of plant analysis results. The corn was grown on soils deficient in these nutrients in several greenhouse pot experiments comparing rate, source, and placement of N or P. Results from such pot experiments were satisfactory for establishing minimum and critical nutrient concentrations in corn if various growth‐limiting factors were properly corrected. These included age of plant, application rates of one or more deficient nutrients, and adequacy of other yield‐limiting factors, including liming and other nutrients.The minimum concentrations of total N or of P in corn forage appear to be rather constant for a given age of plant and can be more accurately estimated than critical concentrations can. The results suggest the estimation of critical values from the minimum concentrations.C‐type curves resulting from plots of dry matter yield vs nutrient concentration could be explained largely by dilution resulting from growth response to application of a second deficient nutrient.