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Comparative Reduction of Calcium and Magnesium Composition of Corn Tissue by NH4‐N and K Fertilization 1
Author(s) -
Claassen Maria Elena,
Wilcox G. E.
Publication year - 1974
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1974.00021962006600040013x
Subject(s) - loam , chemistry , soil water , human fertilization , agronomy , zoology , fertilizer , nutrient , composition (language) , forage , ammonium , magnesium , biology , linguistics , philosophy , organic chemistry , ecology
Ammonium‐N nutrition in nutrient culture has been shown to reduce Ca and Mg uptake to near‐deficient levels in many plants. The addition of K to soils also reduces Ca and Mg contents of plants. Since NH 4 ‐N is often present during the seedling growth period of plants a study was set up on soils with high and low exchangeable Ca and Mg levels to determine the comparative effect of NH 4 ‐N and rate of K on Ca and Mg absorption by corn ( Zea mays L.) plants. Knowledge of these effects could be of benefit in formulating fertilizer programs in crop production where Ca and Mg content is a factor in forage or crop quality. A greenhouse study was conducted to compare the influence of N form and K levels on the absorption of Ca and Mg by corn plants grown in Princeton sand with 67 kg Mg/ha and Fincastle silt loam with 800 kg Mg/ha. The treatments used were 100 ppm N as NH 4 or NO 3 , and 0, 50 and 100 ppm K in factorial design. Aerial portions of the plants were analysed for N, P, K, Ca, and Mg. Increasing levels of K in the soils under NO 3 nutrition reduced the concentrations of Ca and Mg in the corn tissue. However, NH 4 ‐N at the zero K rate reduced Ca and Mg concentrations in the corn tissue to less than that at the highest K rate with NO 3 ‐N. K rate did not significantly change Ca or Mg uptake under NH 4 nutrition on either soil. The exchangeable Mg level of the soil directly affected the Mg composition of the tissue with both NO 3 ‐N and NH 4 ‐N nutrition. The ammonium‐N source reduced Mg uptake by corn on the soil with exchangeable Mg of 67 kg/ha to a deficient level of less than 0.20% in this tissue, which is the critical Mg level of forage associated with incidence of hypomagnesemia in ruminant animals. Thus NH 4 ‐N must be considered an important factor in its influence on cation concentration of tissue grown on low Mg soils during periods when NH 4 ‐N is the predominant N source.