Degree Type


Date of Award


Degree Name

Doctor of Philosophy




Field experiments were conducted in 1981 and 1982 to study the effects of low, moderate and high levels of P and K availability in the soil on growth and nutrient uptake by corn plants. In both seasons, 157 kg of N ha('-1) was applied to all experimental plots prior to planting. Corn grain yields were 4940 and 8600 kg ha('-1) in 1981 and 3920 and 6260 kg ha('-1) in 1982 at the low and high fertility levels, respectively. The corn plants were sampled throughout the growing season, separated into different plant parts, and chemically analyzed;The concentrations of P and K in the plants increased and the concentrations of Zn and Mg (except in the stalks and grain) decreased as the levels of P and K availability in the soil increased. The concentrations of other elements--N, S, Ca, Cu, Mn, Fe, Na, and Al--in the plants did not vary consistently among fertility levels except for slight decreases of N and S in the grain and a slight increase of Ca in the stalks as the PK fertility level increased;Changes in nutrient concentrations during the season varied for different elements, for different plant parts and positions on the plants, and at different levels of P and K availability in the soil;Nutrient contents in the plants increased as fertility level increased. After silking, most of the nutrient accumulation was in upper ear shoots;Soil fertility differences did not markedly influence the amounts of nutrients in the grain at early stages of grain development, but later as the grain developed, the amounts of nutrients in the seeds increased as the fertility level increased.



Digital Repository @ Iowa State University,

Copyright Owner

Abd-Al-Mehdi Salih Al-Ansari



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282 pages