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In two greenhouse experiments, the response of maize plants (Zea mays L.) to macro and micronutrient fertilizers was studied. The first experiment was conducted in Cairo, Egypt in which maize plants were grown on saline soils with ECₑ values of 1.42, 6.12 and 12.1 dSm⁻¹ and fertilized with N, P, K alone and in combination. It was found that maize plants produced the highest dry matter when NP fertilizers were added in the Ca-form compared to the other fertilizer treatments, and this positive response decreased with increasing salinity level. Also, it was found that application of P and K fertilizers either alone or together as PK augmented the adverse effect of salinity on dry matter and nutrients uptake. In addition, the concentration and uptake of Na⁺ ions in the shoot tissues decreased with increasing salinity level up to ECₑ 12 dSm⁻¹. This could be due to Na+ exclusion or accumulation in root tissues. However, application of N and P fertilizers tended to decrease plant content of micronutrients, particularly Fe as well as Zn at high salt levels. The second experiment was conducted in a University of Arizona campus greenhouse. A Pima soil from the Marana area was artificially salinized with NaCl, Na₂SO₄, CaCl₂, and Mg₂SO₄ salts almost to the salinity levels mentioned above. Maize plants were grown and fertilized with NP fertilizer as a basic dressing. Chelated forms of Zn, Fe, and Mn were added with two different methods; soil and foliar spray application. Two pH values of spray nutrient solutions were used; pH 6 and pH 8. Data obtained showed increased dry matter and nutrient uptake in response to spraying maize plants with Zn + Fe or Zn+ Fe + Mn at pH value of 8 at the medium salt level relative to the other treatments. However, maize plants also showed high dry matter and nutrient uptake in response to Zn + Fe + Mn soil application at the high salt level, although Zn-pH 8 gave unexpectedly high dry matter production. It seems probable that this high dry matter obtained could be due to the effect of high pH spray treatment on increasing the activity of some enzymes, e.g. PEP-carboxylase and/or ribulose 1,5 diphosphate carboxylase, as well as the increase in rate of translocating the photosynthates and this effect was augmented by the nutrient(s) applied. Also, it was found that Na uptake decreased while total chlorophyll and chlorophyll a content increased with increasing salinity level. The increase in the chlorophyll content could be due to either Na exclusion by the plants and/or the decrease plant growth due high salts.

An experiment was undertaken to determine the effect of tillage and fertilizer on silage and grain corn production and on soil properties as well as to develop a crop yield model. Conventional, reduced, and zero tillage treatments in combination with inorganic or organic (cattle dairy manure) fertilizer treatments were applied yearly on a clay and a sandy loam soil from 1982 to 1986. The best yields were obtained for the combination of zero or reduced-till and inorganic fertilizers. Zero-till resulted in increased soil density and soil water content and a slight accumulation of P and K in the surface layer of the clay soil. Manure improved soil physical properties especially when combined with zero-till, but resulted in lower N availability to the plants. The factors that limited plant yield in the clay site were plant population, soil nitrate content, bulk density and soil water content. Plant population was the only limiting factor in the sandy loam site. A simplified method for predicting corn yields under different management practices was developed.

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Call number: LD2668 .T4 1978 A51 / Master of Science

Plots of field corn established in Michigan and Arizona were fertilized with two industrial wastes of nitric acid as nitrogen fertilizers. Major contaminants before processing (greater than 1000 mg/l) were Cu, Pb, Ti, Zn, and Zr. Of these, only Cu and Zn were present in significant quantities after neutralization with ammonium hydroxide. Application rates of 0, 67, 135, and 202 kg N/ ha were used, and compared with commercial ammonium nitrate fertilizer at 202 kg N/ ha. No significant differences were found in Pb, Zr, and Ti concentrations in corn tissue or grain due to treatments. Higher Cu and Zn levels occurred in plants from plots receiving the spent acids, but the concentrations were not significantly different from those found using commercial ammonium nitrate. No significant differences were found in corn grain Cu and Zn levels due to treatments.

Vita. / Digitized by Kansas Correctional Industries

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