An experiment was conducted to investigate the effects of N formulation, application rate, and application time on corn yield and quality under Eastern Canadian conditions, to evaluate the hypothesis that application of N will increase corn grain yield and protein concentration without decreasing the total energy content. Three N formulations, each with the rates of 90, or 180 kg ha$ sp{-1}$ were applied at different times. The results indicated that the grain yield increased with increasing N fertilizer rate and with increasing numbers of N application times. N application significantly increased grain protein concentration, on both a per kernel and a dry matter basis, and protein yield. Such as, N application increased the averaged protein concentration, on a dry matter basis, of corn grain by about 8.40% as compared to the control. The protein concentration was not affected by the number of N application times before the plants were 90 cm high. Neither lipid nor non-structural carbohydrate concentration, on both a per kernel and a dry matter basis, were significantly affected by N application in most of the location-years. In addition Near infrared reflectance (NIR) was used to determine the lipid concentration in the aerial corn tissue at different growth stages. The correlation coefficients between the standard analytical method and the NIR method of lipid concentration were all above 0.95, and were significant at 0.01 level.

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 63-66). Also available on the World Wide Web.

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Increased N fertilizer efficiency in crop production is essential for agronomic, economic, and environmental improvement. In order to increase efficiency, a basic knowledge of fertilizer-soil-crop relationships and components is required. Nitrogen components in the soil-corn system were determined on two soils (Chicot sandy clay loam, Grey Brown Luvisol; Ste. Rosalie clay, Humic Gleysol). Fall soil NO$ sb3 sp-$-N levels increased linearly with increasing N rates above the 170 kg ha$ sp{-1}$ N rate. Changes in soil NO$ sb3 sp-$-N over winter were a function of both fall soil NO$ sb3 sp-$-N levels and winter precipitation. Denitrification rates during the non-growing season ranged from 7 to 24 kg N ha$ sp{-1}$, mainly dependent on N fertilizer rates the previous growing season on the Ste. Rosalie soil. Denitrification losses were a small portion of NO$ sb3 sp-$ disappearance over the non-growing season. Almost all fertilizer N at 170 kg N ha$ sp{-1}$ was recovered as crop N, clay fixed NH$ sb4 sp+$ and organic immobilized N at the end of the growing season, where at 400 kg ha$ sp{-1}$ N fall mineral N and unaccounted for N were a major component of the N fractions. High rates (400 kg N ha$ sp{-1}$) compared to normal rates (170 kg N ha$ sp{-1}$) resulted in some increase in yield, greater microbial activity and greater soil organic N, and a significant loss of fertilizer N by denitrification or leaching.

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Grain corn (Zea mays L.) production occupies more farmland than any other annual crop in Quebec and is expanding demand from the livestock sector and the emerging bioethanol industry. Corn production requires high nutrient inputs and intensive tillage (IT). Many producers have thus switched to conservation tillage systems like ridge-tillage (RT) to overcome soil compaction and erosion problems that are common in IT systems. However, fertilizer guidelines developed for IT soils are used in RT although RT adoption greatly modifies phosphorus (P) dynamics. Lower fertilizer P requirements are expected because arbuscular mycorrhizal (AM) symbiosis known to enhance plant P nutrition are minimally disrupted under RT, compared to IT systems. A two-year study was conducted on a commercial farm in the Monteregie region (Quebec, Canada) to investigate the effects of P fertilizer rates and soil P-saturation status on corn early growth, nutrition and yield. Surface soil plant-available P was monitored in situ with anionic exchange membranes (P AEM) from seeding to the end of July. The effects of indigenous AM fungi on corn parameters and rhizosphere soil P pools were also investigated in untreated (AMNI) or AM-inhibited fungicide-treated (AMI) soils. Quebec's P fertilizer guidelines underestimated the soil P fertility in studied soils. Adding inorganic P (Pi) did not improve the early corn P nutrition, growth or yield, and had little impact soil PAEM. Variations in PAEM were better explained by climatic variables. AMNI corn had similar early development and high yield, regardless of whether P fertilizer was applied, whereas AMI plants needed P fertilizer to produce optimal yield. AMNI corn had reduced dependence on Pi inputs due to more efficient uptake of soil solution P i in surface and rhizosphere soils during the first 22 days after seeding (DAS), In the rhizosphere, available-Pi pool appeared to be used first to replenish the resin-P pool, but over the longer term, AM symbiosis also enhanced NaHCO3-Po mobilization through a mechanism that remains unclear. Deeper understanding of the mechanisms by which AM fungi alter soil P dynamics will contribute to the development of more sustainable P fertilizer programs for RT systems.

An incubation study was conducted to evaluate the effects of added urea, NH$ sb4$Cl, and KCl on fixation of NH$ sb4 sp{+}$ and K$ sp{+}$. A field study was carried out to observe the effects of rates and methods of added urea and KCl on the forms and distribution of N and K in soils, and on yields and nutrient uptake of silage corn. / Generally, the fixation of NH$ sb4 sp{+}$ was increased by added N but reduced by added K and vice versa. One exception was that added K increased NH$ sb4 sp{+}$ fixation when NH$ sb4$Cl was the N source. In comparison with NH$ sb4$Cl, urea resulted in greater K$ sp{+}$ fixation but less NH$ sb4 sp{+}$ fixation. / Band placement of urea and KCl showed apparent accumulation of NH$ sb4$-N and NO$ sb3$-N, and exchangeable K$ sp{+}$ in the fertilizer bands, particularly early in the growing season. On the other hand, band placement resulted in lower levels of available N and K in soil between the bands in comparison with broadcast. / Yields of silage corn and nutrient uptake values were increased by N and K fertilizers, except for one soil in the first year. Band placement of urea was superior in the case of frequent and light rainfall but inferior with dry surface soil conditions followed by a relatively large rainfall 3 or 4 days after application. In the latter condition, banding K resulted in less yields on one soil, and banding the two fertilizers together further reduced N utilization on another soil. / Additions of K suppressed Ca and Mg uptake but did not influence N uptake, whereas K uptake was usually enhanced by added N.

Urea and triple superphosphate (TSP) are important N and P fertilizers, respectively, but they suffer from inefficiency because of NH$ sb3$ volatilization and phytotoxicity and P fixation. Combinations of urea and TSP or KCl might improve N and P use efficiency primarily through pH changes. Mixtures of urea, TSP and KCl, either compacted or blended, were studied as to NH$ sb3$ volatilization, denitrification and P transformation in soils, and N and P use efficiency in crops. Soils studied included a Ste. Rosalie clay (Humic Gleysol), an Ormstown silty clay loam (Humic Gleysol), a Chicot sandy clay loam (Grey Browm Luvisol), a St. Bernard loam (Melanic Brunisol) and an Upland loamy sand (Humo Ferric Podzol). Triple superphosphate or KCl reduced urease activity and delayed urea hydrolysis primarily through acidification. Ammonia volatilization decreased when urea was surface-applied with TSP or KCl. The depressive effect of TSP on NH$ sb3$ volatilization was reduced and the KCl effect was increased in the soil with high exchangeable acidity. Phytotoxicity from banded urea, NO$ sb2 sp-$ accumulation and denitrification declined with added TSP. Urea hydrolysis caused a rise in pH and dissolution of organic matter in soils, and as a result, Mehlich (3) and water extractable P increased when urea were banded with TSP. Corn yield and N and P use efficiency were improved with application of mixtures of TSP and urea as compared with urea or TSP alone. Compacted mixtures of urea and TSP or KCl were superior to blended mixtures, possible because of the intimate association of fertilizer dissolution products. Compacted mixtures of urea and TSP or KCl hold promise for improved agricultural productions.