Doctor of Philosophy / Department of Agronomy / Dorivar Ruiz Diaz / The appropriate management for phosphorus (P) fertilizer can have significant agronomic, economic, as well as environmental impact. Studies in Kansas have evaluated different management systems to determine best management practices (BMP). The first component of this dissertation is a comprehensive review of tillage system and P fertilizer placement interaction. This review included studies completed in the U.S. Midwest. Results of this review showed greater corn yields with conventional tillage and broadcast applications when soil test P levels (STP) were below 20 mg P kg⁻¹. However, soybean yield was highest in no-till systems with broadcast P fertilizer applications. The second component if this dissertation was a long-term study conducted in Kansas to evaluate the effect of P fertilizer placement on corn and soybean production. Results showed that under strip-tillage, P fertilizer placement significantly affected corn growth, but, seldom resulted in yield response difference among placement methods. Phosphorus application as starter fertilizer at planting showed the most consistent yield response. In addition to the agronomic aspect of this study, the third component of this dissertation consisted of an economic analysis using partial budgets calculated using both fixed and varying prices and costs to compare management practices. With decreased application costs associated with deep banding in strip-tillage system, net returns are greater than broadcast applications. The highest net responses were observed with starter P fertilizer applications. The fourth component of this dissertation included a study evaluating the effects of chelated fertilizer on nutrients, such as P, Fe, Mn, and Zn in soybean. Results from our study showed that both ethylenediamine tetraacetic acid (EDTA)+P and hydroxyethyl ethylenediamine tetraacetic acid (HEDTA)+P resulted in greater concentrations and uptake of Fe and lower Mn uptake in soybean. However, the application of glucoheptonate (GCH)+P had no negative effect on Mn uptake compared to EDTA+P and HEDTA+P. Across locations, EDTA+P and HEDTA+P showed higher yield than GCH+P. The use of long-term studies and comprehensive reviews can provide a unique perspective and better understanding of the most appropriate BMPs for P fertilizer management. Many agronomic and environmental implications of P fertilizer management and the interactions with tillage systems and soils may only become noticeable after multiple years or in a variety of conditions.

Master of Science / Department of Agronomy / Dorivar Ruiz Diaz / The application of micronutrients to increase yields has become more popular with increased commodity prices and higher yielding crops. Two studies were completed evaluating secondary and micronutrient for soybean (Glycine max [L.] Merr.) and wheat (Triticum aestivum).The objective of the first study was to evaluate the response of soybean, under a double crop system after wheat, to soil-and foliar-applied macro and micronutrients. Macronutrients (N, P, K) were applied at 22 kg ha[superscript]-[superscript]1, micronutrients (Fe, Mn, Zn) were soil applied at 11 kg ha[superscript]-[superscript]1and S was applied at 22 kg ha[superscript]-[superscript]1. Plant response parameters were evaluated including changes in nutrient concentration, and seed yield response. Tissue samples were collected at the respective R1 growth stage. Samples were analyzed for the nutrients applied with the fertilizer treatments. Soybean seed yield slightly responded to soil-applied S, Mn, and Zn. When micronutrients were foliar-applied, seed yield was significantly decreased. The second study evaluated the application of S and micronutrients to winter wheat. The objectives were to evaluate the wheat response to sulfur and micronutrient fertilization and evaluate soil testing and tissue analysis as diagnostic tools. Fertilizer treatments consisted of sulfur, iron, manganese, zinc, boron, copper. All of the micronutrients were sulfate-based products and the sulfur treatments were applied as gypsum. Fertilizer treatments were applied as topdress in early spring. Soil samples were collected before fertilizer application and after harvest. Flag leaf samples were collected and analyzed for the nutrients applied with the fertilizer treatments. Significant increases in tissue concentration were observed when Zn, B, and S were applied. Significant increases in soil test Zn, Cu, B, and S were observed compared to the control treatment. Despite the increases in soil test concentration across locations, no significant increases in yield by any of the nutrients or combination of nutrients were observed.

Master of Science / Agronomy / Dorivar A. Ruiz Diaz Suarez / The effect of tillage on crop yield, early growth, and soil nutrient stratification can be influenced by fertilizer placement. In addition, deeper root systems can enhance the crop ability to uptake water and nutrients. A thorough understanding of how these factors interact can result in increased grain yields and profitability for the producer. Three studies were completed to describe and evaluate different aspects of crop root system and response to fertilizer placement and tillage. The objective of the first study was to characterize the root system of two genotypes of corn (Zea mays) and soybean (Glycine max (L.) Merr.) using image analysis in the greenhouse and in the field, as well as evaluate dry weight accumulation and nutrient uptake patterns by shoot and root plant parts for both crops. Two different genotypes of each crop were sampled during the growing season to access root characteristics such as biomass, length, surface area, average diameter and volume. Significant differences were found in corn where the P1151 AM hybrid had greater root length, surface area and volume than the P1105 AM hybrid. In soybean, the differences were found in nutrient uptake with overall greater nutrient uptake values for the poor drainage variety (PD) compared to the good drainage variety (GD). The objective of the second study was to evaluate the effect of fertilizer placement and tillage system on corn with different genotypes. Three fertilizer treatments were combined with two different corn genotypes selected based on contrasting root systems and two different tillage systems. The three fertilizer placements were sub-surface band, broadcast, and control. The two hybrids of corn used were a P1151 AM hybrid and P1105 AM hybrid. The two tillage systems were no-till (NT) and strip-till (ST). Corn hybrids showed different response in root biomass but did not show a consistent response in other characteristics evaluated. Broadcast and sub-surface band increased nutrient uptake and grain yields over the control but were not significantly different from each other. Tillage showed no difference in corn response. The objective of the third study was to evaluate the effect of fertilizer placement and tillage system on contrasting soybean genotypes. Three fertilizer treatments were combined with two different genotypes selected based on contrasting root systems and two different tillage operations. The three fertilizer placements were sub-surface band, broadcast, and control. The two varieties of soybean used were one recommended for poor drainage (PD) and one recommended for good drainage (GD). The two tillage operations were NT and ST. Soybean root biomass differences were observed by varieties. Sub-surface band treatment favored early soybean growth, biomass and P uptake at the V3 growth stage, but it did not turn into yield increase. Soybean grain yields did not respond to fertilization in this study. Yield was affected significantly by variety selection and response varies by site-year.

by Chu Lee Man. / Bibliography: leaves 176-204 / Thesis (M.Phil.) -- Chinese University of Hong Kong, 1983

Wheat is one of the major crops of Utah and for more than 50 years farmers have been raising wheat on the dry lands of the state. The system they use is known as the alternate cropping or crop-follow system and consists of one year of crop alternating with one year of clean cultivation known as fallow. Wheat removes a considerable amount of the natural plant food elements from the soil each year. This is especially true of nitrogen. According to Bracken and Greaves (9) the original low supply of nitrogen in most Utah soils together with the depleting effects of alternate wheat and fallow has the possibility of making nitrogen rather than moisture the limiting factor of crop production in certain dry-farm areas. The amount of nitrogen removed from the soil by the wheat crop is only a portion of the total supply. Such factors as leaching to a lower depth beyond the feeding range of the plant, erosion, denitrification, and volatilization through biological and possibly chemical action are thought to be responsible for the loss of nitrogen unaccounted for by crop removal. The results of several investigators indicate that this loss is approximately twice as much as was removed by the crop. Since nitrogen is one of the major factors responsible for high yields and high quality of wheat, it naturally follows that any reduction of the amount of nitrogen in the soil produces a corresponding reduction in yield and quality of wheat. Recent reports show that this condition exists in Utah as well as in other areas. As a result of this reduction in yield and quality of wheat, processors are concerned about the problems. The seriousness of the problem cannot be over-emphasized. Ways and means of checking these losses and subsequently increasing the yield and quality are being studied. Three possible procedures for increasing soil nitrogen have been suggested: 1. the use of legumes, especially alfalfa, in a rotation program; 2. non-symbiotic nitrogen fixation: and 3. the use of commercial fertilizers. Since legumes have not been grown to any great extent, the only other natural source of nitrogen has been non-symbiotic fixation. Evidence in this field of investigation, however, indicates that this source is inadequate and that other sources must be bad. Also, the data indicate that no effective methods have been found which increase non-symbiotic fixation. Limited information suggests that further study is needed on the use of legumes for increasing the nitrogen and organic matter content of dry farm soils. This investigation is confined to the use of commercial fertilizers as one solution to the general problem.

The Federal Water Pollution Control Act Amendments of 1972 prohibits the discharge of seafood processing solid wastes into navigable waters after July 1, 1977. Oregon shrimp and crab processors must use other methods of disposal for the 15 to 30 million pounds of solid waste generated annually. The application of shrimp and crab wastes to nearby agricultural land can consume the wastes generated at major processing ports. As they came from the processing plant, shrimp and crab solid wastes contained 1.3% to 1.6% N, 0.47% to 0.54% P, other nutrients, 7% to 14% CaCO��� equivalent, and 64% to 78% water. A greenhouse experiment was established to determine the effects of 1) grinding the wastes, 2) surface vs. incorporated waste applications, and 3) waste applications vs. inorganic N applied at equivalent N rates (56, 168, and 336 kg N/ha) with applications of P, S, and lime supplied with the inorganic N only. The fertilizer materials were applied on two coastal soils, and two pasture crops were grown. Forage yields and the P concentration in 'Potomac' orchard grass (Dactylis glomerata L.) were significantly higher with incorporated waste applications than with surface waste applications. Application method did not affect the P concentration in New Zealand white clover (Trifolium repens L. ). The difference in crop response between application methods would assumably be less under field conditions than was measured in the greenhouse. Grinding crab waste significantly increased forage yields when the waste was surface applied, but not when incorporated with the soil. Unground shrimp waste gave significantly higher forage yields than ground shrimp waste. No significant difference occurred in the forage yields, the N uptake by orchardgrass, or the P concentrations in orchardgrass and white clover among applications of shrimp waste, crab waste, and inorganic nutrients with lime. Applications of shrimp and crab wastes increased white clover yields over the control by a factor of more than 3.5 on Knappa silt loam (pH 4.9 - 5.0) but did not measurably increase the soil pH. It was assumed that the wastes, in the immediate area of the shell material, increased the availability of Ca, P, S, and Mo, decreased soluble soil Al, and allowed effective rhizobial nodulation and N fixation. Increasing application rates of shrimp and crab wastes to Knappa and Nehalem silt loams significantly increased the extractable soil P and Ca, and significantly decreased the extractable soil K after 28 weeks of orchardgrass growth. No consistent effect on soil pH was measured. In a second greenhouse experiment, N rates of 165 and 330 kg/ha and P rates of 61 and 122 kg/ha were supplied by shrimp waste and by inorganic sources to a limed coastal soil in a 2 x 2 x 2 complete factorial arrangement. Applications of shrimp waste resulted in significantly higher orchardgrass yields and P uptake than applications of the inorganic nutrients, but no significant difference occurred in the N uptake. In an irrigated coastal pasture, fresh shrimp waste was applied at 6,726, 17,936, and 35,872 kg/ha and ammonium phosphate (16-20-0 15 S) was applied at 224 and 448 kg/ha and a stand of orchardgrass was established. Forage yields were higher with shrimp waste than with ammonium phosphate. Shrimp waste applications beyond 17,936 kg/ha did not further increase the forage yield or P uptake. Shrimp waste applications increased extractable soil P, SO��� -S, soluble salts, and NO��� -N, but resulted in a depletion of soil K when measured at the end of the growing season. Shrimp and crab processing wastes are effective sources of N and P for crop plants and should be applied at rates necessary to supply the recommended rates of N. / Graduation date: 1978

Thesis (M.S.)--University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (February 9, 2007) Includes bibliographical references.

Thesis (M. Sc.)(Microbiology)--University of Pretoria, 2005. / Includes summary. Includes bibliographical references. Available on the Internet via the World Wide Web.

Thesis (M.S.)--Humboldt State University, 2009. / Includes bibliographical references (leaves 55-57). Also available via Humboldt Digital Scholar.

Thesis (Ph. D.)--Washington State University, December 2009. / Title from PDF title page (viewed on Feb. 19, 2010). "Department of Biological Systems Engineering." Includes bibliographical references.