Title also in Chinese. / Thesis (M.Phil.)--Chinese University of Hong Kong. / Bibliography: leaves 171-188.

Digitized by Kansas Correctional Industries

The detrimental effects of climate change and the threat of diminishing fossil fuel reserves is forcing society to search for renewable sources of energy. Energy can be derived from the biomass of plant material by co-fire combustion with coal or on its own for the production of electricity. Energy can also be created by converting the plant biomass into ethanol, a gasoline substitute. When converted into bioenergy, plant biomass from Short Rotation Woody Crop (SRWC) systems has the potential to offset the use of fossil fuels if the yields can be maintained at profitable levels. The effect of first year application of nitrogen (N) fertilizer on willow biomass production in a SRWC system is not well understood. Using field and growth chamber studies, the objectives of this study were to 1) determine biomass production in the growing seasons following a single application of N fertilizer in the year of planting, 2) determine the N recovery for five willow clones using a 15N tracer, and 3) evaluate the effects of various types and rates of fertilizers on biomass production. Objectives 1 and 2 were addressed in a field fertilization study conducted on agricultural lands in the Moist Mixed Grassland ecozone and at tree nursery in the Boreal Transition ecozone. Willow cuttings were planted and fertilized with 100 kg N ha-1 of granular ammonium nitrate. Twelve trees were fertilized with 5 kg N ha-1 of double 15N-labeled ammonium nitrate and 95 kg N ha-1 of granular ammonium nitrate. In the first growing season trees were browsed to a uniform height making biomass measurements unrepresentative of production potential. Annual shoot biomass production in the second year, however, was 0.39 to 2.0 Mg ha-1 and was not found to be significantly different between fertilizer treatments. Nitrogen recovery by entire trees ranged from 2.87 to 10.6 % in the first growing season and 0.39 to 2.95 % in the second growing season. Objective three was addressed in a growth chamber study. Willow cuttings were planted in pots and fertilized with 0, 50, 100 and 200 kg N ha-1 of granular ammonium nitrate and 100 kg N ha-1 of composted cattle manure. After a 90 day growth period shoot biomass production was significantly greater on the Prince Albert soil (1.28 to 5.34 g tree-1) than on the Saskatoon soil (1.18 to 3.59 g tree-1). No consistent trend between fertilizer treatments was observed. Further exploration into fertilization of willow SRWC systems should consider the application of multiple nutrient fertilizer blends, various rates and year of application to gain a better understanding of nutrient requirements of willow for the entire growth period.

The detrimental effects of climate change and the threat of diminishing fossil fuel reserves is forcing society to search for renewable sources of energy. Energy can be derived from the biomass of plant material by co-fire combustion with coal or on its own for the production of electricity. Energy can also be created by converting the plant biomass into ethanol, a gasoline substitute. When converted into bioenergy, plant biomass from Short Rotation Woody Crop (SRWC) systems has the potential to offset the use of fossil fuels if the yields can be maintained at profitable levels. The effect of first year application of nitrogen (N) fertilizer on willow biomass production in a SRWC system is not well understood. Using field and growth chamber studies, the objectives of this study were to 1) determine biomass production in the growing seasons following a single application of N fertilizer in the year of planting, 2) determine the N recovery for five willow clones using a 15N tracer, and 3) evaluate the effects of various types and rates of fertilizers on biomass production. Objectives 1 and 2 were addressed in a field fertilization study conducted on agricultural lands in the Moist Mixed Grassland ecozone and at tree nursery in the Boreal Transition ecozone. Willow cuttings were planted and fertilized with 100 kg N ha-1 of granular ammonium nitrate. Twelve trees were fertilized with 5 kg N ha-1 of double 15N-labeled ammonium nitrate and 95 kg N ha-1 of granular ammonium nitrate. In the first growing season trees were browsed to a uniform height making biomass measurements unrepresentative of production potential. Annual shoot biomass production in the second year, however, was 0.39 to 2.0 Mg ha-1 and was not found to be significantly different between fertilizer treatments. Nitrogen recovery by entire trees ranged from 2.87 to 10.6 % in the first growing season and 0.39 to 2.95 % in the second growing season. Objective three was addressed in a growth chamber study. Willow cuttings were planted in pots and fertilized with 0, 50, 100 and 200 kg N ha-1 of granular ammonium nitrate and 100 kg N ha-1 of composted cattle manure. After a 90 day growth period shoot biomass production was significantly greater on the Prince Albert soil (1.28 to 5.34 g tree-1) than on the Saskatoon soil (1.18 to 3.59 g tree-1). No consistent trend between fertilizer treatments was observed. Further exploration into fertilization of willow SRWC systems should consider the application of multiple nutrient fertilizer blends, various rates and year of application to gain a better understanding of nutrient requirements of willow for the entire growth period.

In a field study of irrigated chile (Capsicum annum L.) production in southeastern Arizona and southwestern New Mexico from 2008 through 2009, soil and tissue test samples were analyzed for a full spectrum of nutrients at 16 different sites, including nitrogen (N) phosphorus (P), potassium (K), zinc (Zn), iron (Fe), and boron (B), with the objective of evaluating soil and tissue nutrient testing procedures and establishing basic testing guidelines and recommendations with respect to yield potentials. Results for soil and tissue analysis were correlated to yield results. The results provide estimates for baselines which can be tested through subsequent calibration experiments for the development of recommendations for critical soil and tissue test values. These soil test and plant nutrients values will be evaluated in subsequent experiments in an effort to better define fertilizer nutrient inputs in order to gain better nutrient management efficiencies in irrigated chile production systems.

Thesis (M. Sc. (Botany))--Rhodes University, 2000.

Master of Science / Department of Agronomy / Nathan O. Nelson / Phosphorus (P) loss from non-point agricultural sources has been identified as a main contributor to degraded surface water quality throughout the United States. Excessive P inputs to surface waters can lead to eutrophication, increased water treatment costs, and negative health impacts. Therefore, agricultural best management practices (BMP) that promote water quality, through minimizing P loss, must be identified. Studies outlined in this thesis aim to determine the impacts of cover crops and P fertilizer placement on P loss in surface runoff and nutrient cycling in a no-till corn (Zea mays)-soybean (Glycine max) rotation and provide insight into how cover crop species selection and termination method affects potential P loss from crop tissue. The first study examined combined effects of cover crop and P fertilizer placement on total P, dissolved reactive P (DRP) and sediment losses in surface runoff from natural precipitation events. This large-scale field study was conducted near Manhattan, Kansas, at the Kansas Agricultural Watershed (KAW) Field Laboratory during the 2016 and 2017 cropping years. Two levels of cover crop [no cover crop (NC) and cover crop (CC)] and three levels of P fertilizer management [no P (CN), fall broadcast P (FB), and spring injected P (SI)] were used. Flow-weighted composite water samples were collected from precipitation events generating greater than 2.0 mm of surface runoff. Results from this study found the CC treatment increased DRP losses compared to NC in both cropping years; however, CC reduced sediment loss by over 50% compared to NC. Application of P fertilizer increased DRP losses compared CN in both cropping years, although SI resulted in lower quantities of DRP loss compared to FB. In addition, this study found that CC reduced biomass and yield of corn compared to NC and therefore decreased nutrient uptake, removal, and deposition during the 2017 cropping year. However, no negative impacts of CC on biomass or yield were observed during the 2015 (corn) and 2016 (soybean) cropping years. Application of P fertilizer increased the concentration of Melich-3 P and total P in the top 0-5 cm of soil compared to CN; however, no differences between P fertilizer management practice were observed for concentrations of Melich-3 P at 5-15 cm. A greenhouse-based study determined the impacts of cover crop species (brassica, grass, and legume), termination method (clipping, freezing, and herbicide), and time after termination (1, 7, and 14 days after termination) on total P and water-extractable P (WEP) release from cover crop biomass. Freezing increased WEP concentration of crop tissue by more than 140% compared to clipping and herbicide. Additionally, at 7 and 14 days after termination, both concentration of WEP and fraction of WEP compared total P increased compared to 1 DAT. Findings from these studies suggest the use of cover crops may unintentionally result in greater DRP losses in surface runoff. However, addition of a cover crop can dramatically reduce erosion losses. In addition, cover crop species selection can directly impact the quantity of P being taken up and released by crop tissue. Understanding the impact of crop species selection may help create new BMPs which aim to reduce P loss.

The response of wheat to soil fertilised with varying quantities of the water fern Azolla filiculoides was investigated. Experiments were conducted to differentiate between the effects of increased soil mineral status and water status. In the preliminary investigation, experiments were carried out in the greenhouse using potted wheat grown in sand with varying proportions of A. filiculoides that had been subjected tovarious pre-treatments. The pre-treatments were fresh, dry and heated A. filiculoides applied at 20%, 50% and 80% volume per 3000 ml. There were significant differences in the measured growth parameters between the plants grown in the various treatments. In addition, the grain yield of wheat plants varied with the different treatments. Results of the preliminary study showed that the addition of heated and dried A. filiculoides resulted in significantly better growth than the addition of fresh A. filiculoides in sand. For fresh biomass, grain weights, Leaf area ratio (LAR) and relative growth rate (RGR), the performance of dried A. filiculoides was as good as that of the heated A. filiculoides. Productivity of wheat in the heated treatments increased significantly with increasing proportion of A. filiculoides added to sand, while in dry treatments there were no significant increases in productivity in the preliminary study. This supported the hypothesis that A. filiculoides, a notorious water weed can be put to agricultural use under dryland conditions in poor nutrient soils. Further investigations using dried A. filiculoides in sand and topsoil showed that the use of the same amounts of the dried fern made no significant short term impact on topsoil grown winter wheat but significantly improved the productivity of wheat in sand. Results showed that the addition of dried 20% Azolla to sand improved the soil fertility to levels equalling the quality of the control topsoil, but the addition of 80% Azolla to sand led to significantly greater wheat productivity than all other treatments. The addition of dried 20% Azolla (8.14 × 10^3 kg ha^(-1)) in sand produced as much wheat biomass as the addition of the recommended NPK fertiliser (30 kg N ha^(-1)) to sand. A comparison between the topsoil and sand-grown plants showed differences in flowering time but these had no effect on the final grain and above ground biomass.

<p>Sulfur (S) demand has increased as atmospheric deposition of S decreased and soybean (<i>Glycine max</i> (L.) Merr.) production has increased. Soybean growers have invested into agronomic practices to maximize production and alleviate potential S shortfalls including the use of starter fertilizer. For this reason, this study was designed to quantify and qualify the effects of fluid starter S fertilizer on soybean yield. The objectives were to determine an optimum source, rate, and placement of fluid starter fertilizer. A split-plot design of S source-rate and placement was used in 2019 and 2020 at West Lafayette and Wanatah, Indiana. Three starter S fertilizers were used: ammonium thiosulfate (ATS, 12-0-0-26S, Hydrite Chemical), potassium thiosulfate (KTS, 0-0-25-17S, Hydrite Chemical), and K-Fuse (derived from potassium acetate, ammonium thiosulfate and urea 6-0-12-12S, NACHURS) as well as broadcast granular ammonium sulfate (AMS, 21-0-0-24S), and an untreated control. Starter S products were applied at four S rates: 5.6, 11.2, 16.8, and 22.4 kg S ha^-1 to determine optimal S rate and in two placements (single: 0x5x1-cm; dual: 0x5x2-cm). AMS was broadcast at 22.4 kg S ha^-1</p> <p>Placement did not affect a majority of the factors analyzed and was largely factored out when not significant. Leaf concentrations of essential macro-nutrients, including S, were above critical levels and were not affected by starter fertilizer at any site-year. ATS increased manganese (Mn) in 2019 and 2020 and Wanatah. In West Lafayette 2020 (timely planting), all three starter sulfur fertilizers increased yield and protein, while broadcast AMS did not. Yield and protein did not change with starter S fertilizer in the remaining site-years, which was likely due to plantings later than recommended.</p> <p>To evaluate and quantify the effects of fluid starter fertilizer across early and late planting dates, a split-plot design was used with an earlier (May 13, 2020) and late (June 8, 2020) planting dates at West Lafayette, IN, as well as early (P24A80X) and late (P35A33X) maturing soybean varieties at Wanatah, IN. These were crossed with six fertility treatments: ammonium thiosulfate (ATS, 12-0-0-26S), potassium thiosulfate (KTS, 0-0-25-17S), K-Fuse (6-0-12-12S, NACHURS), 28% urea ammonium nitrate (UAN, 28-0-0), ammonium sulfate (AMS, 21-0-0-24S), and an untreated control. Starter S fertilizers were applied at 16.8 kg S ha^-1 and 28% UAN was applied at a 7.9 kg Nitrogen (N) ha^-1rate, all in a single (0x5x1-cm) placement.</p> <p>The earlier planting had greater stand and yield than the later planting. Starter fertilizers did not impact yield, protein or oil compared to untreated control. Earlier-planted soybean with KTS had higher S concentration in the leaves than UTC and other fertility treatments. Variety impacted leaf nutrient and seed protein concentration. Leaf nutrient concentrations was generally higher in the 3.5 variety compared to the 2.4 variety. Protein was higher in the 2.4 variety compared to the 3.5 variety. However, yield was not affected by variety, fertilizer, or a variety x fertilizer interaction. There was also no fertilizer effect on any essential nutrient concentration. </p> <p>Soybean positive response to starter S fertilizer aligned with timely plantings rather than later plantings. Earlier plantings were cool and wet field conditions, which limited mineralization of soil organic matter and the supply of N and S. The highest yield was 4308 kg ha^-1 with KTS in West Lafayette 2020, applied at a rate of 7.5 kg S ha^-1, followed by K-Fuse and ATS, respectively. Given the minimal response to different placements, it can be concluded that the difference between single and dual placements on soybean growth and yield is negligible.</p>

<p>In previous research in continuous corn with no-till management, starter fertilizer consistently increased vegetative plant development rate and plant dry matter prior to sidedressing and decreased grain moisture. However, increased yield did not always occur. The objective of my study was to evaluate the effects of starter fertilizer on plant dry matter and nutrient content throughout the growing season to determine if differences in these parameters determined early in the growing season persisted throughout reproductive growth and explained yield effects. Experiments were conducted in long-term continuous corn no-tillage fields at SEPAC, NEPAC, and TPAC in 2019 and 2020. At TPAC, treatments were control and starter, 46 kg N ha^-1 and 18 kg P ha^-1. At SEPAC and NEPAC, we also evaluated starter fertilizer composition, and the treatments were control, 3.6 kg N ha^-1 and 8 kg S ha^-1; N, 34 kg N ha^-1 and 8 kg S ha^-1; NP, N plus 7.5 kg P ha^-1; and NPK, NP plus 9.5 kg K ha^-1. Starter fertilizer was applied 5 cm below and 5 cm to one side of the seed. Total N rate was equalized by adjusting the N application at sidedressing to compensate for the N applied in starter.</p> <p>Although starter fertilizer treatment effects differed from those of the control, in most cases starter fertilizer effects were the same regardless of composition. Hereafter, ‘starter fertilizer’ will refer to the mean of the three starter fertilizer treatments, N, NP, and NPK for SEPAC and NEPAC or NP in the case of TPAC. Crop growth rate determined by the number of collared leaves was increased by starter fertilizer, compared to the control, at all site-years. Starter fertilizer increased leaf appearance up to one leaf in plots evaluated at the same point in time and final leaf number was also one more leaf per plant. Starter fertilizer increased dry matter as early as V4 compared to the control at SEPAC and TPAC, with differences maximizing around V6-V12. Effects at NEPAC were inconsistent throughout the season. At reproductive stages the magnitude of the differences in dry matter decreased until starter fertilizer and control treatments had similar dry matter at maturity. Before sidedressing, N and P concentrations were greater with starter fertilizer than the control, but after sidedressing concentration of these nutrients were greater with control than starter fertilizer. The differences in N and P concentration between starter treatments and the control increased in later vegetative stages, but decreased during reproductive stages and at maturity. Potassium concentration was generally unaffected by the fertilizer treatments. Plant nutrient content differences between starter fertilizer treatments and the control were similar to differences seen with dry matter, despite the differences in nutrient concentration between starter fertilizer and the control. When compared at the same growth stage, starter fertilizer treatments and the control, had similar DM and nutrient concentration and content. Starter fertilizer, compared to the control, resulted in earlier silking and/or tasseling at all site-years. Starter fertilizer accelerated vegetative crop development, but this did not result in substantial differences in dry matter or nutrient content at similar growth stages, including physiological maturity. Despite this result, increased grain yield with starter fertilizer, compared to the control, occurred at 3 of 6 site-years and ranged from 300 to 1000 kg ha^‑1. Grain moisture was decreased by starter fertilizer at 4 of 6 site-years by at least 5 g kg^-1.</p>