<p>Astronaut diets on the International Space Station (ISS) depend on resupplied packaged food. However, missions to Mars of 3-5 years will not accommodate re-supply. In addition, many human macro and micronutrients degrade during long-term storage. Thus, growing nutritional plants aboard ISS is essential for providing astronauts with fresh, healthy produce. NASA is usingan experimental vegetable- production unit called VEGGIE to grow fresh salad crops aboard ISS to provide astronauts with healthy diets. VEGGIE is a small plant-growth chamber designed as a garden for astronauts that is low in mass and has a low power requirement. Veggie is equipped with light-emitting diodes (LEDs) but is exposed to the ISS cabin environment. Plants are grown with roots in a baked-ceramic substrate (arcillite) incorporating controlled-release fertilizer (Nutricote) and wicks delivering water by capillary action from a reservoir.</p><br><div>The fertilizerprills release nutrients into arcillite slowly over time. Different controlled-release types have the same amount of fertilizer but release it over different time periods. The Purdue Mitchell lab in collaboration with NASA is testing growth of salad crops within VEGGIE analogs under ISS-like environments in a growth chamber. Specifically, we are evaluating effects of different controlled-release fertilizer treatments as well as different substrate particle sizeson “cut-and-come-again” harvest scenarios, comparing productivity and quality of Lettuce as well as anAsian salad crop called Mizuna.<br></div><div><br></div><div>SS environments being mimicked include temperature: 24/21°C D/N, CO2: 2800 PPM D/N, RH: 45-50% D/N, and photoperiod: 16hours.Arcillitemedium contained one oftwo different fertilizer mixes: 7.5g18-6-8 T 70 + 7.5g 18-6-8 T100, or 7.5g18-6-8 T70 +7.5g 18-6-8 T180fertilizer/liter medium. LED Light treatment provides atotal PPFDof 330µmol m--2s-1 PAR; with 270µmol m--2s-1Red(R), 30µmol m--2s-1Blue (B), and 30µmol m--2s-1Green (G). Plants are grown under those conditions for 8 weeks, and harvested three times at 28, 42, and 56 days from planting. At each harvest, yield parameters as well as tissue mineral content have been measured for optimum fertilizer treatment selection.<br></div><div><br></div><div>Lettuce and Mizuna plants grown in a mix of 100% fine substrate particles (Profile) and fertilizer treatment of 50% T100:50%T70 had the higher yield as well as nitrogen contentcompared to those grown in 50%T180:50%T70. Growing mizuna plants in 100% profile resulted in higher shoot fresh weight; although no significant differences occurred for shoot dry weight. In addition, there was no significant interaction between substrate and fertilizer, which is reported by other research as one of the advantages of using controlled-release fertilizer<br></div>

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The response of loblolly pine (Pinus taeda L.) to fertilization and weed control at stand establishment, using various formulations of conventional and controlled release N fertilizers was evaluated in a greenhouse study and at two field trials in the Virginia Piedmont, in 2002 and 2003. The greenhouse study evaluated five fertilizer treatments; 1) check with no fertilizer; 2) granular ammonium nitrate (10-10-10 + micro-nutrients) applied to the soil surface; 3) granular methylene urea (40-0-0) applied to the soil surface; 4) methylene urea (20-10-5) in tablet form applied in the planting hole; and 5) isobutylidenediurea (IBDU) (9-9-4) in tablet form applied in the planting hole. Equal amounts of N and P were applied. Fertilization significantly increased seedling root collar diameter and volume at the end of the first growing season in the greenhouse study. Differences in diameter and volume were still significantly different late in the second growing season, however at the last measurement the differences were no longer significant. An analysis of transformed growth curves for 2003 indicated that the ammonium nitrate treated seedlings had a significantly steeper slope than all other treatments. In field trials, at an old-field site and a cut-over site, the same fertilizer products were tested, except granular diammonium phosphate (18-46-0) was used substituted for the ammonium nitrate. Higher rates of N and P were used in the field trials. Complete weed control increased seedling volume by over 700 % after two growing seasons at the reforested old-field site, however fertilizer effects were not significant. At the reforested cut-over site an interaction between weed control and fertilizer treatments was observed. The MU and DAP granular, and the IBDU tablet treatments each had significantly greater seedling volume than the check and the other tablet controlled release fertilizer. IBDU tablets appear to have high fertilizer efficiency, due to the slow release nature and are safe to place in close proximity to the seedling root system. / Master of Science

Master of Science / Department of Agronomy / David B. Mengel / Nitrogen fertilizers play an essential role in agricultural production in Kansas, particularly in row crops such as corn (Zea mays L.) and grain sorghum (Sorghum bicolor (L.) Moench). A good portion of the corn and grain sorghum grown in Kansas is typically grown using no-till production systems. These systems leave a large amount of surface residue on the soil surface, which can lead to ammonia volatilization losses from surface applied urea-containing fertilizers and immobilization of N fertilizers placed in contact with the residue. Leaching and denitrification can also be a problem on some soils. Current nitrogen prices, as well as concerns over environmental stewardship, are forcing producers to make smarter choices in the fertilizer products used as well as when and how the materials are applied, to optimize their nitrogen use efficiency. A common practice throughout Kansas is to apply N fertilizers prior to planting, sometimes up to 6 month prior to planting. What affect does this practice have on nitrogen availability to the growing crop? Current Kansas State University (KSU) soil test fertilizer recommendations assume 50% nitrogen use efficiency. This means of every pound of nitrogen applied only half will be utilized by the plant and turned into valuable grain. Possible solutions to help increase nitrogen use efficiency are the use of nitrogen additives which are currently on the market and claim to reduce nitrogen loss through denitrification and volatilization as well as the use of timing and application of fertilizers to further increase nitrogen use efficiency. The objective of this study is to evaluate different N fertilizer products, as well as additives and application practices and determine whether specific combinations can improve yield and N use efficiency of no-till corn and grain sorghum. The long-term goal of this study is to quantify some of these relationships to assist farmers in selecting specific combinations that could enhance yield and profitability. In this study five tools for preventing N loss were examined: fertilizer placement, or placing N below the soil surface or in bands on the residue-covered soil surface to reduce immobilization and/or volatilization; use of a urease inhibitor Agrotain (NBPT) that blocks the urease hydrolysis reaction that converts urea to ammonia and potentially could reduce ammonia volatilization; the use of a commercially available additive, Agrotain Plus, that contains both a nitrification inhibitor (DCD) and a urease inhibitor to slow both urea hydrolysis and the rate of ammonium conversion to nitrate and subsequent denitrification or leaching loss; use of a commercial product NutriSphere-N, which claims urease and nitrification inhibition; and the use of a polyurethane plastic-coated urea to delay release of urea fertilizer until the crop can use it. The ultimate goal of using these practices or products is to increase N uptake by the plant and enhance yield. An important measurement that was developed for this research was the use of a greenleaf firing index which used the number of green leaves below the ear at pollination as a key measurement in determining the effectiveness of fertilizer placement, application method, application timing and the use of nitrogen additives. If significant differences in lower leaf nitrogen stress are found, the potential exists to further develop this index and correlate differences observed with key parameters of nitrogen uptake such as ear-leaf nitrogen concentration, total nitrogen uptake and grain yield. Results observed from this research show that the potential to increase nitrogen use efficiency and reduce nitrogen loss do exist with the use of certain nitrogen additives, application methods and application timing. When conditions are conducive for nitrogen loss the use of currently available tools to protect nitrogen from volatilization, immobilization and/or denitrification loss significantly increased yields in the corn experiments. Results from the grain sorghum research indicate that when N losses limit yield, the use of products and practices enhance yield. In locations where nitrogen loss is minimal or low yields limit nitrogen response, the use of these practices was not found to be helpful.

MSc (Eng) dissertation - Faculty of Engineering and the Built Environment / Fertilizers are defined in the broadest sense as products that improve the levels of available plant nutrients or chemical and physical components that directly or indirectly enhance plant growth, yield and quality. The aim of this study was to produce slow controlled release fertilizers from oxidised coal. Two types of coals namely, Waterberg and Twistdraai (products, middlings) were utilised for the production of humic acids through slurry phase oxidation. The highest yields of humic acids were obtained in Waterberg and Twistdraai products samples. Subsequent to that, a nitrogen element was successfully inserted into the humic acid substrate. Humic acids are potential feedstock for modern manufacturing of organic fertilizers. The chemical substances regarded as hazardous to human consumption or those elements that negatively impact on the soil were significantly less detectable.