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Title:Farming in the city: how the urban environment affects vegetable crop production, soil heavy metal contamination and nutrient dynamics, produce nutritive quality, and insect dynamics in urban gardens
Author(s):Wagstaff, Ross Kennington
Director of Research:Wortman, Samuel E
Doctoral Committee Chair(s):Wortman, Samuel E; Davis, Adam S
Doctoral Committee Member(s):Juvik, John A; Bernacchi, Carl J; Briskin, Donald P
Department / Program:Crop Sciences
Discipline:Crop Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(s):Urban agriculture
Urban environment
Urban vegetable
lead contamination
raised bed
urban insect
urban to rural gradient
urban vegetable nutrient
urban food safety
Abstract:Urbanization is a growing trend worldwide and especially in industrialized countries, where urban populations have reached over 80% of total populations. Growing food in urban areas is common in developing countries and accounts for a significant portion of urban dweller’s diet. Developed nations have long since relied on external production for urban consumption. Recently there has been increased interest in urban agriculture as a means of improving diet and reducing poverty in urban areas and to reduce externalities of a global food system. While there is significant understanding of the urban microclimate and ecosystem, there is little understanding of agricultural production systems in the urban environment. To assess the effects of urbanization on urban food production, six experimental gardens were established in 2013 from near to city center of Chicago to rural agriculture land along an urban to rural gradient near 45° 50’ N. Each garden had 40 0.43 m3 raised bed pots filled with compost-soil-sand mix (50, 40, and 10% respectively). Fourteen cultivars of seven common garden vegetable species were grown in the raised bed pots in 2013 to 2015 seasons. Onion and kale were planted in early April (spring), tomato, pepper, and snap bean was planted in late May (summer), and following the spring crops, table beet and Brussels sprout were planted in late July (fall). Two cultivars of each crop was planted in each pot and there were eight replications of each crop in each garden. Crops were sampled during the season for fruit quality, yield, and biomass. Structural equation models were used to compare crop yield to micrometeorological measures. Soil samples taken in the spring and fall as well as plant root simulator probes were used to assess soil nutrients, heavy metal contamination, and soil microbe dynamics. Fruit quality measures included soluble solids, total phenolic content (TPC), and two antioxidant capacity assays (FRAP and DPPH). Insect abundance and diversity was measures using yellow sticky traps and pheromone bait traps. Insect pest infestations were quantified weekly through the growing seasons. Micrometeorological sensors adjacent to the gardens measured and logged temperature, humidity, wind speed, light irradiation, CO2 concentration, and ozone concentration. Ozone levels were higher at peri-urban sites. Temperature, CO2, and vapor pressure deficit were higher in urban sites and lowest in the rural site. Yield of spring and fall crops were generally higher in the urban sites and summer planted tomato and bean was higher in peri-urban and rural sites, whereas pepper had generally higher yield in urban sites. Measures of ozone (-), temperature (+), and growing degree days (+) had a causal relationships with spring and fall planted crops and not summer planted crops. Light interception (+), ozone (-), and distance to city center (mixed) had causal relationship to summer planted crops. Soil lead levels increased slightly over the three years, but no garden had higher lead levels compared among gardens. The compost based soil experienced leaching of calcium, potassium, and magnesium from the soil profile. Despite no fertilization, soil nitrate levels did not decrease, but actually increased due to soil maturation. A peri-urban garden with acidic irrigation water lead to high sulfate levels and reduced phosphorus and lead levels. Produce quality measure soluble solid was negatively related to yield and temperature and unrelated to FRAP, DPPH, and TPC assays. In some crops, soluble solids were greater in rural gardens. DPPH, FRAP, and TPC were positively correlated and were negatively associated with temperature, solar radiation, and vapor pressure deficit. TPC, FRAP, and DPPH were generally not different between garden locations. The common garden pest Helicopvera zea (corn earworm) had greater captures of the adult insect in rural gardens while aphid infestations were greater in urban gardens. Micrometeorological conditions affected plant growth, soil nutrients and microbial, and fruit quality dynamics along a rural to urban transect of Chicago, IL, but the difference does not affect the nutrient quality or safety of urban grown produce.
Issue Date:2016-12-01
Type:Thesis
URI:http://hdl.handle.net/2142/95366
Rights Information:Copyright 2016 Ross Wagstaff
Date Available in IDEALS:2017-03-01
Date Deposited:2016-12


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