Urban agriculture research: Maximizing crop productivity in the face of environmental challenges Sam Wortman Assistant Professor Urban Food Production Department of Crop Sciences swortman@illinois.edu
Soil, air, and water pollutants are the biggest threats to urban agriculture
Lead (Pb) is the primary contaminant of concern in urban soils In Chicago, Pb concentrations are 20x greater than in adjacent rural soils Normal = 20 ppm soil Pb (mg Pb/kg soil) Contaminated soils range from 400 to 2,000 ppm soil Pb
So, is your soil contaminated? 1 st step: Where is your garden and what is the site history? 2 nd step: Take a few soil samples 3 rd step: Interpret the analysis (using EPA guidelines) 4 th step: Manage risks and implement BMPs Sampling methods
If soil Pb levels are high, will my plants accumulate dangerous levels? Eating vegetables from contaminated soil would equate to less than 25% of the Pb we consume in tap water Normal consumption levels of fruits and vegetables is safe Concentration of heavy metals: [roots] > [shoots] > [fruits] Basil Beets
There are options for reducing the risk of plant uptake Manage soil ph above 7 Add PO 4 3- fertilizer Apply compost (or other organic amendments) Pb 3+ is positively-charged, so manage for negatively-charged binding sites in soil
Some best management practices (BMPs) for urban gardening Use mulch or other soil covers Create physical barriers (high tunnels) Amend the soil with organic materials like compost Use raised beds or containers
More best management practices (BMPs) for urban gardening Wear gardening gloves Wash produce Peel root crops or avoid altogether if growing directly in soil DON T EAT SOIL!!! http://www.epa.gov/swerosps/b f/urbanag/pdf/bf_urban_ag.pdf
There are numerous soil management systems being used in urban areas Compost amended soil and mulched walkways Direct soil and grassed walkways Cap-and-fill method with cover crops (Growing Home) Raised-beds
There is limited information on the longterm performance of these systems Experimental systems: 1) Direct soil + conventional 2) Direct soil + organic 3) Cap-and-fill + soil-compost mix + conventional 4) Cap-and-fill + soil-compost mix + organic 5) Cap-and-fill + compost media 6) Cap-and-fill + compost + cover crops Urban open air in direct soil High-tunnel with cap-and-fill method
We are working to establish a network of community research gardens Each bed in the garden is an experimental plot Developing a multi-state collaboration to study regional variability Provide research opportunities for undergrad students on campus could be expanded to involve MGs
Soil, air, and water pollutants are the biggest threats to urban agriculture
Pollutants and microclimatic factors are dynamic across metro areas
These atmospheric changes are influencing plant growth The growing season can be 7-8 days longer in dense urban areas Related to the urban heat island effect Greenhouse gases Mechanical heat Elevated CO 2 concentrations may benefit crops in the absence of extreme temps.
Wind speeds are lower, but the atmosphere is drier in urban areas
Ozone concentrations are elevated in urban and downwind rural areas Ground level ozone reacts with nitrous oxides (fossil fuel emissions) lowering ozone concentrations Elevated ozone results in: Reduced root:shoot ratios Reduced photosynthesis and necrotic leaves Premature leaf senescence Pumpkin leaf Ozone susceptible green bean necrosis
We have established six research sites along a latitudinal transect in Chicago Monitor crop physiological response to CO 2, ozone, temperature, wind speed and direction, light intensity, and humidity
20 yards of uniform growing media per site onore St. Urban Farm, Chicago, IL St. Charles Research Station, St. Charles, IL Cantigny Park, Wheaton, IL
Opportunities for collaboration with MGs in Cook, Dupage, and Kane Counties
Preliminary (2013) environmental data Temperature ( C) 28 26 24 22 20 18 Wind speed (m s -1 ) 3.0 2.5 2.0 1.5 1.0 0.5 Daytime mean (0700-1900 hr) Nighttime mean (1900-0700 hr) Solar radiation (W m -2 ) 550 500 450 400 [CO2] (ppm) 440 420 400 380 360 VPD (kpa) 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 Kuiper's St. Charles Cantigny Cantata Honore St. Garfield [Ozone] (ppb) Site 60 50 40 30 20 10 Kuiper's St. Charles Cantigny Cantata Garfield
Preliminary (2013) yield data Fresh kale yield (g plot -1 ) 1800 1600 1400 1200 1000 800 600 400 May 28 June 13 June 25 July 2 July 15 3681 b 3890 b 2823 c 2723 c 3834 b 4414 a Onion yield (g plot -1 ) 6000 5000 4000 3000 2000 1000 a b c c b b 200 0 Kuiper's St. Charles Cantigny Cantata Honore St. Site Garfield 0 Kuiper's St. Charles Cantigny Cantata Site Honore St. Garfield
Soil, air, and water pollutants are the biggest threats to urban agriculture
Cities are warmer and the atmosphere is drier, so water becomes critical Municipal water can be expensive and seasonally restricted Recycled water sources may be a sustainable alternative For an urban garden, harvested rain water may be the most practical option
Recycled water could contaminate your urban garden Rooftop materials and the atmospheric deposition of contaminants Microbial pathogens from animal waste Important to manage the first flush of rain Subsurface or drip irrigation can limit pathogen exposure
Be conscious of water flow into the garden Rooftop runoff and stormwater drainage from storm drains and roads may be contaminated Rain gardens are great, but might not be the best place to grow food and herbs
Soil, air, and water pollutants are the biggest threats to urban agriculture
Another option is to avoid this complex environment altogether Controlled environment agriculture Vertical farming Hydroponics Aquaponics
Aquaponics systems are often nutrient limited searching for productive and profitable crops
Vertical, hydroponic, high-tunnel production of food addresses many urban agriculture challenges
Follow BMPs and you can safely grow herbs in your urban garden Urban farming and gardening is challenging but possible Rewards outweigh the risks Time in nature Physical activity Fresh, nutritious food Use raised beds, containers, or add organic matter to your soil