Research

Recent Reports:
The Safety of Rainwater Harvesting
Brooklyn College Soil Study Finds “Surprising” Levels of Lead in NYC Soils
Kristy King Announces Insect Study Results


The Safety of Rainwater Harvesting

During the 2010 season, a new feature of the West 104th Street Community Garden is a rainwater harvesting cistern which collects runoff from an adjacent building into a 3,500 liter tank in the West Garden. In response to gardener concerns about the safety of the cistern water in the 104th Street Community Garden, we are providing the following links to websites with relevant information.

Grow NY website
http://www.cenyc.org/openspace/rainwater

Grow NY manual for water harvesting
http://www.cenyc.org/files/osg/RWH.how.to.pdf

Rutgers Extension page for water harvesting
http://water.rutgers.edu/Stormwater_Management/rainbarrels.html

Rutgers facts sheet re: maintaining water harvesting systems
http://njaes.rutgers.edu/pubs/download-free.asp?strPubID=FS1118

The issue of testing the water in the runoff tank on the west side for growing vegetables has been pursued by Steering Committee Member, Nikki Kowalski. She has found that Rutgers University seems to be at the vanguard of the issue and that the testing of the water requires repetitive and costly analysis to be considered conclusive. At this point, Nikki intends to approach Green Thumb to see if they may be interested in funding the analysis. In the meantime, for those gardeners who remain concerned, two of the water barrels on the W/S will carry only hydrant water and will be labeled as such.

Brooklyn College Soil Study Finds “Surprising” Levels of Lead in NYC Soils

The 104th Street Community Garden participated in a soil study performed by The Brooklyn College Environmental Sciences Analytic Center. The following is a preliminary release regarding soil samples throughout the city. The overall results do not necessarily reflect the health of our own garden, but do indicate alarming levels of heavy metals, including lead, in New York City soils. We eagerly await the results of the follow up study and will report any results specific to our garden, when the report becomes available.

Brooklyn College Results

“The Brooklyn College Soil Analysis lab received many soil samples from residents throughout New York City. The lab analyzed heavy metal content in the soil with some surprising results. Lead content in some soils were sometimes as high as 2000ppm. As a follow-up pilot study we would like to measure the air quality in and around some of these gardens. Looking at the air quality may show us whether particulates from the soil are getting into the air, and we would like to see if this is happening and to what degree people are breathing in heavy metals as they work/play around the soil. By performing this pilot study we would like to determine if we need to expand our research not into just soil analysis but into air quality surrounding community and private gardens throughout NYC.”

For more information about lead in NYC gardens, read the New York Times article:

For Urban Gardeners, Lead Is a Concern, May 13, 2009
http://www.nytimes.com/2009/05/14/garden/14lead.html

Lead Remediation Tips

Tips recommended in this article for avoiding high levels of lead in gardening soil include:

    • The best approach to avoiding lead contamination in gardens is what we do at the West 104th Street Garden: Build raised or contained beds lined with landscape fabric and filled with uncontaminated soil. Plants that are grown in containers with soils from a garden center are unlikely to contain high amounts of lead.
    • Replace the contaminated soil or alkalinize it by adding lime or organic matter such as compost. Higher alkalinity (pH level above 7) allows soil particles to bind with lead, making it less likely to be absorbed by plants and the human body if the dirt is inadvertently inhaled or ingested.
    • Plant kitchen gardens with fruiting crops like tomatoes, squash, eggplant, corn and beans, which do not readily accumulate lead.
    • Avoid lead-leaching crops, such as herbs, leafy greens and root vegetables such as potatoes, radishes and carrots.
    • Planting greens, specifically Indian mustard and spinach, for a couple of seasons before growing crops intended for food. This phytoremediation, or plant-based mitigation, allows lead to be removed from the soil. These plants must not be eaten or composted, but disposed of as toxic waste.
    • To avoid contamination from lead dust blowing in the wind or rain splashing off lead-painted structures, situate gardens away from buildings.
    • Wash edible produce thoroughly with water containing 1 percent vinegar or 0.5 percent soap.

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  • Cover soil with sod in areas where you are not planning a garden.

Kristy King Announces Insect Study Results

Factors Contributing to the Assembly and Maintenance of Insect Communities in Manhattan Community Gardens
By Kristy King, MS Conservation Biology, Columbia University

ABSTRACT

My research aims to determine what factors are contributing to the assembly and maintenance of insect communities in Manhattan community gardens. The effects of plant structural complexity, food crop diversity, neighboring land uses, and trees bordering the garden were measured and used as independent variables to predict the diversity, abundance, and ratio of parasitoid wasps and Hemipteran pests. Over fifty morphospecies of parasitoid wasps and seven families of Hemipteran pests were collected over a two-month period in twenty community gardens. Plant structural complexity was found to have no discernable effect on pests or parasitoids in community gardens, but the abundance of pests is positively associated with the diversity of food crops in the gardens (p<0.005; Adj. R2= 0.3384). Parasitoid wasp richness is explained by a combination of pest abundance and the number of trees within a 1m radius of land around each garden (p<0.005; Adj. R2= 0.4067). This implies that insects may be experiencing the landscape on a much larger scale than originally believed, and that individual garden management may not be an important driver of beneficial insect communities in these urban habitat fragments.

Specifics for West 104th Street gardens:
– 21 parasitoid wasps collected; 10 wasp morphospecies collected (this is pretty average, compared with the other gardens that I studied)
– But! Six unique wasp species were collected in the West 104th street gardens! This is high, compared with the other gardens that I worked in. So, of the nearly sixty morphospecies collected in all twenty gardens, roughly one-tenth of them were unique to the West 104th Street gardens. This may be something you can brag about in the grant proposal (a unique and beneficial insect community).
– Plant structural complexity in the West 104th Street garden is average, compared with other New York community gardens.

About the Author:
Kristy King is a graduate student in Conservation Biology at Columbia University. This research was developed for her Master’s thesis. Ms King has general interests in urban ecology, and after graduation in May 2008, she will begin a position with the NYC Parks Department.