#20 Soil Fertility
Unlike rural farmers who can lay land fallow, the limited availability of urban land often requires that urban farmers keep plots in continuous production, which can lead to the eventual depletion of soil nutrients. Deliveries of nutrient-rich soil and soil amendments can be prohibitively expensive, and making compost or other amendments can be time-consuming or impossible to accomplish at the scale farms need. As such, urban farmers should follow certain best practices to maintain and enhance soil fertility while optimizing use of available space. These include crop rotation, cover cropping, and composting or fertilizing. See Factsheets #21 through #23 for more information about these practices.
Soil Testing Services
* Be sure you have read Factsheets #6 and 7 on Soil Contamination and Dealing with Contaminated Soils. There are different approaches to building soil fertility if the soils you have to work with are contaminated.
AgroOne Services will test soil for nutrients and pH and indicate amounts of lime and fertilizer needed. Soil samples can be mailed, shipped via UPS, or taken to Dairy One’s sample pick-up points (see website), where you will fill out forms and pay for the testing. Your county extension office may also accept samples. Many Cornell Cooperative Extension offices can mail the samples for you, assist in analyzing results, take payment for testing or provide forms and boxes to farmers if they wish to mail their own samples. Results will be mailed in approximately two weeks. To contact the lab call (800) 496-3344 or visit http://dairyone.com/analytical-services/agronomy-services/soil-testing/.
For More Information
The following organizational urban growers’ manuals are great sources of information about maintaining soil fertility on urban farms:
- GreenThumb’s (New York City) Gardener’s Handbook – available as a free PDF at greenthumbnyc.org/pdf/gardeners_handbook.pdf
- The Food Project’s Urban Grower’s Manual (Boston, MA) – available as a free PDF at thefoodproject.org/manuals
Low- or No-Cost Soil Amendments
It can be very beneficial to build relationships with local tree service companies and the municipal organization that collects leaves in your city or town. Tree service companies remove dangerous or unwanted trees and chop them up into woodchips, a very valuable carbon product for urban farmers. Woodchips are useful to delineate pathways and also assist with the decomposition of waste in a compost system. Leaf collection is a service towns and cities provide to residents and typically is the responsibility of a Department of Solid Waste, Highway Department or Department of Environmental Conservation. These facilities frequently stockpile the leaves in huge piles. This “leaf mulch” is an excellent soil amendment and often available for free pick-up by town residents. In some cases, delivery may even be available. Check with your local municipality to find out whether woodchips or leaf mulch are available.
General Soil Health Resources
Information on general soil health is widely available, such as from the Cornell University Soil Health website (http://soilhealth.cals.cornell.edu/). The Cornell Soil Health Assessment Training Manual, also available from this website, is a comprehensive source of information about soil health testing and management strategies for improving soil health, including the use of cover crops, organic amendments, tillage, and crop rotation.
The Sustainable Agriculture Research and Education (SARE) publication, Building Soils for Better Crops (3rd Edition) by Fred Magdoff and Harold van Es, 2010, covers aspects of soil quality and practices for ecologically-based soil management and is available for free download or purchase at sare.org/Learning-Center/Books/Building-Soils-for-Better-Crops-3rd-Edition.
The Brooklyn Botanic Garden Handbook, “Healthy Soils for Sustainable Gardens,” is a helpful guide to all-things soil health, and is available for purchase on-line at http://www.bbg.org/gardening/handbook/healthy_soils.
NOFA-NY’s “Organic Soil Fertility and Weed Management” by Steve Gilman (2001) explains how to build soil fertility by well-planned and well-timed tillage, cover cropping, resting, and feeding, and is available for purchase at http://www.chelseagreen.com/organic-soilfertility-and-weed-management.