Soil and Plant Properties in Cardboard Mulch Prepared No-Till Beds

2010 Annual Report for FNE10-677

Project Type: Farmer
Funds awarded in 2010: $6,107.00
Projected End Date: 12/31/2012
Region: Northeast
State: Massachusetts
Project Leader:
Rachel Scherer
Heritage Fields Farm
Co-Leaders:
Richard Baruc
Seeds of Solidarity Farm

Soil and Plant Properties in Cardboard Mulch Prepared No-Till Beds

Summary

Seeds of Solidarity farm has used cardboard mulch for several years for commercial crops of summer squash, pumpkins, and kale. Transplanting through cardboard into small compost-filled holes has been a low-cost way for us to farm with no mechanical tillage. We have also been advocates of cardboard mulch for home and community gardens because it is easily obtained in urban and suburban as well as rural areas, usually for free. We have established permanent raised beds on our farm and in many community settings by placing cardboard directly onto sod in the fall/late winter, planting through in the spring, and repeating for several years. We observe that by the end of the season, the soil beneath the decomposed cardboard is usually quite friable and rich with earthworms and their castings.
This project seeks to describe the properties of the soil and the plants grown in it when cardboard mulch is used, and whether there are any characteristics unique to cardboard or if comparable amounts of newsprint or hay mulches generate the same soil and plant properties.

To maintain our commitment it community education about the role of no-till methods for sustainability, the project includes a strong educational component, that will be enhanced by adding quantitative information to the anecdotal observations that have fueled our interest in cardboard mulching.

Objectives/Performance Targets

Research Plot Events:

The site that was selected was logged in 2005. It was used to store compost in 2006 and 2007. It was unused from 2008 till April 2010 when a 50×36 area was divided into 12 plots, (3) each of four test conditions:

undisturbed soil
12” mulch hay
1” newsprint + 12” mulch hay
1/4” corrugated cardboard + 12” mulch hay
Soil tests were performed prior to dividing plots and setting out mulch on top of the existing vegetation.

Every three days, soil moisture and temperature readings were recorded. The NE corner of each plot’s mulch was lifted, and earthworms apparent at the surface were counted.

Seedlings (summer squash and kale) were transplanted into the plots by creating holes in the mulch using a dibble, removing a shovelful of dirt, replacing it with fully composted chicken manure.
Soil tests were repeated in August and November of 2010.
In August, tissue samples of the plants were tested for plant sap pH and Brix.

2011 Goals: The 2010 implementation of the project was severely affected by repeated destruction of crops by porcupines. Several fencing and trapping strategies were employed, but control was never effectively established. This had two consequences with regard to data collection: 1- no plant-based studies could be completed and 2- continued replanting in the beds disrupted the sample-collection layout and timetable. After consultation with SARE we decided to repeat the entire study in the 2011 growing season, this time aware of the predation hazard in this isolated, forested setting.

A second setback was the unavailability of adviser Christopher Picone for other than email consultations. We have since researched other methods of assessing soil biodiversity, and will reassign the analysis from his students to a commercial lab.

Education Events:

June 12, 2010: Farm Tour at Seeds of Solidarity Farm with visit to SARE plot

June 12, 2010: No-Till Gardening For Life: Workshop at Seeds of Solidarity Farm

October 2,3 2010: 4 Workshops held at the North Quabbin Garlic and Arts Festival on no-till gardening with cardboard mulch and growing grains or garlic in cardboard mulched beds.

January 15, 2010: Northeast Organic Farming Association Winter Conference :
How Cardboard Makes a Garden Grow (beginner)
Home gardeners will learn how to use cardboard to prepare a garden on “new” ground without need for roto-tilling or manual digging, even in dense sod. The step-by-step description of bed preparation for a low-to-no maintenance garden will be supplemented by reporting a 2010 SARE (Sustainable Agriculture Research and Education) grant documenting weed-prevention, moisture and temperature regulation by cardboard mulch.

Cardboard Mulch for Commercial Growers(advanced): We will present results of a SARE (Sustainable Agriculture Research and Education) grant documenting weed-prevention, moisture, and temperature regulation by cardboard mulch. Combined with the low material and labor costs of the method, it invites a close look application for small and mid-size growers, and implementing for different crops.

Accomplishments/Milestones

2010 Results: Soil temperature and moisture

We were able to record and analyze data on soil moisture and temperature in the 4 plot types. Graphs are appended. In general, the soil temperature and moisture tracked air temperature and precipitation conditions in the undisturbed plots, while the mulched plots varied slightly in how they moderated ambient conditions.

Mulch hay and Newsprint+Mulch Hay took longer to warm in the early part of the season, and longer to stabilize mid-season, remaining somewhat cooler than the control and the cardboard+mulch hay plots. The Cardboard+Mulch hay plots warmed faster in spring, stayed cooler in midsummer, and stabilized faster and for longer than any of the other conditions, although by August, all the plots had stabilized and provided more consistent temperature than undisturbed soil.All the experimental mulched plots were dryer through spring and moister through the growing season than the undisturbed soil. The most readily observed difference between the mulches is the stabilization and consistency of the cardboard mulch from July-October, when it showed the most consistent moisture with the least variation with respect to rainfall.

Impacts and Contributions/Outcomes

Plant monitoring in SARE plot 2010:

A balanced level of nutrients in the leaf of the plant will show an ideal pH level of 6.2-6.4. (Bruce Tainio, Acres USA April 2005) This was recorded for tomatoes (salad and paste) basil, summer squashes,and pumpkins.

A lower than ideal pH level will indicate a deficiency in the following minerals: Calcium, Potassium, Sodium or Magnesium. This was recorded for: Lacinato and curly kale, brussel sprouts
A higher than ideal pH level will indicate a deficiency in Phosphates, Nitrate Nitrogen, Sulfates and trace minerals (none ).

The proposed Brix monitoring was hampered by the severe plant predation (see above), which made it impossible to collect statistically significant samples.

Earthworm observations and formulated hypotheses to test

The most intriguing observations in the SARE plots echoed the farm’s longstanding contention that under the cardboard, the earthworm population increases rapidly. We were unable to implement a rigorous method of monitoring the earthworm population in 2010, but intend to put one in place in 2011.

Every 3 days, a corner of the mulch was lifted and the earthworms visible on the surface counted. The cardboard mulched plots had earthworms present after the first 3 days, while the other plots did not have any – if at all- for over one month. There were consistently at least twice as many earthworms in the cardboard mulched plots as any of the others.

This provokes the question – What attracts the earthworms so quickly?
We now hypothesize that access to leaf litter on the undisturbed sod under the cardboard, plus the consistent moisture in that layer, with the addition of very secure protection from predation by birds
makes the cardboard mulched areas a better source of food, shelter, and safe space for reproduction.

A second aspect of earthworm biology that would be positively affected by the cardboard mulch is wintering-over. Earthworms require a gradual adaptation period to winter-over. The more time they have to adjust to colder temperatures, the longer they remain active, and the higher number present will be able to achieve a successful dormancy. Soils with good overwintered earthworm populations can have earlier warming and draining, and the active draining via the earthworm channels minimizes frost damage in the form of soil clumping (Daniel Ernst: The Farmers Earthworm Handbook). The continuous year-round cover of cardboard may be positively influencing this aspect of the earthworm population. A key focus in 2011 will be to monitor earthworm populations.

Collaborators:

Christopher Picone

cpicone@fsc.edu
Faculty
Fitchburg State College
Fitchburg, MA 01420
Office Phone: 9786653079