Improving vegetable yield, profit, and quality of life on urban farms with a new biobased, compostable weed barrier for narrowly spaced crops

Commodities

Practices

Hand weeding vegetables is time
consuming and back-breaking, particularly in narrowly spaced
crops like leafy greens, carrots, and green onions. Many urban
farmers and gardeners have full-time jobs off the farm and tend
their crops in the evenings and on weekends, which makes the
opportunity cost of hand weeding particularly severe. Common
alternatives to hand weeding in these crops include stale seed
bedding, flame weeding, and tillage with harrow and tine weeders;
however, stale seed bedding displaces valuable time in an already
short Minnesota growing season and flame weeding and tillage are
time-sensitive, only partially effective, and can cause
significant crop damage. For most of our crops, mulching is the
most promising option for lasting weed suppression during the
growing season, but traditional plastic mulch films and
geotextile fabrics are not feasible for narrowly spaced crops
because the number of planting holes required compromises the
integrity and function of the barrier. In addition, plastic-based
films and fabrics can contaminate soil and must be removed and
landfilled at the end of their useful life. We need a viable
biobased, mulching strategy to eliminate hand weeding in narrowly
spaced crops on our farms. 

RootThru

Toward the goal of eliminating
hand weeding in narrowly spaced, high density vegetable crops, we
will test the RootThru Weed Barrier in comparison to our current
weed management practices. RootThru is a composite geotextile
fabric made from two sustainable, 100% plant-based materials –
paper and corn. RootThru is unique from other weed barriers
because we can plant our seeds directly on the barrier and the
seedlings grow and root through it; and yet, weed growth is
effectively suppressed below the barrier. Unlike plastic-based
weed barriers, RootThru is biobased and can be taken to a
composting facility after field removal instead of the
landfill. 

RootThru is installed by
following these four steps: 1) prepare the soil by removing weeds
and creating furrows for seeds; 2) unroll the weed barrier onto
the soil, form fabric into furrows, and secure the edges with
soil or landscape staples; 3) plant seeds into furrows directly
on the fabric or into a layer of weed-free compost or soil mix;
4) cover seeds with additional compost or soil mix and irrigate
daily until seeds have germinated and rooted through the fabric.
Once established, RootThru eliminates the need for hand weeding
and frees time and energy to create value elsewhere on the
farm.  

We received free sample rolls of
RootThru in July 2023 to test at Frogtown Farm and Kilimo
Minnesota Farm in carrot, radish, turnip, sweet corn, jute, and
collard greens. Results were promising and individual growers
were enthusiastic about the product. Nura Ahmed, a long-time
grower at Frogtown Farm said, “I couldn’t believe it, there are
no weeds [in my jute crop] …that is really amazing!” Given the
initial anecdotal success of RootThru, we would like to expand
its use on our farms and quantify the potential benefits for our
farms and share those results with other growers. 

In 2024, we will establish field
research and demonstration trials at Frogtown Farm and Kilimo
Minnesota - Lino Lakes Farm to compare the RootThru Weed Barrier
with existing farmer weed management practices (including straw
mulching, hand weeding, and tine weeding). We will use a
mother-baby experimental design whereby there is one controlled,
replicated “mother” trial at Frogtown Farm and at least 3
non-replicated “baby” trials at each farm. Baby trials will be
valuable for providing additional replication of treatments in
the mother trial (additional validation) and for demonstrating
the technology under real-life conditions (thereby improving the
potential for farmer adoption). In the mother trials, RootThru
will be compared to a combination of mechanical and hand weeding
across three replicated, randomized experimental
plots. 

At the end of the experiment,
RootThru will be removed from the field and delivered to a
commercial composter, Specialized Environmental Technologies
(SET) in Rosemount, MN. SET will also provide the compost
necessary for the trials, demonstrating the full circularity and
sustainability of the RootThru system (whereby compost produced
from RootThru in one season can be used to grow crops in RootThru
in subsequent seasons). 

Data collection plans from these
field trials are summarized in the “Measuring Results” section
below.