BRASSICAS AS BIOLOGICAL PLOWS
Jim Wolfemajor threat to the sustainability of Monte-
verde farms is soil compaction. Decades of
intensive dairying have created a hard soil
pan. Precipitation and fertilizer run off this pan rather
than percolating into the soil, which wastes fertilizer,
diminishes grass production, and causes erosion. Tra-
ditional methods of loosening the soil are plowing with
a moldboard plow pulled by oxen or tractor, or shov-
eling by hand. These methods improve forage growth
but also cause substantial soil erosion. Many farmers
plow just before the wet season to ensure moisture for
grass growth; freshly loosened soil is most vulnerable
to erosion. A modern alternative that avoids erosion is
the use of plows that break up the subsoil without dis-
turbing the surface horizon. Subsoil plowing requires
a powerful tractor and cannot be used on steep slopes,
so it has limited application in Monteverde.
A successful alternative is to plant brassicas
(Brassicaceae). A cross between Chinese cabbage and
mustard (known commercially as Tyfon) and forage
rape have produced the best results. First, existing
pasture grasses are chemically "burned" back but not
killed with an herbicide. A complete fertilizer (NPK
10-30-10) is applied to the field. Seed is broadcast
during a wet period (usually in June and October).
Seeding rates are 20% higher than recommended for
a commercial harvest. After spreading the seed, cows
are herded over the entire area; their hooves push the
seeds into the soil.
The brassicas are quick to germinate and grow rap-
idly enough to shade out most weeds and retard the
growth of grasses. Their wide leaves protect soil from
rain-induced erosion. Their thick roots reach down
to about 80 cm and effectively loosen the soil. As they
die and decompose, the root channels allow water and
nutrients to infiltrate the soil. Although pasture does
not produce grass when it is planted in brassicas, the
brassicas themselves are a high-protein forage. After
2-3 months, they reach a height of nearly 1 m and are
ready for harvest. Tyfon may be fed directly to lactat-
ing cows; rape is cut into smaller pieces. Both offer
20% protein and are more digestible than alfalfa. Two
cuttings are possible before grasses take over. Within
several months, the field returns to maximum grass
production.
Using brassicas as biological plows has many ad-
vantages. Expensive machinery and intensive manual
labor are unnecessary. The high-quality forage com-
pensates for the time the land is removed from grass
production. Soil compaction is reversed and erosion
is prevented, which helps farmers maintain long-term
pasture productivity.PASTURE BURNING
Katherine Griffithasture burning can be an agronomically sound
practice (Sanchez 1982,1987), providing phos-
phorus, reducing acidity and aluminum toxic-
ity, and returning unpalatable, overly mature forage
to the soil in the form of ash. Fires cost nothing, in
contrast to fertilizers. They require little managerial
skill or labor, no infrastructure, and little institutional
support. In many environments, however, burning is
a largely destructive practice. In hilly areas, it exposes
the soil to the highly erosive rains at the beginning of
the wet season. Wind carries away much of the ash,
and a potentially large portion of the nutrients are
volatilized. Fires frequently burn out of control. Acontinuous smoky haze covers much of Costa Rica's
Pacific coastal plain during the last month of dry sea-
son as fires burn for days at a time.
During the 1970s, burning became illegal, in
recognition of air pollution, safety hazards, and the
soil degradation that it caused over the long run.
When oil prices rose sharply in 1979, fertilizers were
too costly for many farmers, so government policy
changed; agronomists recommended burning as a way
to maintain pasture fertility. This practice is used in
beef and dual-purpose enterprises in the Monteverde
milkshed but is much less frequently used on dairy
farms. The current legality of burning is ambiguous.411 Agriculture in Monteverde: Moving Toward SustainabilityA
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