MAYA PROJECT RESULTS: Hands-on Habitat Conservation
1. Alternative agricultural methods--saving forest through
use of "green manure" cover crops
Vinicio Montero, agricultural extensionist for CARE
International, explains to farmers the advantages
of using green manure cover
How much forest might be spared by use of appropriate alternative farming methods--especially "green manure" cover crops?
Our efforts in the agricultural sector were geared toward answering this question and toward demonstrating the power of this approach in one small section of the farming landscape.
We worked in three small villages just south of Tikal National Park, focusing in the village of El Caoba. This village is typical of many small villages in the moist tropics of Latin America, and we may take this case as an
example of what might be achievable elsewhere.
Several years of alternating corn and
have produced rich,
dark humus and robust ears of corn.
Our efforts may be divided into four parts. First, by consultation with agronomists, we sought to verify whether the use of "green manure" cover crops would likely permit the continued cultivation of the same acreage
over a multi-year time span. If so, then the potential would seem to exist for saving a great deal of forest that would otherwise by cut down for farming purposes.
Second, we sought to promote the use of one such cover crop--
frijol abono (Mucuna species: also known as velvet bean)--by farmers in our focal village, in order to help save forest there.
Third, we conducted trials, comparing corn yields in association with use of frijol abono with yields without frijol abono, in order to evaluate the magnitude of the potential benefit of this farming method to
Finally, we sought to calculate how much forest would be spared if all the farmers in one small village ceased to cut additional forest, using cover crops instead, to permit sustained cultivation of the same acreage. In order
to achieve this estimate, we conducted a detailed survey of farming and land-use practices in our focal village.
Distributing frijol abono (Mucuna sp.)
The answer we received to the initial question was yes, many instances exist demonstrating that use of green manure cover crops can make long-term cultivation of the same plot of ground both feasible and economically advantageous.
In addition, we found one local farmer who had used frijol
abono for years, allowing him to repeatedly grow corn on the same acreage. Soil in his corn fields was rich with dark humus, and greatly impressed the farmers with whom we visited his fields.
Based on this encouraging evidence, we proceeded, and worked with some 120 farmers in three villages, providing them (through the assistance of CARE) with frijol abono seed, and advising them in its use. Thirty farmers
participated in a most sustained fashion and, over a period of three years, several of them became enthusiastic devotees of this technology, declaring toward the end of the period that they would never again cut down mature
forest for farming purposes--that there was simply no reason to do so, given the potential of the frijol abono system.
Are the advantages of this technology sufficiently compelling to farmers, in order to gain their acceptance? Through controlled trials, we found that use of frijol
abono resulted in a 47% increase in corn yields. Certainly many farmers find this prospect attractive.
A farmer shows off a vigorous new stand of frijol
abono in a slash-and-burn corn field.
Regarding the farming landscape where we worked, how much forest might be spared if all farmers ceased cutting forest for farming purposes? In 1994, of the 194 families comprising the village of El Caoba, 181 families engaged
regularly in farming, mainly subsistence corn-farming. On average, these families cultivated 2.23 hectares each year (about 5.4 acres), felling 2.43 hectares of forest yearly--0.63 hectares of primary forest and 1.8 hectares
of woody regrowth. Assuming the year 1994 was typical of recent patterns, and assuming results of our door-to-door survey are reasonably accurate, the farmers of this village currently fell about 115 hectares or 283 acres
(nearly half a square mile) of mature forest each year--as well as 326 hectares (805 acres, or more than one square mile) of successional forest.
During end-of-season field trip, farmers proudly show
one another the results of their efforts combining frijol
abono and corn.
If use of frijol abono or other green manure crops could permit continued cultivation of crop fields, then the amount of primary forest that might be spared by this single village is roughly 115 hectares yearly. Over
a 10-year period, this amounts to 11.5 square km of forest. Clearly, this would be a significant achievement for conservation. For example, our data on densities of Kentucky Warblers wintering in forest at Tikal (0.96 birds
per hectare of mature forest) indicate that a savings of 11.5 km2 of forest over a
10-year span amounts to winter habitat for 1100 Kentucky Warblers. No doubt thousands of other species of plants and animals would also benefit.
Nothing succeeds like success; corn fields
with frijol abono yielded 47% more corn
than did fields without.
To conclude this section, we consider it entirely feasible for farmers in this area to completely cease cutting of primary forest, and to greatly reduce their cutting of young second-growth, through the use of green manure
In our opinion, a great deal of tropical forest can be saved by changing the dynamics that today lead to continual deforestation by peasant farmers. At the local, grassroots level, making appropriate alternative farming technologies
available to farmers can help them farm for the long term on the same acreage, doing away with the need to cut down additional forest for strictly agronomic reasons. At the nation-wide, political level, dealing with social
issues such as skewed land ownership patterns and poor availability of education, health services, and jobs can also help defuse the demographic and societal pressures that result in landless farmers migrating into remaining
forests in search of land to farm.
Pristine forest on karst terrain
in western Belize.
We feel that international conservation and development agencies would do well to put increased attention into this avenue of forest conservation.
Some Factors Affecting Farmer Acceptance of Cover Crops
Promoting greater use of "green manure" cover crops is not without its challenges.
The enhanced corn production we observed in our trials is certainly attractive to farmers, but obtaining such results depends on additional factors, principally rainfall, which is notably variable in our project area.
Also, there is a certain amount of work and persistence involved in establishing a stand of frijol abono. Hence, not every farmer is necessarily willing to stay the course and give this method a fair trial.
A major factor, however, is likely the following: so long as mature forest is freely available for the felling, many farmers may elect to continue felling forest each year, rather than switching to use of cover crops. This
may occur for various reasons, perhaps mainly because farmers prefer methods with which they already have firsthand experience.
However, where primary forest is already scarce, or where adequate control is exerted by government in order to prevent its felling, then green manures unquestionably offer a viable alternative to farmers. Our feeling is that
with sufficient promotion of green manures, sufficient investment in agronomic research and extension, and sufficient legal mechanisms discouraging felling of primary forest, it should be possible to cease all felling of
primary tropical forest worldwide, without suffering any decline of global crop yields.
Research is needed, especially to tailor practices to local conditions. No single green manure plant is a universal answer to farmers' needs everywhere. Rather, different species and management practices are preferable under
Technical assistance must be made available to farmers through local, field-oriented extension programs. A program of small, low-interest loans to farmers could also help stabilize land use and decrease deforestation rates.
In many tropical nations, additional government investment is badly needed in agricultural research and extension.