TRADITIONAL KNOWLEDGE ON MICROCLIMATE MODIFICATION

AN ETHNO-SCIENTIFIC APPROACH IN TANZANIA

The relatively recent recognition that sub-Saharan Africa is in a deep crisis has fostered many inventorial studies on African affairs. Research endeavours and particularly those in agricultural research have not been excluded from this review rage. And the resulting diagnosis is as negative as on most other subjects studied. These recent reviews on agricultural research have a few main conclusions in common.

Firstly the present situation has its roots in the colonial past, in which a dual agricultural economy emerged: a plantation economy serviced by a network of scientific institutions alongside an African subsistence economy which received little or no scientific attention. This situation largely continued in national research efforts after independence. Secondly, the slow expansion rate of University faculties of Agriculture may be taken as the main cause for the present severe shortage of agricultural scientists, despite long-standing commitments to become more self-reliant in this field. Thirdly, courses at African Universities often use curricula developed outside Africa or by outsiders with too short an experience inside Africa, and there is a general tendency of those remaining in research to continue working on subjects largely irrelevant to local smallholder production. And finally, traditional knowledge on local conditions is not valued. Rarely do researchers and extension workers undertake the additional burden of listening to farmers who are using few inputs from outside and inviting them to participate in outlining, performing, validating and using the results of research.

Whether the last two conclusions will continue to be drawn in the near future depends heavily on the national impacts of recent international trends, because internationally increasing attention is now being directed to local farming systems and smallholder participation in collecting, researching and disseminating the locally most successful traditional agricultural practices. This kind of research, with what we may call an ethno-scientific approach, will not be the only one needed. But as long as most of the African -subsistence (or near-subsistence) farmers will have to practice a low external-input agriculture (with respect to their food crops) it will be an extremely important one. Only if this research policy and other policy measures have led to improvement of their conditions, may research on the introduction of seed, fertilizer and water applications specific to the smallholder economy be able to support the next step upwards.

How to tap local knowledge?
The author spent five years (1975-1980) with counterparts and students building up teaching and an infrastructure for research in physical aspects of agricultural meteorology at the Physics Department, University of Dar es Salaam. However, in that whole period we completely failed to obtain local information on a subject thought to be extremely important for research: how traditional farmers in Tanzania learned by trial and error to modify the microclimate of crops to improve quantity, quality and above all protection of their yields. This failure was, after all, understandable against the background of the conclusions reviewed above. Only limited attention had ever been paid to traditional methods of managing soil, water and vegetation, but the least attention of all had been accorded to local knowledge acquired on management and manipulation of the microclimate. This had been recognised by Professor Gene Wilken, a geographer at Colorado State University, who had made a preliminary review of examples of such modifications applied by traditional farmers from all over the world in 1972. But nobody in agricultural meteorology and microclimate research appeared to pick up the challenge his review provoked.

Failing time and again to obtain much information along the official lines, even after having established with colleagues of the Tanzanian Directorate of Meteorology a National Agrometeorological Committee, we resorted to a scientifically unorthodox method: tapping the public at large through a newspaper contest. Of course, in Tanzania still close to 90% of the population works in agriculture. And even among those reading local Kiswahili and English newspapers the large majority come from rural areas and families. Very many of them have their own low-input “shambas” (agricultural plots) to help them to survive with little means, the harsh economic conditions of the city and/or they have close relatives who are farming and with whom they have strong social links which yield mutual support in harsh times. Knowing we would not reach small peasants directly by a newspaper contest, we hoped to reach those newspaper readers and we stimulated them to write up their examples by offering generous prizes for the best (reviews of) examples.

Traditional microclimate modifications
The contributions we obtained, late 1980/early 1981, were generous in number (more than a hundred) and in more than 25% of cases extremely useful and of high quality. From these we first made a catalogue, a shortened version of which is given in the Table. This shows which manipulations and which kinds of management are used by traditional farmers to modify the microclimate of crops and produce. We were also able to single out a series of subjects which appeared most important and least studied from the point of view of traditional applications. These were shading, mulching (covering by a layer different from the original soil), wind protection and modification at/or surfaces. Other important conclusions were that the examples collected were often extremely local in their application and that there was much room for dissemination of such practices.

Shading is a subject about which a reasonable amount of knowledge has been collected on plant physiological aspects, but hardly any work has been done on aspects relevant to the agricultural meteorology of smallholder farming systems such as agroforestry and other multiple cropping systems. Labour intensive systems using soil and seedling protection and modification of soil temperature and moisture conditions by mulching have been studied extensively in horticulture, but the trend towards more and more climate controlled greenhouse cultivation in Japan and the Western countries has appreciably diminished research in this area. This is even more true for the materials locally available in the tropics.

Wind protection by traditional farmers in the tropics appears to be completely different from the single and multiple row windbreaks used and researched heavily in more developed agriculture. Protection at four sides (or nearly so) and making use of wind reduction by scattered obstacles such as trees and bushes are found to be extremely important but there are hardly any studies of the efficiency of such systems.

Table: Examples of Manipulation of Climate

Manipulation of radiation
-Shading
-Increase or decrease of surface absorption
-Cover for radiation loss at night
-Using solar radiation for field and in-storage drying

Manipulation of heat and/or moisture flow
-Non-Tillage
-Mulching
-Windbreaks or other shelter (storage)
-Protection for ripening purposes
-Influencing flow processes by changing conditions at/on the surface•
-Using warmed air for field and/or storage drying
-Manipulating natural dew fall

Manipulation of mechanical impact of wind, rain and hail
-Changing of wind speed and/or direction
-Planting in lower places or pits or where deep rooting is possible
-Improving soil conditions by natural deposits
-Protection from soil erosion by wind, rain and hail
-Protection of crops and produce against impact by rain, hail and wind
-Use of wind for winnowing

Two general examples
-Fitting cropping periods to the seasons
-Making use of superhuman intervention

Finally, the exposure to the atmosphere of and the impact of the environment on agriculturally relevant surfaces is often modified in ways very particular to traditional technology. This applies to various managements and manipulations such as traditional irrigation, drying, storage and soil and crop protection.

Once the “state of the art” was discovered from studying the Tanzanian examples we did two things. We singled out a few subjects for local MSc research and we tried to rouse international interest in traditional microclimate modification, so as to be able to confirm our findings elsewhere in Africa, in Asia and in Latin America. An official report will be published this year by the World Meteorological Organisation whose Technical Commission for Agricultural Meteorology singled out the subject in 1983 for a specialised Working Group study. The MSc work in Dar es Salaam concentrated on the efficiency of local grass mulch applications, in cooperation with the Tea Research Foundation of Kenya, where efficiency of erosion protection and temperature manipulation by mulches had been studied. Temperature modification and shading efficiency of the same mulches were now studied in Dar es Salaam with the infrastructure built up earlier and physical theories to explain these efficiencies were developed. The result was an operational method of determining quickly the thermal efficiency of local mulches and provision of advice (which we call weather advisories) for farmers on quantities and qualities of dry and live grass mulches traditionally applied. This kind of work showed that even at the MSc level research may be done that can be relevant to low external-input agriculture.

Future Work
Much more has to be done before we have developed a new area of applied research in agricultural meteorology which can be carried out by Third World research students and supervisors and which is rooted in tapping local traditional knowledge.

Based on the Tanzanian experience the author has recently started a project in which he co-supervises PhD research in Kenya, Sudan, Tanzania (with India to be added soon) on the four main subjects reviewed above, by backstopping from the Netherlands and frequent travelling. We are working on the effects of the re-introduction of traditionally applied light shade in tea growing in Kenya, a traditional irrigation method and its water use efficiency for groundnut and sorghum compared to “laissez faire” furrow irrigation in the Sudan, traditional wind protection from scattered trees against wind erosion effects and of parts of homegarden systems against mechanical wind damage in the Sudan and Tanzania respectively.

It appears that tapping local knowledge works in research on low external-input agriculture. But for this to happen it is essential for farmers and extensionists to be involved from the beginning. Only then might we be able, in places where the population pressure is not yet the all-determining and all-overriding factor, to improve a bit, in some cases, on the efficiency of traditional methods. But, even more important, we might in this way succeed in disseminating such traditional technology, now better understood, to places and conditions where it was not applied before.
Kees Stigter

Dr. C. J. STIGTER was a Professor of Physics at the University of Dar es Salaam from 1975 to 1984. He is now a Principal Research Scientist at the Wageningen Agricultural University, the Netherlands.

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