4. Dynamics of farming systems and mecanization

4.1 Land-use intensity

In smallholdings located in the tropics and subtropics very complex farm systems have developed on the basis of the close link between the farm and the household. Even if the management of the individual farms varies, still farms subject to similar environmental, economic and social conditions tendencially possess similarly organized farm systems. Ruthenberg (1980) consolidates such similarly structured farm systems under the heading of farming systems, which can be classified on the basis of varied factors (e.g. according to water supply for irrigation and rainfed cropping, or according to intensity of cycles in shifting cultivation, fallow and permanent cropping).

The various farming systems undergo constant change, produced by

1-increasing population pressure due to population growth or migration (e.g. to fertile areas or near towns),

2-better market access because of improved infrastructure or higher product demand,

3-technical advancement,

4-land-tenure structures (land distribution),

5-intervention of the government etc

Most of these reasons have one thing in common: that as a rule they lead to a greater intensity of land use. The land-use intensity, expressed by the so-called R value, is thereby defined by the relationship of cropping years to the sum of the cropping plus fallow years, which is effectively the intensity of rotation (Ruthenberg, 1980).

According to Boserup (1965 in: Strubenhoff, 1988) an increase of the population is the most important single factor influencing the land-use intensity.

Source: Pingali et al. (1987). Tab. C 2: Population density, land-use intensity and predominantly used agricultural implements

Tab. C 2 shows the relationship existing between the population density and the intensity of land use in the tropics, as well as the most frequently used agricultural implements. The figures here merely represent approximate values, since also other factors naturally influence land-use intensity, such as soil fertility or a profitable marketable crop.

With a low population density the predominant land-use form is therefore the forest-fallow system. After clearance and the usual burning of the natural vegetation, there follows a 1 - 2 year timespan of cultivation. Thereafter, fallow must occur for a duration of upto several decades. With the slash-and-burn method planting can be carried out immediately without further soil tillage. The main reasons for short-term use of a field prepared in this manner are:

1 - the low capacity of the soil to produce good yields, which rapidly declines; the farmer is forced to shift to regenerated and more fertile soils.

2 - the soil is loose and free of weeds following slash and burn. Thus, the labour input on recently cleared fields is less than for loosening used soils and particularly for weed control, which progressively increases with longer use.

Tree stumps and roots remain on the field with this system and thereby check erosion; following the cropping period they can resprout. In conjunction with the subsequent long period of dormancy in forest fallow a development of the original vegetation is possible, also the regeneration of soil fertility.

Increasing population density leads to a decrease in the duration of the fallow period. If the population pressure on the soil further continues, a constant land use results without fallow periods. Continued adherence to the previous production technique without a regulated fertilizer management leads to declining soil fertility. The vegetation that develops on the fallow areas, depending upon the climatic zone, indicates an approximation of the length of the former fallow duration. Increasing R values progressively lead from forest to bush fallow, and finally to grass fallow (short fallow) in the humid zones. In savanna zones of more arid areas this development becomes less obvious due to reducing tree density, however the plant associations also become modified here. (Strubenhoff, 1988)

At the stage of short fallow the problem arises that the fire does not destroy the grass roots and a mechanical removal becomes necessary prior to planting. Perennial grasses then cause weed invasion (Pingali et al. 1987). The declining yield and increasing input of the handhoe to till the soil and control weeds effects a reduction in labour productivity with increasing land-use intensity. According to Strubenhoff (1988) the acceptance of animal traction, with increasing land-use intensity, serves to moderate the drop in labour productivity in hand-hoe cropping systems.

In order to facilitate tillage with an animal-drawn plow, a great deal of labour input for clearance must be invested in the forest fallow stage to remove roots and tree stumps (figure C 11). This decreases with a reduction of the fallow and lapses completely with regular annual cropping. Furthermore, with a lower land-use intensity the year round, inputs for keeping draft animals and feeding are high, since for example cleared pastures are often not available for the animals. Within the stage of grass fallow the inputs for keeping animals increases due to better fodder availability. With permanent land use however the amount of inputs required increases again due to scarce pasture resources. The number of work operations for soil tillage and weed control that can be carried out with the mobilization of draft animals increases considerably with higher R values. The expenditures for training animals, for costs of teaching the farmers and the direct investment for purchasing animals and implements remains essentially independent of the land-use intensity.

With hoe cultivation the overall labour input constantly increases with greater intensity of land use due to an increasing investment for soil tillage and weed control; this cannot be compensated for by a reduction in the amount of clearance. The introduction of draft-animal mechanization is only beneficial at a point at which the labour investment per unit of production in handhoe systems (LH) is greater than the investment in the system with animal traction (LA) (figure C 11)

LH = Labour costs per unit of output, using the hand hoe
LA = Labour costs per unit of output, using animal traction

Fig. C 11: Comparison of labor costs with the practice of hand cultivation and animal-powered cultivation - Source: Pingali et al. (1987)

Pingali al. (1987) think that a more work-effective acceptance of animal traction is generally only given beyond the stage of short or grass fallow (R value = 40). This is confirmed by our survey. As shown in figure C 12, 85 % of the regions having animal traction (61 instances) show an R value of more than 40. It is also evident that with a transition to permanent land use the degree of animal traction increases significantly, i.e. the number of farms with draft-animal mechanization (P < 5%).

Fig. C 12: Distribution of animal traction with increasing land-use intensity

In the 11 regions in which animal traction is also employed with low land-use intensity, two are situated in higher locations and a further six in semihumid/semiarid locations; here clearance does not present a problem for using animal traction in cultivation because of the climate and vegetation. The remaining three cases are in regions having a semihumid climate. Noteworthy is however that here the degree of draft-animal distribution is low with less than 5 % of the farms, and in two cases draft-animal mechanization is propagated under the auspices of technical cooperation programmes (Togo, Tanzania). In all three regions problems are encountered in poorly cleared fields. As a result the farmers use their draft animals chiefly for transportation; with 50 - 70 % this represents the main share of the work done by the animals.

In summary, the following factors could render the use of draft animals attractive to the farmers, also for those with low land-use intensity:

1 - the existence of heavy soils, as tillage with the hoe is very hard work,

2 - cropping in areas where the investment for clearance is low, e.g. in grass savanna or flood plains,

3 - a high value estimation or demand for by-products from draft animals (e.g. dung, meat),

4 - the existence of suitable draft animal types and knowledge of animal husbandry,

5 - already existing experience and knowledge (e.g. for migrants) of animal traction methods.

This stands opposed to the fact that in intensive systems applying permanent land use without fallow the transition to the plough has not been realized. Thus, mechanization with draft animals can be ruled out because of severe risk of disease on the animals (e.g. widespread occurrence of the tsetse fly as a carrier of trypanosomiasis), inaccessibility to the fields, steep slopes and increased risk of erosion. The hand hoe remains the most important tool for soil tillage in these areas.

4.2 Agro-ecological zones

In general, the investment for keeping draft animals increases with higher humidity. Here, especially in tropical lowlands the risk of disease for the animals (in Africa particularly due to the occurrence of the tsetse fly) as well as the natural vegetation, and thus the time investment for clearance. As illustrated in figure C 13 this strongly influences the distribution of draft-animal mechanization. Therefore, according to the survey the areas in the tropics where animal traction has found greater distribution are predominantly in the semihumid/semiarid zones and in the highlands.

Fig. C 13: Distribution of animal traction in relation to climate in the tropics

The conditions for using draft animals are also suitable in semihumid areas. The low number of only four instances in this climatic zone is in the first instance due to the small amount of data available from the questionnaire.

The four regions having draft animals in a humid climatic zone (Cameroon, Dominican Republic, Brazil) lie exclusively in locations where high land-use intensity prevails, and only in one case is the degree of engaging draft animals of relatively greater importance. In this exception in the coastal region of the state of Santa Catarina in Brazil animal traction is found in 30 - 50 % of the farms, with an R value of 100. In addition, the transition to motor mechanization has already taken place to a large extent. Thus, in humid regions having a high land-use intensity the use of draft animals can achieve greater importance due to the absence of investment for clearance and less risk of disease as a result of the reduction of the natural vegetation. The state of SPaulo can also be mentioned as an example: in 1975 over 50 % of the farms worked with draft animals, representing one of the most significant regions where animal traction is distributed in Brazil (Casao 1987). Many industrial centres are found in this tropical humid area. The population density and the land-use intensity are also both very high.

In the subtropics, especially in the warm and summer dry areas, the preconditions for animal traction are suitable. Thus, the investment for clearance and risk of disease is low because of the climate and less lush vegetation. Furthermore, the less rapidly decreasing soil fertility in comparison with the tropics allows a more permanent land use. Also, the greater risk of erosion caused by draft- animal mechanization is highly moderated due to the less intensive rainfalls. In these areas many centres have developed with high distribution of draft animals and century-long tradition of animal traction (e.g. the entire Mediterranean region, Afghanistan, Pakistan).

With increasing humidity in the subtropics there is a corresponding increase of investment necessary for clearance in order to use draft animals, and in the constantly wet areas of the subtropics this investment is very high. Plant growth, due to the occurrence of cooler seasons, as well as the risk of animal diseases is less in the humid tropics and thus the preconditions for draft-animal mechanization are somewhat more reasonable 10 out of 14 respondents from subtropical, constantly wet regions in Brazil reported a high degree of draft-animal use on their farms (more than 30 % with draft animals). Also in the remaining four cases draft animals were used on 10 -30 % of the farms.

The introduction of draft-animal mechanization occurred through immigrants to these regions who have experience with animal traction in their tradition (e.g. Polish, Germans, Italians). Noteworthy is however that in all regions there is a high land-use intensity; in 50 % of the cases the land is used every year (R value = 100). Nevertheless, in five regions difficulties with using draft animals arose due to root residues and poorly cleared fields.

4.3 Criteria for the transition

Strubenhoff (1988) has derived a transitional area for the use of draft animals in cropping considering the land-use intensity and the agroclimatic zone in terms of the growing season (figure C 15). The values given here relate in the first instance to the conditions in tropical lowlands. The switching point must be defined for the particular location on the basis of further local endowment factors.

Fig. C 15: Competitive force of animal traction in relation to land-use intensity and agro-climatic zone. Source: Strubenhoff (1988)

According to Herlemann (1961) mechanization occurred in the development of the agricultural sector of a western industrialized country when the production factor of labour in comparison to land became scarce and the labour productivity had to be increased. This was achieved by a substitution of labour with capital. On the other hand, an intensification took place when the land represented the most scarce factor and the productivity per area was expanded with the aid of inputs such as fertilizer or improved seed. In this case land was replaced by capital. For this reason an intensification of agriculture occurred in heavily populated countries, e.g. Germany and Japan, and an increased mechanization could only happen when the labour force migrated from agriculture to the industry. The development in thinly populated agricultural areas in the USA, with its large area, underwent the exact opposite the intensification followed mechanization.

As a result, western experts in many development projects in the Third World have attempted to increase the labour productivity of the farmers by means of draft-animal mechanization where low population densities and minimal land-use intensity are present. These projects have collapsed as a rule, since, for the reasons mentioned, the use of draft animals in stages of low land-use intensity is not able to facilitate the labour productivity of the hoe farmers, especially in humid regions.

Whether technology can improve labour productivity is soon recognized by the farmers, for labour is the main input factor for agricultural production in most of the regions near the equator. As a consequence the farmers rapidly search out and accept new production techniques which increase the labour productivity with not too great a risk. Other ineffective techniques for them, on the other hand, are not adopted. The assessment of the farmers regarding labour productivity increase of any technique is particularly infallible since the execution of work on the fields, in contrast to that of many development experts, is the object of their immediate personal experience. (MacArther, 1980)