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close this book Animal-Drawn Wheeled Toolcarriers: Perfected yet Rejected
close this folder 7. Observations on Wheeled Toolcarrier Programmes and Reports
View the document 7.1 Observations on technical designs
View the document 7.2 Observations on private sector involvement
View the document 7.3 Observations on terminology
View the document 7.4 Observations on the literature relating to wheeled toolcarriers

7. Observations on Wheeled Toolcarrier Programmes and Reports

7.1 Observations on technical designs

7.1.1 Specifications and compromise

Most of the forty-five designs listed in Table 7.1 have been proven capable of performing agricultural operations on research stations, and thus have been technically competent from the engineering point of view. Indeed it might be argued that one major problem with the majority of toolcarriers is that they were built on the basis of excellence of engineering rather than adaptability to the farming systems. Design considerations have been discussed by Kemp (1980), Bansal and Thierstein (1982) and Garg and Devnani (1983) and emphasis here will be placed on principles rather than specific comparisons. By way of example some of the specifications and prices of three toolcarriers made by one manufacturer are given in Tables 7.2 (p. 110) and 7.3 (p. 111). In Table 7.4 (p. 112) examples are given of the costs of toolcarriers from all current manufacturers who maintained export price lists in 1986/1987.

In general all aspects of wheeled toolcarrier design have to be based on compromises between the need for high versatility and the needs for low cost and simplicity. As a result no toolcarrier can ever be "perfect". The most successful model in recent years has been the Tropicultor and its derivatives. This is very strong and very versatile, but as a consequence it is often considered too heavy and too expensive. One good feature is its high clearance for inter-row cultivation, yet this is offset by a poor feature, for the Tropicultor's height means that the cart option can be unstable when laden, and liable to tip over in deep ruts. Towards the other extreme is the Agribar, which is much lighter and cheaper, yet these benefits have been achieved at a cost of reduced convenience of operation and fewer options.

Table 7.1: List of some toolcarrier designs and numbers manufactured

DATE1

NAME2

COUNTRY3

DERIVATION4

NUMBERS5

1955

Polyculteur (Leger)

Senegal

Jean Nolle

4 (m)

1956

Polyculteur(Lourd)

Senegal/France

Jean Nolle

300 (m)

1957

Polyculteur M-N

France

Jean Nolle

1 200 (m)

1960

NIAE ADT

U.K.

Original

30 (e)

1961

Tracteur Hippo

France

Jean Nolle

25 (m)

1962

Otto Frame

India

Original

100 (e)

1962

Nair Toolcarrier

India

Original

100 (e)

1962

Tropiculteur Mouzon

France

Jean Nolle

1650 (m)

1962

AVTRAC

France

Tracteur Hippo

35 (m)

1963

TAMTU toolbar

Tanzania

NIAE ADT

<10 (e)

1963

Aplos

U.K.

NIAE ADT

600 (e)

1965

Baol polyculteur

Senegal

Polyculteur

800 (e)

1965

Uniwersaloy Kinny

Poland

Original

100 (e)

1965

Xplos

U.K.

NIAE ADT

400 (e)

1967

Balwan toolcarrier

India

Original

50 (e)

1968

Kenmore

U.K.

NIAE ADT

300 (m)

1971

Makgonatsotlhe

Botswana

Original

125 (m)

1971

Versatool

Botswana

Prototype

15 (m)

1972

Makerere Toolbar

Uganda

Prototype

<10 (e)

1973

Tropic Polyculteur

Cameroon

Tropiculteur

50 (e)

1975

ICRISAT Tropicultor

India/France

Tropiculteur

1 400 (m)

1976

UEA Toolcarrier

U.K.

Versatool

<10 (m)

1978

Nolbar/Agribar

India/France

Jean Nolle

40 (m)

1978

Akola Cart TC

India

Prototype

<10 (m)

1978

Agricart

India

Tropicultor

70 (m)

1978

Tropisem

France

Original

50 (e)

1978

Paraguay Tropicultor

Paraguay

Tropicultor

30 (e)

1979

Nikart

India/U.K.

Original

200 (m)

1979

Multicultor CPATSAI

Brazil

Tropicultor

50 (e)

1979

Bultrac

India

Original

<10 (e)

1980

GOM Toolcarrier

U.K.

Nikart

120 (m)

1980

Malviya MFM

India

Original

50 (e)

1980

Udaipur toolcarrier

India

Prototype

<10 (e)

1980

Shivaji MFM

India

Original

50 (e)

1980

Akola toolcarrier

India

Prototype

<10 (e)

1980

TNAU toolcarrier

India

Prototype

<10 (e)

1980

Uyole toolcarrier

Tanzania

Prototype

<10 (m)

1980

Polynol

France

Tropicultor

30 (m)

1981

Sahall Lioness

U.K.

Original

150 (e)

1981

Multicultor CPATSA 11

Brazil

Prototype

<10 (e)

1981

Mozambigue Tropicultor

Mozambique

Tropicultor

506

1981

Yunticultor

Mexico

Nikart

120 (m)

1982

Polycultor 1500

Brazil

Tropiculteur

1100 (m)

1982

CIAE toolframe

India

Prototype

30 (m)

1982

WADA toolcarrier

Cameroon

Prototype

11 (m)

1984

ATSOU

France

Prototype

<10 (e)

1985

Yunticultor Mk II

Honduras

Yunticultor

<10 (m)

1986

Lanark/CECI

Canada

Prototype

<10 (m)

   

TOTAL (very approximate)

10 000

1Approximate date of first prototype.

2Name commonly used to describe implement (some are trade names).

3Principal country of development and/or manufacture.

4Derivation of toolcarrier or source of inspiration (where known).

5Although many are based on manufacturers’ figures (m) some numbers on this table are only estimates (e) of numbers of wheeled toolcarriers made since the design was first developed. They serve only as a general guide and do not relate to numbers sold to farmers or used in the field.

6Figure of Mozambique based on number that may have been manufactured; the materials and components for the fabrication of several hundred toolcarriers were purchased, but since by 1986/87 they still had not been used they are not included in theis list.

Many toolcarriers (including early Polyculteurs and the Nikart) had a fixed wheel track. This reduced manufacturing expense and the number of adjustments necessary. However this also meant that plowing with a single mouldboard plow could be complicated for, if one ox walked in the furrow, the plow body had to be wry offset to the line of draft. On the Nikart this was partially overcome by giving the draw-pole, or "diesel boom", a second offset position. Some workers have said that this has compromised convenience in favour of improvements in draft alignment, although the designers have argued that there is no loss of convenience in this case. Fixed wheel spacing made the inter-row cultivation of crops with different row spacings inconvenient or impossible.

Table 7.2: Comparative specifications of some wheeled toolcariers

Specification

Tropicultor

Nikart

Agribar

Weight (kg)

200

170

135

Wheel type

Pneumatic

Pneumatic

Solid rubber

Wheel diameter (mm)

720

640

300

Wheel bearings

Ball bearing

Ball bearing

Mild steel bush

Transport capacity (kg)

1000

1000

Nil

Pitch adjustment

Gradual/screw

Steps/pin

Steps/pin

Depth adjustment

Steps/pins

Gradual/screw

Steps/bolts

Wheel track adjustment

Yes

No

Yes

Crop clearance

High

Low

Low

Average draft1 (kN)

     

Plowing (rainy season)

1.81

1.77

1.81

First weeding

1.13

0.98

1.13

1Draft measurements taken on station at ICRISAT Centre, Patancheru, India, using similar implements on all three toolbars.

Source: Mayande, Bansal and Sangle, 1985; ICRISAT, 1985; Mekins, undated

Table 7.3: Sample prices of three toolcarriers from one manufacturer1

Specification

Tropicultor

Nikart

Agribar

Basic chassis

600

550

200

Cart frame (without wood)

100

100

n/a

Plows (one left-hand, one RH)

52

52

52

Ridgers (two)

46

46

46

Clamps (ten) and toolkit

50

50

50

Tines (five spring, five rigid)

60

60

60

Wide blade harrow (120 cm)

30

30

30

Inter-row weeding blades (five)

56

56

56

Steerable toolbar

40

40

40

Angle blade scraper

75

75

75

Peg tooth harrow

50

50

50

Disc harrow

100

100

100

Planter/fertilizer applicator2

615

450

125

Basic ex-works price

1874

1659

784

F.O.B. charges3

200

200

200

C.I.F. charges4 to seaport

580

580

290

Total cost (African) seaport

2654

2439

1274

1Figures are based on December 1986 export prices of Mekins Agro Products of Hyderabad, India. These figures are intended only as a general guide and interested customers should contact this firm and/or other firms for current prices and specifications (see Table 7.4).

2Ffor the Nikart the planter/fertilizer applicator is a (complicated) attachement to the toolcarrier chassis. For the Tropicultor it is actually a single purpose implement with its own transport wheels derived from the Nikart planter/applicator. For the Agribar it is a very simple unit in which seeds are fed into the tubes by hand.

3Standard charges for packing and local transport to docks at Bombay or Madras. (Domestic orders are liable for lower standard charges which cover local taxes, surcharges and local delivery)

4Carriage, insurance and freight to overseas port. Based on charges of US $ 2900 per container from Bombay to a West African port (charges elsewhere in the world may be similar). Standard packing is five units per container for Nikart and Tropicultor (with seeders) or ten Agribar units. Orders over fifty units would be completely knocked down and reassembled locally, with economies of scale in freight charges.

Source: Agarwal, personal communication, 1986.

Some toolcarriers (such as the Tropicultor) have had a high, arched chassis, while others (such as the Nikart) have had a low, straight chassis. A low chassis and low centre of gravity gave good stability but late weeding of crops and ridge cultivation were made difficult by the relatively low ground clearance.

Toolcarriers have to be sufficiently strong to stand up to quite severe shock loads (for example a cultivating implement hitting a root) and may also (depending on specification) have to be able to carry the weight of driver and payload. Yet strength implies expense in steel or bracing structures and also weight, and one of the most common criticisms voiced by farmers is that toolcarriers have been "too heavy".

Ease of adjustment is most important, for it has been noted time and time again that if an adjustment is difficult, farmers often will not bother with it. They may complain about the implement and even abandon it completely rather than struggle with an inconvenient procedure. On several toolcarrier prototypes, and even production models, there have been adjustments requiring two spanners and two or even three pairs of hands to release a fitting, support the implement, move and retighten. For example, the Sahall Lioness 3000 cultivating tines were attached to the toolbar by twelve nuts and twelve bolts. In such circumstances it is perhaps not surprising that farmers have tended to leave their implements at one setting. Reports on disappointing toolcarrier adoption that have blamed "inadequate farmer training" have often been referring to implements of great inconvenience rather than great complexity.

Almost all wheeled toolcarriers have had pneumatic tyres, and attempts to save money through use of second-hand tyres have been short-lived. Punctures have been frequently cited as being a major problem. Steel wheels have been used on Tropisem prototypes and are a current option on the CEMAG Policultor (Tropicultor-type) in Brazil. Solid rubber tyres have been fitted to Sahall Lioness toolcarriers and Agribars, but farmer reaction has yet to be gauged. Again it is a question of compromise; simple steel transport wheels are likely to be cheaper and less of a problem than pneumatic tyres but are less effective for road transport.

Ease of raising and lowering implements at the end of rows or for transport to the field is important for overall convenience but by itself is unlikely to be a principal reason for the acceptance or rejection of a design. Accurate depth control is particularly important for seeding and weeding operations and a mechanism that allows on-the-move adjustment (as the Nikart) provides great precison. However such accuracy is not needed in the plowing and transport modes. It can be argued that it is unrealistic to combine on the same implement the precision required for seeding and weeding with the ruggedness and strength required for plowing and transport

Table 7.4: Sample prices of toolcarriers from different manufacturers1

Toolcarrier

Basic chassis

Chassis with basic implements

Chassis, implements and seeder

 

US $

US $

US $

SISMAR Polyculteur2

n/a

1500

2000

GOM Toolcarrier3

n/a

1250

2000

Mekins Nikart4

550

950

1400

Mouzon Tropicultor5

950

1450

2250

Mekins Tropicultor4

600

1000

1600

CEMAG Policultor 15006

800

1250

1650

Mouzon Polynol5

1000

1500

2300

1These figures are based on details supplied by the various manufacturers during the period December 1986 and April 1987. Each manufacturer has different pricing policies and the firgures are not directly comparable between manufacturers. In addition to these prices local taxes of up to 19% may be payable in some cases, and the cost of packing a crate or container and transportiong to a port may add over $ 250 per toolcarrier. Shipping costs will vary but can be in the order of $ 300 - 500 per toolcarrier. These figures are intended only as a general guide and interested customers should contact the various firms for current prices, specifications and conditions.

Addresses:

CEMAG - Ceara Maquinas Agricolas S/A

Av. Gaudioso de Carvalho, 217 - Bairro Jardim Iracema,

C.P. D 79 CEP 60000, Fortaleza, CE, Brazil.

Telex: (085) 1533 CMGL BR Tel.: (085) 228 2377

Geest Overseas Mechanisation Ltd. (GOM)

White House Chambers, Spalding, Lincs. PE 2AL, U.K.

Telex: 32494 GSTGOM Tel.: (0775) 61111

Mekins Agro Products Pvt Ltd.

6-3-866/A Begumpet, Greenlands,

Hyderabad AP 500 016, India.

Telex: 155-6372 Cable: MEKINS Tel.: 227 198

SISMAR (Société Industrielle Sahélienne de Mécaniques, des Matériels Agricoles et de Représentations), B.P. 3214, Dakar, Senegal.

Telex: 7781 SISMAR SG Tel.: 51.10.96 (Pout), 21.24.30 (Dakar)

Société Nouvelle Mouzon

B.P. 26, 60250 Mouy (Oise), France.

Telex: 150990 F Tel.: 44.56.56.18

2Figures based on ex-works (Pout, Senegal) quotation of April 1987 for chassis with plow, ridger, groundnut lifter, steerable weeding tines, and cart body. Seeder comprises three units.

3Figures are for crated toolcarriers FOB U.K. seaport and are based on April 1987 quotation for GOM Toolcarrier (Nikart-type) set including ridger, plow, weeding tines and cart body. Seeder comprises three independent precision units (add $ 600 extra for three fertilizer units).

4Figures based on December 1986 ex-works (Hyderabad, India) export prices. For the Nikart the planter/fertilizer applicator is an attachment to the toolcarrier chassis. For the Tropicultor it is a single purpose implement with its own transport wheels derived from the Nikart planter/applicator.

5Figures based on March 1987 prices at the workshop in France and do not include packing costs nor local taxes. The equipment package here comprises steerable weeder, plow, ridger and cart body. Seeder comprises three independent units.

6Figures based on April 1987 ex-works prices at Taboao da Serra, Brazil. The equipment package includes steerable weeder, plow, ridger and cart body. Seeder is based on three independent planter units.

Sources: CEMAG, GOM, Mekins, Mouzon, SISMAR; personal communications, 1986/87.

7.1.2 Desirable specifications

From this brief discussion it is clear that it will be impossible to draw conclusions as to ideal toolcarrier specifications, for these will depend on those specific compromises that are most appropriate to the farming systems in which they are to be used. For example, the relative profitability of the crops and the costs and availability of labour will determine how important toolcarrier price may be. Social considerations will decide whether the provision of a seat is essential. Thus, while each case will be site-specific, perhaps the relative advantages of the different features may be considered here to assist in decision-making. (In doing so it must be remembered that in practice a farming systems approach is being advocated in which individuals or multidisciplinary teams work with the farmers themselves to determine the optimum equipment specification.)

It has been almost universally observed that farmers have not changed between transport and cultivation modes, and so if one is designing an agricultural implement transport characteristics should not strongly influence design. (This assumes, of course, that a defeatist position is not being adopted as most toolcarriers have actually ended up as simple carts!) Nevertheless it may be noted that the simple platform built into the Tropicultor chassis (not the cart body attachment) has been considered useful for minor transport operations.

Conventional mouldboard plowing is one of the operations in which toolcarriers cannot be expected to excel, for the wheels and chassis tend to mean the plow body is offset to the draft forces (even with a Tropicultor that has the wheel position changed) and as the wheels rise and fall over uneven surfaces the depth of work varies in no relation to the immediate soil characteristics or the animals' behaviour. By comparison a simple mouldboard plow can line up well with the draft forces and the operator can regulate depth constantly (in response to the animals or soil conditions) by simple hand pressure.

High strength in a toolcarrier is mainly required for plowing and transport, yet, as noted above, these are two operations in which toolcarriers do not have particular comparative advantage over conventional implements. This might suggest that less strong, lower weight (cheaper) implements designed mainly for planting and weeding would be more suitable.

Multi-row weeding is fraught with problems if the rows are not completely parallel, and there are sad stories of farmers unintentionally ripping up some of their crops with a wheeled toolcarrier that cannot be as rapidly lifted or steered as single row cultivators. Thus multi-row weeding requires very accurate multi-row seeding. For such seeding wheeled toolcarriers do have some advantages (but also some disadvantages, for in traditional fields with stones or clods a wheel rising over an obstruction can disrupt seed flow). However, precision seeders, such as those designed for the Nikart, are relatively inconvenient and complicated to set up, and there is thus a very strong temptation either not to use them or to leave them permanently in position. (It should be mentioned that the Nikart designers claim that the seeder is not inconvenient to set up, as the seeder frame is held by a single clamp, and once this is secured, all that remains is to loop a chain round a sprocket and clamp the courters. Nevertheless, despite elegant design features, when a relatively heavy and complicated seeder body has been for some months in a farmer's crowded storeroom, the energy required to overcome inertia in order to remount and reset it is considerable.)

ICRISAT was aware of the problems of using seeders on wheeled toolcarriers and saw a need for a single purpose seeder, initially intended for use in conjunction with the Tropicultor. It has therefore recently developed the planter-cum-fertilizer applicator that had originally been designed for use on the Nikart into a single purpose implement. Thus in India the seeder in the full Tropicultor package is now actually a separate single purpose implement. (Although this is an important change in direction, it is somewhat academic as Tropicultor sales have virtually ceased.)

From these various observations on toolcarrier specifications, there seem to be strong and logical reasons for minimizing the importance of transport, plowing and seeding functions, and concentrating on the tine-cultivation operations. It might even be worthwhile to study the characteristics of many well-proven wheeled cultivators developed in Europe and North America in the late nineteenth and early twentieth century. Nevertheless, while such implements may be effective for tine cultivation, their use for multi-row weeding would be dependent on accurate row planting. If accurate row planting is not performed, it is likely that simple weeding implements such as the Houe Sine of Senegal, the Triangle of Burkina Faso, or the traditional narrow blade harrow from India may be more accurate, efficient and much cheaper.

Thus there are quite strong arguments to the effect that the optimal toolcarrier is actually just a tine cultivator, used in conjunction with a single purpose plow, seeder and a cart. In most countries where toolcarriers have been provided, farmers have simply used them as carts and bought other simpler equipment (one exception appears to be Senegal where quite a number were used as single purpose multi-row seeders). Thus, if one can consider farmer reaction to past schemes as an indication of market demand, one would have to conclude that farmers want simple implements and carts.

One final important specification related to both cost and reliability is the ease of manufacture. During recent correspondence, many sources have cited problems relating to quality control. In particular, although the Nikart was designed for ease of local manufacture, the final output of all manufacturers, whether from India, Mexico or the U.K., has been criticized on grounds of manufacturing quality. As few manufacturers have made more than one type of toolcarrier at a time, it is difficult to distinguish the effects attributable to the workshop from any due to the design. Correspondents have not identified such widespread problems with the manufacture of Tropicultors and derivatives, and this may be attributable to its very much longer history of development and manufacture.

No wheeled toolcarrier can be said to have been proven by farmer purchases. The high cost, high quality Tropicultor (and derivatives) is the present world market leader, but this is largely a function of aid donor choice rather than end-user market forces. The low cost toolcarriers without transport options such as the Agribar or the CIAE toolcarrier have never been promoted or widely tested by farmers. Thus there is very little evidence of consumer preference between toolcarriers as very few farmers have ever had a choice of designs. In one of the few cases where a choice was available, farmers in India opted for Tropicultors in favour of Nikarts, but finally returned to traditional implements!

7.2 Observations on private sector involvement

Jean Nolle (1985) suggested that the lack of adoption of multipurpose implements was not caused by the small farmers rejecting the technology, but was because producers were refusing to make and sell such implements. He suggested that producers have had no incentive to make multipurpose implements for they have been able to make more money selling a larger number of single purpose implements He also suggested that the lack of success of his Hippomobile in France was related to a boycott by dealers. It therefore seems useful briefly to review the involvement of the private sector in different regions.

In France the Mouzon company started manufacturing Nolle's Polyculteurs in the late 1950s and has continued (with various company restructuring) to manufacture and market Nolle's designs until the present time. In the past thirty years Mouzon has sold 3000 wheeled toolcarriers, 12000 intermediate toolframes (Arianas) and 53000 simple toolbars (Houe Sine). Other French firms, including Belin International marketed Nolle's toolcarriers for a time but pulled out of the market in the early 1980s when sales proved inadequate.

In the U.K. the NIAE toolcarrier was manufactured mainly by John Derbyshire and by Kenmore Engineering, both of which adapted the design slightly and attempted to identify local agents to market their products in several countries. Both firms were disappointed with their achieved sales (totalling 1400 units) and eventually abandoned manufacturing such products. More recently Geest Overseas Mechanisation manufactured about 120 GOM Toolcarriers (similar to the Nikart). Geest subsequently sold its U.K. manufacturing subsidiary but continued to meet specific orders at a rate of about thirty per year by subcontracting the work. In 1986 Geest saw little market potential for the GOM Toolcarrier, mainly because it was prohibitively expensive for peasant farmers. As a result Geest did not actively market its toolcarriers or maintain stocks of implements or spare parts, but it did continue to meet specific orders in the interests of good public relations (GOM, 1986). The firm of Sahall designed its own toolcarrier in the early 1980s. It gained one large contract for Mozambique and then undertook some exploratory sales missions to Malawi, Kenya and Ethiopia but follow-up sales were not sufficient and in 1985 the firm went out of business.

In Senegal the SISCOMA factory manufactured and marketed wheeled toolcarriers from the 1960s until it ceased business in the early 1980s. Its successor at the premises, SISMAR, initially maintained wheeled toolcarriers as part of its standard range but due to lack of market demand subsequently made these implements only to order. During the period 1983 - 1986, sales averaged less than ten per year. In Cameroon the Tropic factory started to make and sell wheeled toolcarriers in the 1970s but ceased these lines due to lack of sales. In Botswana the Mochudi Farmers Brigade was assisted with aid funds to start production of the Makgonatsotlhe and for eight years attempted to market it. Sales were disappointing and the debts incurred through the toolcarrier programme made it difficult for the Brigade to change to new products.

In India the large manufacturer Voltas attempted to market its Universal Otto Frame in the 1960s and Escorts tried to sell its Balwan toolcarrier, These and other entrepreneurial initiatives appear to have failed through lack of market demand rather than lack of promotion. Following the ICRISAT work on toolcarriers, in the early 1980s several workshops were assisted to start to fabricate wheeled toolcarriers based on Tropicultor or Nikart designs. At least eight firms attempted to market them, but by 1985 there was only a single manufacturer left. This one producer admitted the only real market outlet within India was the rapidly dwindling number of government promotion schemes and so the Director had undertaken sales missions to Africa, North America and Europe to try to obtain orders for donor-assisted aid projects elsewhere in the world.

In Brazil several small workshops were encouraged by the work of CPATSA and reports of the ICRISAT successes to start making wheeled toolcarriers, but most ceased within one year. The one major producer still making toolcarriers in Brazil is actively marketing its Policultor range, but sales are not increasing. Elsewhere in Latin America, there have been several schemes to establish wheeled toolcarrier production, but for a variety of reasons (some unconnected with the toolcarriers) most have been of limited duration.

Thus the private sector has been involved in wheeled toolcarrier fabrication for many years. Some firms have had complementary ranges of single purpose implements while others have only manufactured multipurpose implements. While some companies have ceased manufacturing or trading altogether this cannot be directly blamed on toolcarrier manufacture. In the 1960s firms tried to use private trading companies to market their products, but this did not work as there was no sustained demand from the farmers themselves. By the 1980s the public and aid sector dominated the distribution of agricultural implements in many Third World countries, and this had distorted commercial trading patterns. This distortion, combined with the inability of small farmers to afford wheeled toolcarriers, meant that few companies in the world regarded it as commercially viable to target their manufacturing or marketing towards the end-users. Thus most wheeled toolcarrier-manufacturers that continued in production did so by concentrating on large contracts from governments, aid agencies and development projects.

In 1987 Intermediate Technology Publications released the booklet Multi-purpose Toolbars (ITP, 1987). This derived from the more general publication Tools for Agriculture and attempted to be a brief illustrated catalogue of toolbars and their possible suppliers worldwide. It listed the names and addresses of nineteen manufacturers of wheeled toolcarriers: eight in India, six in Latin America, four in Europe, and one in Africa. The information for these entries had been collected in good faith from the manufacturers during the early 1980s, but by the date of the publication of this booklet thirteen of the nineteen firms listed were no longer actually manufacturing wheeled toolcarriers. Thirteen manufacturers of Nikart type toolcarriers were listed, while in practice in early 1987 there was only one workshop (in Mexico) producing this design on a regular basis. One other workshop in India was still actively trying to market this product, and one British manufacturer made small numbers occasionally in response to specific orders. All the other manufacturers listed had ceased active involvement or interest in such equipment, although some would have still been prepared to quote for large orders. The IT Publication booklet also listed eight manufacturers of Tropicultor-type wheeled toolcarriers, of which only three were still actively involved in manufacturing these implements in 1987. Some other designs listed such as the Sahall and the CPATSA toolcarriers had been completely abandoned. The information on which the publication had been based had been correct when it had been obtained. This illustrates the rapid loss of interest of the private sector as the lack of any real market for these products became clear.

In Tables 7.3 and 7.4 sample prices are given for the basic toolcarrier packages offered by those manufacturers that were actively involved in wheeled toolcarrier production and export in 1986/87.

There seems to be little or no evidence to support Nolle's suggestion that farmers have been deprived of multipurpose implements due to the vested interests of manufacturers. On the contrary the evidence suggests that many manufacturers and distributors would have benefited from developing markets for their products and actively tried to do so. They have on many occasions tried to market wheeled toolcarriers directly, but lack of sales has suggested that there was no genuine market demand from the end-user. As a result some have abandoned their investments in wheeled toolcarriers, while others have concentrated on the irregular but potentially lucrative market for aid donor and development project contracts.

7.3 Observations on terminology

The author has held discussions relating to toolcarriers with a very wide range of research and development workers of many institutions in developed and developing countries. From these it is apparent that the vast majority have understood (incorrectly) that wheeled toolcarriers had been highly successful in some parts of the world. While much of this is due to the optimism of reporting, there has also been considerable misunderstanding relating to terminology, particularly the definition of simple toolbars and more complicated wheeled toolcarriers.

In order to distinguish clearly between different types of multipurpose ("polyvalent") implements, CEEMAT proposed a standardization on the term "multiculteur" for a simple toolbar pulled by a chain and "polyculteur" for wheeled toolcarriers that could be used as carts (CEEMAT, 1971). Unfortunately, in the influential English edition of this major work, this important point of definition was missed out, and neither the French words nor English alternatives were specifically proposed (FAO/CEEMAT, 1972). Nevertheless in this work and the book of Munzinger (1982) the words polycultivator and multicultivator were often used as the English equivalents of the French definitions. The present author would have liked to have recommended the continued use of these words in the English language, perhaps simplified to polycuitor and multicultor. However the term wheeled tooicarrier has already become commonly used and understood, while the distinction between polycultor and multicultor is becoming less clear as some manufacturers have used polyculteur (or similar word) to describe simple toolbars (Tropic in Cameroon; CESMAG in Brazil).

There has been a general (but by no means universal) tendency for English-language writers to use the term toolbar for the simple multiculteur implements and the word toolcarrier for polyculteurs. For this reason the author has proposed standardization on simple toolbar, intermediate toolframe and wheeled toolcarrier. This series of definitions is not ideal, being verbose and with the use of the "value" terms simple and intermediate. However standard terms that convey the required concepts are urgently required, and these definitions each with their descriptive adjective should not create further confusion. :

However for the past twenty years there have been no standard definitions and thus in the otherwise useful review by Bansal and Thierstein (1982) entitled "Animal-drawn multi-purpose tool carriers" the words toolcarrier, toolbar and toolframes were considered synonymous, and simple multiculteur toolbars such as the Houe Sine of Senegal were described as toolcarriers. Without precise words to distinguish simple toolbars and wheeled toolcarriers, there has been a tendency in English publications to confuse the technologies. Translation of the terms multiculteur and polyculteur has been clearly difficult, particularly as some authors using the English language have been unaware that in French "multiculteur" has been clearly defined as a simple toolbar.

One important example of confusion started as a minor inaccuracy in a translation of a paper by Le Moigne, published in the proceedings of the ICRISAT seminar on socioeconomic constraints to development (ICRISAT, 1980). At the end of the proceedings the original French version of the paper is given and in this Le Moigne clearly differentiated between the simple toolbars as "multiculteurs" and the wheeled toolcarriers as "polyculteurs" (Le Moigne, 1980a). Le Moigne also clearly stated that the various designs of wheeled toolcarriers (polyculteurs) including the Nolle Polyculteur, the Tropiculteur, and the Bambey "polyculteur a grand rendement" were not well known and had not been widely adopted in West Africa. For this reason, he explained he had not included their insignificant numbers in his otherwise comprehensive tables of animal traction equipment in use in various West African countries. However in the English version of Le Moigne's paper, which was given prominence in the proceedings, both "multiculteur" and "polyculteur" were translated as "tool carrier" (Le Moigne, 1980b). Thus in the English version of the table of animal-drawn equipment in West Africa one category of equipment is labelled "Toolcarriers". Although this heading was annotated with the word "multiculteurs" in parentheses, the use of the word toolcarrier has apparently given the false impression to some English-language readers that thousands of wheeled toolcarriers were in use in the various West African countries, when the original table referred to the "Houe Sine" type of simple toolbar.

The potential for confusion was compounded in two more widely circulated publications of the Intermediate Technology Development Group, in which Gibbon (1985; 1987)- reprinted the English translation of the table of Le Moigne. In these publications Le Moigne's table is preceded by two others specifically related to wheeled toolcarriers and also by two illustrations of wheeled toolcarriers. Thus readers without detailed knowledge of West Africa and French definitions would almost inevitably be given the impression that the thousands of "toolcarriers" in use in West Africa were wheeled toolcarriers. Indeed this had been the understanding of several British development workers including some members of staff of ITDG, NIAE, ODA and UEA.

A similar example of imprecise terminology and potential for misunderstanding is seen in the book of Ahmed and Kinsey (1984) in which Le Moigne's ICRISAT paper (English version) is also cited. These editors concluded that "toolbars" (in this context they were referring to wheeled toolcarriers as promoted in Uganda) had not been successful anywhere in East and Central Africa. However, the authors continued, such implements were widely used in West Africa (Ahmed and Kinsey, 1984).

As a result of lack of clear definitions in the English language, there is still much misunderstanding in the interpretation of the literature in this field. It is therefore necessary for authors to define clearly their terms and for readers to take particular care to ensure they understand precisely to what technology reports refer.

7.4 Observations on the literature relating to wheeled toolcarriers

7.4.1 Optimism

One characteristic of all the wheeled toolcarrier programmes reviewed has been the optimism regarding the technical competence of the implements, the economics of equipment use and the advantages of newly devised farming systems. With the rather unfair advantage of hindsight it is now clear that much of this optimism was unrealistic, although at the time it may have seemed justified. To quote specific publications here might imply an unacceptable degree of selectivity since there have also been some more moderate statements. However the object of this discussion is to learn from the past and a few specific examples appear necessary to justify some of the conclusions. It must be stressed that the following examples are not cited for the sake of ridicule (for the authors were generally making some very valid points), but merely to illustrate how the very strong impression of success has developed.

In descriptions of equipment the word "perfected" has been used in connection with the Mochudi (Makgonatsotlhe) toolcarrier in Botswana (Eshleman, 1975) and the Yunticultor in Mexico (Olmstead et al., 1986). Many claims have been made for the various farming systems packages developed on station around wheeled toolcarriers. These range from relatively modest claims that by using the Mochudi toolcarrier and tine cultivation system in Botswana erosion would be reduced and weeds would be better controlled (Eshleman, 1975) to the great aspirations for the ICRISAT toolcarrier systems. These latter are illustrated by Brumby and Singh (1981) who concluded: "The total yield potential this [wheeled toolcarrier] equipment package promises is so large and so important to India's foodgrain output that a major effort to propagate its use is warranted."

While it has been the agricultural engineers who have developed technically efficient implements and agronomists who have been largely responsible for the associated cropping systems, it has been the economists who have justified their use, with optimistic models and assumptions. Early economic models developed at Bambey Research Station in Senegal illustrated how the wheeled toolcarriers would allow cultivated surfaces to double, relative to alternative equipment, while at the same time allowing returns to both area and labour to increase (Monnier, 1967 and 1971). Hunt (1975) based her economic coatings of toolcarriers in Uganda on a low hourly rate derived from the very optimistic assumption that Tropiculteurs would work 1600 hours a year (say 320 five-hour days). Binswanger et al. (1980) developed economic coatings for wheeled toolcarrier use in which the practicalities of ownership on small farmers were elegantly avoided by suggesting hypothetical hire costs that an optimizing entrepreneur might charge. ICRISAT economists used such assumptions for several years and claimed that wheeled toolcarriers could be paid for from the additional profits of the new farming system in just one year, if used on at least four hectares (Ryan and Sarin, 1981; Ghodake, 1985). While few reports have given details of prices, some authors, having described the large number of operations a wheeled toolcarrier can perform, go on to cite the price of a toolcarrier chassis and wheels, but without cart or implements (Bansal et al., 1986). This naturally gives a very favourable impression because even the basic implement set (without seeder) generally doubles the price of the toolcarrier.

Optimistic forecasts have been made of toolcarrier production. For example, referring to the project to transfer the Nikart design to accurate production in Indian workshops using jigs and fixtures, Kemp (1983) stated, "This exercise has been eminently successful. Of the two organizations assisted, one had produced and sold over 200 Nikarts by early 1983." The figure of 200 had apparently been quoted by the manufacturer in question. In fact total production of Nikarts in India at that time was still below 100 (Fieldson, 1984) and even by 1986 total sales of Nikarts from all Indian manufacturers had not reached 200.

ICRISAT reports have generally maintained a high degree of optimism and several of the more noteworthy ones were cited in Chapter 3. To take a seemingly innocuous example, the publication ICRISAT in Africa simply stated, "The ten toolcarriers used in the Mali research program have been so successful that the possibility of having them fabricated locally is under investigation." (ICRISAT, 1986). The impression given by such a factual statement was clearly one of considerable potential, which was unrealistic since both ICRISAT staff in Mali and the Malian authorities seriously doubted the applicability of wheeled toolcarriers off the research station.

7.4.2 Failure to follow optimistic reports

There have been very few attempts to update reports of experience after the initial optimistic results. As a result the only records available for a conventional literature review are the reports of successes. For example early work in East Africa was reported in the East Africa Agricultural and Forestry Journal and the Journal of Agricultural Engineering Research. Early work in Botswana was reported in World Crops. Early work on the Nikart was reported in Appropriate Technology, Ceres and Machinisme Agricole Tropical. Encouraging work in India has been published in Agricultural Mechanization in Asia, Africa and Latin America. The author is unaware of anyone who has written optimistically about wheeled toolcarriers in these journals following up early work with a discussion of the actual problems encountered or of farmer dissatisfaction with the equipment.

7.4.3 Discounting disadvantages

Any technology has disadvantages as well as advantages, and objective publications are likely to cite examples of both and draw conclusions based on the relative balance of technical, social and economic benefits and costs. It is quite possible for a publication to be strongly in favour of wheeled toolcarriers, while mentioning some of the problems associated with this technology. Thus Bansal and Thierstein reviewed several drawbacks of wheeled toolcarriers (cost, need for training and back-up services, and requirement to link them to comprehensive technology packages) while still being highly positive. Kemp (1983) while extremely optimistic on the future of the Nikart noted that while it had been specifically designed for easy interchange between cart and cultivation modes, farmers tended to use only one of these options.

However a few publications have neglected the discussion of disadvantages. The 1981 edition of the ICRISAT wheeled toolcarrier bulletin failed to mention any possible problems relating to the adoption of wheeled toolcarriers. This had to be corrected in the 1983 edition that does have a heading "Drawbacks of the tool carrier" which notes some of the problems associated with cost and maintenance. An article in the French agricultural development journal Inter Tropiques Agricultures also illustrates the promotion of the toolcarrier without any reference to possible disadvantages. The illustrated article describes a wide range of possible operations, stressing the timesaving role of the toolcarrier, and concludes with a summary of the advantages: consistency of agricultural operations achieved with less effort of the animals and multipurpose use throughout the year. No mention was made of any possible disadvantages (Inter Tropiques, 1986). While professional agriculturalists might be cautious if they were to read such positive promotion in the pamphlets of manufacturers, the existence of such articles in the literature of national aid agencies and international research centres has tended to reinforce the impression that the wheeled toolcarrier is a well-proven and successful technology.

7.4.4 Some expressed disquiet

While it is clear that many of the published reports emanating from the wheeled toolcarrier programmes have been excessively optimistic or unbalanced, this has by no means been universal. Nevertheless most examples of disquiet were in reports of restricted circulation. As early as 1964 an internal CEEMAT document noted some of the problems of wheeled toolcarriers (CEEMAT, 1964). These included the restricted manoeuvrability during field operations and the fact that their high initial cost made it more difficult for farmers gradually to build up a range of equipment than if they started by using the most important single purpose implements (e.g. a seeder in Senegal or a plow in Mali). In 1985, in an international journal, a senior officer at Bambey Research Centre in Senegal noted that the wheeled toolcarriers had significant disadvantages as well as advantages, notably their high cost and their complexity. He doubted that the toolcarrier would spread rapidly among small farmers as the toolcarrier was twice the price of a complete set of single purpose implements. His calculations excluded the provision of simple ox carts as these were apparently unavailable in Senegal at the time (Nourrissat, 1965). Some evaluations have admitted major problems in The Gambia (Mettrick, 1978), Botswana (EFSAIP, 1984) and India (Fieldson, 1984, Kshirsagar et al., 1984) although, in contrast to the optimistic reports, pessimistic papers have seldom been published in international journals. More recently workers engaged in programmes promoting wheeled toolcarriers in Brazil and Nicaragua have expressed strong reservations about the desirability of such technology (Bordet, 1985; Bertaux, 1985).

7.4.5 The attitude of reference publications

In contrast to many reports produced by the programmes themselves, reference publications have generally taken a relatively cautious approach to wheeled toolcarriers. It is noteworthy that, although CEEMAT has been closely involved in wheeled toolcarrier development, its major animal traction reference work, which was published in English by FAO, is very objective on the subject of toolcarriers. Toolcarriers are presented among very many other animal traction equipment options and no attempt is made to promote them over any other technology. Toolcarriers are described as a potentially important step forward, but it is also noted that they require well cleared, flat land, a comprehensive and profitable cropping system to justify their expense, and an advanced infrastructure and extension service to promote them (CEEMAT, 1971; FAO/ CEEMAT, 1972). In another reference work on animal traction based on an extension manual for Niger, CEEMAT did not dwell at all on wheeled toolcarriers and merely sets out some of their advantages and disadvantages(CEEMAT, 1974).

In his work on animal traction in Africa, Munzinger only briefly mentioned toolcarriers. He noted that in a few (unspecified) countries toolcarriers were of importance and that there was a good chance for their further promotion and utilization, citing as his reference the ICRISAT Information Bulletin(Munzinger, 1982; ICRISAT, 1981). However in the same volume Viebig was more cautious, and while giving descriptions of the technical advantages and disadvantages he concluded that: "Promotion of these implements is advisable only in special cases, following detailed examination of the conditions under which they are to be used. In some cases it has been discovered that the technically attractive but also elaborate and expensive polycultivators are simply used as carts after a while." (Viebig, 1982).

7.4.6 The citation of other countries

In the general publication "ICRISAT and the Commonwealth" that was produced at the time of the meeting in India of the Heads of the Commonwealth and the visit to ICRISAT of Queen Elizabeth II there is a section entitled "A multipurpose wheeled tool carrier" (ICRISAT, 1983). This includes a photograph of farmers using a wheeled toolcarrier, and superimposed on the photograph are the names of twenty-two countries: Botswana, Brazil, Burma, Cameroon, Dominican Republic, Ethiopia, France, India, Indonesia, Kenya, Mali, Mexico, Mozambique, Pakistan, Paraguay, Senegal, South Africa, Sri Lanka, Tanzania, U.K., Upper Volta (Burkina Faso) and Zimbabwe. The text explains that this is a list of countries in which wheeled toolcarriers have been used or are currently in use, to which they have been supplied, or in which they are manufactured. The information was factually correct, and by these criteria the list could have been expanded. Through such a list an impression is given that links the technology with a large number of countries in the mind of the readers.

Kemp (1983) quite correctly and factually stated that the Nikart was being evaluated in Botswana, Mali, Zimbabwe and Mexico and several publications have illustrations of toolcarrier use in a variety of different countries. For example, the ICRISAT information bulletin on wheeled toolcarriers has photographs taken in India, Brazil, Mozambique, Botswana and Mexico (ICRISAT, 1983), and Nolle (1986) provided illustrations of his toolcarriers from Senegal, France, Madagascar, Mexico and Nicaragua.

The Intermediate Technology Publications booklet on toolbars (ITP, 1987) provided thirteen illustrations of wheeled toolcarriers and the names and addresses of nineteen toolcarrier manufacturers worldwide. This resource publication is likely to be referred to and circulated for several years to come and yet, as noted in Section 7.2, even at the time of publication the large majority of manufacturers listed (fourteen out of nineteen) had actually stopped any active involvement with wheeled toolcarriers. Someone contacting the various manufacturers would naturally find this out. Nevertheless the general impression left with anyone looking at this publication would inevitably be that in 1987 wheeled toolcarriers were being quite widely manufactured on four continents.

In all these examples the citations of countries were valid, and there was no suggestion of "name-dropping" merely for effect or any attempt to provide an unrealistic impression. Nevertheless most citations of countries have been made in the context of very positive articles and it appears that one consequence of such passing references to countries has been that many development workers have gained a strong impression that wheeled toolcarrier technology has been widely accepted in such countries. In fact in some countries cited fewer than ten wheeled toolcarriers have been in use, and these have only been evaluated on research stations.

7.4.7. Multiplication and legitimization of "success" stories

Articles in professional journals are unlikely to reach decision-makers, but these people are often influenced by formal and informal media channels that like to promote apparently successful innovations. In Africa a large number of English-speaking Africans (and expatriates) listen to the BBC, and several have reported hearing of wheeled toolcarriers from "The Farming World" agricultural programme. Many aid agencies sponsor publications such as "Overseas Development", "Inter Tropiques Agricultures" and "Exchange" that have included brief illustrated articles on wheeled toolcarriers. The fact that wheeled toolcarriers seem photogenic means that magazine editors may use such photographs to illustrate general articles. For example, in a general discussion on animal traction published in the widely circulated Afrique Agriculture, Yves Bigot did not mention wheeled toolcarriers, yet two out of the three untitled photographs used to illustrate the article were of wheeled toolcarriers in use in Africa (Bigot, 1985). Many voluntary agencies disseminate news snippets or whole publications. For example, animal traction projects in Africa requesting information on possible equipment from Volunteers in Technical Assistance (VITA) received copies of the optimistic publication "The Mochudi Toolbar: Makgonatsotlhe, the machine which can do everything". These are all examples of excellent information dissemination channels that are doing a great deal of valuable work in stirring up existing knowledge. However they can only pass on information flowing into them, and if all the reports they receive on a topic are optimistic, they will naturally disseminate this impression.

To take another example, until recently the introductory slide show of the International Livestock Centre for Africa (ILCA) contained a picture of a "farmer" (perhaps a research station employee) sitting on a Nikart wheeled toolcarrier in Ethiopia as the commentary explained that African farmers will adopt innovations that are shown to be suitable. Although ILCA scientists themselves have had reservations about the suitability of wheeled toolcarriers, the slide show (prepared by information experts rather than research scientists) clearly gave a psychological "stamp of approval" to the wheeled toolcarrier technology. The use of this seemingly innocuous slide by ILCA was traced after some African researchers had told the author that they thought that ILCA had carried out successful research on wheeled toolcarriers and was advocating their use. Thus ILCA had (apparently unintentionally) been promoting wheeled toolcarriers to many influential visitors from all over Africa.

As a final example, an agricultural textbook designed for secondary schools in Nigeria and English-speaking West Africa had a wheeled toolcarrier on its front cover. The text stated that these implements were becoming more widely used in many areas (Akubuilo, 1978).

These secondary "media" channels have three important effects. Firstly they greatly multiply the audience, secondly they simplify the information to fit the time or space available and thus tend to make optimistic reports even more positive, and thirdly they have the effect of "legitimizing" the information. To have heard of a success story on international radio, through an aid agency publication, from an NGO resource centre, through a textbook or from an international research centre gives the information more credibility and status than a technical research report Most aid agency publications have disclaimers in small print at the front to say that the organization does not necessarily endorse the views contained in the articles. This is a legal safeguard, but, as advertising experts know, the important thing is that the product has become linked in a persons's mind with the reputation of the sponsoring organization.

There is no suggestion whatsoever that any fault or blame should be attached to such media channels, for they are doing excellent work in spreading information. In the case of wheeled toolcarriers they have achieved a remarkable accomplishment by making agricultural planners and decision-makers throughout the world aware of the technology and its "success". The problem has been that no organization appears to have fed into the system any of the disadvantages of the implements, or the problems experienced by farmers. Thus the initial success stories of research scientists have multiplied and achieved legitimacy.

7.4.8 Effects of the literature and media

In the period 1985 to 1987 the results of the optimistic reports, the concentration on advantages, the passing citation of countries, and the multiplication and legitimization processes were very clear. The great majority of research and development workers in this field, together with staff of aid agencies, were under a strong impression that the wheeled toolcarriers had been successfully used and adopted in many parts of the world. This statement is not just speculation, for between 1983 and 1987 the author visited animal traction programmes in twenty countries and discussed the role of wheeled toolcarriers with research and development workers. Through seminars, professional meetings and correspondence the author has had contact with another twenty countries, and a clear pattern has emerged. Workers are under the very strong impression that wheeled toolcarrier technology is very successful - somewhere else. Researchers have often admitted problems in their own country or region but have also cited assumed successes elsewhere.

For example, in East Africa many people are under the impression that wheeled toolcarriers are widely used in West Africa (Ahmed and Kinsey, 1984). Authors in Britain (Gibbon, 1985), France (Poussett, 1982) and India (Bansal and Thierstein, 1982) have given similar impressions relating to widespread diffusion in West Africa. In West Africa, people have cited successes in southern Africa (derived from reports from Botswana) and in India (derived from reports from ICRISAT), while those in southern Africa have pointed to the success of wheeled toolcarriers in Asia. Workers in Bangladesh reported the success of the ICRISAT technology in India (Sarker and Farouk, 1983) and in 1986 even some staff of ICRISAT Headquarters in India were under the impression wheeled toolcarriers had proven successful in India itself. However, as already noted, others in India have cited their successful introduction within West Africa. Meanwhile in Latin America reference is made to the achievements in both Africa and India.

In the course of the background research for this present publication, the author has visited many of the countries cited by colleagues as "successes" in the use of this technology and has been repeatedly surprised to find that the actual situation involved far fewer toolcarriers and much less extensive testing than he had been led to believe from professional discussions and the literature. For example, until 1985 the author himself was under the impression that wheeled toolcarriers were actually being used by farmers in Mali. It is only after he had visited Mali and established that this was not the case that he has been able to realise the full extent of the overall optimism. For since ascertaining the real situation he has been told by several influential and distinguished workers in the field that Mali has been a clear success story. Had it not been for his field visits he would naturally have believed this.

Until December 1986 the author himself also believed the apparent success of wheeled toolcarriers in India. As recently as May 1986 he submitted an article to the journal "Appropriate Technology" stating that, while lessons from Africa were clear, India was apparently still going through the stage of accelerating increase, and it was too early to judge whether this increase would continue. Although he had reviewed a large number of articles, he had not come across a single one that had counteracted the false impression of success he had been given from the literature. At this time he was also engaged in correspondence and professional discussion concerning wheeled toolcarriers with several organizations, including ICRISAT and NIAE. Yet no organization volunteered any information that might counteract the effect of the optimistic literature. It was only during a professional visit to ICRISAT in December 1986 that he learnt that the peak in India had actually been passed in 1984, two years before. Many of the problems had been documented in 1984 by ICRISAT and NIAE in internal reports, but these had not been disseminated. Fortunately it was still possible to update the text of the article in question (Starkey, 1987) or it too would have unintentionally contributed to the general impression of "success somewhere else".

This example is not intended to imply there was any conspiracy of silence, for it merely demonstrates an obvious point: individuals and organizations are much more likely to provide information on their successes than their disappointments. However it does illustrate one very important point: if an individual actively searching for information in both published and unpublished form is given, and passes on, an impression of optimism and success, then under present circumstances those obtaining information through standard, public channels have very little hope of obtaining a realistic picture.

This is worrying and for this very reason the author is slightly concerned lest his very open verdict on present evidence from Latin America of "not proven either way" turns out to be-a third example of optimism. There may well have been cases of clear farmer rejection of which he is unaware. It would be ironical if unjustified optimism in this publication were to stimulate continued investment in toolcarriers in situations comparable to those in which they have already been found inappropriate.