Biophysical Performance

Long-term on-station trials in Yaoundé (ICRAF 1996) demonstrated that rotational hedgerow intercropping has the potential to maintain high levels of maize production without degrading the soil resource base. A detailed diagram of the treatments of this trial can be found in Annex 1. As shown in Table 5-1, rotational hedgerow intercropping with 2 years of fallow (T3 and T4) resulted in consistently high and significantly greater maize yields than cropping once a year without trees (T1a) and 2 years cropping followed by natural fallow without trees (T1b). In the topsoil, important soil fertility indicators (organic C, available P, pH and exchangeable Mg, Ca, K) under the rotational hedgerow intercropping system (allowing 2 years of fallow) were significantly higher than under the annual cropping and seasonal fallow system without trees. In spite of the excellent on-station performance, on-farm evaluation of hedgerow intercropping revealed much lower biophysical performance of the technology under farmer management (Table 5-2). Yield improvements of maximum 40% were reported on-farm against 100% on-station; this may not be enough to convince farmers to adopt the technology without additional benefits (Table 5-3).

Table 5-1: Tree fallow cropping cycles and maize grain yields (t ha-1_{), on-station} Yaoundé 1990 1991 1992 1993 1994 1995 1996 Treat ment 1 2 1 2 1 2 1 2 1 2 1 2 1 2 Tot T1a 1.52 NF 2.98 NF 3.54 NF 2.54 NF 2.17 NF 2.33 NF 2.69 NF 17.77 T1b 1.52 NF 2.98 NF 3.54 NF 2.54 NF NF NF NF NF 3.58 NF 14.16 T2 2.13 TF 3.70 TF 4.79 TF 5.09 TF 4.55 TF 3.33 TF 3.68 TF 27.27 T3 TF TF TF TF 6.28 TF 6.09 TF TF TF TF TF 6.51 TF 18.88 T4 2.72 TF 4.48 TF TF TF TF TF 5.27 TF 4.82 TF TF TF 17.29 SED 0.38 - 0.28 - 0.14 - 0.44 - 0.14 - 0.36 - 0.35 - Source: ICRAF Annual Report 1996, p 127

NF = natural bush fallow

TF = tree fallow of Leucaena leucocephala and Gliricidia sepium mixture

T1 Control treatment of continuous maize cropping with 1 season of maize (in the first rainy season April- June) and 1 season natural fallow (in the second rainy season September-November) each year; in 1994 plots were split to allow the comparison with a 2-year natural fallow (T1b) in addition to continuous cropping (T1a)

T2 Continuous maize cropping with 1 season of maize grown between the rows of trees (regularly pruned back as hedgerows) and 1 season of tree fallow during which the hedges were allowed to grow unchecked

Table 5-2: Effect of tree fallow on maize yield in researcher-designed/researcher- managed trials in farmers’ fields in Abondo and Nkolfep, Cameroon

Maize dry grain yield (t ha-1₎ Village Farm

tree fallow natural fallow

Farm 1 3.63 2.38 Farm 2 4.75 3.16 Farm 3 5.26 2.88 Farm 4 2.87 2.00 Farm 5 2.23 1.71 NKOLFEP Farm 6 3.29 2.43 Farm 7 3.61 3.20 ABONDO Farm 8 3.29 2.76 MEAN 3.62 2.57 SED CV% 0.24* _{(significant at p<0.05)} 15 Source: IRA/ICRAF 1997

Table 5-3: Benefits and disadvantages of tree fallows, in order of importance, as stated during an evaluation session on a farmers’ field day, Abondo, June 1997

Benefits Disadvantages 1. Enhanced fertility/improved yield 1. Labour requirement in nursery

2. Weed suppression 2. Labour requirement for tree cutting 3. Secondary products: stakes, honey production 3. Presence of roots

4. Reduced fallow period 4. Yield response only after several years 5. Save on fertilisers

Source: IRA/ICRAF 1997

5.2.2 Profitability

To determine the profitability of tree fallows, net financial benefits were calculated using enterprise budgeting (CIMMYT 1988; Alimi and Manyong 2000). Hereto, tree biomass and crop yields were collected from researcher-designed, researcher-managed trials. However, as complete yield data under farmer conditions were only available for very few farms and few years, enterprise budgets were developed using yield data from a ten-year-old on-station trial (Table 5-1). The data were adjusted (yield adjustment factor of 0.8) to on-farm conditions, as recommended by CIMMYT (1988). Data and labour inputs for planting and managing the trees were collected by monitoring work rates through observation on on-station and researcher-designed/researcher-managed on-farm trials, and using farmers’ recall after one season in researcher-designed/farmer-managed on-farm trials. Prices were collected from local markets. For more details on the methodology, the reader is referred to chapter 3.3.2 in this document.

Cost-benefit analysis of rotational hedgerow intercropping over a period of 12 years showed that the proposed technology is not profitable (Annex 2; Table 5-4). This can be explained by the high upfront investment costs for tree establishment (633,500 FCFA ha-1 _{≈967 € ha}-1₎

and the labour requirements for cutting back and pruning hedges. Total labour increase in a rotational hedgerow intercropping system compared to natural fallows was estimated at 37% over a 12-years period. Over these 12 years, cropping in the natural fallow system required 1055 workdays ha-1_{, whereas cropping using RHI technology required 1430 workdays ha}-1_.

The increase in labour apparently is not compensated by increased outputs, as the returns to labour of RHI (1322 CFA workday-1 _{≈2 € workday}-1_{) were much lower than those of natural}

fallows (1899 CFA workday-1 _{≈2.9 € workday}-1_).

One way of bringing establishment costs down is by reducing the price for tree seedlings. Sensitivity analysis demonstrated that returns to land for RHI increased from negative to 272,289 CFA ha-1 _{(≈ 416 € ha}-1_{)when costs of tree seedlings were divided by two (Table 5-}

4). Prices for tree seedlings used in the cost-benefit analysis came from a study carried out in 1997 (IRA/ICRAF 1997), which calculated prices for potted calliandra seedlings. Faced with labour shortages for tree establishment, farmers tested different methods such as transplanting of wildings, direct seeding, bare rooted seedlings, size reduction of polythene bags in order to reduce time for filling and to facilitate transport of the seedlings from the nursery to the field. Another strategy to reduce labour costs suggested by farmers was starting the nursery in the rainy season to reduce watering, which counts for more than 50% of total costs (IRAD/ICRAF 1997; IRAD/ICRAF 1999). Unfortunately, no systematic evaluation of the various methods of tree establishment has taken place in Cameroon. However, experiences have shown that survival rates of calliandra, established through direct seeding and bare-rooted seedlings, were low under humid forest conditions, although this method worked quite well in other places, such as Central Kenya (Franzel et al. 2003) and Uganda (Nyeko et al. 2004).

Another possibility of reducing tree establishment costs and possibly subsequent labour costs for cutting back and pruning is reducing tree density. Asaah et al. (2003) found that calliandra trees planted at 1 m x 2 m (5000 trees ha-1_{) and at 2 m x 2 m (2500 trees ha}-1₎

produced greater or similar amounts of leaf biomass than trees planted in hedges at 4 m x 0.25 m (10,000 trees ha-1_{), suggesting that the same soil fertility improvement can be}

obtained with considerably fewer trees than recommended in the original design. These tree arrangements, however, were not evaluated with farmers under ICRAF’s fallow management programme. A study by the International Institute of Tropical Agriculture (IITA) on farmers’ preferences for different fallow tree arrangements in the humid forest zone of Cameroon (Lekeulem 1999) indicated that farmers preferred hedgerow to equidistant and cluster arrangements because of the ease of working in the alleys. Experimenters claimed that tree roots in equidistant arrangements hinder land preparation, weeding and even harvesting. Another constraint highlighted by farmers was the competition between crops and trees, which seems to be more important in equidistant arrangements. Therefore, it is rather unlikely that farmers would go for 1 m x 2 m or 2 m x 2 m, despite the fact that these arrangements require fewer trees, reduce establishment costs and turn the tree fallow technology into a more profitable activity than natural fallows (Table 5-4). The break-even

Table 5-4: Sensitivity analysis showing the effects of changes in key parameters on the profitability of rotational hedgerow intercropping compared to natural fallow, humid forest zone of Cameroon

Natural

Fallow Rotational Hedgerow Intercropping with beekeeping Rotational Hedgerow Intercropping without beekeeping Base analysis Returns to land (CFA ha-1_{) r = 20%} 282,181 70,831 - 47,046

Break-even point Year 1 Year 11 Not before year 12

Total labour (workdays/ha) 1055 1446 1430

Returns to labour

(CFA/workday) r = 20% 1899 1322 1117

Change in key parameters

Returns to land

(CFA ha-1_{) r = 10%} 441,650 476,175 253,987

Returns to land

(CFA ha-1_{) r = 25%} 234,129 (- 35,442) (- 123,868)

Calliandra seedling price – 50% NPV (r = 20%)

Break-even point 282,181 Year 1 272,289 Year 7 154,413 Year 7 Tree density/4 (2500 trees ha-1₎

NPV (r = 20%)

Break-even point 282,181 Year 1 373,018 Year 4 255,142 Year 4 r = interest rate

Source: on-station and on-farm experimental data

Literature (Buresh and Cooper 1999; Adesina et al. 2000) suggests that farmers’ interest in tree fallows increases when trees also provide other benefits than soil fertility improvement alone, such as fodder, fuelwood, staking material, etc. One of such additional benefits of RHI with calliandra is that the trees flower almost all year round and are suitable for bee- forage (Duguma and Mollet 1997). After a bee-keeping training workshop organised in 1997 for farmers experimenting with calliandra fallows in the humid forest and savannah zones of Cameroon, participants started integrating beehives in their calliandra plots. Hence, we included beekeeping in the cost-benefit analysis of RHI (Annex 2; Table 5-4), assuming that the activity can only take place during the fallow phase. Associating honey production to the RHI budget, made the Net Present Value positive, though still much lower than that of natural fallows.

Time is an important factor in soil fertility improving technologies. Benefits are cumulative over time and tend to be relatively low during the initial years following adoption. The time lag between costs and benefits of adoption for farmers, coupled with the fact that small-scale resource-poor farmers have short-planning horizons and high discount rates, implies that planted fallows can be very unattractive to farmers (Izac 2003). Table 5-4 demonstrates that by changing the discount factor from 20 % to 10 %, RHI with beekeeping becomes more profitable than natural fallow system.