Structure and management of cocoa plots

Plot establishment

35.4% of the farmers reported that they established their cocoa plots by converting natural forest land. Cocoa agroforestry usually follows a few seasons of dry land agricultural crops. 22.9% reported to have converted other perennial cropping sys-tems (coconut or coffee), and 25% that they converted land with annual crops. 28.5%

of the plots were purchased as established cocoa plots between 1970 and 2005. Be-tween 1995 and 2005, the average price was 582.8 USD ha^-1. Even after adjustment for inflation, plot prices significantly increased since 1995 (P< 0.001, inflation ad-justed according to International Monetary Fund, World Economic Outlook Data-base, April 2009).

Plot structure

The entire CC gradient was covered although zero shade plots were found in the Palu valley where cocoa plots are often grown under coconut trees. CC ranged from 1.6%

to 98.6% in 2008 (average CC 42.4% in 2008). Cocoa plot size was between 0.4 and 3.3 ha (0.63 ha on average) with 75% of the plots smaller than 1 ha. With substantial variability, mean planting density was 854 (STD 346.2) cocoa trees per ha. Planting density was highest in Palolo. Cocoa tree age varied between 3 and 27 years. In Pa-lolo, cocoa trees were slightly older on average reflecting a longer cocoa cropping history.

We found high variability of intercrops and shade trees. Native forest trees were pre-sent on 66% of the plots with up to 9 different species per plot. A high share of forest trees was found in Kulawi valley plots. A total of 80 different native forest tree spe-cies were identified by farmers. 91 % of the plots were intercropped with 1 to 5 intercrops (mean 1.8). In total, 20 different intercrops were found. Intercrops were predominantly bananas and perennials such as fruit trees, coconut or coffee. Vanilla or vegetables were also frequently grown. The highest diversity of intercrops was found in Palu valley.

Pest and disease pressure

Cocoa Pod Borer (CPB) (Conopomorpha cramerella) and Black Pod Disease (BPD) (Phytophthora palmivora L.) spread rapidly: Farmers reported that BPD and CPB arrived in their villages around the year 2000 or later. In 2007 BPD and CPB oc-curred on 100% and on 99% of all plots respectively. Farmers estimated yield losses of 24.3% on average due to CPB (median 20%, maximum 70%), and 20.5% due to BPD. BPD and CPB induced yield losses are correlated (r= 0.45, P<0.001). Plots farther away from the forest edge showed lower CPB yield losses (r= -0.215, P=0.01). Yield losses due to BPD decreased with higher altitude (r= -0.32, P<0.001).

Recommended cultural control techniques to combat CPB and BPD include 4 major steps: frequent harvest (at 14 days interval), cocoa pruning, sanitation of pod husks (removal, burning or burying of affected pods) and fertilization (ACDI/VOCA 2005). None of the household applied all 4 steps, and only 8.4% reported employing 3 steps. Whereas 37.8% of farmers practiced sanitation of pod husks, not a single

household harvested at a 14-day-interval. In contrast 51.7% of the farmers used pes-ticides. Farmers who had suffered high yield losses already when CPB first occurred at their plots, reported spraying pesticides more frequently later (r=0.28, P=0.013).

About half of the households stated that they were able to reduce yield losses occur-ring by CPB (51%) and BPD (53.8%) attacks since begin of infestation. More fre-quent pruning of cocoa trees helped reducing BPD (r= -0.177, P=0.041), higher fer-tilizing and pesticide application frequency reduced CPB yield losses (r= -0.2, P=0.018 and r= -0.176, P=0.038 respectively), whereas an increase in CC between 2007 and 2008 led to increasing CPB yield losses (r=0.279, P=0.001).

Soil characterization

Cocoa plots are located on lower slopes, alluvial fans and at the border of the alluvial basins, resulting in geologically young topsoil. According to the WRB/FAO (2007) soil classification, the following soil types were found: Cambisols, Gleysols, Phaeozemes, Stagnosols and Fluvisols. Cambisol was found on 30 of 48 plantations in different specifications (gleyic, eutric, stagnic, fluvic, endoskeletic). The following catena of soil types was identified from the slope to the basin: Cambisol followed by stagnic/ gleyic Cambisol and in the basins Gleysol, and fluvic/ gleyic Cambisol. A comprehensive characterisation of the stocks and available nutrients from the 48 in-vestigated plots is provided in Tab. 2.

Table 2. Stocks and available nutrients within the first 30 cm of the topsoil.

Ct Nt Pt Pav Caex Kex Mgex Alex CECeff

n 44 48 44 40 40 40 40 40 48

Mean 52.068 5.024 2.193 12 6.889 664 1.148 301 341

SD 15.831 1.752 1.312 10 2.904 292 773 333 137

Max 98.914 8.612 7.279 41 13.132 1.515 3.357 1.463 648 Median 49.902 4.992 1.856 10 6.168 636 765 202 298

Min 25.257 1.756 458 1 1.578 247 407 42 130

All units are kg ha^-1·0.3m^-1 except CECeff [kmol ha^-1 0.3m^-1]; av. = available, ex. = exchangeable. Many plots are classified as low nutrient plots mainly for C and Pav. For Nt and exchangeable Al, plots are evenly distributed across all three categories.

For the remaining nutrients and CEC_eff, most plots attain a medium to high nutrient

Table 3. Nutrient status distribution of cocoa plots according to Lanfer (2003); Num-bers of cocoa plots in each category (low to high); numNum-bers vary due to data gaps (missing analyses).

Ct Nt Pav Caex Kex Mgex Alex CECeff

n 44 48 44 40 40 40 40 48

Low 38 18 34 1 0 1 12 1

Medium 6 19 6 3 12 0 12 29

High 0 11 4 36 28 39 16 10

Only 43% of surveyed households ever fertilized their cocoa plots, and in 2007 even only 27.3% did so. 30.1% of farmers stated that soil fertility was already reduced compared to the time when they started to manage the plot. There is no correlation between plot fertilization and cocoa yields.

Cocoa yields

2007 yields showed a broad range (7-1613 kg ha^-1) with an average of 476.9 kg ha^-1 and pronounced seasonality (Fig. 3).

Figure 3. Average monthly yields in 2007 (n=143, error bars show standard devia-tions).

Canopy closure, presence of stagnant soil water conditions, number of native forest tree species and number of intercrops were correlated – in this order – with decreas-ing yields (Tab. 4). Increasdecreas-ing yields were correlated with cocoa tree density and labour input. Among themselves, plot structural parameters were frequently corre-lated. Aggregated in a Management Index (MI) as a proxy for plot structure intensi-fication, they revealed substantial explanatory power for cocoa yield variation (Fig.

4).

Table 4. Correlation of plot structure parameters and cocoa yields (n=143).

Cocoa yield

Pearson correlations; n.s.: not significant; displayed correlation coefficients significant at p<=0.1; *: p<=0.05; **: p<=0.01.

Figure 4. Cocoa dry bean yield 2007 in relation to a Management Index MI (0-4) composed of plot structural parameters.

Influences of soil parameters surveyed on a subset of plots (n=48) on cocoa yields are not very strong. In regression analysis, only total soil phosphor content is a yield determinant (Tab. 5). The model improves when a dummy for stagnant soil water conditions is included, which has a negative influence on yields.

Table 5. Regression analysis, dependant variable: cocoa yield (n=43).

Cocoa dry bean yield [kg ha^-1]

vs. R² p Coeff.

total soil P

Coeff.

stagnant water Total soil P [kg ha^-1] 0.21 0.002 0.456

(p=0.002) Total soil P [kg ha^-1],

stagnant water (0/1) 0.27 0.002 0.453 (p=0.002)

-0.25 (p=0.07)

Processing and marketing

Of four main post-harvest activities, cracking of the cocoa husk followed by extrac-tion of the beans require, by far, most labour per hectare (Fig. 5).

Figure 5. Labour requirement for cocoa bean processing (means of n=144 plots).

71.8% of all cocoa beans were sold within the same village, mostly to small traders or middlemen. Only 14.4% of sales were done at a cocoa collection centre in the province capital Palu.

Producer prices at farm gate rose quickly in early 2007, and peaked in July (Fig.6) closely following world market price (FOB, ICCO monthly averages; ICCO 2008).

Farmers of the project region received on average 70.2% (minimum: 62.4%, maxi-mum 77.4%) of the world market price. The linear correlation between local and world market prices is very high (r=0.834, P=0.01).

Figure 6. Cocoa producer prices in the LLNP region and world market prices in 2007 (monthly averages in USD t^-1 dry beans; world prices according to ICCO 2008).

One-way-ANOVA with Tukey post-hoc tests showed the following significant cocoa price differences (p<0.01): Prices were higher when cocoa beans were sold directly in Palu compared to sales in the neighbour village (+11.1%) or at the home village (+16.2%). Higher prices were also achieved by selling directly to a big merchant compared to selling to a middleman (+13.7%) or to a small trader (+15.5%). Prices gained in Palolo valley were significantly higher than in the other valleys (+6.4%).