Tending and growth performance

Land preparation before planting

Since all the land was previously planted with agricultural crops, 92 percent of the respondents cleared land, and eight percent prepared bedding and terraces/platforms before planting (Table 27).

Table 27. Land preparation before planting

Fertilizer application

All respondents applied fertilizer during and after planting. Common fertilizers applied during planting were chicken manure, phosphate, NPK and urea (Table 28). After planting, companies discontinued chicken manure application while the individual planters continued to apply this type of fertilizer. NPK was the most common fertilizer used during and after planting by companies and individual planters. All companies applied NPK only after planting.

Table 28. Types of fertilizer used during and after planting

Note: One company applied more than one type of fertilizer during planting.

Various reasons were given for choosing a specific fertilizer during and after planting (Table 29). Cost considerations were most important for companies. Of the six companies, four percent indicated that a particular fertilizer was used because of low cost while 17 percent attributed their choice to its availability and another 17 percent to ease of application. Two-thirds of the individual planters applied the fertilizer recommended by RISDA. Other reasons included low cost, availability, ease of application and perceived positive impact.

Table 29. Reasons for choosing the type of fertilizer

In general, the frequency of fertilizer application is about the same for companies and the individual planters (Table 30). Except for the first year when companies applied fertilizer three times (compared to two for individual planters), the number of fertilizer applications was the same from year 2 onwards. The average number of fertilizer applications declined to once a year from year 5 onwards.

Table 30. Average number of fertilizer applications per year

Weeding

Weeding was done in various ways (Table 31): over the total area (56 percent), using line weeding (22 percent), by circle weeding (11 percent) and by chemical spraying (four percent). Not all of the respondents weeded every year. The extent of weeding depended on the perception of the need to do so. In a certain year, no weeding would be done. For example, in year 1 of planting, one company and three individual planters did not weed as weed pressure was low.

Table 31. Types of weeding

The average number of weedings per year generally declined after the third year (Table 32). Weeding was discontinued from the fifth year onwards.

Table 32. Average number of weedings per year

Two individual planters did not weed at all. They perceived that weeding would reduce soil moisture especially during the dry period and this would increase pest infestations and diseases. They also felt that weeds retain soil moisture, which is important for tree growth especially during dry spells. Consequently, they attribute the good growth performance of their trees to lack of weeding.

Climber cutting

On average, companies cut climbers once a year during the first three years of planting. The individual planters rarely cut climbers.

Survival rate and replanting

In general, the survival rate of trees was very high (Table 33). It was about 95 percent during the first three years of planting. Consequently, replanting was not done. There was no obvious difference in survival rate between mixed and single species plantations. The survival rate of teak that was inter-cropped with banana was low. This might be related to waterlogging on clay soils.

Table 33. Average survival rates (%)

Height and diameter increment

Table 34 shows that for single-species plantations, the average annual height increment was about 1.9 m (teak), 1.5 m (sentang) and 3.3 m (Maesopsis eminii). For mixed plantations, it was 1.7 m (teak and banana), 0.8 m (teak and oil palm), 0.8 m (teak and tongkat ali), and 1.3 m (sentang and rubber). This seems to indicate that in single-species plantations trees grew faster than when they were inter-cropped, although the differences were not very pronounced for sentang.

Table 34. Average tree height (m)

Figures in parentheses are the range.  n.a. = not available.

There were also some differences in the diameter growth trees planted in mono- and mixed cultivation (Table 35). In monocultivation, the average annual dbh increment was 2 cm (teak), 2.4 cm (sentang) and 1.6 cm (Maesopsis eminii). In the case of inter-cropping, the values were 3.3 cm (teak and banana), 1.4 cm (teak and oil palm), 1.2 cm (teak and tongkat ali), and 1.9 cm (sentang and rubber).

Table 35. Average diameter at dbh (cm)

n.a. = not available.