Survival and growth performance of teak under monocrop system and intercropped with oil palm

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1 Sepilok Bulletin 13 & 14: (2011) Survival and growth performance of teak under monocrop system and intercropped with oil palm F.R. Chia Forest Research Centre, Sabah Forestry Department, P.O. Box 1407, Sandakan, Sabah, Malaysia. Abstract. Survival percentage and growth performance of 10-year-old teak planted under monocrop system and intercropped with oil palm were assessed. The survival percentage recorded in 10-year-old monocrop and intercrop was 84.72% and 88.64% respectively. The overall performance of teak was better in the intercrop plot. Ten years after planting, the trees had reached a mean height of m and m, with mean DBH (diameter at breast height) of cm and cm, in monocrop and intercrop respectively. The oil palm yield was significantly lower in the intercrop plot as compared to monoculture of oil palm after 10 years. The agroforestry system recommended for these 2 species is block planting instead of intercropping. Keywords: agroforestry, growth performance, oil palm, survival, teak INTRODUCTION Intercropping between agricultural crops and forest species is considered as a practical agroforestry system in Sabah (Rahim & Anuar 2001). For the past decade, fast growing timber species with clear bole, erect growth with small and sparse canopy held high above the trunk together with high market value was recommended as a companion crop to commercial agricultural crops like oil palm. This concept suggests the early returns from oil palm will sustain the growth of the timber species to maturity and subsequently gain profit. Teak (Tectona grandis L.) was one of the species which was recommended as a companion crop for oil palm back in the 1990s (Tee et al. 1995). Teak was recommended due to its fast growing nature and different statures and rooting habit from oil palm (Tee et al. 1995). The height difference, light and sparse canopy of teak allow solar radiation to reach the oil palm. The strong tap root that penetrates below the root regime of oil palm reduces the competition of soil nutrients between these two crops (Tee et al. 1995). To prove the physical feasibility and economic viability of this agroforestry concept, research plots were established in 1999 by intercropping teak with oil palm. 33

2 Earlier assessment by Chia et al. (2004) reported that intercropping of fast growing timber species with oil palm is a practical agroforestry system, in terms of economics and land use. The growth performance of teak and oil palm yield were better in the intercrop system compared to monocrop cultivation at 4 years of age. This result indicates that oil palm performed better in the intercrop system at the early stage (first 2 yielding years) before canopy closure. However, the actual trend of the results can only be gathered after canopy closure. Lee et al. (2005) reported that the canopy closure for oil palm occurs at the age of about 8 to 12 years. Therefore the objective of this study is to reassess the growth and yield of teak and oil palm planted side by side at the age of 10 years in Sungai Daling agroforestry plots. MATERIALS & METHODS The demonstration plots were established in 1999 covering an area of 7 ha in Sungai Daling ( 'N, 'E), Kolapis A, Lungmanis Forest Reserve, Sandakan. Kolapis A is situated 65 km west of Sandakan. The area is undulating and the soils are Orthic Acrisols belonging to the Tanjung Lipat family of the Kretam association, a well-drained sandy loam to sandy clay loam (Acres & Folland 1975). The oil palm and teak were planted at alternate rows with a spacing of 4.5 m x 9 m, while for the monocrop plot, teak was planted in line with 9 m x 9 m (Table 1). The teak seed originated from Bandau, Kota Marudu whilst oil palm seedlings identified as DxP or tenera variety were purchased from a local commercial nursery. The plot layout was in block system where each block consisted of one system of planting and covered an area of 1 ha. Fertilizer was applied thrice a year to oil palm plot (AF1) and intercrop plot (AF3). The amount of NPK fertilizer applied was 1 kg/palm. The teak was enumerated annually by measuring their height and DBH. The fresh fruit bunches (FFB) of oil palm were collected bi-monthly. Table 1. Planting density of oil palm and teak. Block Species Area (ha) Planting distance (m) Date of planting Density (tree/ha) AF1 Oil palm 1 9 x 9 20/4/ AF2 Teak 1 9 x 9 23/3/ AF3 Oil palm + teak 1 9 x 9* 9 x 9* 22/4/ /2/1999 *Note: Planting distance between teak and oil palm is 4.5 m x 9 m RESULTS & DISCUSSION The survival percentage of teak was more than 80% in both monocrop and intercrop plots 10 years after planting (Table 2). The survival percentage of teak was higher in intercrop (88.64%) than monocrop (84.72%). The actual density after 10 years was 122 and 117 trees in monocrop 34

3 and intercrop plots respectively. No mortality was recorded after 7 years in monocrop plot. The relatively high survival percentage for these plots indicates that teak is suitable to be planted in the area. Table 2. Survival percentage of monocrop and intercrop plots. Year (Age) Survival (%) Monocrop Intercrop 2000 (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) Figure 1 shows the mean height and DBH for teak within 10 years after planting. The growth performance of teak was significantly better under intercrop system. Analysis using t-test showed that the mean height and DBH of teak were higher in the intercrop plot compared to the monocrop plot (P < 0.01) within 10 years. Better growth in intercrop plot might be due to closer spacing where teak would tend to grow straight with clear bole (Plates 1 & 2). Ten years after planting, the trees had reached a mean height of m and m in monocrop and intercrop respectively. The height performance in intercrop plot was comparable to the plot in Gum-Gum at m with planting espacement of 3.05 m x 3.05 m (Chia et al. 2008). The mean DBH at 10 years had reached cm and cm in monocrop and intercrop respectively, almost double the size of that in the Gum-Gum plot at the same age with cm (Chia et al. 2008). The higher DBH in intercrop plot might be due to the fertilizer applied to the palm. This result indicates that teak grows better in fertile soil. The mean annual increment (MAI) in height peaked at the second year after planting and started to drop after the third year and leveled off after 7 years (Figure 2). The average MAI for height in 10 years was 1.82 m and 1.69 m for intercrop and monocrop respectively. The DBH grew faster in the first 5 years ranging between 3.5 cm to 5 cm annually (Figure 2). The average MAI for DBH in 10 years was 3.17 cm and 3.02 cm in monocrop and intercrop respectively. Figure 2 shows that the growth rate of teak decreased over the years and similar trend was also recorded after 10 years at Gum-Gum (Chia et al. 2008). This finding indicates that teak grows faster in the first 10 years after planting. 35

4 : Age (year) Figure 1. Mean height and DBH of teak planted under monocrop and intercrop systems within 10 years after planting. 36

5 Plate 1. Teak in intercrop plot. Plate 2. Teak in monocrop plot. 37

6 MAlheight (m monocrop intercrop Figure 2. Mean annual increment of height and DBH of teak planted under monocrop and intercrop systems within 10 years after planting. 38

7 Oil palm yield Fresh fruit bunches (FFB) collection started in April 2003 or 4 years after planting. Figure 3 shows that the FFB yield in the monocrop started to overtake the intercrop in the fifth year after planting. As teak was planted at the same time with oil palm, at the fifth year after planting, most of the teak had reached about 12 m in height (Figure 1) or above the canopy of oil palm. It was noted that the fallen leaves of teak could cover the young oil palm inflorescences at the early stage (Plates 3 & 4). These fallen teak leaves might affect the health and quality of the pollen, and also hinder the oil palm weevil from pollinating. This might affect the overall yield of oil palm. However, further research is needed to clarify this. Figure 3 shows that the FFB yield was extremely low at between 6 and 8 tonnes per hectare per year in monoculture plot as compared to a well-managed estate with average between 15.9 and 20.3 tonnes per hectare per year (Ooi 2008). This might be due to the unselected seed source and poor agricultural practices in this plot. Improved seed source or planting material, good agricultural practices together with proper amount of fertilizer are factors that ensure optimum yield of oil palm (Basiron 2007, Ooi 2008). It was reported earlier that the oil palm canopy begin to close at the age of 8 to 10 years, and oil palm yield will only decrease slightly after 12 years (Lee et al. 2005). However, Figure 3 shows the FFB yield in the intercrop plot dropped drastically after 9 years which indicates that the canopy closed earlier with the introduction of teak. Physically the fruit size of oil palm was also smaller and lighter in the intercrop plot (Figure 4). The average weight for one fresh fruit bunch in monocrop and intercrop at 10 years was 12.3 kg and 9.9 kg respectively. This might be due to the oil palm fronds not being able to spread fully for exposure to sunlight to achieve maximum production (Tee et al. 1995). Hensen (1991) reported that the early expansion of young oil palm canopy to facilitate radiation capture is of crucial importance for yield, while the efficiency of radiation conversion to dry matter becomes more important later on when the canopy reaches full expansion. This indicates that planting density is an important factor for oil palm yield. Thus tree species like teak are not recommended to be intercropped with oil palm as it will increase the tree density and create upper canopy competition between the oil palm fronds and the teak branches. However, in order to maximize land use and yield of oil palm, the recommended agroforestry system might be block planting. 39

8 Figure 3. Yield of fresh fruit bunches (FFB) (tonnes/hectare) for 7 consecutive fruiting years Oil Palm Oil Palm + Teak O 6-44 ba Age Figure 4. The size of FFB in terms of weight (kg) in monocrop and intercrop plots. 40

9 Plate 3. Teak leaves dropped onto the oil palm inflorescences. Plate 4. Fallen teak leaves cover the oil palm inflorescences. 41

10 CONCLUSIONS This study indicates that teak grows better in intercrop with oil palm than monocrop. It suggests that teak should be planted at closer spacing to maximize height growth. However, the yield of FFB of oil palm decreased drastically after canopy closure. The yield of FFB was significantly lower in the intercrop plot as compared to monoculture of oil palm. This result suggests that in order to maximize oil palm production, teak is not recommended to be intercropped with oil palm. Block planting is recommended if agroforestry is to be implemented in oil palm plantation. ACKNOWLEDGEMENT Thanks are due to the staff of the Agroforestry Section of the Forest Research Centre (FRC), Sepilok, for the help in data collection. REFERENCES Acres, B.D. & Folland, C.J. (1975). The soils of Sabah. Vol. 2. Sandakan and Kinabatangan districts. Land Resource Study 20. Ministry of Overseas Development, Surrey, England. 164 pp. Basiron, Y. (2007). Palm oil production through sustainable plantations. European Journal of Lipid Science and Technology 109: Chia, F.R., Rahim, S., Martin, R.A., Anuar, M. & Kodoh, J. (2004). Preliminary results on the growth and yield of high value timber species and oil palm under agroforestry system. (In) Ahmad Zuhaidi, Y., Hashim, M.N., Abd Rasip, A.G., Rosdi, K., Najib Lotfy, A. & Suhaimi, W.C. (eds.), Proceedings of the National Seminar on Agroforestry 2004: The Way Forward, September 2004, FRIM, Kepong. Chia, F.R., Pang, K.K.N. & Lapongan, J. (2008). Growth performance of some planted timber species in Gum Gum Forest Reserve, Sabah. Poster presented at 15th Malaysian Forestry Conference, October, Kuching. Henson, I.E. (1991) Limitations to gas exchange, growth and yield of young oil palm by soil water supply and atmospheric humidity. Transactions of Malaysian Society of Plant Physiology 2: Lee, Y.F., Chia, F.R., Anuar, M., Ong, R.C. & Ajik, M. (2005). The use of Laran and Binuang for forest plantations and intercropping with oil palm in Sabah. Sepilok Bulletin 3: Ooi, T.C. (2008). Raising oil palm yields. New Straits Times 25 January Rahim-, S. & Anuar, M. (2001). Experience on agroforestry development in Sabah lessons learnt. Paper presented at the National Seminar on Agroforestry, April 2001, Malacca. Tee, B., Patel, M.F. & Chiew, A. (1995). Teak in Sabah, a sustainable agroforestry, the Harris Salleh experience. Sejati, Kota Kinabalu. 42