Labile carbon and carbon management index in peat planted with various crops.

Changes in soil carbon (C) from forest to agriculture land in Mukah, Sarawak, and Simpang Renggam (SR) Johor were studied. The changes in labile C (CL) (Mukah, 0.7–43%; SR, 0.2–20%) were greater than changes in the total C (CT) (Mukah, 0.5–9%; SR, 0.3–7%) as compared to the forest. In Mukah, oil palm and pineapple ecosystems showed approximately 18% and 6% increases in CL at a soil depth of 0–15 cm, respectively, as compared to the forest, and thus had greater C management index (CMI) values. In the sago ecosystem, the decline in CL was approximately 26% at the soil depth of 0–15 cm as compared to the forest. In SR, oil palm and pineapple ecosystems showed approximately 0.2% and 19% decreases in CL, respectively, at soil depths of 0–15 cm, resulting in low CMI value. The CL and the CMI can be used to monitor the rate of changes in soil C for different land uses on peat

Spatial variability of pineapple yields on tropical peat.

The spatial variability of pineapple yields from a one-hectare field located on a tropical peat was quantified. In situ yield measurements were recorded based on 0.6 × 25-m rectangular grids. A total of 60 geo-referenced yield records were obtained. Recording points were spaced 8 × 18 m. Yield data were subjected to semivariogram and kriging analyses. The average pineapple yield was 93.3 kg per grid with a CV of 13.7%. The spatial structure of pineapple yields was fitted using an exponential function with a total variation (sill) of 137.6, a random variation (nugget) of 49.3, and an effective range of 38.1 m. Based on the nugget to sill ratio, pineapple yields showed a moderate spatial dependence. A map comprising measured and interpolated yield values showed that 31% of the field had yields close to the field average, 36% had yields above the average, and 33% with yields below the average. These results suggest that site-specific management of pineapple is necessary

Performance Evaluation of a Simple, Locally-Designed Padi Thresher

Performance evaluation studies of a padi thresher designed at Universiti Pertanian Malaysia Cawangan Sarawak indicated that it was a high capacity thresher. Using manual labour, it was capable of threshing padi at a rate of 45 to 68 kg/hr. The skill and the physical power of the operator determined the actual rate of threshing. However, when engine powered, threshing was accomplished at a constant 121.3 kg/hr. Thresing efficiency was found to be 87% or higher and product purity was 79% or higher. The possibility of this thresher being adopted for use by padi farmers is good because there is a marked increase in output per man-hour over manual threshing. In addition, it is cheap, light and easy to fabricate

Physiological response of of hopea odorata Roxb. And mimusops elengi linn. Seedlings Under combined nutrient and water Stresses

The physiological response of Hapea odarata and Mimusops eiengi seedlings under drought and various fertilisation rates subjected to nursery conditions was investigated. The experiment was a 6 x 2 factorial design and slow release fertilizer (Best Tab, 20: I O:S N PK) was applied once at the beginning of the experiment and was placed 10cm below the surface in tablet form (NPK 20: 1 O:S). The watering treatments were no stress (seedlings were kept well watered at field capacity ~. 0.3 MPa) and water stress (water was withheld until the soil water potential was ~ - 1.S MPa and then rewatered to field capacity). Physiological measurements were made on mature fully·expanded leaflets of the seedlings. Both species responded differently to conditions of drought and fertilisation with H. odorata seedlings receiving 30g of fertiliser under well-watered conditions had the highest rate of photosynthesis and stomatal conductance throughout the 12 -months period. In contrast, M. eiengi seedlings receiving SO g offertilizer application recorded the highest rate of photosynthesis and stomatal conductance. Both species exhibited drought tolerance via maintenance of high water potential at the end of 12·moflth experimental period. They possess "sensitive stomata" or stomata which close rapidly on exposure to water stress. Such a stomatal response may effectively reduce water loss and maintain high water content during water stress in the urban area. Another important factor is that photosynthetic processes can still be carried out under water stress although at a reduced rate. Fertilisatiofi reduces the impact of drought through its effect on stomatal closure thus reducing transpiration increasing photosynthetic rate and maintaining a much more positive internal water balance which is vital for almost near normal plant function~ng

Decomposition of leaf and fine root residues of three different crop species in tropical peat under controlled condition.

A study examining the decomposition rates of leaf and fine root residues of oil palm (Elaeis guineensis), sago (Metroxylon sagu) and pineapple (Ananas comosus) crops in peatland soils was conducted under controlled conditions. The fourteen- month study showed that sago leaf residue was the most resistant to decomposition with only 30 % mass loss, while pineapple leaf residue was found to be the easiest to decompose, accounting for 90 % of the mass loss. In contrast, the highest (70 %) mass loss of fine roots was observed in sago, while the lowest (50 %) was in pineapple. Nutrient concentration in plant tissues correlated significantly with mass losses of leaf and fine root residues. The high C:N in plant tissues, resulted in slow decomposition of sago leaves and pineapple fine roots. Decomposition of the different plants were in the order: pineapple > oil palm > sago drained = sago undrained for leaf residues, and, sago drained = sago undrained > oil palm > pineapple for fine root residues

Charge characteristics in relation to mineralogy of selected soils from South-east Asia

The mineralogy and charge characteristics of 7 soils from the Philippines, Indonesia and Malaysia were studied. The soils consisted of an Entisol, 3 Alfisols, an Andisol and 2 Oxisols. Smectite, mica and quartz were present in the clay fraction of the Entisol. In the Alfisols, smectite and kaolinite were the dominant minerals. The Andisol was dominated by halloysite, whereas the Oxisols were dominated by kaolinite and oxides. The amount of kaolinite increased towards the surface, while halloysite decreased, indicating the transformation of halloysite to kaolinite during the course of weathering. Differences in mineralogy of the various soil types were reflected clearly in the differences in charge characteristics. Soils with smectite (Entisol and Alfisol) had high a negative charge. The Andisol, which contained halloysite, and the Oxisol, with kaolinite and oxides, had high amounts ofpositive charge, but moderate amounts ofnegative charge. The availability ofCa in the soils depended upon exchangeable Ca and the efJective cation exchange capacity (ECEC)

The mineralogy and chemical properties of soils on granite gneiss in three climatic zones in Sri Lanka

Granite gneiss occurs sporadically throughout Sri Lanka. Depending on the climatic conditions and topography of the area, the rock undergoes different degrees of chemical weathering. The mineralogy and chemical properties off four common granite gneiss soils occuning in three agro-ecological zones in Sri Lanka were studied. The soil in the wet zone is low in pH and basic exchangeable cations, while the soils in the wet zone are high in pH and basic exchangeable cations. The colour of the soils changes from yellowish-brown to red as the soils get drier, pesumably due to the presence of haematite and/or goethite. Kaolinite, halloysite and smectite are present in all the soils irrespective of the climatic conditions; the amount of halloysite decreases towards the surface. Biotite is abundant in the soil of the intermediate and dry zones, but is absent in the soil ofthe wet tone. Gibbsite is present in the highly weathered soil of the wet zone. The concentration of Ca in soil solution is dependent on the amount in the soils existing in the form of exchangeable Ca. Additionally, the solution Ca concentration is significantly correlated with the soil ECEC and the ECEC/CEC ratio