Field grown Acacia mangium : how intensive is root growth?

Under rainfed conditions, root development of trees can be very unpredictable and variable, depending on the amount and distribution of rainfall received. This becomes more critical when the rainfall is seasonal and the soil has a high clay content. Our investigation dealt with the root development of Acacia mangium established as plantation forest on a soil with heavy clay texture in Kemasul Forest Reserve, Malaysia. The distribution of active roots was measured at 9- and 21-month-old plantations using the radioactive 32P injection method. Growth at different distances from the tree base and at different soil depths was studied. After nine months of field planting, we found that roots were mostly concentrated at the surface within 1000 mm distance from the tree base. At one year after the first measurement, roots were traced as far as 6400 mm away. A large part of these roots, however, were detected within 3700 mm distance in the upper 300mm soil. At this stage, roots still did not go deeper than 450 mm depth, probably due to the high clay content at lower depth and low pH. This rapid root growth indicates that below-ground competition can be very intense if this species is established as a mixed-species plantation

Assessment on the quality of recycled paper mill sludge mixed with oil palm empty fruit bunch compost.

Recycled Paper Mill Sludge (RPMS) is currently disposed off in the landfill and the costs are becoming expensive. Therefore, an alternative disposal through land application of RPMS and empty fruit bunches (EFB) (as a bulking agent) compost requires investigation. This study was conducted to determine the physico-chemical characteristics of composted RPMS and EFB mixtures, their phytotoxicity and the effect of the composts on plant growth performance. Composting experiment was arranged in a completely randomized design (CRD) with four replicates. The RPMS were mixed with EFB in 3 ratios, that is 1:1, 1:2 and 1:3 (RPMS: EFB) based on volume/volume. The mixtures were filled in a polystyrene box up to 90% volume and water was sprinkled onto the compost (50% moisture content) to accelerate decomposition. During composting, the compost was turned every three days to ensure that the material on the outside of the pile was turned from the center outwards to dissipate heat. The RPMS and EFB compost mixtures were evaluated for physical, chemical, phytotoxicity and short term plant growth effects. These composts mixtures had no toxicity effects on plants, had 100% seed germination, high in nutrient contents, low in C/N ratio and had fine particle size of <18 mm. The concentrations of heavy metals were also within the recommended level of the Council of European Communities (CEC) for compost. Compost produced from a ratio of 1:1 volume is suitable for land application as compared to 1:2 and 1:3 (RPMS: EFB). However, further study should be carried out to evaluate the effect of raw and RPMS compost on soil fertility, plant productivity and quality

Effects of mulching and fertilizer on nutrient dynamics of sand tailings growth with acacia hybrid.

Studies on the contribution of oil palm empty fruit bunch (EFB) mulch mat and its impact on fertiliser loss through leaching on sand tailings are lacking. Sand tailings in Malaysia formed through tin mining activities are problematic soils for agriculture and forestry. An experiment with two types of EFB mulch mat applied in combination with NPK (nitrogen:phosphorus:potassium) fertiliser was established in pots containing sandy tin tailing soil to assess their effects on soil nutrient enrichment and leaching. Application of mulch mat reduced leaching of fertiliser compared with treatments without mulch mats. Incorporating fertiliser inside the mulch mat at the production stage could be the best way of applying inorganic fertiliser on sandy soils as the amounts of N, P and K loss was reduced significantly compared with treatments without mulch. There was poor synchronisation between fertiliser input and plant nutrient demand. The amount of fertiliser applied seemed to be in excess of the uptake capacity by roots especially for highly mobile nutrients N and K. Application of mulch mat on sand tailings however did not ameliorate the soil nutrient properties after 16 weeks. This could be due to the porous nature of the sand tailings

Spatial variability of selected forest soil properties related to carbon management in tropical lowland and montane forests

A better understanding of spatial variability of forest soil properties related to carbon (C) sequestration will improve management strategies towards conserving forest areas that project higher C stocks. This study was aimed at determining spatial variability of soil C, C:N (nitrogen) and forest floor depth in tropical lowland and montane forests at varying topographic positions. Quadrants of 10 m ×10 m were established for soil (0-15 cm depth) and forest floor sampling along three slope positions. This amounted to 120 quadrants at the montane forest and 60, in the lowland forest. Soil and forest floor samples were geo-referenced using global positioning system. Univariate statistics, including normality check, non-spatial outlier detection and data transformation were performed on test variables, followed by variography and kriging analyses to quantify spatial variability. Results showed that spatial structure of test variables differed across topographic positions and within the lowland forest. Surface maps showed distinct spatial clustering and displayed acceptable accuracy of interpolated values. Soil C stocks were highest in the summit, followed by toeslope, sideslope and Jengka Virgin Jungle Reserve. Site specific management for carbon sequestration monitoring in tropical forest should be based on topographic delineation

Carbon stocks in different carbon pools of a tropical lowland forest and a montane forest with varying topography

Increasing atmospheric carbon dioxide concentrations at alarming rates have triggered the need to revisit potential opportunities in conserving and monitoring carbon (C) stocks for climate change mitigation. The dynamic nature of tropical forests based on topographic variations and biomass components needs reliable estimation of forest C to support conservation and forest monitoring strategies. This study was aimed to determine C stocks of varying components (i.e. litter, soil, aboveground biomass and roots) in a tropical lowland forest and a tropical montane forest at varying topographic positions. Systematically designed 10 m × 10 m plots were established for soil (0–15 cm depth), litter and aboveground biomass sampling along three slope positions at the montane forest and one plot in the lowland forest due to minimal topographic variability. Basic soil characteristics and botanical distribution of both forest sites were determined. Carbon stocks were significantly higher in the tropical montane forest, where litter and soil C stocks at the summit were three and five folds significantly higher compared with the lowland forest. No significant differences were found in vegetation structure (mean diameter at breast height, mean height and stand basal area) but the aboveground biomass ranged from 100 to 120 Mg C ha-1 and was the most dominant pool (> 40%) for all sites. Soil C pools were comparable (100 to 120 Mg C ha-1) with aboveground biomass pools at the summit and toeslope position of the montane forest

Application of waste raw and composted recycled paper mill sludge on orthosiphon stamineus and its effects on heavy metals in soil

The paper industry plays a major role in the global economy of the world. A study was conducted on the waste paper mill sludge applied on the Orthosiphon stamineus for 4 crop cycle for 1 year growth at Glasshouse, Faculty of Agriculture, Universiti Putra Malaysia. Waste Paper Mill Sludge (PMS) and waste composted Recycled Paper Mill Sludge (RPMS) was used with nitrogen (0, 100, 200 and 400 kg ha-1) at the ratio of 1:1 (Recycled Paper Mill Sludge (RPMS): Empty Fruit Brunch (EFB). The growth parameters were measured twice a month for 6 months. Plant nutrients and heavy metals uptake were determined. The paper mill sludge has the potential to be a supplementary N fertilizer as well as a soil amendment. The application of waste RPMS with N significantly contributed to the improvement in plant dry matter (28.5 g plant-1) and improved soil physical and chemical properties. Total concentrations of heavy metals in soils were below the critical values. Hence, the waste paper mill sludge can be successfully used as soil amendment in acidic soil without any serious threat. The use of waste paper mill sludge for the soil fertility showing improvement in land application signifies a unique opportunity to recycle sludge back to the land to alleviate the potential waste management problem

Characterization and feasibility assessment of recycled paper mill sludge for land application in relation to the environment

The disposal of industrial paper mill sludge waste is a big issue and has a great importance all over the world. A study was conducted to determine the chemical properties of recycled paper mill sludge (RPMS) and assess its possibilities for land application. RPMS samples were collected from six different paper mills in Malaysia and analyzed for physical and chemical properties, heavy metals, polycyclic aromatic hydrocarbons, (13)C-NMR spectra and for the presence of dioxins/furans. The RPMS was dewatered, sticky with a strong odour, an average moisture of 65.08%, pH 7.09, cation exchange capacity (CEC) 14.43 cmol (+) kg(-1), N 1.45, P 0.18, K 0.12, Ca 0.82, Mg 0.73, Na 0.76 and Al, 1.38%. The polycyclic aromatic hydrocarbons (PAHs) and heavy metals levels were below the standard Class 2 limits. The dioxin and furan were in below the standard concentration of Class 1. The most prominent peak in the (13)C-NMR spectra of RPMS was centered at 31 ppm, proving the presence of methylene (-CH2) groups in long aliphatic chains, with lipids and proteins. The signal at 89 ppm and highly shielded shoulder at 83 ppm were due to presence of cellulose carbon C-4, and the peak at 63 and 65 ppm was due to the cellulose carbon spectrum. The RPMS therefore contains significant amount of nutrients with safe levels of heavy metals and PAHs for environment and can be used as a fertilizer and soil amendment for land application

Application of raw and composted recycled paper mill sludge on the growth of Khaya senegalensis and their effects on soil nutrients and heavy metals

The paper industry performs an essential role in the global economy of the world. A study was conducted on the paper mill sludge that is applied on the Khaya senegalensis for 4 crop cycle for 1 year growth at glasshouse, Faculty of Agriculture, Universiti Putra Malaysia. Paper Mill Sludge (PMS) and composted Recycled Paper Mill Sludge (RPMS) was used with nitrogen (0, 150, 300 and 600 kg ha-1) at the ratio of 1:1 (Recycled Paper Mill Sludge (RPMS): Empty Fruit Bunch (EFB). The growth parameters were measured twice a month for 6 months. Plant nutrients and heavy metal uptake were determined. The paper mill sludge has the potential to be a supplementary N fertilizer as well as a soil amendment. The application of RPMS with N, significantly contributed to the improvement in plant growth parameters such as plant height (193 cm), basal diameter (27.00 mm), total plant biomass and improved soil physical and chemical properties. Total concentrations of heavy metals in soils were below the critical values. Hence, the paper mill sludge can be successfully used as soil amendment in acidic soil without any serious threat. The use of paper mill sludge for soil fertility, shows improvement in land application and signifies a unique opportunity to recycle sludge back to the land to alleviate the potential waste management problem

Rotan manau intercropped with rubber: rate of root growth between three and four years after planting

Efficient fertiliser management depends partly on understanding the active root distribution. In the present study, the active root distribution of 3- and 4-y-old plantation grown rotan manau (Calamus manan) was assessed using isotope tracer technique. For the 3-y-old rotan manau, three distances from the plant base (0.5, 1.0 and 1.5 m) at 5 and 30 cm depths were examined. For the 4-y-old plants, two distances, viz-á-viz at a centre between two rattan plants and another in the middle between two rattan plants and two rubber trees were studied. The isotope used was 32P, applied as a solution with KH2PO4. The rotan manau plants had been established under mature rubber plantation. High proportions of feeder roots were found at 0.5 and 1.0 m distances at the surface (5 cm depth) for the 3-y-old plants. Uptake of 32P was also observed for the application at 1.5 m distance for both depths but the counts were small. Statistical analysis gave a highly significant difference within the distances and within the different depths. For a better synchronisation between fertiliser application and plant uptake, it seems that application at approximately between 0.5 and 1.0 m distance around the plant is most appropriate at this age. At four years after planting, important uptake was obtained only for the two plants located near the application area. Anyhow, to some extent it reflected that roots had already extended for another 1 m compared to the 3-y-old plants

Spatial variability of forest floor thickness for estimation of refined carbon stocks in a tropical montane forest

Spatial variations of forest floor thickness in tropical montane forest influences carbon stocks estimates in forest floor and soil, microbial decomposition and soil conservation. Delineation of forest floor thickness according to decomposing layers (litter, hemic, sapric) and total forest floor will provide refined measurements of forest floor carbon stocks to improve site-specific carbon management. This study was aimed at determining spatial variability of the depths of decomposing forest floor layers in a tropical montane forest at varying topography. Sampling grids (10 m × 10 m) were established along three slope positions (summit, sideslope and toeslope) with 120 quadrants and their depths measured. Forest floor samples were georeferenced using a global positioning system. Variables were first explored using univariate statistics, including normality check, non-spatial outlier detection and data transformation. Variography and kriging analyses were used to quantify spatial variability of forest floor depths. Results showed that spatial structure of test variables differed across topographic positions. The coefficient of variation for test variables ranged from 27 to 64%. Surface maps displayed distinct spatial clustering and acceptable accuracy of interpolated values. Hemic and total forest floor were highest at the toeslope where hemic constituted approximately 80% of total forest floor. Site-specific management of forest floor carbon stocks in tropical montane forest should be based on topographic delineation