Wan Rasidah Kadir

Soil and Belowground Characteristics of Pasoh Forest Reserve

We describe the soil and belowground characteristics of the Pasoh Forest Reserve (Pasoh FR), Peninsular Malaysia. Soil survey was conducted using the Malaysian classification system in primary and regenerating forests of Pasoh FR. The physical and chemical properties of various soil horizons were measured at the selected soil pits. Soil N dynamics as a soil biological process was also studied in a range of forest environments, including gap and closed forest. The fine root biomass in the topsoil was also quantified in primary forest. Pasoh FR has at least 18 soil types. The soils of Pasoh FR are whitish to yellowish in color rather than reddish. When compared to the other Southeast Asian tropical forest soils, the particle size distribution is characterized by lower sand and higher silt contents. Chemically, the Pasoh FR soil accumulates greater amounts of Al. Most CEC (cation exchange capacity) are occupied by Al. The high Al content leads to lower P availability. The pool of inorganic N at 0–10 cm soil depth ranges from 14.8 to 23.9 µgg N g-1. Net N mineralization rate in topsoil in the primary forest is estimated to be 100 kgN ha-1 yr-1. Nitrification is pronounced at uppermost layer. The fine root biomass (FRB) less than 2,3 and 5 mm in diameter (d) are 624, 751, 970 g m-2, respectively. Within the top 20 cm, the FRB (< 1 mm in d) constitutes 73% of the total FRB (< 5 mm in d) from 0–4 cm and about 40% in subsequent layers. The Pasoh FR soil is supposed to be infertile. Net N mineralization is observed mainly in the topsoil. These facts suggest that the FRB (< 2 mm in d) constitutes a major part of the total, especially in the top soil to effectively absorb mineral nutrients released from decomposing organic matter.

Characterization and Feasibility Assessment of Recycled Paper Mill Sludges 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, 13C-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 13C-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.

Evaluation of Controlled-Release Property and Phytotoxicity Effect of Insect Pheromone Zinc-Layered Hydroxide Nanohybrid Intercalated with Hexenoic Acid

A controlled release formulation for the insect pheromone hexenoic acid (HE) was successfully developed using zinc-layered hydroxide (ZLH) as host material through a simple coprecipitation technique, resulting in the formation of inorganic-organic nanolayered material with sustained release properties. The release of HE from its nanohybrid was found to occur in a controlled manner, governed by a pseudo-second order kinetics model. The maximum amount of HE released from the nanocomposite into solutions at pH 4, 6.5, and 8 was found to be 84, 73, and 83% for 1100 min, respectively. The hexenoate zinc-layered hydroxide nanomaterial (HEN) was found to be nontoxic for plants when green beans and wheat seeds were successfully germinated in all HEN concentrations tested in the experiment, with higher percentage of seed germination and higher radical seed growth as compared to its counter anion, HE. ZLH can be a promising carrier for insect pheromone toward a new generation of environmentally safe pesticide nanomaterial for crop protection.

Nutrient retranslocations during the early growth of two exotic plantation species

Retranslocation of nutrients before leaf abscission is an important pathway of nutrient conservation. This article reports the extent of nutrient withdrawal by Acacia mangium Willd. and Khaya ivorensis A. Chev., before leaf fall. Measurements were carried out based on the nutrient content in intact green leaves and freshly fallen litter, collected at the plantation age of 24 months. Results showed that A. mangium consficated back about 78% of P compared to only 26% by K. ivorensis. A. mangium could probably need some of these P for the N2 fixation process beside for surviving on a soil with poor P availability. The withdrawal of nitrogen seems less critical but the trend relates to the availability of nutrients in the soil. The fact that A. mangium took back about 22% of N, which was far more higher than what has been taken back by K. ivorensis, is not fully understood as the former species has the capability to fix the atmospheric nitrogen. The withdrawal of K was about 13% for both species and this value shows K is more limiting than N as far as K. ivorensis is concerned. Magnesium, on the other hand, was not retranslocated.

Amelioration of composting process by fertilizers

Six different composts, four of them produced from oil palm residues and two commercial composts, were studied for their stability and quality. The composts were analyzed for their total C, total N, C/N ratio, mineral N, nitrogen mineralization index, CO2 production, biomass C, specific respiration rate, germination rate, pH values and plant growth index. Composts of oil palm (Elaeis guineesis) trunk and oil palm empty fruit bunch treated with N and P showed good stability and higher quality as compared to other composts. Their C/N ratios were the lowest (14-18) but their pH values were comparatively low (4.6-6.4). They had a good amount of total N (0.95-1.84%) with higher nitrate than ammonium nitrogen. The specific respiration rates were very low (0.25-0.63) which is an indication that these two composts are stable. Plant growth test supported conclusions based on the microbiological tests. Their properties were considered as suitable for planting media application. Compost quality can be further improved by adding bunch ash, which has high values of pH and is also a by-product from the oil palm industry. The applied nitrogen mineralization index could not be used with all kinds of composts as stability index. Both of the commercial composts showed high C/N ratios (34-68) and very low values of total and mineral nitrogen compared to oil palm residues composts. They were considered having low nutritional value and not recommended for planting media application.

Synthesis and Characteristics of Valeric Acid-Zinc Layered Hydroxide Intercalation Material for Insect Pheromone Controlled Release Formulation

A new intercalation compound of insect pheromone, valeric acid (VA), based on zinc layered hydroxide (ZLH) as host release material, was successfully prepared through coprecipitation method. The as-produced organic-inorganic nanolayered material, valerate nanohybrid, VAN, shows the formation of a new peak at lower 2θ angle with basal spacing of 19.8 A with no ZnO reflections, which indicate that the intercalation of anion between the inorganic ZLH interlamellae was accomplished. The elemental, FTIR, and ATR analyses of the nanohybrid supported the fact that the intercalation with the percentage anion loading was calculated to be 23.0% (w/w). The thermal stability property of the resulting nanohybrid was enhanced compared to the unbound anion. Field emission scanning electron micrograph of the ZnO has a nonuniform granular structure but transforms into flake-like structure with various sizes after the intercalation process. Release kinetics of anion from the interlayer of intercalated compound exhibited a slow release behavior governed by the pseudo-second-order kinetic model at different pHs of aqueous media. The valerate anion was released from VAN with the highest release rate at pH 4. These findings provide the basis to further development of controlled release formulation for insect pheromone based on ZLH intercalation.

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.