Preliminary study on simulation of climate change impacts on rice yield using DSSAT 4.5 at Tanjung Karang, Selangor

Weather plays a very important role in determining crop yields. There is a strong relationship between climate and crops. The growth requirements are different for every crop throughout the whole plant development process. Each crop and crop variety has specific climatic tolerances and optimal conditions. The objectives of this study were to determine the physico-chemical characteristics of soils for rice cultivation and the effects of climate towards rice yield through simulation using Decision Support System for Agro-technology Transfer ver 4.5 (DSSAT4.5). This study was carried out in Tanjung Karang, Selangor.Four plots with the size of 5 m x 5 m were planted with MR 219 seedlings. Three soil samples were taken from each plot at a depth of 0-20 cm for the upper layer and 20-40 cm for the second layer before planting activities. Physico-chemical characteristic of these soils such as particle size distribution, organic matter, bulk and true density, pH, electrical conductivity, cation exchange capacity and organic carbon contents were determined according to the standard methods. The soil texture in this area was silty clay for the upper layer and clay for the second layer. The percentage of soil organic matter was high at about 9.0% to 11.8%. Soil bulk density was in the range of 1.37 g cm-3 to 1.41 g cm-3, whereas the true density was between 2.5 g cm-3 and 2.75 g cm-3. Soil of this area was slightly acidic with pH value of about 5 to 6. Electrical conductivity recorded ranged from 2.13 mS cm-1 to 2.60 mS cm-1, whereas cation exchange capacity was between 13.5 meq/100 g to 15.5 meq/100 g. Percentage of organic carbon was higher in the upper layer at 2.07-2.74% than in the second layer at 1.25-1.73%. To obtain the yield, ten matured rice plants were randomly selected and harvested. Yield recorded was 5.75 tons ha-1 and the weight of 1000 grains was 24.8 g. Yield simulation by using DSSAT 4.5 crop simulation model, indicated that yield was projected to decrease slightly as the daily solar radiation and rainfall decreased, and slightly increased as the temperature increased

Physico-chemical properties, carbon dioxide emissions and carbon stock in peat soil used for turmeric cultivation at Kuala Langat Selatan, Selangor, Malaysia

Measurement of carbon dioxide emissions in peat soil was done in a turmeric cultivation area on August 2009 and January 2010 at Kampung Tumbuk Darat, Kuala Langat Selatan, Selangor. The objective of this research was to determine the quantity of CO2 emissions from peat soil as well as the carbon stock that is stored in the peat soil. Other parameters that were investigated included soil pH, soil temperature, soil bulk density, soil organic carbon, soil fresh water content, organic matter, humic acid and fulvic acid content. A total of 30 carbon dioxide emission sampling points in rectangular grid arrangement was prepared in a survey plot of 1 hectare. The survey plot was further divided into sub-plots of size 20 m x 25 m. Soil samples were randomly taken at the depth of 0-15 cm to 50-65 cm using an auger. Sampling of CO2 emissions was done using the static alkali absorption method (Kirita Method). The organic carbon content was determined using the Walkley-Black method, while the humic and fulvic acid content was determined using the basic molecule isolation method. Other soil properties were determined using standard methods of determination. The surface temperature of peat soil was between 28oC and 30oC. The bulk density of the area was as low as 0.20 g cm-3. On the other hand, the soil fresh water content, soil organic matter, and peat soil humic acid was very high. The minimum quantity of CO2 emissions in the peat soil on August 2009 and January 2010 was 40.92±21.62 t CO2 ha-1 yr -1 (467.10±246.86 mg CO2 m-2 hr-1) and 41.51±13.41 t CO2 ha-1 yr -1 (473.86±153.12 mg CO2 m-2 hr -1), respectively. Carbon stock for the month of August 2009 and January 2010, respectively was 297.70 t ha-1 and 456.60 t ha-1. T test showed that there were significant (p<0.05) differences in many of the soil parameters such as the pH, water content and organic carbon. Correlation analysis showed that CO2 is influenced by the organic matter, water content and temperature

Effects of surfactant on geotechnical characteristics of silty soil

Surfactants are often used as a cleaning agent for restoration of oil-contaminated soil. However the effect of surfactant on the geotechnical properties of soil is not clearly understood. In this study, the effects of surfactant on silty soil were investigated for consistency index, compaction, permeability and shear strength. Sodium dodecyl sulfate (SDS) was used in this study to prepare the surfactant-treated soil. Our results showed that the soil with added surfactant exhibited a decrease in liquid and plastic limit values. Maximum dry densities increased and optimum moisture contents decreased as contents of added surfactant were increased. The presence of surfactant assists the soil to achieve maximum density at lower water content. The addition of surfactant decreased the permeability of soil from 6.29×10-4 to 1.15×10-4 ms-1. The shear strength of soil with added surfactant was examined using the undrained unconsolidated triaxial tests. The results showed that the undrained shear strength, Cu was significantly affected, decreased from 319 kPa to 50 kPa for soil with 20% of added surfactant. The results of this study showed that the presence of surfactant in soil can modify the mechanical behaviour of the soil

Pengambilan logam berat oleh pokok daun kari (Murraya koeniggi) dalam tanih ultrabes dari Felda Rokan Barat, Kuala Pilah, Negeri Sembilan, Malaysia

Kajian ini telah dijalankan di kawasan tanih ultrabes di Felda Rokan Barat, Kuala Pilah, Negeri Sembilan. Sebanyak lima belas sampel tumbuhan dan substratnya telah diambil dari kawasan kajian dengan kaedah berkelompok. Tujuan kajian ini adalah untuk menentukan kandungan logam berat Fe, Ni, Cr, Mn, Co, Zn, Cu, Cd dan Pb di dalam tanih dan bahagian akar, batang dan daun tumbuhan. Koefisien penyerapan biologi (BAC) ditentukan secara perkiraan. Kandungan logam berat di dalam tumbuhan diekstrak secara penghadaman basah manakala kandungan di dalam tanih diekstrak dengan kaedah pengekstrakan berjujukan. Kandungan logam berat di dalam larutan ekstrak tanih dan tumbuhan ditentukan menggunakan spektrofotometer penyerapan atom kaedah nyalaan (FAAS). Hasil kajian menunjukkan kepekatan logam berat paling tinggi dalam substrat pokok daun kari Murraya koenigi adalah Fe, diikuti oleh Mn, Cr, Co, Ni, Zn, Cu, Cd dan Pb dengan purata kepekatan masing-masing sebanyak 1699.64 mg/kg, 532.59 mg/kg, 212.43 mg/kg, 195.02 mg/kg, 174.97 mg/kg, 48.11 mg/kg, 43.86 mg/kg, 3.65 mg/kg dan 0.48 mg/kg. Kepekatan logam berat tersedia bagi Mn dan Pb adalah lebih tinggi berbanding logam berat tersedia yang lain berdasarkan peratus. Kandungan Fe dan Mn adalah tinggi di dalam semua bahagian tumbuhan. Walau bagaimanapun, berdasarkan nilai purata kumulatif BAC, hanya logam Pb menunjukkan nilai penimbunan yang agak tinggi dalam tumbuhan. Kajian ini menunjukkan pokok daun kari (Murraya koenigi) bukan tumbuhan penumpuk logam berat berdasarkan kepada nilai BACnya yang rendah