Approximately 13% of the land area of Sarawak, Malaysia is covered by Histosols. Recent land and agricultural policies encourage utilization of Histosols for agricultural purposes to meet the national food requirements. Increasing stress on this ecosystem requires a better understanding of the resource and its behavior. Mineral terric substrata are common in many Histosols. A transect of 50 m at Kota Samarahan (Sarawak) was selected for this study to evaluate the impact of terric materials on the properties of the overlying organic tier. Six basic forms of subsurface discontinuities were recognized: symmetrical dome, asymmetrical dome, flat top, flat base, orthogonal and irregular. The degree of horizonation was different in all the soils. The pH of the soils was quite similar. All soils had net negative charges that increased with depth, however, the actual amounts of net charges varied between the soils. The soils had negligible amounts of exchangeable cations. The fiber contents, cation exchange capacities, FTIR spectra and Cu2+ adsorption studies showed critical differences. Despite the fact that these soils are mapped as one mapping unit, major differences in critical properties are expected to influence the behavior and performance. Variations in subsurface discontinuities cast some doubt on the reliability of conventional mapping techniques in such soils. The information generated is very useful to improve soil survey procedures and the subsequent use and management of these soils.
Keywords: Terric material, Histosol, sapric, hemic
A 29th year old hectare of rubber land, with 270 trees, contained 158 tonnes of dry matter at the time of felling. About 56% of it, or 89 tonnes, were removed from the field to be processed into Hevea-wood furniture. The balance of 44% or 69 kg of plant debris, which comprised the roots, smaller branches, twigs and leaves, were left to decay in the field when zero burning was practised. The leaves took 29 weeks to decay completely. The smaller branches of 0 - 5 cm diameter took 73 weeks, those of 5 - 10 cm took 94 weeks, while both the big branches of 10 - 15 cm diameter and the roots took 129 weeks. The amount of nutrients locked up in a hectare of rubber land were 72 tonnes of carbon, 999 kg of calcium, 826 kg of nitrogen, 767 kg of potassium, 154 kg of magnesium and 107 kg of phosphorus. With zero burning practice, about 44% of these nutrient amounts would be released back to the environment due to decay. These would be equivalent to 2 tonnes of ammonium sulfate for nitrogen, 0.3 tonne of CIRP for phosphorus, 0.7 tonne of muriate of potash for potassium and 0.3 tonne of kieserite for magnesium, per hectare.
Keywords: Nutrient fixed, nutrient release, carbon sequestration
Cameron Highlands, with elevations exceeding 1,000 m above sea level, experiences mild temperature, ranging from 14°C to 24°C throughout the year, conducive for the growth of a wide range of sub-tropical crops. Steeplands may not be recommended for agriculture, but the favourable cool climate has encouraged the development of several agricultural activities in the area. A study was conducted to compare the level of sustainability of land planted with tea, vegetables and floriculture. Results showed that soil loss exceeded 83 t/ ha/yr in open cabbage farms. The erosion under tea was low, while that in chrysanthemum farms under rain-shelter was less than 1 t/ha/yr, which is about 80 times smaller than that in open vegetable farms. High amounts of organic fertilizers ranging from 49 to 84 t/ha/season are used in vegetable and flower farms and this has led to considerable pollution of surface water. In cabbage farms, about 3.2% (43 kg/ha) of the applied N and 5.5% (109 kg/ha) of the applied K were removed through runoff. During peak runoff periods, the concentration of NO3 in runoff water reached 25 ppm, exceeding the permissible limit. The runoff loss of inorganic elements in floriculture farms under rainshelter was low, with a value of 0.7 kg N and 3.5 kg K per hectare per season. The concentration of NO3 in the runoff was also within the acceptable limit of 10 ppm. The results suggest that open vegetable farming in the highlands is not sustainable due to erosion and pollution from the applied fertilizers. It appears that cultivation of crops under rainshelter is more sustainable.
Keywords: Erosion, sustainable agriculture, soil conservation, water pollution
In recent times, one of the major challenges in crop cultivation is the proper interpretation of field maps, which influences the variability of crop yields significantly. The ability to find and comprehend soil factors influencing crop yield variability will enable us to manage the soils efficiently. A study was conducted in a commercial paddy farm at Kahang, Peninsular Malaysia with the objective of quantifying and characterizing the nature of spatial soil nutrients (N, P and K) variation. Soil samples (0-15 cm) were collected at 20 m × 20 m grid pattern from the studied plot (3.85 ha) at the beginning of paddy (MR211 variety) planting and analyzed for total N, available P and exchangeable K. A GeoExplorer II was used to record the soil sampling points and boundary of the plot to interpret the spatial maps in GIS platform with proper coordinates. Geo-statistical analysis was used to characterize the spatial variation of soil nutrients. The coefficient of variation of soil nutrients for the study area was more than 50% where soil P was found to be very high (130%). Semi-variance analysis showed that the sill was reached at 350 m to 450 m (1 to 2 samples ha-1) for soil N, P and K The kriged soil nutrient (N, P and K) maps showed that a large portion of the area (>90%) in the study plot contained soil N lower than 3 g kg-1, soil P lower than 10 mg kg-1, and soil K more than 0.45 cmol, kg-1. The study indicated that soil analysis and the geo-statistical technique are useful to illustrate the spatial variation and interpretation of soil nutrients with the help of GPS and GIS. This integrated technique is a useful prognostics management tool to enhance site-specific management practices.
Keywords: E.coli survival, moisture effect, Semongok series, temperature correction coefficient, temperature effect
In a study of heavy metal distribution in soils grown with cocoa in Peninsular Malaysia, soil samples from 10 soil types were analyzed for Cd, Cu, Ni, Pb and Zn, cation exchange capacity (CEC), organic C, pH, electrical conductivity (EC), available P and clay content. The soils developed over intermediate volcanic parent material (andesite) showed higher concentration of heavy metals compared to the alluvial soils at a depth of 0-20 cm. Total soil Ni and Zn are correlated with pH (P<0.01, r=0.27 and r=0.33, respectively), total soil Cd and Zn with EC (P<0.05, r=0.18 and P<0.01, r=0.38, respectively), total soil Cu and Zn with CEC (P<0.05, r=0.18 and P<0.01, r=0.37 respectively), total soil Cd with organic C (P<0.05, r=0.17), and total soil Cd, Cu, Ni and Zn with clay content (P<0.01, r=0.65; P<0.01, r=0.54; P<005, r=0.16; and, P<0.05, r=0.48, respectively). The concentrations of Cd, Cu and Ni in cocoa beans grown on soils developed from andesite was higher compared to those grown on alluvium. Meanwhile, for Cu and Zn concentration in cocoa beans, there was no significant difference between soils developed from andesite and alluvium. The concentration of heavy metals in soils tends to influence the concentration of heavy metals in cocoa tissues. Influence of P fertilization was exhibited by the significant correlations of Cd and Zn with extractable P (P<0.01, r=0.25 and P<0.01, r=0.40, respectively). For the Benta Series only, cadmium concentration in cocoa beans had reached the maximum permitted concentration (MPC) as defined by the Malaysian Food Act of 1983 and Food Regulations 1985. Zinc in cocoa beans, for some other soils, was either above or reached the MPC level.
Keywords: Cocoa beans, heavy metals, correlation study, transfer coefficient, maximum permitted concentrations
High precipitation and low soil cation exchange capacity (CEC) of highly weathered acidic tropical soils require large amounts and many rounds of fertilization to increase the potential of these soils from leaching losses of soil ammonium (NH4+) and potassium (K+). This study was conducted to evaluate the exchange properties of natural and synthetic zeolites on soil NH4+ and K+. A Bungor Series soil (Typic Paluedults) was taken from a depth of 0 to 5 cm for this leaching experiment. Each soil treatment was added either with equal amounts of NH4+ or K+ and treated with and without zeolites. The treated soil was then leached with deionised water for 20 days and the soil leachate was collected at 5day interval, to analyze for NH4+ and K+ concentration. The results of this study showed that all types of zeolites were able to reduce substantial leaching losses of soil NH4+ and K+. The natural zeolites were better than the synthetic zeolites in retaining these cations. The study has demonstrated that zeolites could be used as an effective soil amendment to reduce leaching losses of soil NH4+ and K+ in acid tropical soils with low CEC.
Keywords: Zeolites, clinoptilolite, acid soil, ammonium, potassium