The Response to Potassium and Uptake by Maize (Zea mays L) on Two Malaysian Soils

The respon·se to four levels of Kfertilizer (0, 100,200 and 300 kg K 20/ha) by maize (Zea mays var. Metro) on two known K-deficient soils of different texture (Munchong and Serdang) formerly under rubber, 1Uas studied in a pot experiment for three months, in relation to various K extraction methods. A sigl~ificant increase in the dry matter yield of maize was found in the sandier Serdang soil, with 100 kg K 20jha; higher levels did not give increased yields. At 100 kg K 20jha level, dry matter yield response was also detected for clayey Munchong soil, but the total K uptake was significantly higher at 200 kg K 20 in this soil than in Serdang soil. Extractable K by CR3COOR gave the highest significant correlation with the stem portion in Serdang soil (r = 0.921) and with the leaf in Munchong soil (r = 0.819)

Weathering behaviour of a basaltic regolith from Pahang, Malaysia

The characteristics and degree of weathering in a deep saprolitic regolith developed on basalt were investigated. A 15 m deep regolith of soil-saprolite-rock sequence, located along a new road cut in Pahang, Malaysia, was selected. The intensity of weathering in this regolith was assessed by various weathering indices, as well as by the changes in the physiarchemical properties, clay mineralogy and the microfabric characteristics of the profile. All assessments gave strong evidences of intense weathering, even at the stage of saprock formation. Extreme depletion of major elements such as K, Na, Ga and Mg, and significant enrichment of Fe, Ti, Gu and Nb occurred during saprolitization process, and, these perhaps explain the extreme weathering pattern of this regolith

Alleviating an Acid Sulfate Soil Cultivated to Rice (Oryza sativa) Using Ground Magnesium Limestone and Organic Fertilizer

Rice yield on acid sulfate soils in Malaysia is very low, presumably due to AI and/or Fe toxicity. This study wasconducted to ameliorate an acid sulfate soil in the Kemasin-Semerak Integrated Agricultural Development Project, located in Kelantan, Peninsular Malaysia, for rice cultivation. Rice variety, MR 219, was used as the test crop. Treatment included the use of various rates of ground magnesium limestone (GML), with or without an organic fertilizer. This acid sulfate soil had an initial pH of < 3.5 at depth below 45 cm. Exchangeable AI in the soil was high, especially in the subsoil. The first crop of rice was disturbed by floods. The result for the 2"d crop showed a promising trend; applying 4 t GMUha in combination with an organicfertilizer, the topsoil pH had increasedfrom 3.95 to 4.21, increasing the exchangeable Ca and Mgfrom 1.58 and 0.48 cmol/kg soil to 2.57 and O. 79 cmol/kg soil, respectively. In this treatment, the rice yield was 7.5 tlha, which was much higher than that produced by farmer's practice of about 2 tlha. The increase in yield was due to the combined effects of increasing pH and exchangeable Ca and Mg and of lowering AI and Fe concentration in the soil solution

A Decision Support System for Rice Cultivation on Acid Sulfate Soils in Malaysia

Ameliorative steps to put acid sulfate soils into productive use can be organized by a decision support system. The model uses microeconomic analysis to get an optimal rate of lime and fertilizer in maximizing profit. A glasshouse experiment was conducted on an acid sulfate soil in Malaysia to get the potential yield. A field trial was conducted for validation purposes. The recommended rate of fertilizer application of 150-200 kg ha-1 N. 20-30 kg ha-1 P and 150-200 kg ha-1 K were applied during the critical stage of the rice growth. Field Adjusting Factor (FAF) of 0.40 has been found and this was used to analyze the production function. Using TableCurve 3D software. an equation for production function was established. Validation using experimental data showed that the equation has a good capability. shown by the value of p&gt;0.2 (t-test) and MEE of 2%. The model. named as RiCASS (Rice Cultivation on Acid Sulfate Soil) was developed and successfully simulatedthe maximal profit under 4 different scenarios. The recommended rate of lime (GML) was 6.5 t ha-1 for maximal profit and 2.5- 3.0 t ha-1 for the farmers, practice. Keywords: Acid sulfate soil. decision support system. field adjusting factor. lime. ric