Alleviating acid soil infertility constrains using basalt, ground magnesium limestone and gypsum in a tropical environment.

Ultisols and Oxisols in the tropical regions are often acidic, with high Al but deficient in Ca and/or Mg. This limits maize production. Studies were conducted to investigate the efficacy of basalt, ground magnesium limestone (GML) and gypsum as acid soil ameliorants. Results showed that basalt improved soil fertility by increasing soil pH, cation exchange capacity (CEC) and exchangeable Ca, Mg and K and available P, with a concomitant lowering of exchangeable Al. In the soils treated with GML, Ca remained in the zone of incorporation. When GML was applied together with gypsum, Ca moved deeper into the soil profile. Sulfate, SO42-, adsorption onto the surfaces of oxides resulted in an increase in pH and negative charge. The increase in pH was due to the replacement of OH- by SO42-. Beneficial effects of GML application at the rate of 4 t ha-1 lasted for about 8 years with the effect being comparable to application of 1 t GML ha-1 annually

Solid waste management: land application of agricultural & industrial by-products

The generation of industrial wastes shows an increasing trend throughout the world including Malaysia. Recycling of these wastes or by-products on land is the most economically feasible. However, the presence of trace metal(loid)s is an issue of concern. Therefore, these by-products need to be assessed in terms of trace metal(loid)s content and their bioavailability before they can be land –applied. Bioavailability of trace metal(loid)s in the soil system can be transferred to the food chain via plant uptake and leaching to ground water or transported via surface runoffs to water bodies. Thus, the ultimate goal of remediation is to reduce the transfer of trace metal(loid)s to the food chain. One of the remediation method recommended is the in-situ immobilization technique. In this technique, the remediation of trace metal(loids-rich or contaminated soils will be through manipulating their bioavailability by using a range of soil amendments such as liming materials, organic materials or biosolids, phosphate compounds and metal oxides (Ferich materials). The soil chemical processes exploited to immobilize metal(loid)s in-situ are the adsorption and precipitation processes

Assessment of uptake of readily available plant micronutrients from soils amended with coal fly ash

A greenhouse experiment was conducted on two soils of different texture, Tebuk sandy clay and sandy mine tailings. They were treated with different rates of coal fly ash (0, 10, 20, 40, 80 and 160 Mg ha-1) and the uptake of B, Cu, Fe, Mn and Zn by spinach grown in these soils were determined at six weeks growth The experimental set-up hosen for this study was a factorial 2 (different soil textures) X 6 (six rates of fly ash application) arranged in completely randomized design with 4 replications. Application of fly ash increased the pH and EC of the soils Tissue uptake of B, Cu, Fe, Mn and Zn and plant dry matter weight were influenced by fly ash application rates and soil texture type. Boron uptake increased while Cu, Fe, Mn and Zn uptake decreased with increases in addition of fly ash to the soils The highest spinach dry weight was obtained with the application of 20 Mg ha-1 for the Tebuk soil and 40 Mg ha-1 for the sandy mine tailings

Effect of dolomitic limestone and gypsum applications on soil solution properties and yield of corn and groundnut grown on Ultisols

A study was conducted to determine soil solution properties and relative tolerance of corn and groundnut plants to soil acidity. Corn followed by groundnut was planted on Ultisols one month after lime or gypsum was incorporated into the topsoil. Soil samples were collected after corn and groundnut harvest. Soil solutions were extracted by the immiscible replacement method of soil water with fluorocarbon trichlorofluoroethane. Results showed that total Al, inorganic Al, Ca, and Mg concentrations were erratically affected by the treatments. However, total Al values were indicated to be high when solution pHs were low, especially at treatments with low amounts of lime or high amounts of gypsum. It appeared that Ca released from the dissolution of gypsum had replaced Al in the exchange complex, causing the high concentrations of Al in the solution. Solution pH, corresponding to 90% relative yields of corn and groundnut, were 4.7 and 4.3, respectively. This means that groundnut is more tolerant to soil acidity than corn. Liming Ultisols at low rates may be necessary for groundnut cultivation. For corn cultivation, the liming rate is 2 t ha-1, which supplies adequate amounts of Ca and Mg for the growth of corn plants

Concentrations and chemical forms of heavy metals in some ultisols in Johore, Peninsular Malaysia

The concentrations of heavy metals in soil are associated with biological and geochemical cycles and are influenced by anthropogenic activities such as agricultural practices, industrial activities and waste disposal. A total of 36 surface soil samples (Typic Kandiudult, Rengam Series) were collected from some major vegetable growing areas developed over granite. Twelve soils from areas not cultivated with vegetables but also developed over granite were also sampled for background values. The pseudo-total heavy metals, (Cu, Pb, Zn and Ni) were determined by the aqua-regia method. Chemical properties such as pH, organic carbon and CEC were also analysed. Some selected cultivated soil samples (24 of Ultisols and 12 of background soils) were analysed for chemical partitioning using a modified Tessier's procedure (Fl: exchangeable fraction, F2: fraction bound to organic matter, F3: fraction bound to amorphous iron oxides and F4: residual fraction). Mean values of the total heavy metals for the cultivated soils are Cu (23.3 mg kg-'), Pb (18.0 mg kg4), Zn (49.4 mg kg-') and Ni (6.0 mg kg-'). Comparison of these values to the contents in the background soils show that Cu and Zn have significantly increased. However, all these values are below the contaminated levels established for the country's agricultural soil limits (95th percentile). From the partitioning study, the general trend in the Ultisols for Pb and Ni is residual > oxalate >exchangeable>organic. For Zn and Cu, the oxalate extractable phase is highest followed by the residual phase. Zinc and Pb contents in the soils are also positively correlated with the pH of the soil

Fertility and suitability of the Spodosols formed on sandy beach ridges interspersed with Swales in the Kelantan - Terengganu Plains of Malaysia for kenaf production.

A study was conducted to evaluate the suitability of sandy soils in the Kelantan - Terengganu Plains (Peninsular Malaysia) and suggest measures to improve their fertility for kenaf production. The coastal landscape is scarcely utilized for crop production due to the inherently low soil fertility, nutrient imbalance and water deficit which can seriously inhibit crop growth. Three sandy Spodosols with humus - rich spodic horizon were found, locally named as Rhu Tapai, Rudua and Jambu Series with sandy matrix (>95% sand), low CEC (0.16-4.52 cmolc kg-1) and high acidity (pH 4-5). The mineralogy data showed quartz (dominant), with gibbsite, hematite and feldspars in trace amounts that result from high degree of weathering. The Corg of Bs and Bhs horizon was about 2%, with C/N ratio of 14 to 25, respectively; this can be exploited for kenaf production. Hence, we evaluated these sandy Spodosols for kenaf production using Wong (2009) Crop-Suitability Classification and found the soil to be marginally suitable under Class 4 described as 4Dnt where D stand for drainage, n for nutrient and t for texture. The major limitations were found to be excessive drainage, nutrient imbalance and sandy texture. Therefore, management practices recommended to improve the soils are (1) mulching the soils with different types of organic materials to retain water and plant nutrients; and (2) irrigating the soils during the dry period. If these agronomic practices are carried out, these soils could be productively used for growing kenaf