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.
Keywords: Basalt, ground magnesium limestome, gypsum, Oxisols, soil acidity, Ultisols
pland rice farmers in Malaysia still depend on resultant ash from burning for K and N sources. Efficient use of chemical fertilizers in upland rice needs accurate assessment of required nutrient elements. The present study was performed to determine the N, P, and K requirements of three upland rice varieties grown on idle land (Bukit Tuku soil, AQUIC KANDIUDULT) using four response models. A glasshouse experiment was conducted using 0-200 kg N ha-1 (urea, 46% N), 0-120 kg P2O5 ha-1 (TSP, 45% P2O5), and 0-150 kg K2O ha-1 (MOP, 60% K2O), each at five levels. Three upland rice varieties used in the experiment were Ageh, Kendinga and Strao. The grain yield (14% moisture content) was measured at harvest and fitted using linear (L), linear with plateau (LP), quadratic (Q), and quadratic with plateau (QP) response models. The QP proved itself as the best fitted response model for the determination of fertilizer recommendation rates for maximum yield of upland rice cultivars used. The fertilizer rates were 112 kg N ha-1, 78 kg P2O5 ha-1 and 158 kg K2O ha-1 for Ageh (QP); 138 kg N ha-1 (LP), 87 kg P2O5 ha-1 (QR), 119 kg K2O ha-1 (QP) for Kendinga; and 125 kg N ha-1 (Q), 85 kg P2O5 ha-1 (LP) and 127 kg K2O ha-1 (L) for Strao.
Keywords: Fertilizer recommendation rates, linear, linear plateau, nutrient requirement, quadratic plateau, upland rice
A study was conducted to evaluate the spatial variability of selected soil chemical properties of paddy soils in the Barat Laut Paddy Project area in Selangor. A total of 138 geo-referenced soil samples were collected from the area at 0-20 cm depth after harvest, at an interval of 80-90 m to determine the selected chemical properties: pH, organic carbon, total nitrogen (N), available phosphorus (P) and exchangeable potassium (K). Geostatistical analyses were applied to examine the within-field spatial variability using semivariograms and kriged maps. Kriged maps for each property were prepared using geostatistical software package based on the results of spatial dependence. The effective ranges for the areas were about 6 km for pH, 1 km for organic carbon, 8 km for total N and available P and 9 km for exchangeable K, respectively. Kriged maps produced showed that most of the area have pH values within the range of 4-4.5 (moderately acidic) and high amount of organic carbon content (3-5%). The kriged maps also showed that a large portion of the study area (66%) have high total N (0.30-0.40%), with low amount of available P (< 40 mg kg-1) covering 70% of the total study area, while most of the area have optimum content of exchangeable K (> 0.10 cmol(+) kg-1). These results suggest the need for a site specific approach in managing paddy soils particularly with regard to nutrient management. The results also suggested that future soil sampling in these area can be carried out by increasing the sampling interval depending on the soil properties, and appropriate management should be applied according to the variations which exist.
Keywords: Spatial variability, Geostatistics, Paddy soil, Chemical properties
In Malaysia, glufosinate ammonium (GLUF) is a commonly used herbicide in oil palm plantations to control broad-leaved weeds and grasses. Adsorption and desorption of (GLUF) were studied using the batch equilibrium technique in four mineral soils, Inceptisols (Selangor), Oxisols (Munchong) and Ultisols (Serdang and Rengam) series and peat (Histosols) collected under oil palm cultivation from 0-15 cm and 15-30 cm depths. Adsorption coefficients of the herbicide were correlated with soil properties i.e. organic matter content, clay content, cation exchange capacity (CEC) and pH. The concentrations of GLUF used were (0, 0.25, 0.5, 1, 1.5, 3, 5 and 10 μg/mL). The adsorption and desorption isotherms were fitted using linear and Freundlich equations. Adsorption of GLUF was in the following order: Selangor > Rengam > Munchong > peat > Serdang. The results indicate that the adsorption of GLUF is positively correlated only with clay content. The high sorption of the Selangor soil could be explained by the high clay content in Selangor series soil compared to the other soil series. However, the order of GLUF desorption was in the following order: Serdang> peat > Munchong > Rengam > Selangor. Results indicate that adsorption of GLUF was mainly on the clay fraction of the soil and the binding strength of adsorbed GLUF was high as indicated by the order of GLUF desorption from the soils.
Keywords: Batch equilibrium test, linear equation, Freundlich equation, Glufosinate ammonium, sorption isotherm
Use of coal fly ash (CFA) as a soil ameliorant is hindered by the lack of macronutrients in the ash, besides, there are also concerns about its high concentration of microelements, especially boron. Sewage sludge (SS) on the other hand, has a high amount of macronutrients especially nitrogen. However, it also contains high concentrations of micronutrients especially Zn. This study was carried out to evaluate the potential of CFA as a soil ameliorant to immobilize heavy metals from SS-treated soil and whether the SS could provide supplementary macronutrients for maize growth requirement. A laboratory soil incubation study was conducted using 3 kg mixture of soil, SS and CFA. In all treatments, the SS was applied at 5% w/w. The rates of coal fly ash varied from 0, 2.5, 5, 10, 20 and 40% w/w. The soil solution was collected and analyzed weekly for pH and soluble Zn, Cu and B. A similar experiment was conducted in a glasshouse but using CFA at rates up to only 20% w/w on maize as a test plant. Although the acid neutralizing capacity of this CFA is only 0.50% of calcium carbonate equivalent (CCE), the high rates of CFA application increased the soil solution pH. Treatments of CFA at 10% and above reduced Zn concentrations in soil solution to less than 1 mg L-1. The reduction in Cu and B concentrations in the soil solution were not apparent in this study. Uptake of Zn by the maize plants was found to significantly decreased in treatments of 10% CFA and above. Nitrogen uptake by maize decreased in the treatment using more than 10% CFA. Only the highest treatment of CFA (20% w/w) exceeded the B toxicity level for maize (98-100 mg kg-1). Coal fly ash and sewage sludge mixture can be used as a soil ameliorant provided attention is given to the B toxicity and P and K deficiency problems that might be faced by plants such as maize.
Keywords: acidic tropical soil, glasshouse study, maize plants, soil solution study
Poor management of plant nutrients and ignorance of the Liebig’s Law of Minimum for plant nutrients requirement is an obstacle in efforts to increase rice production in Malaysia. Ignorance of the importance of micronutrients application by Malaysian farmers hinders the achievement of high yields in rice production. Six farmers’ plots were used to examine the importance of micronutrients in rice production in Sawah Sempadan, Tanjong Karang, Malaysia. Soil and foliar samples were collected and analyzed to determine the micronutrients content and then compared with the critical nutrients levels needed by rice. Special fertilizers comprising formulated mixture of K, Mg, Zn, Cu, Mn and B were then distributed to farmers along with a recommended manuring programme. The timing and quantity of fertilizer applied were closely supervised. The investigations were carried out over two continuous seasons where rice yield data were collected and subjected to statistical analysis. The results showed that the application of special fertilizers in conjunction with proper field maintenance was able to increase rice production by 27%, from 4.62 tonnes per hectare to 5.87 tonnes per hectare.
Keywords: Fertilizer, Law of Minimum, micronutrients, rice
anagement of micronutrient B in soil is difficult because of its high mobility. Soil sampling and analysis is the first important step in managing the nutrients required by plants. This study was conducted to evaluate the B status in soils of rice growing areas in Kedah and Kelantan which are the main rice growing states of the country. Soil samples were collected from 15 soil series namely Kranji, Sedeka, Guar, Kundur, Tualang, Teluk Chengai, Kuala Kedah, Rotan, Sedu, Kangkong, Batu Hitam, Lubok Itek, Tepus, Telemong and Chempaka to determine B status and other physico-chemical properties. The soils of paddy growing areas investigated were very low in available B status. All the fifteen soil series had B below 0.5 mg kg-1, irrespective of depth and locations. Kundur and Chempaka Series soils had the highest B content (0.46 mg kg-1) among all the series while the Tualang Series soil had the lowest B (0.22 mg kg-1). Boron status in soils differed significantly with depth; the upper layers had higher B concentrations compared to lower depths because of high organic carbon content. Boron showed a positive correlation with organic carbon content but a negative correlation with soil pH.
Keywords: Correlation study, hot water extractable B, paddy soils
Chromobacterium violaceum is a pathogenic soil bacterium producing violacein and hydrogen cyanide both of which is controlled by quorum sensing with the same signal molecule homoserine lactone (C6-HSL). A study was carried out to determine if quorum sensing was a factor that was required for inhibiting the growth of green bean (Vigna radiata) seedling. The results showed that C. violaceum which reached quorum level inhibited the growth of green bean seedling as much as 86.5% for the shoot length and 92.1% for the root length. However inhibition was reduced to 37.5% for the shoot and 17.5% for root if the quorum level of C. violaceum was not reached under an aseptic environment. Furthermore sterilised inoculant (killed) which had not reached quorum level would not affect the growth of green bean seedlings. These results indicate that quorum sensing in C. violaceum is a factor that determines its inhibitory effect on seedling growth.
Keywords: Chromobacterium violaceum, quorum sensing, seedling growth, Vigna radiata inhibition