Point of Zero Charge Determination and the Inluence of P, Basic Slag, Organic Matter and Lime Applications on Colloidal Charge and Quality of Oxisols

The colloidal charge manipulation of highly weathered soils using point of zero charge (PZC or pHo) approach is important in improving soil chemical properties. The objective of this study was to determine the PZC and manipulate colloidal charge surfaces of Oxisols in order to increase their quality. PZC was determined by adjusting pH values from 3 to 7 using potentiometric titration. The change of colloidal surface charges was measured using two extractants; NH4-acetat pH 7 and NH4Cl. A glass house experiment was carried out using 4.5 kg soil/pot. Soil was taken from Sonay, South East Sulawesi and from Sitiung, West Sumatra. Soil was taken from surface layer (0-20 cm) and subsurface layer (20-40 cm) for each location. Four factors consisted of P fertilizer, basic slag, organic matter and lime were used to manipulate colloidal surface charge. The treatment rates were 100, 200 and 400 ppm P for P fertilizer; 2, 4 and 8 t/ha for basic slag; 10, 20 and 40 t/ha for organic matter; 1.5, 3 and 6 t/ha for lime, and a complete control. All 13 treatments with three replications, were arranged using a randomized complete block design in which each layer of two Oxisols is used as a block. The results showed that values of PZC for a surface layer of Sonay Oxisol (OSY) and for surface and subsurface layers of Sitiung Oxisol (OSG) are similar, i.e, pHo was 3.5. In addition, the PZC value for the subsurface layer of OSY occurs at pH 5 which is the highest pHo value compared to three other layers. The PZC value of OSY, at a surface layer is higher than its soil pH value (5.0 vs 4.4) suggesting that colloidal surfaces bear a positive charge. In contrast, the PZC values for the surface layer of OSY and surface and subsurface layers of OSG were lower than their soil pH values, indicating the colloidal surfaces bear a negative charge. Application of P, basic slag, organic matter, and lime was able to manipulate colloidal charge surfaces having positive charges become negative and that the low negative charge of colloidal surfaces become more negative as evidenced from the increase cation exchange capacity (measured in NH4Cl) compared to a control treatment. Application of P, basic slag,organic matter, and lime could increased quality of Oxisols as shown by decreasing K leaching and by increased soybean yields, which drastically increased compared to a control treatment

Cadmium Adsorption Capacity on Inceptisols Brebes and Its Uptake by Shallot as Plant Indicator

A research had been done in the laboratory and greenhouse of the Indonesian Center for Soil and Agroclimate Research and Developmant to study cadmium adsorption capacity, availability, and its uptake by shallot as plant indicator in order to antisipate Cd pollution in soil and plant in the future. The steps of the research were adsorption study in the laboratoryand followed by greenhouse trial. Cadmium adsorption study was using the rate of 0; 10; 30; 40; 50; 60; 70; 80; 90; and 100 ppm. The trial on response and plant uptake on cadmium used 2 kg soil pot-1 then planted with shallot var. Bima for 2 months. The experiment utilized completely randomized design with six treatments and three replicates. The rates of Cd were 0; 25; 50; 100; 200; and 400 ppm Cd (Cd(NO3)2). The results showed that Inceptisols Brebes adsorption, maximum adsorption, andbuffering capacity are 14.78 ml μg-1; 879 μg g-1 and 12,987 ml μg-1, respectively. The cadmium availability in the soil could be calculated by using the equation: Cdexchangeable = 0.0532(Cdapplied) – 1.6757, r2 = 0.9686 (after treatment); Cdexchangeable = 0.0671(Cdapplied) + 0.924, r2 = 0.9903 (after harvest). Application of 50 ppm Cd reduced shallot production up to 31% significant with total uptake of 4.57 ppm Cd. The Cd uptake increased significantly for treatment 25 ppm, Cd in shallot tuber(2.36 mg Cd per kg dry weight), and at 200 ppm Cd in leaves (7.16 mg kg-1). The cadmium content in tuber at treatment 2 ppm Cd (2.36 ppm Cd) exceeds critical value/permissible limit of vegetable for consumption

Characteristics of Phosphate Rock Materials From China, Indonesia and Tunisia and Their Dissolution in Indonesian Acid Soils

Dissolution of phosphate rock (PR) in soils is a primary concern for P in the PR to be available for plant. The dissolution of three PR materials, China (CPR), Ciamis (IPR) and Gafsa (GPR), in eight acid Indonesian soils (pH in water 4.1-5.7) was tested in a closed incubation system. Experiment was conducted in Soil Chemical Laboratory, Universiti Putra Malaysia and Indonesian Center for Agricultural Land Resources Research and Development from January to April 2002. The dissolution was determined from the increase in either 0.5 M NaOH extractable P (∆P) or 1 M BaCl2-triethanolamine (TEA)-extractable Ca (∆Ca) in soils amended with PR compared with control soil. Dissolution of the IPR was the highest (30-100%) followed by GPR (17-69%) and then by CPR (20-54%). The maximum dissolution followed the order: Bogor Ultisols > Bogor Oxisols > Subang Inceptisols > Bogor Inceptisols > Sukabumi Oxisols > Lebak Ultisols > Sukabumi Inceptisols > Lampung Ultisols. PR dissolution indicated a positive correlation with P retention capacity. The results implied that the extent of PR dissolution for the three PR sources (China, Indonesia and Tunisia) increased with increasing P retention capacity of the soils. PR dissolution can be based on a calibration curve of ∆Ca meaning that if ∆P is high then the amount of PR dissolution measured by ∆Ca in PR materials is also high

Banking efficiency and stock market performance: an analysis of listed Indonesian banks

Indonesian banking, Emerging markets, Productivity, Efficiency, C23, C52, G21,