Influence of Soil Parent Materials and Soil-Related Factors on the Growth and Yield of Rubber Under Felcra Scheme, Sendayan

The influence of two terrain classes (i.e. 5 to 25% and 25 to 50% slopes) on soils developed from two parent materials (i.e. granite and sedimentary rocks) on the growth and yield of rubber (Hevea brasiliensis) after four years of tapping was evaluated by using the field data, viz. girth and yield of rubber from 1980 to 1983, obtained from the Federal Land consolidation and Rehabilitation Authority (FELCRA) Scheme at Sendayan, Negri Sembilan. RUbber grown on sedimentary rock derived soil on steep slopes (25 to 50% slope) after four years of tapping showed significantly bigger girth than those grown on same soil on undulating to rolling terrain (5 to 25% slope). The mean monthly and yearly dry weight of rubber after four years of tapping was significantly higher in areas planted on sedimentary rock derived soils located on steep terrain. The growth of rubber as influenced by the interaction of parent material and slope over time was not significant during the same period of tapping. However3 the overall yield of rubber was significantly higher on soils derived from sedimentary rocks on steep terrain than on soils derived from granite on similar terrain

Mineralogical and Chemical Properties of Some Acid Sulfate Soils in Malaysia and Their Effects on the Growth Performance of Oil Palm Seedlings (Elaeis Ruineensis, Jacq)

Acid sulfate soils are charllcterized by a very low pH and a high aluminium concentration resulting from the chemical and biological oxidation of pyrite upon drainage. These soils have low agricultural potential due to high acidity and poor physical conditions, which adversely affect crop growth. Successful reclamation and management of acid sulfate soils would require an in-depth understanding of the soil's chemical and mineralogical properties. In this study, acid sulfate soils at Pulau Lumut, Kelang were mapped, characterized morphologically and chemically,and classified. Soil solutions were extracted on samples from soil pit,limed and oxidized soils and a pot experiment at the matrix suction of 10 kPa and the activities of the major cations and anions were calculated by Geochem. XRD and TGA were carried out to deter mine the mineralogy of the various soil horizons. The morphological features of the minerals in the soils were studied by TEM and SEM. A controlled pot experiment was conducted to assess the performance of oil palm seedlings grown on acid sulfate soils under freely drained and waterlogged conditions

Alumínio extraível e formas de AL na solução de solos derivados de rocha granitica em Portugal

Extractable aluminium (Al) was determined in surface and subsurface horizons of eleven pedons derived from granite occurring in Portugal, under a wide range of precipitation. Five successive extractions with 1 M KCl, 0.5 M CuCl2 and 0.33 M LaCl3 were used. Monomeric (Alm) and organic (Alorg) forms of Al in the soil solution, extracted at field capacity, were also determined. Amounts of extracted Al were greatest with the 0.5 M CuCl2 and lowest with the 1 M KCl. These amounts showed strong positive correlation with soil organic C contents. Soil horizons having high contents (56-80 g kg-1) of organic C showed the highest amount of extractable Al by the 0.5 M CuCl2 (12.2-30.9 cmolc kg-1). Organically bound Al extracted by the 0.5 M CuCl2 and 0.33 M LaCl3 was also highest in these soils (7.6-10.1 and 4.7-8.3 cmolc kg-1, respectively). In contrast, lowest amounts of Al extracted by the 1 M KCl, 0.5 M CuCl2 and 0.33 M LaCl3 (0.9-4.3, 4.1-17.1 and 2.2-7.2 cmolc kg-1, respectively) were observed in horizons containing low organic C content (3-22 g kg-1). Concentrations of total (AlT), monomeric (Alm) and organic (Alorg) Al in the soil solution of studied soils also increased with increasing soil organic C content, but only Alm was significantly correlated with soil organic C content. Solution of soils having low organic C contents (3-6 g kg-1) showed the lowest concentrations of AlT, Alm and Alorg (0.09-1.60, 0.06-0.38 and 0.03-1.29 μg mL-1, respectively). In contrast, the concentrations of AlT (7.1-17.2 μg mL-1), Alm (0.8-0.9 μg mL-1), and Alorg (7.6-16.9 μg mL-1) were much higher in soils containing high amounts of organic C (37-73 g kg-1). In order to monitor the effects of Al in the soil and quality of sub-superficial water, changes in the concentration of monomeric forms of Al and their activities in the soil solution need further stud

Laboratory Studies on the Release of Cations and Anions in Acid Sulfate Soils from Pulau Lumut,Selangor

Acid sulfate soils in Peninsular Malaysia are characterized l7y low pH and high amounts of At. Alleviation of toxic ions in the soils l7y controlled drainage is recommended. However, potential acidity remains in the soils due to slow release of toxic ions during mineral weathering. A study was conducted to determine the release of Al and other ions l7y repetitive extraction of samples from the field and l7y aerobic incubation of samples in the laboratory. The results showed that Al was released continuously from the soils even after the sixth extraction. When the soils were allowed to undergo free oxidation under aerobic conditions Al, Mn, Fe, Ca, Mg, K, Na and S were released into the soil solutions due to breakdown of clay minerals. Activities of these ions increased significantly, resulting in an increase of electrical conductivity of the soil solution. Additionally, pH of the soil solution dropped. These commonly observed properties of acid sulfate soils have great implications on their management practices