A pot experiment and a field experiment were conducted to investigate the effect of Azolla pinnata, applied alone or in combination with urea, on rice plants under Malaysian conditions. Result of the pot experiment show that application of Azolla significantly increased the number of tillers and panicles, dry straw weight and grain yield over the control; similar results were obtained from the application of urea. There was no significant difference between the various Azolla treatments. In the filed, the recovery rate with Azolla application at 30 DAT was higher than when applied at transplanting; results with urea-N application were similar.
Keywords: Azolla pinnata, green manure, 15N-labelled fertilizer, N availability
This study investigate the effectiveness of two phosphate rocks (PRs), an unreactive phosphate rock from China (CPR) and a reactive phosphate rock from North Carolina, USA (NCPR) compared to triple superphosphate (TPR), a highly water-soluble phosphate fertilizer. These fertilizers were tested using three crops of corn (Zea mays L) grown consecutively on a Serdang series soil (Typic Paleudult). 32P isotope dilution technique was used to access their P availability. The rate of P used was 100 kg P ha-1, applied once at the beginning of the experiment. NCPR was as efficient as TSP in providing P to the first crop, while CPR showed the lowest percentage of utilization. In the second crop, NCPR was the superior source of P. However, in the third crop all three sources showed very poor percentages of utilization. The total amount of P taken up by the three crops of corn was 13.65, 18.04 and 8.56 kg ha-1 from TSP, NCPR and CPR respectively. Thus this study suggests that NCPR is an effective source of P for corn and can be used as a substitute for the water-soluble phosphate fertilizers. CPR is not a suitable phosphate source.
Keywords: Phosphate rock, isotope dilution, specific activity, relative availability
The research of potassium (K) was investigated by leaching clay, silt, and coarse + fine sand fraction from five soils with different physical and chemical properties with sulphuric acid (H2SO4). The results showed that the exchangeable K in each of the size fractions was easily depleted. The amount of K extracted increased with acid concentration in the following decreasing order; clay > silt > coarse + fine sand. The effective amount of K released per unit weight of soil, express as a percentage of total release, was 49, 33, and 18% for clay, silt, and + fine coarse sand, respectively. The release of K was closely associated with the amount of Al exchange sites but also from the mineral structures which underwent slow dissolution in acid conditions. In soils with appreciable amounts of K-bearing minerals, the release of K was high. The use of 1 M H2SO4 for determining soil K status was suggested to be a better method.
Keywords: Extraction, soil-K, size-fractions, sulphuric acid
A study was conducted to investigate runoff rate, its temporal distribution and soil loss on four 0.1-ha plots (treatments) in cocoa cultivation with slopes ranging from 14% to 19%. Treatments T1 and T2 were intercropped with bananas and Gliricidia. T1 was kept chemically weed-tree, T2 was allowed to establish Indigofera spicata and grasses Treatments T3 and T4 were not intercropped. T3 was kept chemically weed-free; on T4 Indigofera spicala was established with grasses Surface cover influenced total runoff and runoff rate At banana planting, the surface cover for T1, T2, T3 and T3 was 45, 40, 73 and 77%, respectively and the corresponding peak runoff rates for a large event on September 28 were 64, 37, 30 and 15 mm h-1. The planting of bananas drastically altered the soil surface Sediment concentrations in T1 and T2 increased from 0 4 kg/ms to 6 1 and 12 7 kg/ms respectively. Pass-through sediment or suspended load constituted more than 50% of total soil loss, indicating a high loss of the finer soil material Soil loss as pass-through sediment and as trapped sediment or bedload was related to runoff rate, cover management and cropping. Large soil losses are attributed to high runoff rates on surfaces without adequate contact cover. In soils where pass-through sediment is a major component of total soil loss, these losses are accompanied by a serious reduction in soil quality.
Keywords: Overland flow, soil erosion, sloping land, runoff rate, soil management
To investigate the effect of OM on the CEC of Kelantan plain soils. bum soil series in a toposequence, namely Tok Yong, Chempaka, Laung and Jabil. were used Calibrated amounts of OM-CEC and yield-CEC models of POMES were added to the soil, which were then incubated anaerobically. The increase in CEC of the soils corresponded more or less to the expected CEC of 16 cmolckg-1 as predicted by the model This study shows that the organic matter POMES could be used to increase the nutrient retention capacities 01 the less fertile soils of the Kelantan plain. There was a strong indication that the increase in CEC was dependent on the physico-chemical properties of the soils in relation to the amount of organo-mineral complex that could he formed In a field experiment conducted at Mulong Lating, Kelantan to evaluate the effect of OM addition on rice performance, six levels of organic matter (POMES) and three levels of N with optimum levels of P and K fertilizers here used in the treatment combinations A significant yield enhancement was obtained with OM incorporation corresponding to 0.5% C, irrespective of N levels, with an average yield increase of 1 t ha-1, that would provide a regional yield increase of 33,000 t per season.
Keywords: Fertility, soils, organic matter, rice yields
Experiments were conducted to study the rate of water absorption by clod of different sizes and initial moisture content using the capillarity method. Clods were prepared by molding wet clay soil into cubes for easy contact with the wet surface of a water-conducting material. Prepared samples ex-posed to wetting were examined by cutting 5-mm thick slices, starting the base. For confined conditions, a measured load was applied on every clod tested. The results of the clod-wetting experiments show that the rate of water absorption by capillarity was greatest when clods were initially very dry and that smaller clods tended to absorb water faster than bigger cloths confined. However, confining had no significant effect on absorption when the initial condition was very wet.
Keywords: Water absorption, soil clods, confined and unconfined conditions