Effectiveness of vetiver, ruzi and verano in controlling runoff and loss of nitrogen, phosphorus, and potassium on sandy soil of an undulating land
1999
Phoemphun Kiratikasikon (Khon Kaen Univ., Khon Kaen (Thailand). Faculty of Agriculture. Dept. of Land Resources and Environment)
Northeast region possesses an undulating landform. Most of the soil is sandy. Applied fertilizers are subjected to leaching and be carried away with runoff and erosion. The study was carried out to determine the effectiveness of vetiver, ruzi and verano stylo in controlling runoff and loss of applied nitrogen, phosphorus and potassium in sandy soil of an undulating land. The study was consisted of three experiments. The experiment 1 and 2 commenced in 1993. Vetiver and ruzi were grown in a 1*5 m plot of 6 percent slope. Nitrogen, phosphorus and potassium were applied at a rate of 100 kg N, P, K per hactare. The fertilizers were applied to the plots of the first and second experiment in 1993 and 1994 respectively. The Third experiment was commenced in 1994. Vetiver, ruzi and verano were grown in the plots of the same size as the others. The fertilizers were also applied in 1994. The design for all experiments was a randomized complete block. Runoff water was collected and measured at every rainfall after fertilizer application. Right after fertilizers application, soil samples were taken for the determination of the water soluble nitrogen, phosphorus and potassium. Similar determinations were made to the soil samples taken at the end of experiments. The result showed that the amount of runoff water from the plants growing plot was half of that from the bared plot. Vetiver, ruzi and Verano were equally effective in controlling runoff. The loss of applied phosphorus was related to the magnitude of runoff. Percentage of applied phosphorus in the runoff from plant growing plot and bared plot were 37 and 16 respectively. Very little of nitrogen and potassium were detected in runoff and the surface soil at the end of experiments. It is believed that most of them were leached down through the soil profile.
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