کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4574686 | 1629523 | 2010 | 10 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Sediment induced soil spatial variation in paddy fields of Northwest Vietnam
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
فرآیندهای سطح زمین
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
The aim of this study was to assess the impact of various sedimentation pathways (flooding, irrigation and runoff) on the spatial variability of soil fertility in rice paddy terraces in tropical mountainous regions of Northwest Vietnam. Topsoil samples were taken during two subsequent rice cropping seasons and analyzed using a combination of diffuse reflectance mid infrared spectroscopy and conventional lab analysis. A mixed model was used (i) to evaluate the spatial variability among and within paddy cascades before planting in function of field position to the main irrigation channel, and (ii) to assess the impact of various sediment deposition pathways on soil nutrients and textural changes. The topsoil taken before planting contained on average 1.75 ± 0.57 g 100 gâ 1 soil organic carbon (SOC), 0.18 ± 0.06 g 100 gâ 1 total nitrogen (TN) with silt being the dominating soil fraction (0.68 ± 0.11 g gâ 1). Moderate sediment delivery of high quality through the irrigation system resulted in a significant enrichment in lower lying paddies following a linear trend for SOC (SOC (g 100 gâ 1) = 1.4 + 0.02 Distance (m), R2 = 0.31 â 0.62), total nitrogen (TN (g 100 gâ 1) = 0.11 + 0.004 Distance (m), R2 = 0.33 â 0.61) and a significant linear decrease in the sand fraction (sand (g gâ1) = 0.3 â 8 Eâ04 Distance (m), R2 = 0.28 â 0.48) with increasing distance from the irrigation channel along the cascade. Comparison of the samples taken before planting and after harvesting proved that the spatial variability in the topsoil was induced by sediment deposition resulting in a decrease of 0.11 g 100 gâ1 of SOC and 0.01 g 100 gâ1 of total N and an increase of 0.02 g gâ1 of the sand fraction in paddies close to the irrigation channel which received less nutrient rich sediment deposition. However, besides the effect of sediment rich irrigation water, direct sediment depositions originating from the highly eroded and unfertile uplands or deposited during flooding events (typhoons) strongly decreased soil fertility in the rice fields due to their low nutrient and high sand content. In conclusion, the alterations and maintenance of soil fertility of rice fields depended on the balance of the various sediment sources, i.e. quality and quantity, and is thus, strongly related to both upland management and extreme weather events and irrigation practices. These findings are relevant in the framework of site-specific fertilizer management by taking advantage of spatial variability in soil fertility along cascades of rice paddy terraces in tropical mountainous regions.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Geoderma - Volume 155, Issues 3â4, 15 March 2010, Pages 298-307
Journal: Geoderma - Volume 155, Issues 3â4, 15 March 2010, Pages 298-307
نویسندگان
P. Schmitter, G. Dercon, T. Hilger, T. Thi Le Ha, N. Huu Thanh, N. Lam, T. Duc Vien, G. Cadisch,