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Wakatsuki, Toshiyuki
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Agriculture, Biological Sciences & Forestry Environmental Science

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Characteristics and Stocks of Soil Nutrient under Various Land Use Types in a Super Wet Tropical Rain Forest Padang, West Sumatra Hermansah, Hermansah; Sendi, Nofrita; Yulnafatmawita, Yulnafatmawita; Matsunaga, Tsugiyuki; Wakatsuki, Toshiyuki
JOURNAL OF TROPICAL SOILS Vol 15, No 1: January 2010
Publisher : UNIVERSITY OF LAMPUNG

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5400/jts.2010.v15i1.55-62

Abstract

In order to clarify the characteristics and stocks of soil nutrient under various land use types in a super wet tropical rain forest in Padang, West Sumatera. We investigated the nutrient characteristics of the several samples of soils under different land use such as cacao plantation (CP), cinnamon plantation (CMP), mixed garden (MG), and primary forest (PF) in Gadut Mountain, Padang, West Sumatra. The soil nutrient characteristics varied among the different land use types. The range of nutrient characteristics under four land use type were 4.60 – 7.01% and 0.4 – 0.60 % for total carbon and total nitrogen and were 9.80 – 24.59, 0.68 – 2.07 and 0.30 – 0.8 mol (+) kg-1 for Ca, Mg and K, respectively. The highest content of soil nutrient status was found under MG, while the lowest soil nutrient status found at PF. This result indicated that the MG with various vegetation types might contribute in enriching the organic matter in soil. The soil nutrient content such as TN, exchangeable Ca, Mg and K tended to decrease with soil depth of each land use type. However, the sodium (Na) content in soil tended to increase within the soil depth. These were presumably due to evaporation of Na at surface soil within the study area was low. These study results showed that spatially the nutrient properties of soil were closely related to the land use type and management practices. It was suggested that the nutrient characteristics of soils under various land use types in a super wet tropical rain forest region, in Gadut Mountain, Padang West Sumatra were significantly affected by the land use types and land coverage.
Using Selected Structural Indices to Pinpoint the Field Moisture Capacity of Some Coarse-Textured Agricultural Soils in Southeastern Nigeria Igwe, Charles Arizechukwu; Hermansah, .; Obi, Martin Eze; Wakatsuki, Toshiyuki
JOURNAL OF TROPICAL SOILS Vol 16, No 2: May 2011
Publisher : UNIVERSITY OF LAMPUNG

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5400/jts.2011.v16i2.151-159

Abstract

Over- or underestimation of field capacity (FC) of agricultural soils could misguide soil and water management and this might have negative agronomic and environmental impacts. The study sought to identify the moisture tension for reliably estimating in the laboratory the FC of some sandy soils with low-activity clay minerals and at different levels of structure development in Nsukka agroecological zone in southeastern Nigeria. Fifty-four samples of topand subsoils under contrasting vegetation cover at three locations in the zone were analyzed for texture, organicmatter contents, bulk density and total porosity. Saturated hydraulic conductivities (Ksat) of the samples were equallydetermined. Water-conducting and water-filled porosities at each of 0.06-, 0.10- and 0.33-bar tensions were implied from water retention data at the respective tensions. The soils were categorized based on their levels of structure development using a structural stability index [(organic matter: silt+clay) %] as follows: very low (< 4%), low (4-7.5%) and moderate to high (> 7.5%) stability soils. Series of simple correlation tests were run among the waterconducting porosities at the various tensions and the Ksat of the soils. In each case, the soil was assumed to have attained FC at that moisture tension which the associated water-conducting porosity showed significant positive correlation with the Ksat. Our results revealed that the 0.06-bar tension overestimated the FC of the soils. The 0.10-bar tension, the commonly used moisture tension for the purpose in the study area, proved suitable only for soils within the moderate to high structural stability category. From all indications, the 0.33-bar tension best corresponded to the FC of the less structurally developed soils in the other two categories. The level of soil structure development should therefore be considered before deciding the suitable moisture tension for the determination of FC of these and similar soils in other tropical locations.Keywords: Coarse mineral soils, field moisture capacity, saturated hydraulic conductivity, structural stability,water-conducting pores
Co-Authors Hermansah Hermansah, Hermansah Hermansah, . Igwe, Charles Arizechukwu Matsunaga, Tsugiyuki Obi, Martin Eze Sendi, Nofrita Yulnafatmawita Yulnafatmawita