[Gray correlation analysis of the impact of land use type on soil physical and chemical properties in the hilly area of central Sichuan, China.]

Abstract

A case study was conducted in a small watershed of Sichuan hilly basin. In order to eva-luate the effect of land use type on soil characteristics, the soil physical and chemical properties of the 0-10 and 10-20 cm soil layers were analyzed through comparison between bare land and four land use types i.e., slope cropland, leveled cropland, orange forest and conservation forest. The results suggested that capillary porosity, non-capillary porosity, total porosity, and contents of soil organic matter, total nitrogen, total phosphorus, alkali-hydrolysis nitrogen, available phosphorus and available potassium under the same land use type in the 0-10 cm soil layer were more than those in the 10-20 cm soil layer, while the soil bulk density was the opposite. Moreover, there was no significant difference in total potassium between the two soil layers. The orange forest had the largest capillary porosity, non-capillary porosity, total porosity, the highest contents of total phosphorus, available phosphorus and the smallest soil bulk density under the same soil layer. The content of soil organic matter was highest under the conservation forest in the 0-10 cm soil layer and highest under the orange forest in the 10-20 cm soil layer. The order of grey correlation was conservation forest (0.9441)> orange forest (0.8858)> leveled cropland (0.6300)> bare land (0.5397)> slope cropland (0.4714) for the 0-10 cm soil layer, and conservation forest (0.8919) > orange forest (0.8401)> leveled cropland (0.5773)> bare land (0.5301)> slope cropland (0.5175) for the 10-20 cm soil layer. In conclusion, conservation forest was the best type to improve soil physical and chemical properties, and slope cropland was the worst type.