Assessment of certain soil properties related to different land‐use systems in the Kaya watershed of the humid forest zone of Cameroon

Abstract

A field survey was conducted in the Kaya watershed of the humid forest zone of Cameroon to assess changes in particle size distribution and chemical soil properties related to different land-use systems. The strongly acid soils are mainly composed of sand and clay, and are poor in organic carbon, total nitrogen, mineral nutrients and effective cation exchange capacity (ECEC), with the major portion of nutrients stored in the topsoil, together with organic matter. Land-use systems significantly affect the sand and the clay fractions and have high proportions of sand in soils of cropped fields, secondary forest and river valleys and high clay percentages under dense forest and fallows. Soil pH and exchangeable Al in the topsoil and the subsoil, organic carbon, available P, base saturation and Al saturation in the topsoil and ECEC in the subsoil significantly differ with the land-use systems. Soils of food-crop fields and river valleys presented a higher fertility level than under secondary and dense forests. Permanent vegetation coverage and/or exposure to heavy rains of the soils, disturbance due to land preparation, organic matter supplied by the vegetation, nutrient cycling, nutrient restitution and nutrient uptake could be differentiation factors. For agricultural development, utilization of residue from harvest to cover the soil surface, liming and P fertilization appeared as the first and the most important management options. Nitrogen and K fertilization could be added according to crop requirements. Since farmers cannot afford to buy lime and mineral fertilizers and agroforestery is hardly practised, the utilization of cheap and widely available wood ash as a liming agent and supplier of P and K is a promising option. Field trials at the farmer level are proposed to evaluate this.

Assessment of some important fertility parameters related to different land-use systems in the humid forest zone of southern Cameroon

“…But Voundi Nkana and Tonye (2002) did not find any changes in silt fraction distribution, may be because they dealt with 0-20 cm soil layer while this study dealt with 0-10 cm soil layer. Lal (1996) and Voundi Nkana and Tonye (2002) found similarly that continuous cropping and intensive land-use both affect the particle size distribution and these changes depend on cultivation duration. Shepherd et al (2000) indicated no effect of land-use systems on soil particle size distribution.…”

A Review of Land Ecological Security Evaluation in China

“…At present overseas research focuses on microeconomic point of view such as soil quality evaluation in natural science point of view, and ultimately serves the optimization of land use patterns. Of course, the evaluation itself does not determine the manner of land use, land ecological security evaluation should be a key influence for this choice of implementation (Vondi Nkana J C. & Tonye J., 2003;Jonathan B & Butcher., 1999;Johnes P. J. et al, 2007;Siim Veski et al, 2005;Jesse Bellemare et al, 2002;Bai-ming Chen, 1996). China should make its own characteristics and contributions in the field of land ecological security evaluation based on making use of macro-evaluation advantages and combining features of China's land resources.…”

Monitoring land use/land cover change impacts on soils in data scarce environments: a case of south-central Ethiopia

“…The result of these studies could be encapsulated in three categories: the negative impacts, the positive impacts and the absence of impacts of LULC change on soils properties. SOM content was very low in cultivated lands, and very high under natural vegetation (Amsalu et al, 2007;Bewket & Stroosnijder, 2003;Nkana & Tonye, 2003). Negassa and Gebrekidan (2004) have noted an increase in bulk density and a decline in CEC, SOM, K + , Ca 2+ , Mg 2+ and total N. Amsalu et al (2007) reported significantly higher pH on cultivated soils than uncultivated soils.…”

“…Nkana and Tonye (2003), Schipper and Sparling (2000) and Shepherd, Buresh, and Gregory (2000) reported that soils under forest show lower fertility level. Nkana and Tonye (2003), Schipper and Sparling (2000) and Shepherd, Buresh, and Gregory (2000) reported that soils under forest show lower fertility level.…”