Impact of land management system on crop yields and soil fertility in Cameroon

The impact of direct-seeding mulch-based cropping systems (DMC), direct seeding (DS) and tillage seeding (TS) on <i>Sorghum</i> yields, soil fertility and the rehabilitation of degraded soils was evaluated in northern Cameroon. Field work consisted of visual examination, soil sampling, yield and rainfall data collection. Three fertilization rates (F1: 100 kg ha^&minus;1 NPK + 25 kg ha^&minus;1 of urea in DMC, F2: 200 kg ha⁻¹ NPK + 50 kg ha⁻¹ of urea in DMC and F3: 300 kg ha⁻¹ NPK + 100 kg ha⁻¹ of urea in DMC) were applied to each cropping system (DS, TS and DMC), resulting in nine experimental plots. Two types of chemical fertilizer were used (NPK 22.10.15 and urea) and applied each year from 2002 to 2012. Average Sorghum yields were 1239, 863 and 960 kg ha⁻¹ in DMC, DS and TS, respectively, at F1, 1658, 1139 and 1192 kg ha⁻¹ in DMC, DS and TS, respectively, at F2, and 2270, 2138 and 1780 kg ha⁻¹ in DMC, DS and TS, respectively, at F3. pH values were 5.2–5.7 under DMC, 4.9–5.3 under DS and TS and 5.6 in the control sample. High values of cation exchange capacity were recorded in the control sample, TS system and F1 of DMC. Base saturation rates, total nitrogen and organic matter contents were higher in the control sample and DMC than in the other systems. All studied soils were permanently not suitable for <i>Sorghum</i> due to the high percentage of nodules. F1 and F2 of the DS were currently not suitable, while F1 and F3 of DMC, F3 of DS and F1, F2 and F3 of TS were marginally suitable for <i>Sorghum</i> due to low pH values

Solid Earth, 6, 1087–1101, 2015

www.solid-earth.net/6/1087/2015/ doi:10.5194/se-6-1087-2015 © Author(s) 2015. CC Attribution 3.0 License. Impact of land management system on crop yields and soil fertility in Cameroo

Morphology, Physicochemical Characteristics and Land Suitability in the Western Highlands of Cameroon

The aim of the study was to evaluate the morphology and physicochemical properties of soils and their suitability to potatoes, maize and beans, in order to contribute to stop rural migration, prevent conflicts between farmers and breeders and contribute to the increase of agricultural yields in the eastern slope of the Bambouto Mountain, Cameroon. Morphologically, the studied soil profiles are poorly or more developed, characterized respectively by AC or ABC horizon sequences. All the soil samples recorded acidic pH (4.8 to 5.5) except in the Bawa and in Zavion footslope where this pH is slightly acidic (6.0 to 6.2). Nitrogen contents are low to medium (0.04 to 0.225), except in midslope and footslope of Zavion site where these contents are very high (0.406 and 0.436% respectively). Organic matter contents increase from the Medji (1.42%) site to Zavion site (9.84%). High content of organic matter in Bawa located at the same altitude as Medji is related to the basaltic bedrock which glasses weathering might induce increase of organic matter content, while high content in Zavion might be mostly related to the increase in altitude and the decrease of temperature which slacks up microorganism activities. Phosphorous level is very low and largely under the critical limit (20 ppm) for all the study sites. Calcium is the dominant exchangeable cation, with contents ranging between 0.13 and 7.53 cmol(+)/kg of soil. The cation exchange capacity varied between 2.03 and 29.59 cmol(+)/kg of soil. Base saturation percentage fluctuates from 11.80 to 39.70%. The production of bean, maize and potatoes in the study sites is limited due to high rainfall and wetness, high slope gradient and soil fertility problems which could respectively be solved by promoting crops cultivation at the end of the raining season, terracing of arable land and fertilization and liming. &nbsp

Soils and their distribution on Bambouto volcanic mountain, West Cameroon highland, Central Africa

Morphological, physical and chemical studies were carried out on soils of Mount Bambouto, a volcanic mountain of the West Cameroon highland. These studies show that the soils of this region can be divided into seven groups according to Soils Taxonomy USA [Soil taxonomy: a basic system of soil classification for making and interpreting soils surveys: USDA Agriculture Handbook 436: Washington, DC, US Government Pronting Office, 1975, 754]: lithic dystrandept soils, typical dystrandept soils, oxic dystrandept soils, typical haplohumox soils, typical kandiudox soils, tropopsamment soils and umbriaquox soils. A soils map of this region at scale 1:50,000 has been drawn up, using the seven soils groups above as soil cartography units. These soils are organised into of three main categories: soils with andic characteristics in the upper region of the mountain (lithic dystrandept soils, typical dystrandept soils and oxic dystrandept soils); ferrallitic soils in the lower part of the mountain (typical haplohumox soils and typical kandiudox soils) and imperfectly developed soils (tropopsamment soils and umbraquox soils)

Clayey soils from Boulgou (North Cameroon): geotechnical, mineralogical, chemical characteristics and properties of their fired products

peer reviewedIn this study, clayey soils are characterized as backfill and potential fusible raw materials for engineering. Geotechnical tests (particle size distribution, Atterberg limits, densities) and chemico-mineralogical analyses (X-ray fluorescence, X-ray diffraction and Fourier transform infrared) were carried out on samples collected from field in the locality of Boulgou (North Cameroon) followed by the determination of mechanical properties of fired bricks (850–1200 °C). The excavations carried out have revealed a thick layer of clayey soils (~ 2 to 2.5 m) over a sandy layer. This clay formation presents some stratifications with limited influence variation in terms of mineralogy. Mean grain size distribution is dominated by sand (62–80%), clay (12–25%) and silt (6–9%). It corresponds to silty–clayey soils regarding their methylene blue values (3.3–5.6), with low plastic (13–22%) to high plastic (33%) characteristics. They are classified by USCS as clayey sand/silty clay, while one sample is a poorly graded sand (SP). Clay minerals observed are kaolinite (6–12%), montmorillonite (2–6%) and illite (8–10%). Those parameters associated with their fine nature and high compressibility make them suitable engineering applications for backfill material and barriers. From chemical analyses, relatively high contents in alkali and alkaline earth elements (~ 4 to 6%) to be used as potential fusible raw materials for fired bricks or gres ceramics were revealed. Bricks characteristics are varied: linear shrinkage (0.3 to 9%), bulk density (1.8 to 2.3 g/cm3), water absorption (19.7 to 1.3%) and flexural strength (0.3 to 17.4 MPa). Overall, the requirement for fired brick (< 20%) is met up by the water absorption values. As from 1050 °C, these soils are made suitable for brick-making with good characteristics (metallic sound, good cohesion and flexural strength)