The influence of soil intrinsic properties on soil erosion: the case of northern slopes of the Uluguru Mountains, Morogoro, Tanzania

Enhancing Dissemination of Soil and Water Research Outputs of SADC UniversitiesSoil erosion and resulting land degradation have been identified as serious problems since the 1920s in Tanzania. Soil erosion in Tanzania is mainly water induced and results from rainwater runoff on fragile lands such as steep slopes, overgrazed lands and other degraded lands due to various factors like deforestation and over-cultivation. This paper discusses a study carried out to assess the contribution of soil properties to soil erosion in the Northern slopes of the Uluguru Mountains. Two geomorphic units along mountain ridges and foothills on slopes ranging from 30 to 70% were studied for various soil physical characteristics including clay ratio, dispersion ratio, particle size analysis, bulk density, infiltration rate, gravel content, aggregate stability and soil loss due to erosion. Results from the study revealed that on one hand high soil organic matter, dry stable aggregates (>2 mm), bulk density and infiltration rate reduce significantly (P< 0.05) rill and interrill erosion. On the other hand, clay ratio, silt, very fine sand and gravel content increase soil erosion. The study argues that the application of organic material would improve soil physical properties and hence reduce soil erosion. Appropriate farming practices such as terracing, contour farming strip farming among others which stabilise soil aggregates are also recommended to minimise soil erosion

Using Pedotransfer Functions to Predict Saturated Hydraulic Conductivity for Layered Soil Profiles a Case Study at the Sokoine University of Agriculture Farm, Tanzania

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Major factors influencing the occurrence of landslides in the northern slopes of the Uluguru mountains, Tanzania

Landslide mitigation largely depends on the understanding of the nature of the factors that have direct bearing on the occurrence oflandslides. Identification of these factors is of paramount importance in setting out appropriate and strategic landslides control measures. The present study focused on the identification of the major factors influencing the occurrence oflandslides in the Northern slopes of the Uluguru Mountains, Tanzania. The main objective was to establish relationship between spatial distribution of landslides and their causative factors. Such information would enable the planning of appropriate and strategic control measures. Aerial photographs, field survey and Geographic Information System (GIS) techniques were employed to identify the landslides features which occurred during EL NINO rains, spatial distribution and their corresponding factors. The results show that landslides dominate the geomorphic units with slope gradient ranging from 25% to over 80%. The most affected geomorphic units are in the order: debris slopes> incisions and V-shaped valleys > amphitheatres. Factors which cause theoccurrence of landslides are both soil and terrain related. The most important soil characteristics are presence of shallow soil solum with low bulk density and high macro porosity overlying a relatively less porous saprolite or hard bed rock. The terrain related factors include: undercutting of slopes by roads and pathways and presence of very steep concave side slopes. Water flow from roads and pathways and seepage from irrigation channels are precursors for the triggering oflandslides in the study area

Soil acidity management by farmers in the Kenya highlands

Declining soil fertility attributed to soil acidity is a major soil productivity problem in sub-Saharan Africa. A study was carried out in nine counties across the Kenya highlands, namely Meru, Embu, Kerugoya, Nyeri, Kiambu, Kinangop, Siaya, Busia and Eldoret, where the problems associated with soil acidity are prominent. The study aimed at assessing farmers' awareness of soil acidity, and establishment of common acidity management practices following administration of structured questionnaires. From the information gathered through personal interviews via questionnaires, <37% of the farmers were attached to a farmers training group in all study sites; among them, <4% were aware of soil acidity problems and <8% had carried out chemical analysis of their soils. The farmers who had applied lime at least once on their farms were <3% in all sites. Most farmers (>80%) used both inorganic fertilizers and manure on their farms, with the majority using DAP, CAN and farmyard manure. On cultural soil fertility management, choice of subsequent crop was dictated by sustainability rather than cropping system like rotation. There was a significant (P<0.05) negative relationship between livestock keeping and soil fertility management, with <30% of the farmers returning crop residues back to the farm. Most of them fed crop residues to their livestock. Only 8% of the farmers incorporated crop residues into the soil. There was a significant (Ps 0.05) positive correlation between education level and inorganic fertilizer use in crop production. Farmer's age and maize yields correlated negatively with each other. Additionally, farmers' training programmes and frequencies positively influenced choice of inorganic fertilizers and levels of application. Training is therefore one of the most significant issues affecting soil fertility management in the Kenya highlands. To further enhance the understanding of soil acidity and fertility management in Kenya highlands, farmers training should be prioritized

Phosphorus Adsorption and Its Relation with Soil Properties in Acid Soils of Western Kenya

Low available phosphorus (P) is one of the major hindrances to crop production in acid soils of western Kenya. Although considerable work has been done to establish P levels in the region, there is paucity of information on which to base fertilizer recommendations due to potential crop production differences caused by different soil types and climate. Phosphorus adsorption capacity and its relationship with some soil properties were evaluated in acid soils from nine locations of western Kenya. Adsorption data was obtained by equilibrating the nine soil samples with 30ml of KH2PO4 in 0.01 M CaCl2, containing 0, 80, 150 and 300 µg ml-1 for 48 hours with shaking for 30 minutes at intervals of 8 hours. Langmuir, Freundlich and Tempkin adsorption models were fitted to the test results and relationship between P adsorption and soil properties determined by correlations. The result of this study showed that the soils were strongly to extremely acidic (pH 4.83 - 3.76), had high exchangeable Al3+ (&gt;2 cmol Al kg-1), Al saturation of (&gt; 20% Al) and calculated maximal phosphorous adsorption varied from 770.83 to 1795.83 mg kg-1 soil. Comparing the models, Freundlich linear model showed a better fit to the tested soils compared to Langmuir and Tempkin models. The regression coefficients (R2) for the fitted Freundlich P adsorption isotherms was highly significant ranging from (0.995- 1.000) for all tested soils. Analysis of relationship between adsorption maximum and soil attributes revealed that adsorption maximum positively correlated with clay content, exchangeable P, exchangeable acidity and Aluminium saturation and negatively correlation with organic matter and electrical conductivity. Due to differences in maximal P sorption capacities within the tested area, blanket P fertilizer recommendation may affect crop productivity in some sites. There is therefore need for further research to determine optimal Phosphorus requirements for soils in each research site

Soil acidity management by farmers in the Kenya highlands

Declining soil fertility attributed to soil acidity is a major soil productivity problem in sub-Saharan Africa. A study was carried out in nine counties across the Kenya highlands, namely Meru, Embu, Kerugoya, Nyeri, Kiambu, Kinangop, Siaya, Busia and Eldoret, where the problems associated with soil acidity are prominent. The study aimed at assessing farmers' awareness of soil acidity, and establishment of common acidity management practices following administration of structured questionnaires. From the information gathered through personal interviews via questionnaires, <37% of the farmers were attached to a farmers training group in all study sites; among them, <4% were aware of soil acidity problems and <8% had carried out chemical analysis of their soils. The farmers who had applied lime at least once on their farms were <3% in all sites. Most farmers (>80%) used both inorganic fertilizers and manure on their farms, with the majority using DAP, CAN and farmyard manure. On cultural soil fertility management, choice of subsequent crop was dictated by sustainability rather than cropping system like rotation. There was a significant (P<0.05) negative relationship between livestock keeping and soil fertility management, with <30% of the farmers returning crop residues back to the farm. Most of them fed crop residues to their livestock. Only 8% of the farmers incorporated crop residues into the soil. There was a significant (Ps 0.05) positive correlation between education level and inorganic fertilizer use in crop production. Farmer's age and maize yields correlated negatively with each other. Additionally, farmers' training programmes and frequencies positively influenced choice of inorganic fertilizers and levels of application. Training is therefore one of the most significant issues affecting soil fertility management in the Kenya highlands. To further enhance the understanding of soil acidity and fertility management in Kenya highlands, farmers training should be prioritized

Soil acidity management by farmers in the Kenya Highlands

Journal of Agriculture and Ecology Research International 5(3): 1-11, 2016; Article no.JAERI.22519Declining soil fertility attributed to soil acidity is a major soil productivity problem in sub-Saharan Africa. A study was carried out in nine counties across the Kenya highlands, namely Meru, Embu, Kerugoya, Nyeri, Kiambu, Kinangop, Siaya, Busia and Eldoret, where the problems associated with soil acidity are prominent. The study aimed at assessing farmers' awareness of soil acidity, and establishment of common acidity management practices following administration of structured questionnaires. From the information gathered through personal interviews via questionnaires, 80%) used both inorganic fertilizers and manure on their farms, with the majority using DAP, CAN and farmyard manure. On cultural soil fertility management, choice of subsequent crop was dictated by sustainability rather than cropping system like rotation. There was a significant (P<0.05) negative relationship between livestock keeping and soil fertility management, with <30% of the farmers returning crop residues back to the farm. Most of them fed crop residues to their livestock. Only 8% of the farmers incorporated crop residues into the soil. There was a significant (Ps 0.05) positive correlation between education level and inorganic fertilizer use in crop production. Farmer's age and maize yields correlated negatively with each other. Additionally, farmers' training programmes and frequencies positively influenced choice of inorganic fertilizers and levels of application. Training is therefore one of the most significant issues affecting soil fertility management in the Kenya highlands. To further enhance the understanding of soil acidity and fertility management in Kenya highlands, farmers training should be prioritized

Soil acidity management by farmers in the Kenya Highlands

Journal of Agriculture and Ecology Research International 5(3): 1-11, 2016; Article no.JAERI.22519Declining soil fertility attributed to soil acidity is a major soil productivity problem in sub-Saharan Africa. A study was carried out in nine counties across the Kenya highlands, namely Meru, Embu, Kerugoya, Nyeri, Kiambu, Kinangop, Siaya, Busia and Eldoret, where the problems associated with soil acidity are prominent. The study aimed at assessing farmers' awareness of soil acidity, and establishment of common acidity management practices following administration of structured questionnaires. From the information gathered through personal interviews via questionnaires, 80%) used both inorganic fertilizers and manure on their farms, with the majority using DAP, CAN and farmyard manure. On cultural soil fertility management, choice of subsequent crop was dictated by sustainability rather than cropping system like rotation. There was a significant (P<0.05) negative relationship between livestock keeping and soil fertility management, with <30% of the farmers returning crop residues back to the farm. Most of them fed crop residues to their livestock. Only 8% of the farmers incorporated crop residues into the soil. There was a significant (Ps 0.05) positive correlation between education level and inorganic fertilizer use in crop production. Farmer's age and maize yields correlated negatively with each other. Additionally, farmers' training programmes and frequencies positively influenced choice of inorganic fertilizers and levels of application. Training is therefore one of the most significant issues affecting soil fertility management in the Kenya highlands. To further enhance the understanding of soil acidity and fertility management in Kenya highlands, farmers training should be prioritized

Soil morphology, physico-chemical properties and classification of typical soils of Mwala district, Kenya

A soil profile representative of typical soils of Mwala District, Kenya, was dug to study its morphology, soil physico-chemical characteristics and to classify it using two internationally known soil classification systems. Disturbed and undisturbed soil samples were taken from designated pedogenic horizons for physical and chemical analysis in the laboratory. Soil morphological observations revealed that the pedon is well drained and very deep with dark brown to dark yellowish brown topsoil overlying brown to strong brown sandy clay loam to sandy clay subsoil. Clay eluviations - illuviation is a dominant process influencing soil formation in the study area as indicated by the clay gradient between the eluvial and illuvial horizons and the presence of clay cutans in the subsoil. The soil is characterized by weak fine subangular blocky throughout its pedon depth. Laboratory analysis indicates that the soil is very strongly acid (pH 4.6–5.0) throughout the profile, has very low N (<0.1%) and low OC (0.6-1.25%). The pedon has low CEC (6.0-12.0 cmol (+) kg -1 ) and low base saturation (20mg kg -1 ) in the topsoil -1 while it is low (7-20mg kg ) in the major part of the subsoil. Using field and laboratory analytical data, the representative pedon was classified to the subgroup level of the USDA Soil Taxonomy as Typic Haplustults and to Tier-2 of WRB as Haplic Cutanic Acrisols (Humic, Hyperdystric, Endosiltic). The general fertility of the soils of the area is discussed highlighting their potentials and constraints

Effectiveness of mulching under miraba in controlling soil erosion, fertility restoration and crop yield in the Usambara mountains, Tanzania

Soil erosion is a major threat to food security in rural areas of Africa. Field experiments were conducted from 2011 to 2014 in Majulai and Migambo villages with contrasting climatic conditions in Usambara Mountains, Tanzania. The aim was to investigate the effectiveness of mulching in reducing soil erosion and restoring soil fertility for productivity of maize (Zea mays) and beans (Phaseolus vulgaris) under miraba, a unique indigenous soil conservation measure in the area. Soil loss was significantly higher (p < 0·05) under miraba sole than under miraba with mulching, for example, 35 versus 20 and 13 versus 8 Mg ha 1 y 1 for Majulai and Migambo villages, respectively, in 2012. Soil fertility status was significantly higher (p < 0·05) under miraba with Tughutu mulching than under miraba sole, for example, 0·35 versus 0·25% total N, 37 versus 22 mg kg 1 P and 0·6 versus 0·2 cmol(+) kg 1 K for the Majulai village; and 0·46 versus 0·38 total N, 17·2 versus 10·2 mg kg 1 P and 0·50 versus 0·2 cmol(+) kg 1 K for the Migambo village. Maize and bean yields (Mg ha 1 ) were significantly higher (p < 0·05) under miraba with Tughutu mulching than under miraba sole, 2·0 versus 1·3 for maize and 0·9 versus 0·8 for beans in Majulai; and 3·8 versus 2·6 for maize and 1·0 versus 0·8 for beans in the Migambo village in 2012. This implies that Tughutu mulching is more effective in improving crop yield than Tithonia, although both could potentially protect the arable land from degradation caused by water erosion under miraba. Copyright © 2014 John Wiley & Sons, Ltd