Spatial Soil Loss Assessment Using USLE in Lake Ol Bolossat Catchment

Erosion by water is one of the most common types of soil degradation which occurs in all climatic regions and is widely considered to be a serious threat to the long-term viability of agriculture in many parts of the world. Lake Ol Bolossat in Nyandarua County, Kenya, is a high altitude lake that was formed on Rift Valley escarpment and faces the challenge of siltation due to increased soil erosion. Over the last few decades, the lake has been encroached and lake area has been overgrazed reducing the vegetation cover around the Lake. An assessment of spatial soil erosion loss was conducted using USLE model and GIS which showed that most parts of the Lake catchment have soil loss beyond tolerable levels of nine tons per year. The soil erosion range was between zero and 22, 525.5 tons per year. The land uses that were more vulnerable to soil loss are croplands, grazing lands with sparse vegetation and barelands which had soil loss ranges of 10–50 tons, 100 to 1000 tons and 500 to 22,525.5 tons per year respectively. The study recommended for immediate interventions by policy makers, researchers and development partners in curbing the soil loss problem

Sustainable development of crop-livestock farms in Africa

Crop-livestock farms across Africa are highly variable due to in agroecological and socioeconomic factors, the latter shaping the demand and supply of livestock products. Crop-livestock farms in Africa in the 20-first century are very different from most mixed farms elsewhere in the world. African crop-livestock farms are smaller in size, have fewer livestock, lower productivity and less dependency on imported feed than farms in most countries of Europe, the Americas and the intensive agricultural systems of Asia. This paper discusses the role African crop-livestock farms have in the broader socio-agricultural economy, and how these are likely to change adapting to pressures brought on by the intensification of food systems. This intensification implies increasing land productivity (more food per hectare), often leading to more livestock heads per farm, producing fertilized feeds in croplands and importing feed supplements from the market. This discussion includes (1) the links between crop yields, soil fertility and crop-livestock integration, (2) the increasing demand for livestock products and the land resources required to meet to this demand, and (3) the opportunities to integrate broader societal goals into the development of crop-livestock farms. There is ample room for development of crop-livestock farms in Africa, and keeping integration as part of the development will help prevent many of the mistakes and environmental problems related to the intensification of livestock production observed elsewhere in the world. This development can integrate biodiversity, climate change adaptation and mitigation to the current goals of increasing productivity and food security. The inclusion of broader goals could help farmers access the level of finance required to implement changes

Assessment of soil organic carbon fractions and carbon management index under different land use types in Olesharo Catchment, Narok County, Kenya

Abstract Background The changes in land use and land cover have a strong effect on the total soil organic carbon, its fractions and its overall soil health. This study carried out in Olesharo Catchment, Kenya, was to quantify the differences in total organic carbon (TOC), particulate organic carbon (POC), mineral organic carbon (MOC) and carbon management index (CMI) among four land use types: grasslands, shrublands, agricultural lands and barelands. It was also purported to evaluate the use of CMI as an indicator for soil degradation or improvement in response to land use and land cover changes. Results The results of the study show that the mean values of TOC, POC and MOC are significantly different between land use types. Thus, shrublands have significantly higher TOC (22.26 g kg−1) than grasslands (10.29 g kg−1) and bare lands (7.56 g kg−1). They also have significantly higher POC (7.79 g kg−1) and MOC (10.04 g kg−1) than all the other land use types. The agricultural lands have higher CMI than grasslands (53% vs 41% relative to shrublands) suggesting that grasslands face serious degradation through overgrazing. Conclusions This study shows that different land use types have an influence on soil organic carbon pools, and consequently on the CMI, the CMI could be used as an indicator for soil degradation or improvement in response to land use and land cover changes

Amendment of Tephrosia Improved Fallows with Inorganic Fertilizers Improves Soil Chemical Properties, N Uptake, and Maize Yield in Malawi

Maize production in Malawi is limited mainly by low soil N and P. Improved fallows of N-fixing legumes such as Tephrosia and Sesbania offer options for improving soil fertility particularlyNsupply. The interactions of Tephrosia fallows and inorganic fertilizers on soil properties, N uptake, and maize yields were evaluated at Chitedze Research Station in Malawi. The results indicated that the level of organic matter and pH increased in all the treatments except for the control. Total N remained almost unchanged while available P decreased in all plots amended with T. vogelii but increased in T. candida plots where inorganic P was applied. Exchangeable K increased in all the plots irrespective of the type of amendment. The interaction of N and P fertilizers with T. vogelii fallows significantly increased the grain yield. The treatment that received 45 kg N ha(-1) and 20 kg P ha(-1) produced significantly higher grain yields (6.8 t ha(-1)) than all the other treatments except where 68 kg N ha(-1) and 30 kg P ha(-1) were applied which gave 6.5 t ha(-1) of maize grain. T. candida fallows alone or in combination with N and P fertilizers did not significantly affect grain yield. However, T. candida fallows alone can raise maize grain yield by 300% over the no-input control. Based on these results we conclude that high quality residues such as T. candida and T. vogelii can be used as sources of nutrients to improve crop yields and soil fertility in N-limited soils. However, inorganic P fertilizer is needed due to the low soil available P levels

Amendment of Tephrosia Improved Fallows with Inorganic Fertilizers Improves Soil Chemical Properties, N Uptake, and Maize Yield in Malawi

Maize production in Malawi is limited mainly by low soil N and P. Improved fallows of N-fixing legumes such as Tephrosia and Sesbania offer options for improving soil fertility particularly N supply. The interactions of Tephrosia fallows and inorganic fertilizers on soil properties, N uptake, and maize yields were evaluated at Chitedze Research Station in Malawi. The results indicated that the level of organic matter and pH increased in all the treatments except for the control. Total N remained almost unchanged while available P decreased in all plots amended with T. vogelii but increased in T. candida plots where inorganic P was applied. Exchangeable K increased in all the plots irrespective of the type of amendment. The interaction of N and P fertilizers with T. vogelii fallows significantly increased the grain yield. The treatment that received 45 kg N ha −1 and 20 kg P ha −1 produced significantly higher grain yields (6.8 t ha −1 ) than all the other treatments except where 68 kg N ha −1 and 30 kg P ha −1 were applied which gave 6.5 t ha −1 of maize grain. T. candida fallows alone or in combination with N and P fertilizers did not significantly affect grain yield. However, T. candida fallows alone can raise maize grain yield by 300% over the no-input control. Based on these results we conclude that high quality residues such as T. candida and T. vogelii can be used as sources of nutrients to improve crop yields and soil fertility in N-limited soils. However, inorganic P fertilizer is needed due to the low soil available P levels

Amendment of Tephrosia Improved Fallows with Inorganic Fertilizers Improves Soil Chemical Properties, N Uptake, and Maize Yield in Malawi

Maize production in Malawi is limited mainly by low soil N and P. Improved fallows of N-fixing legumes such as Tephrosia and Sesbania offer options for improving soil fertility particularly N supply. The interactions of Tephrosia fallows and inorganic fertilizers on soil properties, N uptake, and maize yields were evaluated at Chitedze Research Station in Malawi. The results indicated that the level of organic matter and pH increased in all the treatments except for the control. Total N remained almost unchanged while available P decreased in all plots amended with T. vogelii but increased in T. candida plots where inorganic P was applied. Exchangeable K increased in all the plots irrespective of the type of amendment. The interaction of N and P fertilizers with T. vogelii fallows significantly increased the grain yield. The treatment that received 45 kg N ha−1 and 20 kg P ha−1 produced significantly higher grain yields (6.8 t ha−1) than all the other treatments except where 68 kg N ha−1 and 30 kg P ha−1 were applied which gave 6.5 t ha−1 of maize grain. T. candida fallows alone or in combination with N and P fertilizers did not significantly affect grain yield. However, T. candida fallows alone can raise maize grain yield by 300% over the no-input control. Based on these results we conclude that high quality residues such as T. candida and T. vogelii can be used as sources of nutrients to improve crop yields and soil fertility in N-limited soils. However, inorganic P fertilizer is needed due to the low soil available P levels

Effects of tillage and cropping systems on maize and beans yield and selected yield components in a semi-arid area in of Kenya

Conservation of soil moisture through tillage practices is an important management objective for crop production in semi-arid areas. A study to evaluate the effects of tillage practices on maize and bean yields was conducted in Mwala Sub County, Eastern Kenya, in the long (LR) and short rains (SR) of 2012/13. The tillage treatments were: Disc Ploughing (DP), Disc Ploughing and Harrowing (DPH), Ox-ploughing (OX), Subsoiling – Ripping (SSR), Hand hoeing with Tied Ridges (HTR) and Hand hoeing (H) only. There were three cropping systems of Sole Maize (SM), Sole Bean (SB) and Maize - Bean intercrop (M + B), which were investigated in a Split-Plot Design field experiment with four replications. Data on maize and bean yield and yield components were monitored throughout the four cropping seasons. Maize plant height, leaf area and leaf area index, maize and beans grain and biomass yields were significantly affected by tillage (P < 0.05). No significant effect of cropping systems on the maize height was observed. Higher maize grain yields (P < 0.05) were obtained in the sole maize plots in LR 2012 (5.01 Mg ha -1 ), SR 2012 (4.19 Mg ha -1 ) and in the SR 2013 season (2.82 Mg ha -1 ). A three - season bean grain yield average by tillage shows that DPH > SSR > DP > OX > HTR > H, with values ranging from 0.75 Mg ha -1 to 1.46 Mg ha -1 (P < 0.05). Intercropping reduced the seasonal means of bean grain yields (P < 0.05) with a 54 % decrease by intercropping (0.73 Mg ha -1 ) compared to the sole bean (1.6 Mg ha -1 ). Thus, the DP and DPH improved crop yield and yield components and can be recommended as tillage practices in the semi-arid region

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

Increasing potato equivalent yield increases returns to investment under potato-legume intercropping systems

In order to enhance sustainable intensification of potato-based cropping systems, especially in sub-Saharan Africa (SSA), there is a need to investigate the economic viability of investing in this lucrative venture. This study evaluated the economic returns under legume intercropping systems using value/cost ratio (VCR) and benefit/cost ratio (BCR) under treatments comprising of potato intercropped with dolichos (Lablab purpureus L.) (P-D), climbing bean (Phaseolus vulgaris L.) (P-B) and garden pea (Pisum sativum L.) (P-G), and a potato pure stand control (P-S). Across the seasons, tuber yield was not significantly (p < 0.05) affected by intercropping with P-D, whereas under P-B and P-G, it decreased by 19% and 16%, respectively compared to P-S. P-G, P-B and P-D recorded 6, 7 and 12% higher potato equivalent yield (PEY) relative to P-S. P-D was the most profitable intercropping system with VCR of 35 and BCR of 5.1 as compared to values recorded in P-S of 31 and 5, respectively. Regression of VCR against PEY resulted in a stronger coefficient (0.98) compared to that of BCR against PEY (0.82) implying that VCR is a simple tool that could be adopted for economic returns to investment studies such as potato-legume inter-cropping systems

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