George N. Karuku

University of Nairobi | UON · Department of Land Resource Management & Agricultural Technology

This study carried out a greenhouse experiment to evaluate growth and yield response of maize, capsicum, and kale to a nanocomposite slow-release fertilizer (SRF). Higher biomass and yields were observed in SRF amendments compared with conventional fertilizer (CF) treatments at similar rates though not statistically significant. Crops were mainly r...

Perennial grasses form the bulk of nutrition for livestock in semi-arid grassland ecosystems in addition to the provision of other ecosystem services such as carbon storage. A study was undertaken to evaluate the performance of ecotypes of two common perennial semi-arid grasses (Panicum maximum and Cenchrus ciliaris) under different soil types and...

Low crop yields due to erratic rainfall and deteriorating soil fertility in smallholder farmers’ fields of Sub-Saharan Africa have prompted a quest for more resource-efficient production practices. In-situ water harvesting technologies have been proposed as climate-smart agriculture coping mechanisms to alleviate these problems, however, their full...

Africa has recently experienced adverse climate changes and has recognized tremendous advancement of numerous Climate Smart Agriculture (CSA) technologies with ability to promote resilience and productivity. However, these good strategies are not only unknown, but their extensive uptake remain subtle particularly beyond the scope area, especially a...

Kisambo BK, Wasonga OV, Kipchirchir OK, Karuku GN, Kirwa EC. 2023. Forage yields and quality of Cenchrus ciliaris and Panicum maximum ecotypes under varied harvest intervals in a semi-arid environment in Kenya. Intl J Trop Drylands 7: 102-111. Livestock production in Kenya typically relies on native pastures for nutrition and efforts are ongoing to...

Livestock production is a key sector in tropical Africa, sustaining millions of livelihoods in rangelands. It majorly relies heavily on indigenous vegetation including grasses which form the main basal diet. Grazing or defoliation is one of the processes which influence plant functional traits and productivity of range grasses. The objective of thi...

Crop growth is co-regulated by nutrient economy, water uptake and biomass accumulation. While cotton (Gossypium hirsutum L) requires substantial quantities of nitrogen (N), phosphorus (P) and potassium (K), these nutrients are frequently limiting in cotton growing areas. A study was conducted to determine the most limiting nutrient on water and nut...

Livestock production is a key sector in tropical Africa, sustaining millions of livelihoods in rangelands. It majorly relies heavily on indigenous vegetation including grasses which form the main basal diet. Grazing or defoliation is one of the processes which influence plant functional traits and productivity of range grasses. The objective of thi...

Perennial grasses form the bulk of nutrition for livestock in semi-arid grassland ecosystems and are a key livestock feed source in addition to the provision of a range of ecosystem services. A pot experiment was conducted to examine the responses of four perennial indigenous grass ecotypes grown in three different soil types (ferralsols, fluvisols...

Background Livestock production is an economically significant activity in grassland‐based production systems with herbivory, a critical process in modifying plant structure and regulating biomass dynamics in these areas. Methods A grazing simulation experiment was undertaken in a semi‐arid environment in Kenya to determine the effects of clipping...

Background: Crop production in the arid and semi-arid lands (ASALs) is constrained by erratic rainfall and poor soil fertility. Therefore, climate smart agriculture mechanisms such as in-situ rainwater harvesting technologies and recommended fertilizer rates would be vital for ensuring food security. Objective: To evaluate selected in-situ water ha...

p> Background: Crop production in the arid and semi-arid lands (ASALs) is constrained by erratic rainfall and poor soil fertility. Therefore, climate smart agriculture mechanisms such as in-situ rainwater harvesting technologies and recommended fertilizer rates would be vital for ensuring food security. Objective : To evaluate selected in-situ wate...

Investments in climate smart agriculture (CSA) are often hampered by inadequate finance. The risks of climate change further scare away private investors from this technology. However, household savings have been established as a key contributor to farm investment in rural households. This study sought to analyze the influence of household savings...

Background: Soil hydraulic parameters in non-saturated conditions are crucial for explaining soil water dynamics in the field. It is therefore necessary to understand the link between soil water potential and hydraulic conductivity in the soil in order to estimate plant available water and hence simulate its movement within the soils. However, meas...

Background: Phosphorous is a limiting crop nutrient in highly weathered tropical soils due to fixation, and its availability for plants’ uptake is influenced by soil physico-chemical characterics, land use type and management practices. Objective: To evaluate the relationship between selected physico-chemical properties and phosphorous sorption cha...

Climate smart agriculture (CSA) technologies are innovations meant to reduce the risks in agricultural production among smallholder farmers. Among the factors that influence farmer adoption of agricultural technologies are farmers’ risk attitudes and household livelihood diversification. This study, focused on determining how farmers’ risk attitude...

p> Background: Phosphorous is a limiting crop nutrient in highly weathered tropical soils due to fixation, and its availability for plants’ uptake is influenced by soil physico-chemical characterics, land use type and management practices. Objective: To evaluate the relationship between selected physico-chemical properties and phosphorous sorption...

Adept use of fertilizers is critical if sustainable development goal two of zero hunger and agroecosystem resilience are to be achieved for African smallholder agroecosystems. These heterogeneous systems are characterized by poor soil health mainly attributed to soil nutrient depletion. However, conventional methods do not take into account spatial...

In this work, a biodegradable cellulose-based nanocomposite PHG has been devel�oped by heterogeneously grafting acrylic monomers onto cellulose fibers in the pres�ence of nano-HA. The use of cellulose derived from WH could reduce the cost of production, impart biodegradability, and enhance the swelling and mechanical strength while at the same tim...

Background: Globally, more than 40% of annual food production comes from irrigated lands, and agriculture is the largest consumer of water, at 70% of all freshwater withdrawals. As water scarcity becomes more acute worldwide, increasing the effectiveness of agricultural water resources becomes a priority for enhanced food production. Methodology...

p> Background: Globally, more than 40% of annual food production comes from irrigated lands, and agriculture is the largest consumer of water, at 70% of all freshwater withdrawals. As water scarcity becomes more acute worldwide, increasing the effectiveness of agricultural water resources becomes a priority for enhanced food production. Methodology...

The main deterrent factors for achieving sustainable agricultural production in Eastern Kenya are irregular rainfall and low available water capacity. Knowledge on crop performance, water needs and optimization of deficit irrigation schedules would therefore help to minimize water stress and thus increase ASALs' achievable yields. The study was und...

Background: Sweet potato producers in Kenya practice either sole cropping of or relay cropping and rarely do intercropping which aims at maximizing on time and space. Objective. To assess the relative performance of sweet potato under various cropping systems. Methodology: This study was conducted in Katumani, Kenya for two seasons; 2018/2019 and 2...

Sufficient soil moisture in the root zone is critical for optimal crop development. Excess or deficit water leads to reduced crop growth and yields. A field study was done to determine the effect of available water on performance of PH4 maize variety on sandy clay loam soil at Bura Irrigation Scheme, eastern Kenya. Three water depletion level treat...

The objective of this study was to assess the impact of climate change on intercrops of maize and improved pigeonpea varieties developed. Future climate data for Katumani were downscaled from the National Meteorological Research Centre (CNRM) and Commonwealth Scientific and Industrial Research Organization (CSIRO) climate models using the Statistic...

Climate-Smart Agriculture (CSA) strategies have been introduced in Nyando basin (comprising Kisumu and Kericho Counties) in Kenya, and farmers have comparatively taken up the practices. This has resulted in diversification of farming crops/livestock and incomes to bridge seasonal shortfalls under erratic harsh weather conditions due to climate chan...

p> Background: In the wake of the changing climate, the current water crisis has increasing relevance for the human race, hence estimation is an integral part of planning, development and management of water resources of the country based on several meteorological parameters. Hypothesis. No significant changes in water requirements sweet potato cro...

Determining if the vast soil health degradations across the seven major soil groups (orders) of Sub-Saharan Africa (SSA) can be managed on the basis of a one-size-fits-all or location-specific approach is limited by a lack of soil group-based understanding of soil health degradations. We used the relationship between changes in nematode population...

The study was carried out at Lichinga and Sussundenga Research Station to assess the effects of cow manure and inorganic fertilizer on height, Stover yield, grain yield, yield quality for both maize and legumes of a maize/legume intercrop. A factorial design experiment with a split plot arrangement and replicated three times per site was used. The...

p> Background. Inappropriate agricultural practices such as use of heavy machinery, excessive tillage and unbalanced use of inorganic fertilizers, inappropriate irrigation practices and poor water management techniques, pesticide overuse , inadequate crop residue and/or organic carbon inputs, and poor crop cycling negatively affect soil characteris...

Background. Soil health assessment has been based on narrow disciplinary approaches that overlook the multiple and interacting biological processes that are the basis of sustainable crop productivity. Objective. Determine the influence of seasonal variations in nematode assemblages in different soil groups, sites and disturbance levels as an indica...

A farm survey was conducted within a 100 km² sampling block to collect data on the spatial variation in unfertilized maize biovolume and grain yields in relation to soil organic carbon (SOC), total nitrogen, phosphorus and extractable cations. Key soil factors associated with crop performance were identified using stepwise multiple linear regressio...

The precision of crop growth simulation models is a paramount facet in their use for evaluating on-field management practices for improved crop yields. Aqua Crop model version 5.0 was evaluated for experimental yields of bulb onion (Allium cepa L.) grown in West Ugenya Sub County, Kenya for two seasons (March to May long rains season, and October t...

Water insecurity is a threat to pastoral livelihoods and sustainability. The Water Act of Kenya, 2002, created the Water Resource Users' Associations (WRUAs) to enhance water resource conservation access at the local level. Nevertheless, environmental degradation has increased in recent times, further exacerbating water crisis and threatening livel...

Polymer nano-composite was prepared by grafting partially neutralized acrylic acid onto swollen cellulose isolated from water hyacinth in the presence of nano-hydroxyapatite (nano-HA) using N,N-methylene-bis-acrylamide (MBA) as the cross-linker and ammonium persulphate (APS) as the free radical initiator. Water absorption tests showed an increase i...

Slow release fertilizer (SRF) composite was formulated by incorporating nano-hydroxyapatite (nano-HA) and water soluble fertilizers (urea, (NH4)2HPO4 and K2SO4) into cellulose-graft-poly(acrylamide) polymer hydrogel. Fourier Transform Infra-red spectra revealed existence of chemical interaction between the monomer, cellulose, urea and nano-HA. The...

Effect of formulated slow release NPK fertilizer [cellulose-graft-poly(acrylamide)/nano-hydroxyapatite/soluble fertilizer] composite (SRF) on the performance and yield of maize, kale and capsicum was evaluated in a greenhouse experiment. No significant difference in growth parameters was observed between SRF and commercial fertilizer (CF) treatment...

Maize accounts for almost a third of annual global grain production. The demand for the grain is on the rise because it is used as human food, feed for livestock and in production of biofuel. This increase in demand is putting pressure on land and the available water. Measures to improve WUE in maize production therefore cannot be overemphasized. O...

Few studies have evaluated improved pigeonpea varieties developed and released in Kenya for soil fertility improvement and contribution to the productivity of cereal-based cropping systems prevalent in marginal areas. A study comprising field and greenhouse experiments was conducted between 2009 and 2013, in order to evaluate improved pigeonpea vari...

Effect of formulated slow release NPK fertilizer [cellulose-graft-poly(acrylamide)/nanohydroxyapatite/soluble fertilizer] composite (SRF) on the performance and yield of maize, kale and capsicum was evaluated in a greenhouse experiment. No significant difference in growth parameters was observed between SRF and commercial fertilizer (CF) treatments...

Watershed conservation and land use practices affecting it.

Swollen cellulose fibres isolated from water hyacinth were utilized in the synthesis of water hyacinth cellulose-graft-poly(ammonium acrylate-co-acrylic acid) polymer hydrogel (PHG). Acrylic acid (AA) partially neutralized with NH3 was heterogeneously grafted onto swollen cellulose by radical polymerization reaction using N,N-methylene-bis-acrylami...

The study was conducted between long rain season (LRS) in semi-arid Yatta sub-county, to evaluate the influence of tillage practices, cropping systems and organic inputs on the yield of sorghum and sweet potato. A Randomized Complete Block Design with a split-split plot arrangement replicated thrice was used. The main plots were tillage practices (...

Abstract In Yatta sub-County, a semi-arid land, there is scanty information on the causes and effects of climate change, as well as agricultural adaptation strategies. This scanty information assessment of climate related risks, and decision making about appropriate adaptation measures. A survey was conducted in two wards of Yatta, Kenya, to identi...

Low use efficiencies of inorganic fertilizers coupled with their rising costs has diverted attention of farmers towards organic sources. A study was conducted in Yatta sub-county between October 2012 to February 2013 short rains and April-August 2013 long rainy seasons to evaluate the how tillage, cropping and organic inputs influenced soil nutr...

Incubation studies were conducted to determine the effect of lime at the rate of 10tons ha- 1, Diammonium phosphate and Ammonium sulphate at 200kgha-1and Triple Superphosphate at 100kg ha-1 on nitrogen mineralization, nitrification process and priming effect. Three soil types were used namely luvisols from semi-arid Katumani, andosol and ferralsols...

Runoff farming is reported to improve land productivity and crop yields in hot and dry climates. This study was conducted to assess the available rainwater that can be harvested in a conserved catchment in a drought prone agroecological zone. The study was carried out in the Cyili sub-catchment, southern province of Rwanda, which has an irregular r...

Polymer nano-composite fertilizer formulation has the potential to enhance nutrient use efficiency. Slow release fertilizer (SRF) composite was formulated by incorporating nano-hydroxyapatite (nano-HA) and water soluble fertilizers (urea, (NH4)2HPO4 and K2SO4) into water hyacinth cellulose-graft-poly(acrylamide) polymer hydrogel. Fourier Transform...

Despite silicon not considered an essential nutrient, it is typically abundant in soils and is known to have beneficial effects when added to rice crops and several other plants. These beneficial effects include disease and pest resistance, structural fortification, and regulation of the uptake of other ions. In this study, the effect of silicic ac...

Land degradation and low rainfall seriously constrain agricultural production in arid and semi-arid areas. A study was conducted at Katumani Research Centre between 2009 and 2013 to investigate the effect of pigeonpea and crop residues on soil physical properties and maize yields. Sole-and inter-crops of maize and pigeonpea varieties drawn from thr...

Land degradation and low rainfall seriously constrain agricultural production in arid and semi-arid areas. A study was conducted at Katumani Research Centre between 2009 and 2013 to investigate the effect of pigeonpea and crop residues on soil physical properties and maize yields. Sole-and inter-crops of maize and pigeonpea varieties drawn from thr...

The preservation and sustainable development of soil and water resources is one of the basic principles for the development of Kenya. Throughout the course of history, all the social improvement and economic development are deeply concerned with soil loss and ecological environmental protection. Poor soil and water conservation measures will lead t...

The preservation and sustainable development of soil and water resources is one of the basic principles for the development of Kenya. Throughout the course of history, all the social improvement and economic development are deeply concerned with soil loss and ecological environmental protection. Poor soil and water conservation measures will lead t...

Despite silicon not considered an essential nutrient, it is typically abundant in soils and is known to have beneficial effects when added to rice crops and several other plants. These beneficial effects include disease and pest resistance, structural fortification, and regulation of the uptake of other ions. In this study, the effect of silicic ac...

Low yields due to declining soil fertility continue to be a major constraint to onion production in Kenya, necessitating imports to meet market demand. A field experiment was carried out for two seasons in West Ugenya Sub-County during the 2015 and 2016 short and long rains seasons, respectively to evaluate the effect of combining organic and inorg...

Kenya is classified as water scarce country yet the existing fresh water resources are under constant threat of pollution resulting from wastewater inflows. Wastewater contains nitrates and phosphates that stimulate excessive plant growth when released into water bodies thus deteriorating their quality. The purpose of the study was to evaluate the...

ABSTRACT: Kenya is classified as water scarce country yet the existing fresh water resources are under constant threat of pollution resulting from wastewater inflows. Wastewater contains nitrates and phosphates that stimulate excessive plant growth when released into water bodies thus deteriorating their quality. The purpose of the study was to eva...

Nitrogen mineralization potential is important so as to prevent over-fertilization that could lead to groundwater contamination or under-fertilization that could lead to poor nutrient provision by crops leading to low yields. Three soil types were selected on the basis of groups, agro-ecological zone, organic matter content and land use. The soil s...

This study was conducted to assess agricultural practices for generating maximum maize productivity in drought prone agro-ecological zones. The experiment was conducted in Cyili sub-catchment in Southern Province of Rwanda, which has an irregular rainfall distribution and a prolonged dry season. The experimental design consisted of a randomized des...

Trials for the effectiveness of Plantmate organic manure and Prime EC Foliar Plant Food for increased yields for selected crops were done in five different Agro-ecological zones and soil types, in Kenya. The approach was executed through controlled greenhouse experiment and in the field. The trials data obtained indicated Plantmate organic manure a...

Parasitism by Striga weed is the major cause of maize yield losses in the Lake Victoria Basin. Severity of attack is greater in soils with poor fertility. This study evaluated the effects of two different maize varieties and inorganic nitrogen sources on striga parasitism and maize yield in Kisumu West, Busia and Teso South districts of western Ken...

Introduction Water-based interventions haphazardly introduced in the drylands of Kenya have led to the introduction of piospheres used as concentration mounts. Not much is known about the effect of these piospheres on soil physio-chemical properties, especially in the Kenyan rangelands where the government and other development agencies have create...

Introduction Scarcity of water in the rangelands of Kenya has led to the introduction of piospheres. Previous research has however produced contrasting results on the effects of piospheres and seasonality on Shannon-Wiener’s diversity index, and therefore, this information is still deficient. In this study, the impact of these piospheres on plant s...

Water insecurity is a threat to pastoral livelihoods and sustainability. The Water Act of Kenya, 2002, created the Water Resource Users’ Associations (WRUAs) to enhance water resource conservation access at the local level. Nevertheless, environmental degradation has increased in recent times, further exacerbating water crisis and threatening livel...