Bio

PROF. GACHENE CHARLES K K

Currently an Associate Professor in LARMAT and past Chairman of Dept of Soil Sc and ,Dept of LARMAT.  A specialist in soil and water management. Has over 126 publications of which 58 are in refereed journals, 42 published book chapters, 18 in refereed proceedings, 30 proceeding papers, 5 manuals and 15 soil survey advisory reports.

Publications


2013

Eunice, G, Gachene CKK, Jesse TN, Omondi SM.  2013.  Nitrogen Fixation by Natural Populations of Acacia Senegal in the Drylands of Kenya Using 15N Natural Abundance. Abstract

Nitrogen (N) fixation was estimated for three Acacia senegal (L.) (A. senegal) Willd. varieties (A. senegal var. senegal, kerensis, and leiorhachis) growing naturally in different sites in the dryland areas of Kenya. The quantities of N2 fixed were estimated by the 15N natural abundance method, using leaves as the sampling material. Balanites aegyptiaca (B. aegyptiaca) was selected as the reference species growing in the same area. Soil samples were also collected under A. senegal trees for nodule assessment. Leaf 15N natural abundance values (δ15N) were significantly different between A. senegal and B. aegyptiaca. These values averaged 6.35, 4.67, and 3.03% for A. senegal var. kerensis, leiorhachis, and senegal, respectively, and were lower than those of the adjacent reference species. There were also significant differences in the amount of N2 fixed (%Ndfa) among the varieties. A. senegal var. senegal showed the highest levels of N2 fixation with a mean of 36% while A. senegal var. kerensis and leiorhachis had equal estimates of 25%. However, no nodules were observed in the collected soil samples. Leaf N values were significantly different among the varieties with a mean of 2.73, 2.46, and 4.03% for A. senegal var. kerensis, leiorhachis, and senegal, respectively. This study shows that the three varieties of A. senegal are able to fix N2 in their natural ecosystems and the differences could probably be due to soil properties and nutrient availability under the different environments. The species can hence be utilized as plantations in agriculture and land rehabilitation programs.

2012

Karuku, GN, Gachene CKK, Karanja N, Cornelis W, Verplancke H, Kironchi G.  2012.  Soil hydraulic properties of a nitisol in Kabete, Kenya. Abstract

Water relations are among the most important physical phenomena that affect the use of soils for agricultural, ecological, environmental, and engineering purposes. To formulate soil-water relationships, soil hydraulic properties are required as essential inputs. The most important hydraulic properties are the soil-water retention curve and the hydraulic conductivity. The objective of this study was to determine the soil hydraulic properties of a Nitisol, at Kabete Campus Field Station. Use of an internal drainage procedure to characterize the hydraulic properties and soil and water retention curves allowed for the establishment of the moisture and matric potential at field capacity and permanent wilting point. The Bt2 (84 -115) and Bt3 (115 - 143 cm) had the highest clay contents of 619 compared to Ap, AB and Bt1 horizons. The PWP was attained at soil moisture contents of 0.223, 0.284, 0277, 0.307 and 0.314 m3m-3 in the Ap, AB, Bt1, Bt2, and Bt3 horizons, respectively. Horizontal saturated hydraulic conductivity (Ksat) was high at 6.0 cm hr-1 in Ap horizon and decreased to 0.4 cm hr-1 in the subsurface horizon (Bt3). Ksat in the vertical direction was higher than horizontal and ranged from 8.3 cm hr-1 in surface layer to 0.6 cm hr-1 in Bt3 horizon, with exception of Bt1 and Bt2 where horizontal Ksat was greater than vertical. The Ap horizon also had the highest crop extractable water. Though the AB and Bt1 had the same water content at low matric suction, the variation was very wide as the SWRC approached saturation point. Bt1 and Bt2 also had similar water contents at suction range of – 7kPa after which Bt1, tended towards Bt3. Bt3 had the narrowest range of crop extractable water and thus was attributed to texture. The Bt3 retained the most amount of water at 0.314 m3m-3concluding that θPWP increased with depth. The total available water capacity between FC and PWP in the profile was 79.2 mm m-1. The study observed that the field capacity, crop available water contents and hydraulic conductivities were influenced positively by soil organic matter. The Van Genuchten parameters of air entry value (α) and pore size distribution (n) indicated that pore size distribution was not even in the AP and AB horizons. The field capacity was attained at higher matric potential at -5kPa for Bt1 while Bt2 and AP, AB, Bt2 and Bt3 was at -10kPa.The functional relationship, K(θ) = aθb that deals with water redistribution as a result of soil hydraulic properties and evaporative demand of the atmosphere was highly correlated to soil moisture content and texture with R2 values > 0.85.

2011

Githae, EW;, Gachene CKK;, Njoka JT;, Odee DW;, Omondi SF.  2011.  Genefic Diversity of Gum Arabic-producing Acacia senegal Variefies in Kenya using Inter-Simple Sequence Repeat (ISSR) and Chloroplast Simple Sequence. Abstract

Acacia senegal is a drought-tolerant, multi-purpose tree species, highly valued for gum arabic production and increasingly being used in agro-forestry in Sub-Saharan Africa. Despite its long history of use, there has not been exhaustive genetic evaluation of the extant genetic resource base of A. senegal in Kenya for genetic improvement of the species. Inter-simple sequence repeat (ISSR) and chloroplast microsatellite (cpSSR) markers were used to study genetic diversity among seven Kenyan populations of A. senegal embracing three putative varieties: kerensis, leiorhachis and senegal. The two marker types detected similar levels of Nei’s gene diversity (HISSR = 0.211, HcpSSR = 0.212) among the A. senegal populations. Acacia senegal var. kerensis exhibited the highest diversity using ISSR markers (HISSR = 0.248), followed by varieties leiorhachis (HISSR = 0.218) and senegal (HISSR = 0.151). Analysis of molecular variance (AMOVA) detected significant genetic variations within and among populations (P < 0.001 and P < 0.01 for ISSR and cpSSR, respectively). Based on the unweighted pair group method with arithmetic mean (UPGMA) dendrogram of the seven populations, two regions were differentiated (north and south). Both markers demonstrated their potential for delineating population structure at local and regional levels, and infra-specific relations within the species, hence their potential as tools for conservation, improvement programmes and sustainable use of the species. This study provides baseline genetic information for the domestication of A. senegal varieties in Kenya.

Macharia, PN;, Gachene CKK;, Mureithi JG;, Kinyamario JI;, Ekaya WN;, Thuranira EG.  2011.  The effect of introduced forage legumes on improvement of soil fertility in natural pastures of semi-arid rangelands of Kajiado District, Kenya. Abstract

A two phase study was carried out from 2002 to 2005 in the semi-arid rangelands of Kajiado District, Kenya to determine the effect of introduced forage legumes on soil fertility improvement of natural pastures. During legume evaluation phase, Neonotonia wightii (Glycine), Macroptilium atropurpureum (Siratro), Lablab purpureus cv. Rongai (Dolichos), Mucuna pruriens (Velvet bean) and Stylosanthes scabra var. Seca (Stylo) were screened for adaptability and growth performance under the semi-arid conditions for two years. Results of soil analysis showed there were significant increases in soil pH (4.92 to 5.36), organic carbon (1.17 to 2.57%) , nitrogen (0.17 to 0.22%) and potassium (1.23 to 1.68 me%) probably due to the large amounts of organic residues produced by the legumes (particularly Glycine, Siratro and Stylo which are perennials). The calcium content decreased significantly from 7.97 to 4.50 me% (which was attributed to plant uptake) while the decrease of phosphorus was not significant. During the second phase of study for 1½ years Glycine, Siratro and Stylo were integrated into natural pastures. The results showed that only the soil pH significantly increased from 5.23 to 5.31 while all the other nutrients decreased results, which were attributed to production of less organic residues by the legumes compared to the residues produced during the legume evaluation phase. The study concluded that Glycine, Siratro and Stylo were capable of improving the soil fertility of semi-arid natural pastures only if the respective dry matter production was 10.31, 7.81 and 3.52 tha-1, amounts which were able to produce large amounts of organic residues.

Zziwa, E, Kironchi G;, Gachene CK, Mugerwa S;, Mpairwe D.  2011.  Production systems, land cover change and soil factors affecting pastur e production in semi1arid Nakasongola. Abstract

The current pace of rangeland degradation imparted by appalling land use and management systems is greatly limiting the potential of the soil resource to support pasture production in semi - arid rangeland s of Uganda. Our objectives were to determine the effects of land cover change and production systems on pasture biomass yield and to identify the critical soil factors affecting pasture production in Nakasongola. The area was stratified into three product ion systems and three land cover types from which six pasture and soil samples were collected following a Modified - Whittaker sampling method. Pasture biomass was significantly high (p < 0.0001) under herbaceous cover (2019 kg/ha) compared to woody (1302 kg /ha) and bare which had no pasture biomass. The settled production system had a significantly (p = 0.013) high pasture biomass (1266 kg/ha) compared to non settled (1102 kg/ha) and semi settled systems (953 kg/ha). Biomass yield was more associated with hi gh levels of organic matter (r = 0.91), calcium (r = 0.91), magnesium (0.83), nitrogen (r = 0.77) and base saturation (r = 0.88). It can be concluded that maintaining native vegetation cover of the rangelands and increasing levels of limiting nutrients are the major strategies for increasing pasture production in semi - arid rangelands of Nakasongola

Eunice, GW, Charles K K, Jesse T N.  2011.  Soil physicochemical properties under Acacia senegal varieties in the dryland areas of Kenya. Abstract

Acacia senegal is a multipurpose drought-tolerant tree or shrub legume and is commonly used in agroforestry systems in sub-Saharan Africa for gum arabic production and soil fertility improvement. Despite its wide distribution in Kenya, there has not been exhaustive evaluation on the effects of the extant varieties (kerensis, leiorhachis and senegal) on soil properties under their canopies for sustainable utilization of the species. Three sites in the drylands of Kenya representing the three varieties were selected for assessment. Soil samples were collected under tree canopies at a depth of 0 to 25 cm and were compared with the soils from the open canopies. There were significant differences in soil physicochemical properties among the three varieties (P<0.05 and P< 0.01). Soil nutrients under the canopies were higher than in the open canopies mainly due to effects of litter accumulation. The three varieties have beneficial effects on soil nutrient status in their natural ecosystems and would most likely improve crop productivity in agroforestry systems as well as enhance herbage productivity in the rangelands. The varieties growing under different soil types may have an effect on their gum Arabic production and quality. Key words: Acacia senegal varieties, soil nutrients accumulation, sustainable utilization.

2010

Karuma, A, Gachene CKK, Gicheru PT, Mwang'ombe AW, Mwangi HW, Clavel D, Verhagen J, Kaufmann VR, Francis J, Ekaya W.  2010.  Effects of legume cover crop and sub-soiling on soil properties and maize (zea mays l) growth in semi arid area of Machakos District, Kenya. Abstract

Low crop yields in the semi arid areas of Kenya have been attributed to, among other factors, low soilfertility, low farm inputs, labour constraints and inappropriate tillage practices that lead to pulverized soils. The aim of this study was to determine the effects of legume cover crops (LCC) on soil propertiesand maize growth in the semi arid area of MachakosmDistrict, Kenya. The study was undertaken in farmers’ fields. The field experiments were carried out in a randomized complete block design with four treatments each replicated four times during the 2008/2009 long (LR) and short rain (SR) seasons. The treatments were T1 = maize + dolichos (Lablab purpureus) + subsoiling; T2 = maize + dolichos + nosubsoiling; T3 = maize alone + no subsoiling; T4 =maize alone with subsoiling). Results from the field experiments showed that rainfall amount and its distribution affected the growth and yield of dolichos and maize. There were significant differences in ground cover between the treatments at P ≤ 0.05 in all the different weeks after planting when measurements were taken. The penetration resistance in all the plots ranged from 3.83 - 4.18 kg cm-2 with treatment T4 having the highest and treatment T1 lowest penetration resistance. There were also siginificant changes in soil N in plots which were under dolichos compared to plots without dolichos. The results obtained in this study also indicated that subsoiling in combination with dolichos had the greatest potential of improving soil properties and crop yields in semi arid environments of Kenya.

Maobe, SN, Mburu MWK, Akundabweni LSM, Ndufa JK, Mureithi JG, Gachene CKK, Makini FW, Okello JJ.  2010.  Residual Effect of Mucuna pruriens Green manure Application Rate on Maize (Zea mays L.) Grain Yield. Abstract

Maize grain yield is constrained by inadequate supply of nitrogen caused by insufficient application of fertilizers that are found to be costly and unaffordable in smallholder farming. Therefore there is need to search for locally available and potentially low-cost N sources. Beneficial residual effect from mucuna biomass application during subsequent cropping seasons of maize, hence fertilizer saving, is considered one of the possible solutions. However, there are residual aspects of herbaceous legume green manure application that are not clear and warrant further investigation: The application rate of green manure biomass required to make substantial residual effect on yield of maize produced in subsequent cropping seasons is unknown. The effect of mucuna green manure application rate on seasonal persistence of the residual influence is not adequately described. Consequently, on-farm research was carried out in southwest Kenya in the period 2002-2005. The objective was to determine residual effect of mucuna green manure application rate on maize grain yield during the subsequent first and second cropping seasons after incorporation. Treatments investigated were: mucuna green manure applied at rates of 0, 30, 60, 120, 240 and 480 kg N haG1; and inorganic fertilizer-urea at 30, 60 and 120 kg N haG1. At tissue N concentration of 1.6 to 2 % for mucuna, the application rates worked to 1.5, 3, 6, 12 and 24 t DM haG1 equivalent of its green manure biomass. Randomized complete block design with three replications was used and maize variety H614 planted. Data was collected on maize grain yield at harvest. Genstat discovery edition 2 was used in data analysis. Results obtained showed that mucuna green manure and inorganic fertilizer-urea N do not have residual effect on maize grain yield during the first and second subsequent planting seasons, regardless of the rate applied. These being wide range of mucuna application rates, 1.5 to 24 t DM haG1, would suggest that change in tissue N concentration of the herbaceous legume, while other factors remain similar, would have little if any dramatic alteration on the observed residual response trend.

Baaru, MW;, Onwonga RN.  2010.  Assessment of changes in natural resources: a participatory approach. AbstractWebsite

This study analyzed changes in natural resources in Machakos District of Kenya using participatory approaches. The results show that natural resources have decreased since the ranch became a settlement scheme. Natural forests decreased, vast land was cleared, rivers dried-up while soil erosion, drought, temperatures and land degradation increased. Land productivity declined and most farmers abandoned the traditional crops for modern high value crops. However, farmers adopted various coping strategies. Drought resistant crops, early maturing crops and water harvesting were some of the strategies adopted by farmers. The results also show that resource base management at the community level was still a challenge and a lot of investment needed to be made in this area. As part of the study, farmers knowledge of changes in natural resource use was assessed in a resettlement area. Over a period of about 50 years, significant land degradation has occurred as a result of increased population pressure, poor natural resource management and climate change effects. This was reflected in poor/low land productivity and reduced availability of water. Farmers responded by moving away from growing indigenous crops to growing short-duration crop

2009

GATHAARA, NV;, NGUGI JN.  2009.  Gender, soil and water conservation in Machakos district, Kenya. AbstractWebsite

Gender mainstreaming is crucial in soil and water conservation initiatives. The existing technologies though, as designed, are expected to be gender neutral, lead to gender differences at the adoption stage. This was confirmed during a study conducte d in Kathekakai settlement scheme, Machakos district where despite both men and women participating in soil and water conservation initiatives, women’s efforts to adopt the recommended technologies were hampered by their limited access to authoritative infor ma- tion and lack of control over land. Women though playing major roles as farmers (64.6%), could not make key decisions on land u se. Previous reports indicate that the women in Machakos district contributed significantly to soil and water conservation efforts in the mid 1980’s leading to terracing of over 70% of the district. Gender mainstreaming efforts need to be enhanced for achievement o f sustainable and effective soil and water conservation for improved agricultural production and livelihoods

2008

Rutunga, V;, Karanja NK;, Gachene CKK.  2008.  Six month-duration Tephrosia vogelii Hook.f. and Tithonia diversifolia (Hemsl.) A.Gray planted-fallows for improving maize production in Kenya. Abstract

An experiment including planted Tephrosia vogelii and Tithonia diversifolia fallow species and natural fallow was conducted at Maseno, Kenya, for assessing whether these fallows grown on a nutrient depleted land could produce sufficient green manure in six month period, whether their biomass retained on the same plots or transferred to continuously cropped plots with or without added P fertiliser could increase yield of consecutive maize crops and whether it is useful to regularly repeat these fallows on same plots. First fallow was established in randomized complete blocks with three replicates. At harvesting, biomass was recorded, then either incorporated in situ or transferred to continuous cropped plots split with and without added P fertiliser and monitored for the effect in improving consecutive maize crops. The second fallow was managed on this split plot design. The two-planted shrubs fallows produced more than 9 Mg total dry biomass and accumulated 154 to 234 kg N.ha-1, which were significantly higher compared to the production in the natural fallow. The shrubs were also superior to natural fallow for P accumulation (5-22 kg versus 2 kg.ha-1). The aboveground dry biomass harvested from planted T. vogelii and T. diversifolia and either incorporated in situ or transferred into continuously cropped plots increased maize yields by 2.5 folds compared to the unmanured crop, the control. Supplementing the organic materials with an additional 20 kg P inorganic fertilizer increased the 1st maize yield by about 40%. Productivity in the plots with T. vogelii or T. diversifolia aboveground biomass removal was low for the subsequent fallow and maize crops when compared to the performance in plots where biomass was incorporated. To achieve sustained yields of maize in depleted soils requires regular improved fallowing at least one season alternating with one season maize, and additional P inputs

K, PROFGACHENECHARLESK, Rutunga V, Karanja NK.  2008.  Decomposition rates of biomass obtained from six month-old Tephrosia vogelii, Tithonia diversifolia and natural fallow vegetation at Maseno, Kenya. Biological Agricultural & Horticultural Journal, Vol 1. Biological Agricultural & Horticultural Journal, Vol 19(1), 49-62.. : F.N. kamau, G. N Thothi and I.O Kibwage Abstract

A model for the establishment of a four-dimensional regional geodetic reference datum is presented. Starting from the three-dimensional integrated geodetic network model, formulations for the establishment of a four-dimensional regional datum are developed. Astronomic latitudes, astronomic longitudes, gravity values, gravity potential differences, gravity differences, and GPS-vectors are considered as observables. The estimated parameters defining the datura are point coordinates, deflections of the vertical and geoidai undulations, and velocities and accelerations on the positional coordinates. The network datum is considered observed over several epochs with parameters estimated from previous epochs being introduced into later epochs as stochastic prior information parameters.

2007

Wangechi, SW;, Chemining’wa GN;, Nderitu JH;, Gachene CKK.  2007.  Response of snapbean to inorganic N-fertilizer and farm and Manure in Mwea.
K, PROFGACHENECHARLESK.  2007.  GN Chemining. Biological Agricultural & Horticultural Journal, Vol 19(1), 49-62.. : F.N. kamau, G. N Thothi and I.O Kibwage Abstract
A model for the establishment of a four-dimensional regional geodetic reference datum is presented. Starting from the three-dimensional integrated geodetic network model, formulations for the establishment of a four-dimensional regional datum are developed. Astronomic latitudes, astronomic longitudes, gravity values, gravity potential differences, gravity differences, and GPS-vectors are considered as observables. The estimated parameters defining the datura are point coordinates, deflections of the vertical and geoidai undulations, and velocities and accelerations on the positional coordinates. The network datum is considered observed over several epochs with parameters estimated from previous epochs being introduced into later epochs as stochastic prior information parameters.

2006

K, PROFGACHENECHARLESK.  2006.  Macharia PN and Gachene CKK. 2006. Forage legumes for the improvement of natural pastures of semi arid rangelands of Kajiado District. In Jg Muriethi, CKK Gachene, JW Wamuongo and M Eilitta (eds) Enhancing agricultural productivity in East Africa: Develop. Biological Agricultural & Horticultural Journal, Vol 19(1), 49-62.. : F.N. kamau, G. N Thothi and I.O Kibwage Abstract
A model for the establishment of a four-dimensional regional geodetic reference datum is presented. Starting from the three-dimensional integrated geodetic network model, formulations for the establishment of a four-dimensional regional datum are developed. Astronomic latitudes, astronomic longitudes, gravity values, gravity potential differences, gravity differences, and GPS-vectors are considered as observables. The estimated parameters defining the datura are point coordinates, deflections of the vertical and geoidai undulations, and velocities and accelerations on the positional coordinates. The network datum is considered observed over several epochs with parameters estimated from previous epochs being introduced into later epochs as stochastic prior information parameters.
K, PROFGACHENECHARLESK.  2006.  Karuku G, Gachene CKK and Macharia P. 2006. Soil water behaviour under different cover crops and under different residue management practices. In Jg Muriethi, CKK Gachene, JW Wamuongo and M Eilitta (eds) Enhancing agricultural productivity in East Africa:. Biological Agricultural & Horticultural Journal, Vol 19(1), 49-62.. : F.N. kamau, G. N Thothi and I.O Kibwage Abstract
A model for the establishment of a four-dimensional regional geodetic reference datum is presented. Starting from the three-dimensional integrated geodetic network model, formulations for the establishment of a four-dimensional regional datum are developed. Astronomic latitudes, astronomic longitudes, gravity values, gravity potential differences, gravity differences, and GPS-vectors are considered as observables. The estimated parameters defining the datura are point coordinates, deflections of the vertical and geoidai undulations, and velocities and accelerations on the positional coordinates. The network datum is considered observed over several epochs with parameters estimated from previous epochs being introduced into later epochs as stochastic prior information parameters.
K, PROFGACHENECHARLESK.  2006.  Gachene CKK and Mwangi H. 2006. Green manure cover crops for soil erosion control and and conservation agriculture in Central and Eastern highlands of Kenya. In Jg Muriethi, CKK Gachene, JW Wamuongo and M Eilitta (eds) Enhancing agricultural productivity . Biological Agricultural & Horticultural Journal, Vol 19(1), 49-62.. : F.N. kamau, G. N Thothi and I.O Kibwage Abstract
A model for the establishment of a four-dimensional regional geodetic reference datum is presented. Starting from the three-dimensional integrated geodetic network model, formulations for the establishment of a four-dimensional regional datum are developed. Astronomic latitudes, astronomic longitudes, gravity values, gravity potential differences, gravity differences, and GPS-vectors are considered as observables. The estimated parameters defining the datura are point coordinates, deflections of the vertical and geoidai undulations, and velocities and accelerations on the positional coordinates. The network datum is considered observed over several epochs with parameters estimated from previous epochs being introduced into later epochs as stochastic prior information parameters.
K, PROFGACHENECHARLESK.  2006.  Nyambati EM, Mureithi JG, Gachene CKK and Gitari JN. 2006. Managing green manure legumes for improved maize production in Kenyan highlands. In Jg Muriethi, CKK Gachene, JW Wamuongo and M Eilitta (eds) Enhancing agricultural productivity in East Africa: De. Biological Agricultural & Horticultural Journal, Vol 19(1), 49-62.. : F.N. kamau, G. N Thothi and I.O Kibwage Abstract
A model for the establishment of a four-dimensional regional geodetic reference datum is presented. Starting from the three-dimensional integrated geodetic network model, formulations for the establishment of a four-dimensional regional datum are developed. Astronomic latitudes, astronomic longitudes, gravity values, gravity potential differences, gravity differences, and GPS-vectors are considered as observables. The estimated parameters defining the datura are point coordinates, deflections of the vertical and geoidai undulations, and velocities and accelerations on the positional coordinates. The network datum is considered observed over several epochs with parameters estimated from previous epochs being introduced into later epochs as stochastic prior information parameters.

2005

Mugendi, D;, Kironchi G;, Gicheru PT;, Gachene CKK;, Macharia PN;, Mburu M;, Mureithi J;, Maina F.  2005.  Modelling soil organic matter dynamics in the Kabete long-term experiment in Kenya. Abstract

In order to meet the challenges of increasing food production, many agricultural production technologies are being developed and recommended for use by the small- scale fanners who are also the main agricultural producers in sub-Saharan Africa. Whereas some ofthe technologies seem promising in the short-term, their long-term effects on soil productive properties are largely unknown. Soil organic carbon which is closely related to soil productivity has been used to measure the impact caused by the application of external inputs to soils since it is known to respond to such changes. However changes in soil organic carbon caused by the applied inputs are slow, often taking several decades to emerge. Therefore simulation models have been used to predict the likely long¬tenn changes in soil organic carbon, hence soil productivity, as a result to continuous application of external inputs to soils. The work reported here evaluates the applicability of ROTH C-26.3, the current version of the Rothamsted carbon model, to simulate the turnover of soil organic matter in soil under tropical conditions using soil organic carbon concentrations from the Kabete long-term trial measured 22 yrs after the start of the experiments. Measured and Long-term field experiments offer the best modeIled soil organic carbon were closely practical means of monitoring and correlated showing the applicability of the understanding the changes caused by model to simulate soil organic matter different agricultural systems, since these turnover in the tropical soil. The results show changes are slow, often taking many years that even the continuous application of to appear (Powlson et al., 1987; Poulton, inorganic fertilizer alone failed to stop the 1996). The Kabete long-term experiment in decline in soil C. When crop residues were Kenya has now run for long enough to yield returned, decline was slowed. However the useful information on the effects of inorganic only treatments able to stop the decline involved large additions of animal manure. The model predicts a lengthy and difficult amelioration process for degraded soils that have received no organic inputs particularly in the smallholder farms where only small amounts of organic resources are available to restore soil organic matter back to agronomically viable levels. Howeverthe use of Farmyard manure alone or in combination with inorganic fertilizer wi111ead to higher equilibrium C concentrations than the initial amount of soil organic C at the start of the trials.

Kironchi, G;, Gicheru PT;, Gachene CKK;, Macharia PN;, Mburu M;, Mureithi JG;, Maina F.  2005.  Effect of liming and triple superphosphate fertilizer application on growth and root nodulation of common bean (phaseolus vulgaris) in soils of old tea lands. Abstract

Effect of liming and application of phosphatic fertilizer on growth and root nodulation of common bean in an old tea land was investigated. A field trial was conducted where tea had been uprooted after 70 years of monoculture under high inorganic fertilizer input. Lime was applied at 0, 4, 8 and 12 tonnes ha-1 and triple superphosphate at 0, 5, 10 and 15 g per planting hole. The treatments were combined in a factorial design and investigated for effects on the soil pH, nodule formation, and some plant growth parameters. Lime application raised the soil pH and also significantly (P= 0.05) increased dry matter production and nodule quantity. Phosphorus also increased dry matter production and nodule quantity significantly (P = 0.05). These observations are discussed in regard to ways of enabling bean crop grow on old tea lands.

Gicheru, PT, Gachene CKK.  2005.  Effects of soil management practices and tillage systems on soil moisture conservation and maize yield on a sandy loam in semiarid Kenya. Abstract

Maize is an important crop in the high and medium rainfall areas of Kenya and thus, there is a need for additional information on the effect of tillage and soil management practices on water conservation and yield of maize. The objective of this study was to determine the effects of seven soil management practices: bare with conventional tillage (BC), bare with minimum tillage (BM), incorporated mulch with conventional tillage (IMuC), manure with conventional tillage (MaC), manure with minimum tillage (MaM), surface mulch with conventional tillage (SMuC), and surface mulch with minimum tillage (SMuM) on water conservation and yield of maize. Soil water content was greater in minimum tilled plots than in the conventionally tilled (hand hoeing) plots during the study period. This was demonstrated by the manure with minimum tilled treatment, which had the highest soil moisture (7.6% and 8.3%) both at 0-7 cm and 7-23 cm depth. However, when organic matter additions were analyzed separately, it was observed that manure irrespective of tillage had the highest soil moisture in both depths (7.6% and 8.1%). The differences within the treatments occurred when soil water contents were highest shortly after the rains. When the amount of soil water for each management practice was averaged for all the seasons, a significant difference was found at P = 0.0001. Manure (Ma) and surface mulched (Smu) treatments had significantly higher soil moisture content than the other treatments. The higher moisture content found under these treatments was attributed to higher infiltration rates, better cover that reduced the rainfall kinetic energy, and to better structural stability contributed to by higher organic carbon. Compared with the traditional form of hand hoeing, minimum tillage increased available soil water content drastically and crop performance was improved. Grain yields were greatest in manure and lowest in bare treatments. There were significant differences in grain yield in all treatments.

K, PROFGACHENECHARLESK.  2005.  Hydroeconomic evaluation of rainwater harvesting and management technologies: Farmers. Biological Agricultural & Horticultural Journal, Vol 19(1), 49-62.. : F.N. kamau, G. N Thothi and I.O Kibwage Abstract
A model for the establishment of a four-dimensional regional geodetic reference datum is presented. Starting from the three-dimensional integrated geodetic network model, formulations for the establishment of a four-dimensional regional datum are developed. Astronomic latitudes, astronomic longitudes, gravity values, gravity potential differences, gravity differences, and GPS-vectors are considered as observables. The estimated parameters defining the datura are point coordinates, deflections of the vertical and geoidai undulations, and velocities and accelerations on the positional coordinates. The network datum is considered observed over several epochs with parameters estimated from previous epochs being introduced into later epochs as stochastic prior information parameters.
K, PROFGACHENECHARLESK.  2005.  Participatory evaluation of residue management effects of green manure legumes on maize yield in the central Kenya highlands. Journal of Sustainable Agriculture, Vol. 25(4), 49-68. Biological Agricultural & Horticultural Journal, Vol 19(1), 49-62.. : F.N. kamau, G. N Thothi and I.O Kibwage Abstract
A model for the establishment of a four-dimensional regional geodetic reference datum is presented. Starting from the three-dimensional integrated geodetic network model, formulations for the establishment of a four-dimensional regional datum are developed. Astronomic latitudes, astronomic longitudes, gravity values, gravity potential differences, gravity differences, and GPS-vectors are considered as observables. The estimated parameters defining the datura are point coordinates, deflections of the vertical and geoidai undulations, and velocities and accelerations on the positional coordinates. The network datum is considered observed over several epochs with parameters estimated from previous epochs being introduced into later epochs as stochastic prior information parameters.

2004

Gachene, C K K; Mureithi, JG.  2004.  Lost and reclaimed: A case study of gully rehabilitation in central Kenya highlands using low-cost measures. Abstract

Gully control and reclamation activities using low-cost measures were carried out in early March 2001 at Gatanga division, Kenya. The study area was selected on the basis of previous work carried out in farmers fields by the Legume Research Network Project (LRNP). The project’s main objective is to introduce green manure legume species that perform well in different agro ecological zones of Kenya mainly for the purpose of soil fertility improvement and erosion control in smallhold farms. Area studied is characterized by a mean annual rainfall of about 1100 mm with a bimodal distribution, deep red soils, steep slopes and intensive landuse. Field activities were carried out in one of the farms which had literally been abandoned due to gully erosion. The length of the gully was 130 m with an average width and depth of 1.62 and 1.4 m, respectively. Work involved planting of grasses (mainly Brachira humidocola) and mucuna (Mucuna pruriens) on the floor and sides of the gully. In addition ‘macro-contour lines’ were constructed in the farm which involved planting lines of mucuna, sesbania (Sesbania sesban) and napier grass (Pennisetum purpureum) along the terrace embankments. Through photographs taken over a 3 year period, evidence is given to show that the gully has completely healed and that the farm has been brought back to productivity.

Mureithi, J G; Gachene, WCKK; J.  2004.  Legume research network project: a sythensis report of phase 1 (1994-2000). Abstract

The Legume Research Network Project (LRNP) was started in 1994 (by then known as the Legume Screening Network) to evaluate suitable legume species for different agro-ecological environments and to subsequently incorporate the “best bets” into the existing farming systems. Initial Network activities included the screening of about 40 legume species, among them, green manuring species, food legumes and forage species. The screening trials were conducted in 11 sites across the country especially where soil infertility had been identified as a major constraint to crop production. The Network extended its activities to include research on legume residue management, integrated nutrient management, livestock feeding and cowpea screening trials. Each site had the task of bulking seeds of promising legume species. The Network members are from KARI, University of Nairobi (UoN), Environmental Action Team (EAT, an NGO based in Kitale) and Community Mobilisation Against Desertification (C-MAD, an NGO based in Rongo near Kisii). The main collaborators are the Ministry of Agriculture, and Rural Development staff, and the farmers from different regions of Kenya. The following are the major highlights of phase 1 activities: ♦ Promising green manure (GM) legume species: The most outstanding green manure legume species across Network sites based mainly on biomass accumulation are Mucuna pruriens, Lablab purpureus, Crotalaria ochroleuca, and Canavalia ensiformis. ♦ Inoculation of best-bet legume species: The rhizobia inoculation study concluded that inoculation of best-bet legumes in the study sites was not necessary but further systematic studies to characterise the native rhizobia and to determine their levels in the soil should be undertaken. ♦ Response of legume species to phosphorus: Three Network sites participated in this trial, namely Kakamega, Kisii and Gatanga. In Kakamega and Kisii, legumes did not respond to application of P. In Gatanga they responded to application of P at the rate of 20 kg ha-1 but did not respond substantially to application beyond this rate. ♦ Potential benefits of GM legume technologies for improved maize yields: Incorporating mucuna biomass (4 - 11 t DM ha-1) into the soil for maize production increased maize yields by 120%. The additional labor required for digging mucuna into the soil was compensated by increased maize yields. Returns to labour were higher in mucuna (US$ 11.50) than in maize only plots (US$ 8.00). Besides, farmers in Gatanga and Kisii Network sites reported that additional labour required for incorporation of legume biomass was minimal because incorporation and land preparation for the companion crop were done simultaneously. ♦ Potential for soil moisture conservation: In a semi-arid site Machakos,mucuna on the surface as mulch gave better yields than incorporating it in the soil probably because of the moisture conservation effect. A farmer in Embu reported that soil moisture was retained for a longer time in plots where mucuna was grown than in plots without mucuna. ♦ Potential for soil improvement: Integrated Nutrient Management (INM) at three sites, Kakamega, Embu and Mtwapa, mucuna and crotalaria were evaluated in field studies that involved the combinations of green manure, FYM and inorganic fertilisers. Higher maize yields were obtained by combining green manure legume with FYM and inorganic N. ♦ Potential for feeding livestock: Livestock feeding studies at, Mtwapa and Katumani showed that performance of cattle and goats improved when fed on legume forage. In Mtwapa, dairy cows fed on mucuna and lablab forage had a daily DM intake of about 9.2 kg cow-1, which was similar to cows fed on Gliricidia sepium forage, a proven fodder tree for the coastal Kenya. Milk yield (6.5 kg day-1) was only 8% less than that produced by cows fed on gliricidia forage. In Katumani, goats supplemented with Neonotonia wightii gained on average 16.37 g while those on basal diet alone lost 23.81g daily.

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