Browsing by Author "Kiboi, Milka N."
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Item Farming systems’ typologies analysis to inform agricultural greenhouse gas emissions potential from smallholder rain-fed farms in Kenya(Elsevier B.V, 2020) Musafiri, Collins M.; Macharia, , Joseph M.; Ng’etich, Onesmus K.; Kiboi, Milka N.; Okeyo, Jeremiah; Shisanya, Chris A.; Okwuosa, , Elizabeth A.; Mugendi, Daniel N.; Ngetich, Felix K.Most sub-Saharan Africa smallholder farming systems are highly heterogeneous. Direct quantification of greenhouse gas emissions from these farming systems is hampered by di- versity at farm-level. Each farm contributes differently to greenhouse gas (GHG) emissions and consequently GHG inventories. Typologies can be used as a mechanism of addressing farming systems’ heterogeneity by grouping them into specific farm types. With the GHG quantification simplification initiatives in mind, we developed smallholder farm typologies based on soil fertility inputs. We assessed nitrogen application rate, soil fertility manage- ment technologies and the socio-economic factors diversity among the farm typologies in the central highlands of Kenya. We used data from a cross-sectional household survey with a sample size of 300 smallholder farmers. We characterized the farm types using princi- pal component analysis (PCA). To develop farm typologies, we subjected the PCA-derived typologies related factors to cluster analysis (CA). The results showed six farm types: Type 1, comprising cash crop and hybrid cattle farmers; Type 2, comprising food crop farmers; Type 3, composed of coffee-maize farmers; Type 4, comprising millet-livestock farmers; Type 5, comprising highly diversified farmers, and Type 6, comprising tobacco farmers. Land size owned, total tropical livestock unit, the proportion of land and nitrogen applied to different cropping systems were significant in the construction of farm typologies. Uni- variate analysis showed the household head’s level of education, hired labour, group mem- bership, access to extension services, and proportion of income from cropping activities as critical factors influencing farm typologies in the study area. This study demonstrates the importance of smallholder farm typologies in identifying greenhouse gas emissions hotspots, designing quantification experiment and policy framing. We concluded that poli- cies and intervention measures targeting climate-smart agriculture at smallholder farmsItem Microbial biomass and acid phosphomonoesterase activity in soils of the Central Highlands of Kenya(Elsevier, 2018-12) Kiboi, Milka N.; Ngetich, F.K.; Mugendi, Daniel N.; Muriuki, A.; Adamtey, N.; Fliessbach, A.Soil biological properties are the most sensitive soil quality indicators that respond quickly to short-term soil fertility management changes. We studied the combined effects of tillage and soil external inputs on total soil organic carbon and nitrogen, microbial biomass carbon (MBC) and nitrogen (MBN) and acidphosphomonoesterase activity (ACP). This was done in Meru South and Kandara sub-counties in Kenya for three consecutive cropping seasons. Tillage was the main factor [minimum (D0) and conventional (D15)], and soil external inputs were the sub-factors: sole mineral fertiliser (F), crop residues + mineral fertiliser (RF), crop residues + animal manure + legume intercrop Dolichos lablab L. (RML), crop residues + mineral fertiliser + animal manure (RFM), crop residues + Tithonia diversifolia + animal manure (RTiM), crop residues + Tithonia diversifolia + rockphosphate (RTiP) and an unfertilized treatment (Control). During the study period, we experienced frequent dry spells and meteorological droughts in the two sites. We found no significant effects of the tillage systems and mineral fertilisers applied alone or combined with crop residues on the biological properties. All additional organic inputs to the soils enhanced the biological soil properties. On average, MBC in the treatments with organic inputs only was enhanced by 51% in Meru South and 19% in Kandara. MBC-to-TOC ratio was significantly different (p = .0003) under soil external inputs in Meru South. On average, MBN in the treatments with organic inputs was enhanced by 66% in Meru South and 25% in Kandara. Compared with the control, ACP was higher under RML, RTiP and RTiM by 26%, 20% and 17%, respectively in Meru South. In Kandara, ACP was higher under RTiM and RTiP by 25% and 23%, respectively, compared with the control. The increase in microbial biomass indicates that application of organic inputs contributed to soil organic C, thereby stimulating the microbial growth and enzyme activity. Thus, use of organic inputs or in combination with mineral fertilisers are feasible alternatives for sustaining soil organic carbon through increased microbial biomass leading to soil organic matter build-up, which is a vital element of soil quality and fertilityItem Phosphorus availability and exchangeable aluminum response to phosphate rock and organic inputs in the Central Highlands of Kenya(Heliyon, 2021) Omenda, Jane A.; Ngetich, Kipchirchir F.; Kiboi, Milka N.; Muna, Mucheru; Mugendi, Daniel N.Soil acidity and phosphorus deficiency are some of the constraints hampering agricultural production in tropical regions. The prevalence of soil acidity is associated with phosphorus (P) insufficiency and aluminum saturation. We conducted a two-seasons experiment to evaluate soil phosphorus availability and exchangeable aluminum in response to phosphate rock and organic inputs in acidic humic nitisols. The field experiment was installed in Tharaka Nithi County in the Central Highlands of Kenya. The experimental design was a randomized complete block design with treatments replicated thrice. The treatments were: Green manure (Tithonia diversifolia Hemsl.) (60 kg P ha 1), phosphate rock (60 kg P ha 1), goat manure (60 kg P ha 1), Tithonia diversifolia (20 kg P ha 1) combined with phosphate rock (40 kg P ha 1), manure (20 kg P ha 1) combined with phosphate rock (40 kg P ha 1), Triple Super Phosphate combined with Calcium Ammonium Nitrate (TSP þ CAN) (60 kg P ha 1) and a control (no input). During the long rains of the 2018 season (LR2018), Tithonia diversifolia þ phosphate rock had a significantly higher reduction (67%) of exchangeable aluminum than the sole use of Tithonia diversifolia. Grain yield under TSP þ CAN was the highest, followed by the sole organics during the LR2018. Tithonia diversifolia þ phosphate rock resulted in a 99% and a 90% increase in NaHCO3-Pi compared to sole phosphate rock and sole Tithonia diversifolia, respectively. Tithonia diversifolia led to 14% and 62% higher resin-Pi and NaOH-Pi, respectively, compared to manure in the short rains of 2017 (SR2017). The increase in NaOH-Po after the two seasons was statistically significant in sole TSP þ CAN. Based on the observed reduced exchangeable aluminum and additional nutrients like Ca, Mg, and K in the soil, sole organic inputs or in combination with phosphate rock treatments are feasible alternatives for sustaining soil phosphorus. Our findings underscore an integrated approach utilizing organic amendments combined with phosphate rock in acidic humic nitisols' phosphorus nutrient management.Item Phosphorus availability and exchangeable aluminum response to phosphate rock and organic inputs in the Central Highlands of Kenya(Heliyon, 2021-03) Omenda, Jane A.; Ngetich, F. K.; Kiboi, Milka N.; Mucheru-Muna, M.; Mugendi, Daniel N.Soil acidity and phosphorus deficiency are some of the constraints hampering agricultural production in tropical regions. The prevalence of soil acidity is associated with phosphorus (P) insufficiency and aluminum saturation. We conducted a two-seasons experiment to evaluate soil phosphorus availability and exchangeable aluminum in response to phosphate rock and organic inputs in acidic humic nitisols. The field experiment was installed in Tharaka Nithi County in the Central Highlands of Kenya. The experimental design was a randomized complete block design with treatments replicated thrice. The treatments were: Green manure (Tithonia diversifolia Hemsl.) (60 kg P ha 1 ), phosphate rock (60 kg P ha 1 ), goat manure (60 kg P ha 1 ), Tithonia diversifolia (20 kg P ha 1 ) combined with phosphate rock (40 kg P ha 1 ), manure (20 kg P ha 1 ) combined with phosphate rock (40 kg P ha 1 ), Triple Super Phosphate combined with Calcium Ammonium Nitrate (TSP þ CAN) (60 kg P ha 1 ) and a control (no input). During the long rains of the 2018 season (LR2018), Tithonia diversifolia þ phosphate rock had a significantly higher reduction (67%) of exchangeable aluminum than the sole use of Tithonia diversifolia. Grain yield under TSP þ CAN was the highest, followed by the sole organics during the LR2018. Tithonia diversifolia þ phosphate rock resulted in a 99% and a 90% increase in NaHCO3-Pi compared to sole phosphate rock and sole Tithonia diversifolia, respectively. Tithonia diversifolia led to 14% and 62% higher resin-Pi and NaOH-Pi, respectively, compared to manure in the short rains of 2017 (SR2017). The increase in NaOH-Po after the two seasons was statistically significant in sole TSP þ CAN. Based on the observed reduced exchangeable aluminum and additional nutrients like Ca, Mg, and K in the soil, sole organic inputs or in combination with phosphate rock treatments are feasible alternatives for sustaining soil phosphorus. Our findings underscore an integrated approach utilizing organic amendments combined with phosphate rock in acidic humic nitisols' phosphorus nutrient management.Item The response of soil physicochemical properties to tillage and soil fertility resources in Central Highlands of Kenya(Pagepress, 2020) Kiboi, Milka N.; Muriuki, Anne; Ngetich, Felix K.; Adamtey, Noah; Mugendi, Daniel N.To attain agricultural sustainability, use of soil resources and tillage requires equal consideration for chemical and physical components of soil fertility. We assessed responses of selected soil physical and chemical properties to tillage and soil fertility amending resources. The study was carried out in Meru South and Kandara sub-counties located in the Central Highlands of Kenya for four cropping seasons. The experimental design was split-plot with tillage as the main factor - conventional (D15) - and minimum (D0) tillage and soil fertility resources (SFR) as sub-factors - mineral fertilizer (F), crop residues + fertilizer (RF), residues + fertilizer + animal manure (RFM), residues + Tithonia diversifolia + manure (RTiM), residues + Tithonia diversifolia + phosphate rock (Minjingu) (RTiP), residues + manure + legume intercrop (RML) and control (no input). Compared with control, aggregate stability was significantly higher on average under SFRs with sole organics by 19% in Meru South. Total N and available P were higher under integration of fertilizer and organics in both sites. Calcium increased under sole organic or integration with fertilizer in Meru South and under sole organics in Kandara. Magnesium significantly increased under all SFRs compared with control in Kandara. Soil organic carbon significantly (P=0.02) increased under D0 by 6% compared to D15 in 0-5 cm depth in Kandara. Application of RTiM had the highest SOC in all depths’ at Meru South. SOC significantly increased under RTiP and RML by 11% in 0-5 cm depth and under RML by 13% in 5-10 cm depth at Kandara. Mineral-N (NO3 –-N and NH4 +-N) was higher under D0 at planting compared with D15 in Meru South. In Kandara, NO3 –-N and NH4 +-N were significantly higher by 17% and 30%, respectively under D0 compared with D15 at planting during SR16 season. Higher mineral N was recorded under F application on the 30th and 45th days in both sites. The highest mineral-N content was on the 45th day after planting during SR16 season and on the 30th day during LR17 season at Meru South. In Kandara, NO3 –-N and NH4 +-N were highest on the 45th day and 30th day, respectively, during SR16 season. During LR17 season, mineral-N was highest on the 30th day in Kandara. The study highlights that minimal soil disturbance and organic inputs use or integration with fertilizers are feasible alternatives for improving soil fertility in the Nitisols of Central Highlands of Kenya.Item Soil fertility inputs and tillage influence on maize crop performance and soil water content in the Central Highlands of Kenya(Elsevier, 2019-05) Kiboi, Milka N.; Ngetich, F.K.; Fliessbach, A.; Muriuki, A.; Mugendi, Daniel N.Rigorous land ploughing and cropping fertiliser treatment and mineral fertiliser combined with animal manure treatment) consistently enhanced maize crop growth and development as observed through enhanced chlorophyll content, plant height and yields. Application of soil fertility inputs significantly improved grain and stover yields except in the crop residue combined with animal manure and legume intercrop treatment (perhaps due to nutrients’ competition since Lablab has an intensive rooting system). Sole organic inputs enhanced soil moisture content in both sites. Emerging from the study, however, is the lack of advantage of minimum tillage over the conventional tillage, within the period under consideration. Thus, this study highlights the possibility of improving soil water holding capacity through application of organic inputs such as crop residues, Tithonia diversifolia and manure, either singly or in combination. It further underpins the uniqueness of an integrated approach to soil fertility and low soil moisture content in the tropical sub-humid regions experiencing erratic rainfallivity in the Central Highlands of Kenya due to low and declining soil fertility, inappropriate tillage methods, soil water scarcity and prolonged dry-spells. In this study, we assessed the effects of two tillage systems and soil fertility inputs on maize crop performance and soil water content. The research was carried out in Chuka and Kandara sites in the Central Highlands of Kenya for four seasons; long rains 2016, short rains 2016, long rains 2017 and short rains 2017. The experimental design was a split plot with tillage method (minimum and conventional) as the main treatments and soil fertility inputs as the sub-treatments: Sole mineral fertiliser, mineral fertiliser combined with crop residue, mineral fertiliser combined with animal manure, Tithonia diversifolia combined with phosphate rock (Minjingu), animal manure intercropped with Dolichos Lablab L. and a Control (conventional tillage with no inputs). Except for the control, and sole mineral fertiliser, crop residue was applied as mulch in all treatments. Based on the results, the treatments with mineral fertiliser (sole mineral fertiliser combined with mineral fertiliser treatment and mineral fertiliser combined with animal manure treatment) consistently enhanced maize crop growth and development as observed through enhanced chlorophyll content, plant height and yields. Application of soil fertility inputs significantly improved grain and stover yields except in the crop residue combined with animal manure and legume intercrop treatment (perhaps due to nutrients’ competition since Lablab has an intensive rooting system). Sole organic inputs enhanced soil moisture content in both sites. Emerging from the study, however, is the lack of advantage of minimum tillage over the conventional tillage, within the period under consideration. Thus, this study highlights the possibility of improving soil water holding capacity through application of organic inputs such as crop residues, Tithonia diversifolia and manure, either singly or in combination. It further underpins the uniqueness of an integrated approach to soil fertility and low soil moisture content in the tropical sub-humid regions experiencing erratic rainfall.Item Soil nutrients and crop yield response to conservation-effective management practices in the sub-humid highlands agro-ecologies of Kenya(Heliyon, 2021) Kiboi, Milka N.; Ngetich, Felix k.; Muna, Mucheru; Diels, J. Diels; Mugendi, Daniel N.Crop productivity in most smallholder farming systems in Sub-Saharan Africa experience low use of soil amendment resources, low and erratic rainfall, frequent dry spells, and droughts. Rain-fed agriculture has a high crop yield potential if rainfall and soil nutrient input resources are utilized effectively. Thus, in 2011, we set up an on-farm experiment in Meru South (sub-humid) and Mbeere South (marginal sub-humid) sub-counties in upper Eastern Kenya to assess conservation-effective management (CEM) practices effects on maize (Zea Mays L.) yields response and soil nutrients. The CEM practices were; tied ridging (TR), mulching (MC), and minimum tillage (MT), with conventional tillage (CT) as a control. There were frequent dry spells and droughts during the experimental period. The experiment ran for four seasons, from the long rains season of 2011 (LR11), short rains seasons of 2011 (SR11), long rains season of 2012 (LR12), short rains 2012 (SR12), and long rains season of 2013 (LR13). In Meru South, TR and MT treatments had significantly higher phosphorus content (100% and 66%, respectively) than the control. Also, in the same site, Cu and Zn were high in MT than in CT treatments. In the Mbeere South site, the aboveground biomass yield was significantly higher in TR treatment (by 71%) than CT during SR11, while in LR12 season, it significantly increased by 72% and 46% under MC and TR treatments, respectively, than the control. The TR treatment had significantly higher aboveground biomass than the control (84% and 115%) in the SR12 and LR13 seasons. In Meru South, MC treatment had significantly higher aboveground biomass, which was significantly higher, by 39%, during the SR11 season and 46% in TR treatment in SR12 season than the control. This study highlighted tied ridging as the best-fit practice for enhancing maize crop aboveground biomass production in rain-fed farming systems of marginal lands and sub-humid regions receiving unreliable rainfall. Further, we recommend longer-term experimentation to explore CEM effects on soil nutrients.Item Suitability of different data sources in rainfall pattern characterization in the tropical central highlands of Kenya(Heliyon, 2020-11) Oduor, Nathan O.; Ng'etich, Felix K.; Kiboi, Milka N.; Muriuki, Anne; Adamtey, Noah; Mugendi, Daniel N.Uncertainty in rainfall pattern has put rain-fed agriculture in jeopardy, even for the regions considered high rainfall potential like the Central Highlands of Kenya (CHK). The rainfall pattern in the CHK is spatially and temporally variable in terms of onset and cessation dates, frequency and occurrence of dry spells, and seasonal distribution. Appraisal of the variability is further confounded by the lack of sufficient observational data that can enable accurate characterisation of the rainfall pattern in the region. We, therefore, explored the utilisation of satellite daily rainfall estimates from the National Aeronautics and Space Administration (NASA) for rainfall pattern characterisation in the CHK. Observed daily rainfall data sourced from Kenya meteorological department were used as a reference point. The observation period was from 1997 to 2015. Rainfall in the CHK was highly variable, fairly distributed and with low intensity in all the seasons. Onset dates ranged between mid-February to mid-March and mid-August to mid-October for long rains (LR) and short rains (SR) seasons, respectively. Cessation dates ranged from late May to mid-June and mid-December to late December for the LR and SR, respectively. There was a high probability (93%) of dry spell occurrence. More research needs to be done on efficient use of the available soil moisture and on drought tolerant crop varieties to reduce the impact of drought on crop productivity. Comparison between satellite and observed rain gauge data showed close agreement at monthly scale than at daily scale, with general agreement between the two datasets. Hence, we concluded that, given the availability, accessibility, frequency of estimation and spatial resolution, satellite estimates can complement observed rain gauge data. Stakeholders in the fields of agriculture, natural resource management, environment among others, can utilise the findings of this study in planning to reduce rainfall-related risks and enhance food security.