Browsing by Author "Ngetich, Felix K."

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    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 farms
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    Planting Pits’ Effects on Soil Nutrients in a Sorghum and Pigeon Pea Rotation in Semi-arid Areas of Eastern Kenya
    (Science Domain International, 2016-12) Yegon, Rebecca; Mtakwa, Peter W.; Mrema, Geoffrey C.; Ngetich, Felix K.
    Planting pits are rain water harvesting structures that trap water and nutrients in surface runoff and rain water falling directly into the pits. Planting pits have been promoted for improving crop yields without considering the nutrient dynamics. To contribute to this knowledge, a study was conducted to determine the soil nutrient content after four seasons of growing sorghum and pigeon pea in rotation in “Chololo” and “Five by Nine” pits. Two planting pits; “Five by Nine” and “Chololo” with a control without water harvesting replicated three times were arranged in a randomised complete block design. The study was done for four seasons in Embu and Tharaka-Nithi counties in semiarid Eastern Kenya. Soil pH, total organic carbon, total nitrogen, available phosphorus, exchangeable potassium, calcium, magnesium and sodium were determined. “Chololo” pits significantly increased total organic carbon by 0.06 mg kg-1 and total nitrogen by 0.4 mg kg-1 relative to without water harvesting in Machang’a. The potassium content significantly increased by 0.4 cmolc kg-1 and 0.54 cmolc kg-1 in “Five by Nine” and “Chololo” pits in Machang’a relative to without water harvesting. There was an insignificant effect on soil phosphorus, calcium, magnesium and sodium. After four seasons of planting pits, total nitrogen, potassium and calcium increased in both soils and phosphorus in Machang’a relative to the beginning of the study. Total organic carbon significantly decreased in “Chololo” pits and without water harvesting in Machang’a. Phosphorus significantly decreased in Nkarini whereas magnesium and pH decreased in both soils. Nutrients in “Five by Nine” and “Chololo” pits depended on the soils and crops grown and should thus be promoted together with periodic soil testing.
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    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.
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    Soil Greenhouse Gas Fluxes From Maize Production Under Different Soil Fertility Management Practices in East Africa
    (2020-06) Macharia, Joseph M.; Pelster, David E.; Ngetich, Felix K.; Shisanya, Chris A.; Mucheru-Muna, Monicah; Mugendi, Daniel N.
    In sub-Saharan Africa (SSA), few studies have quantified greenhouse gas (GHG) emissions following application of soil amendments, for development of accurate national GHG inventories. Therefore, this study quantified soil GHG emissions using static chambers for two maize cropping seasons (one full year) of four different soil amendments in the central highlands of Kenya. The four treatments were (i) animal manure, (ii) inorganic fertilizer, (iii) combined animal manure and inorganic fertilizer, and (iv) a no-N control (no amendment) laid out in a randomized complete block design. Cumulative annual soil fluxes (February 2017 to February 2018) ranged from −1.03 ± 0.19 kg CH4-C ha−1 yr−1 from the manure inorganic fertilizer treatment to −0.09 ± 0.03 kg CH4-C ha−1 yr−1 from the manure treatment, 1,391 ± 74 kg CO2-C ha−1 yr−1 from the control treatment to 3,574 ± 113 kg CO2-C ha−1 yr−1 from the manure treatment, and 0.13 ± 0.08 to 1.22 ± 0.12 kg N2O-N ha−1 yr−1 in the control and manure treatments, respectively. Animal manure amendment produced the highest cumulative CO2 emissions (P < 0.001), N2O emissions (P < 0.001), and maize yields (P = 0.002) but the lowest N2O yield-scaled emission (YSE) (0.5 g N2O–N kg−1 grain yield). Manure combined with inorganic fertilizer had the highest cumulative CH4 uptake (P < 0.001) and N2O YSE (2.2 g N2O–N kg−1 grain yield). Our results indicate that while the use of animal manure may increase total GHG emissions, the concurrent increase in maize yields results in reduced yield-scaled GHG emissions.