Theses & Desertations

POTATO (Solanum tuberosum L.) TUBER YIELD AND QUALITY AS INFLUENCED BY POTASSIUM FERTILIZER IN UASIN GISHU COUNTY, KENYA

2025-05-22T08:33:30Z

POTATO (Solanum tuberosum L.) TUBER YIELD AND QUALITY AS INFLUENCED BY POTASSIUM FERTILIZER IN UASIN GISHU COUNTY, KENYA OKETCH, ANTHONY OTIENO Irish potato is the second most important food crop after maize in Kenya. However, the national average tuber yield is 9.8 tonnes ha-1 which is low compared to optimum production of 41 tonnes ha-1 . There is unmet production demand for potato tubers with high processing quality in Kenya, which can meet international standards for products such as chips and crisps. Potassium (K) is one of the macronutrients taken up in larger amounts by potato and is known to enhance both its yield and quality traits. However, researchers have not reached a consensus on whether K should be applied in Kenyan farms. To determine the effectiveness of potassium fertilizer on tuber yield and quality enhancement as well as profitability due to the fertilizer application, a field experiment was conducted at University of Eldoret farm in Uasin-Gishu County during the short and long rains seasons of 2020 and 2021 respectively. Two sources of potassium, muriate of potash (MOP) and sulphate of potash (SOP) were used at rates of 0, 60, 120, 180 and 240 kg ha-1 of K during the short rains and 0, 30, 60, 90, 120 and 180 kg ha-1 of K during the long rains. Treatments were laid out in a Randomized Complete Block Design replicated three times in a 2x5 factorial during the short rain and 2x6 factorial during the long rain season. Destiny variety of potato was planted. The rate of 120 kg ha-1 of K as sulphate of potash increased marketable tuber yield by 51% relative to the control in the short rains. In the long rains, 30kg ha-1 of K as muriate of potash gave tuber yield of 40.54 tonnes ha1 and profit of 111.86%. SOP significantly enhanced tuber dry matter compared to MOP by 5.6% in both seasons. Further, 180 kg ha-1 of K in form of SOP gave the highest tuber concentration of vitamin C (19.56 mg g -1 ) but similar MOP rate reduced vitamin C content by 5.89 mg g-1 compared to control during long rains. In the short rains, 120kg K/ha gave the highest tuber starch content while similar rate of SOP recorded 4.77% lower tuber starch content. The highest rate of MOP (240kg K/ha) significantly lowered the tuber starch content compared to control. It was concluded that in areas with similar ecological conditions as the study area, tuber dry matter content can be increased by application of sulphate of potash and potato farmers can optimize on their profits and tuber content of vitamin C by application of 30kg/ha of K as MOP and 180kg/ha K as SOP respectively during the long rain season. It is recommended that a similar study be done in different soils where potato is grown and with different varieties.

ENHANCING SOIL NITROGEN THROUGH CROP ARRANGEMENTS AND FERTILIZER: A COMPARATIVE ANALYSIS OF MBILI INTERCROPPING AND CONVENTIONAL METHODS FOR SUSTAINABLE MAIZE- SOY BEAN FARMING IN WESTERN KENYA

2025-04-15T05:44:44Z

ENHANCING SOIL NITROGEN THROUGH CROP ARRANGEMENTS AND FERTILIZER: A COMPARATIVE ANALYSIS OF MBILI INTERCROPPING AND CONVENTIONAL METHODS FOR SUSTAINABLE MAIZE- SOY BEAN FARMING IN WESTERN KENYA OROKO, PERIS NYABOKE Low fertility in highly weathered and degraded soils largely accounts for low and unsustainable crop yields in most African countries. Nitrogen (N) is the most deficient among other nutrients because other than being required in large quantities, is and very susceptible to leaching losses. The study assesses soil N replenishment technologies' impact on adoption rates, yields, and economic benefits of maize-soy bean cropping systems in western Kenya. A baseline survey was conducted on adoption levels of the existing soil N replenishment technologies in three farmer associations (FAs) in June 2011. Management of Beneficial Interaction of Legume Intercrops (MBILI), Mono, and conventional cropping systems’ effects was evaluated on soil N content. In conventional cropping system, Maize (IR) was planted at 75 cm row spacing and 30 cm in-row spacing with soy bean seed planted between the maize at 10 cm spacing. Imazapyr Resistant (IR) maize and soy bean were used as the test crops. The experiment was a split-plot design with two factors (cropping systems as the main factor and fertilizer interventions as the sub factor) arranged in a randomized complete block design (RCBD) with three replications. During the short rains of 2011, (Farm yard manure) FYM (0.965% N) was sourced from the University of Eldoret farm. An application of 75 kg N/ha led to 7.8t /ha of manure. In the long rains and short rains in 2012, FYM from the farmers with 0.39%, 0.73%, and 0.85% N in Teso, Vihiga, and Bungoma counties respectively was applied at 75 kg N/ha. The initial soil characterization results showed that soil cation exchange capacity (CEC) was largest in Vihiga (9.88 cmolc/ kg), Bungoma (5.38 cmolc/ kg) but relatively low in Teso (1.78 cmolc/ kg). In 2011, short rains season, soil Nitrate-N levels were significantly the largest in the fourth week after planting (1.95 mg/kg soil). Maize mono, MBILI and soya mono all had significantly larger Nitrate-N than soils in which a conventional cropping system was practiced. However, in 2012 the long rains season, Nitrate-N, was the largest in preseason (2.62 mg/kg) which decreased to 0.56 mg/kg during 4WAP, before rising to 0.74 mg/kg and 1.49 mg/kg during the eighth and twelfth weeks after planting, respectively. Whereas the cropping system had no significant influence on Nitrate-N, the application of FYM 75 kg N/ha produced a significantly (p<0.05) larger soil Nitrate-N level (1.49 mg/kg) compared with Calcium Ammonium Nitrate (CAN) 30 and 75 kg N/ha at all sampling periods and depths. Maize planted with 75 kg N/ha application yielded 2.24 t/ha and 2.25 t/ha maize grain in FYM treatments, which were significantly larger than the 30 kg N/ha (or FYM 30kg N/ha which gave 1.53 t/ha and 1.64 t/ha respectively. Soy bean yields were significantly larger in the monocropping system compared to both MBILI and the conventional intercropping system. The mean Land Equivalent Ratio (LER) values were always > 1.0 for intercropping cropping system. In maize and soy bean, Nitrogen Use Efficiency (NUE) was largest in the mono-cropping system, followed by MBILI, and lastly, in conventional farming. The largest NUE was realized in FYM30N and CAN30N, whereas FYM75N and CAN75N were lower, suggesting increasing the N application reduces its use efficiency. High soil Nitrate-N was positively correlated (r = 0.430) with yields and NUE at 4WAP in 2011. The MBILI cropping system had the largest gross margin (Kshs 46 164/ha). The largest number of soy bean nodules was in FYM regardless of the application rate and lowest in CAN, implying that FYM is more efficacious in nodulation, especially when applied to nutrient-poor soils. From survey result, least used technologies were found to be Ua Kayongo (IR seed), MBILI intercropping, fortified compost, and use of Farm yard manure and liming. This informed the selection of technologies for this study. Findings from this study showed that MBILI cropping system planted at 30 kg N/ha optimizes crop yields, Nitrate-N utilization, nodulation and NUE, and gross margins.

FINGER MILLET (Eleusine coracana) AND SOYBEAN (Glycine max) RESPONSES TO NPK FERTILIZER IN ZINC-AMENDED SOILS OF WESTERN KENYA

2025-04-08T09:58:27Z

FINGER MILLET (Eleusine coracana) AND SOYBEAN (Glycine max) RESPONSES TO NPK FERTILIZER IN ZINC-AMENDED SOILS OF WESTERN KENYA OUMA, OLUOCH VICTOR Low agricultural productivity in SSA is attributed primarily to declining soil fertility. About 65% of the agricultural soils in SSA are degraded as a result of nutrient depletion without adequate replenishment. Under normal circumstances within the region, Nitrogen (N), phosphorus (P) and potassium (K) are the commonly addressed deficiencies through fertilizer application. However; crops are becoming less responsive to that strategy. Zn deficiency has been identified to contribute significantly to that low response of crops to NPK fertilizer leading to low economic returns on fertilizer use. Despite being droughttolerant crops, finger millet (Eleusine coracana) and soybean (Glycine max) yields are consistently lower than 1000 kg ha-1 in western Kenya with or without NPK fertilizer application. Therefore, on-farm trials were conducted in Bungoma and Siaya Counties of western Kenya during two subsequent cropping seasons (long & short rains of 2019). The study evaluated responses of two varieties of finger millet (U15 and SEC915) and soybean (SB19 and SB134) to NPK after addition of Zn. Zn was applied at 0, 1.5, and 3 kg ha-1 and NPK at blanket rates of 100 kg ha-1 N, 30 kg ha-1 P, 50 kg ha-1 K. Soil parameter that include soil nutrient status at 0, 90 and 134 days and plant tissue parameters including leaves and grain nutrients contents were measured at different stages of soybean and millet growth and development. Results indicate that addition of Zn to NPK fertilizer application is a valuable strategy to improve N bioavailability, mobilize P and exchangeable K in soils. However, no significant difference (p > 0.05) was observed between the treatments. Further, the strategy significantly (P < 0.05) increases P and Zn leaf content in finger millet while in soybean significant (P < 0.05) increases in P, K and Zn leaf content were observed. Results also showed that application of Zn alongside NPK fertilizer significantly (p < 0.05) increased the grain Zn content and uptake which translated to larger grain yields. Further, the largest agronomic Zn fertilizer efficiency (AEZn) was realized when Zn was applied at 1.5 kg ha-1 for both crops. For all Zn fertilizer treatments, there were strong and positive relationships between grain yields and Zn uptake. Apparent Zn recovery was low for both crops in the first season which led to an accumulation of this micronutrient in the soil. This later increased the root-shoot translocation of Zn into finger millet and soybean leaves. Generally, the application of Zn alongside NPK fertilizer was profitable for both crops at all sites. The study recommends applying Zn along with NPK fertilizer in Zn-depleted soils to increase finger millet and soybean yields. Further research should be carried out to establish these other limitations that hinder both crops from reaching their potential yield.

TERRACE ADOPTION AND ITS ROLE IN SOIL ORGANIC CARBON DYNAMICS IN AGROPASTORAL WESTPOKOT COUNTY, KENYA

2025-04-08T08:34:30Z

TERRACE ADOPTION AND ITS ROLE IN SOIL ORGANIC CARBON DYNAMICS IN AGROPASTORAL WESTPOKOT COUNTY, KENYA MUTIO, JAMES MUMO Drylands of West Pokot experience severe soil erosion that has affected the community’s livelihood and socio-economic dynamics. The severity of erosion in the region is sustained by vulnerable soils and human activities that trigger scarce vegetation cover and low biodiversity. Among the conservation measures adopted in the area, terraces have the potential to accelerate the restoration process. However, insufficient information on terrace adoption factors and benefits limits scaling. This study identified factors that influence the adoption of Fanya Juu and Fanya Chini terraces and assessed their impact on soil organic carbon dynamics in common land use systems in Chepareria, West Pokot County. The study was conducted in two phases, aiming to (1) establish agropastoral socio-cultural factors that influence residents of dryland Chepareria region to adopt soil conservation measures, with particular interest on Fanya Juu and Fanya Chini, and (2) delve into assessing how adoption of terraces influences ecosystem recovery by using soil organic carbon dynamics as an indicator. Socio-cultural data were collected through self-administered semi-structured questionnaires, focus group discussions, cross-sectional field measurements, and observation of existing terrace characteristics. To examine the influence of terraces on SOC dynamics, soils were sampled in Arenic Lixisols, which dominates lowland parts of Chepareria, where the study was conducted. The experiment evaluated the influence of integrating the two terraces in common land uses in the region, which includes maize-beans intercrop and pastures, on soil organic carbon dynamics. Results indicate that Chepareria residents are aware of the ongoing soil erosion at farm and landscape levels. Community-driven approaches, gender, size of land, and topography are key factors contributing to adopting soil and water conservation practices. Results on the influence of terraces on SOC dynamics established persistent high TOC (13 g C kg-1) in pasturelands with terraces. In comparison, degraded land with no intervention was found to have the lowest TOC (6.0 g C kg-1). Terraced farms with longer residence time (> 4 years old) had significantly higher organic carbon than (<4 years old). Other soil properties remained stable with terrace age (1-5 years). Labile SOC and non-labile SOC differed significantly within and across land use types with or without terraces (p<0.05). Pasture and crop systems with terraces were found to have high labile SOC content of 5.9 g C kg-1 and 7.2 g C kg-1, respectively. Labile SOC increased from 1 year old to 5 years after construction. Combined pasture and terraces had a significantly high carbon management index (CMI) of 161.7, with the least amount found in degraded lands. The weighted enrichment ratio (WER) decreased with the time the terraces had stayed in the system, indicating stabilization of the land use system and evidence of reduced on-farm resource leakages. In conclusion, land degradation is a significant challenge acknowledged by the locals of West Pokot. Terracing restores the ecosystem functions as observed in the improved SOC dynamics of LUTs with Fanya Juu and Fanya Chini. However, terraces should be introduced to highly disturbed systems like croplands, which also have high SOC changes.

INFLUENCE OF FERTILIZER TYPES AND INTERCROPPING ON SOIL CHEMICAL PROPERTIES AND CROP PERFORMANCE IN SELECTED PARTS OF BUSIA COUNTY WESTERN KENYA

2025-04-02T10:12:10Z

INFLUENCE OF FERTILIZER TYPES AND INTERCROPPING ON SOIL CHEMICAL PROPERTIES AND CROP PERFORMANCE IN SELECTED PARTS OF BUSIA COUNTY WESTERN KENYA BARASA, JOSEPHINE NANJALA BARASA In order to address the low soil fertility and low crop yields within Busia county of western Kenya, an integrated soil fertility study was carried out during the 2016 SR and 2017 LR at Busia ATC and Teso farmers field study sites. Information on the underlying soil fertility constraints was based on a desk top review as a basis for field trials involving FYM, Mavuno fertilizer and their mix. A split plot arrangement under RCBD experimental design with fertilizers at the main plot and legume intercrops at sup plot levels in three replications. A recommended (26 kg P ha-1 ) fertilizer rate was adopted for each of the treatments applied except for the control for sorghum and (30 kg P ha-1 ) for the legumes. All treatments applied significantly (p<0.05%) increased all measured soil parameters including soil pH, available P, total N and the micronutrients: Zn and Cu. These contributed to significantly (p<0.05%) high sorghum grain yield above the control by 240%, 288% and 268% under FYM, Mavuno and their mix respectively at Busia site and 11.4 %1.11% and 8.3% for Teso site during the 2016 SR and and 30%, 36% and 29% for Busia and 75%, 73%and 79% for Teso during 2017 LR respectively. Intercropping impacted positively on all soil parameters measured including sorghum crop performance, N and P uptakes by the sorghum crop and sorghum grain contents. Significantly (p<0.05) higher legume intercrops yields were realized from the residual effects of all inputs. Sorghum/groundnut intercrop recorded the highest average gross returns under all ttreatments: FYM, mavuno, or FYM+mavuno combined. This study showed that FYM, mavuno sole, or combined greatly improved the soil fertility of Busia and Teso sites which translates into higher crop yields observed. However, for long-term soil fertilitysustainability FYM and FYM+mavuno combination is recommended. For higher returns from the crop mix, sorghum/groundnuts under all the tested inputs FYM, mavuno, and FYM+mavuno combined are recommended for the farmers’ adoption, given the higher prices offered on the market for the groundnuts.

EFFECT OF SOIL AMENDMENTS ON THE PERFORMANCE OF SELECTED AFRICAN INDIGENOUS VEGETABLES IN UASIN GISHU AND TRANS NZOIA COUNTIES

2021-12-06T07:56:32Z

EFFECT OF SOIL AMENDMENTS ON THE PERFORMANCE OF SELECTED AFRICAN INDIGENOUS VEGETABLES IN UASIN GISHU AND TRANS NZOIA COUNTIES KIBIRU, BENSON African Indigenous Vegetables (AIVs) have high nutritive value, require less inputs and can be a reliable source of income to resource challenged families. However, their production in western Kenya is hampered by limited information on their soil nutrition requirements. To meet these needs two studies (Agronomic trial and soil pH study) were conducted during the rainy season and dry season, which was between July 2013 and March 2014 under drip irrigation. The studies aimed at determining the best fertilizer-variety combination and ideal soil pH level in the two regions for growing AIVs. The experiments were laid out in a Randomized Complete Block Design in a split-split plot arrangement for the agronomic trial and a split-plot for pH study. Both experiments were replicated three times. In the agronomic study, three vegetable types formed the main plot treatments which included Spider plant (Cleome gynandra), African Nightshade (Solanum scabrum) and Amaranthus spp. Varieties formed the sub plot treatments which were Local variety, UG-SF-15 and ML-SF-29 for spider plant; Local variety, UG-AM-40 and Ex-Zim for Amaranthus spp and Local variety, BG-16 and SS-49 for African nightshade. Fertilizer treatments formed the sub-sub plots and include Mavuno fertilizer, poultry manure and the control. In the soil pH study, species (African nightshade, Amaranths & Spiderplant) formed the main plot treatment while the lime rates formed the sub plot treatment. Data were collected on cumulative fresh yield, soil pH trend and characterization, biomass and nutrient concentration, root biomass and root length density and chlorophyll content at flowering. Data were subjected to ANOVA using SAS version 9.3. In the agronomic study, the results exhibited that fertilizer application significantly (p=0.05) increased cumulative fresh yield of all selected varieties of the three AIVs. In African nightshade, developed variety BG-16 with mavuno fertilizer had the highest mean cumulative yields in Eldoret (9,980 kg/ha) and Kitale (13,880 kg/ha). In Amaranths, developed variety UG-AM-40 with poultry manure recorded the highest yields in Eldoret (4,490 kg/ha) and Kitale (6,060 kg/ha). In spiderplant, local variety (LV-SP) and developed variety (UG-SF-15) recorded highest yields with mavuno fertilizer while developed variety ML-SF-29 had highest yields in Eldoret (2600 kg/ha) and Kitale (3830 kg/ha) with poultry manure. In the soil pH study, acid soils responded to liming, whereby all the liming rates were significantly different at P=0.05. A mean pH of 6.33 for liming rate 4.1625 t/ha , 5.78 for liming rate 2 t/ha and 5.18 for the control were achieved. Generally, in all the species, fresh biomass at floweing was highest at lime rate 2 t/ha with a target pH of 5.5. For dry biomass mixed response was exhibited with Amaranth recording highest biomass at lime rate 2 t/ha (2370 kg/ha), spiderplant at zero liming(1350 kg/ha) and African nightshade at lime rate 4.16 t/ha with a target pH 6.5 (1340 kg/ha). In all the vegetable species, %N and % P in the plant tissue increased tremendously in the rainy season though no significant differences (p=0.05) were exhibited. Root biomass increased with increase in lime applied. In all the species zero lime treatment had the lowest dry root biomass. There were significant differences in spider plant and amaranthus (P=0.05) whereby, treatments with zero lime (NL0 and AL0) were significantly different from the other lime rates. However, in spiderplant there were no significant differences (p=0.05) between the lime rates. Overall, the studies concluded that yields of AIVs will greatly increase with utilization of improved germplasm, use of appropriate fertilizer and maintaining ideal soil pH through liming of acid soils.

EFFECTIVENESS OF PROMISING COMMERCIAL BIOFERTILIZERS ON SOYBEAN PRODUCTION IN BUNGOMA COUNTY, WESTERN KENYA.

2021-12-01T12:36:01Z

EFFECTIVENESS OF PROMISING COMMERCIAL BIOFERTILIZERS ON SOYBEAN PRODUCTION IN BUNGOMA COUNTY, WESTERN KENYA. MAJENGO, COLLINS OTIENO The study was conducted to compare the performance of promising commercial bio-fertilizers that have been evaluated under the green-house conditions at TSBF-CIAT, in farmers’ conditions through the use of promiscuous soybean variety (SB19). The trials were laid out on small scale farms in Bungoma County, situated in Western Kenya. The experiment was established in March 2010 during the long rains (LR) and repeated during the short rains (SR) of 2010; laid out in multi-locational one farmer field one replicate design. Treatments were not replicated within each field. During LR 2010, 50 farms were researched on and 100 farms in the second season (SR 2010). A promiscuous medium-maturity soybean variety TGx1740-2E (SB 19) was inoculated with Legumefix (Rhizobia) or/and Rhizatech (mycorrhizae) inoculants. The mycorrhizae inoculum was applied to the soil in the seed furrows at the recommended rate of 30 kg ha-1. Nodulation was examined at mid-podding (50% podding) by carefully uprooting all plants with their entire root system from a 1 m2 section in each plot. Nodules were counted and weighed; the root and shoot parts separated, and fresh and dry weights assessed. Analysis of variance was conducted to determine the effects of (and interactions between) the two inoculants on plant parameters using a mixed linear model (MIXED procedure, SAS). Rhizobial inoculation resulted in significantly (p<0.01) higher nodule biomass (0.93 g plant-1) compared to the control (0.27 g plant-1) across many farms. Mycorrhizal inoculation had no significant effect on nodulation when applied solely (0.38 g plant-1), but co-inoculation of Rhizobia and mycorrhizae increased nodule biomass further by 0.09 g plant-1. There was a significant difference (p<0.01) in terms of biomass yield between treatments. Rhizobial inoculated plants had the highest biomass production of 2086 kg/ha. Rhizobial inoculation resulted in higher grain yields of 1116 kg/ha above the control. Soybean inoculation increased both nitrogen and phosphorus uptake in the biomass. Rhizobial inoculant had the highest soybean N uptake of 48.6 N kg/ha which was significantly different (p<0.05) from control and sole application of mycorrhizae. Statistical analysis showed that soil factors (pH, P, C, N) significantly (p<0.001) affected soybean grain yields during both seasons. It is concluded from this study that rhizobial inoculants have a high potential as commercial bio-fertilizers and can substitute the need for mineral N fertilizer in the legume farming systems. However, there is need to target these inputs to the most responsive fields. Further studies are needed to elucidate the conditions under which synergism between both inoculants may occur, with specific focus towards soil P availability and management of P inputs.

EVALUATION OF NITROGEN FERTILIZER, LIME AND SOIL-WATER EFFECTS ON THE YIELD AND MALTING QUALITIES OF BARLEY (Hordeum vulgare L.)

2021-11-24T09:20:23Z

EVALUATION OF NITROGEN FERTILIZER, LIME AND SOIL-WATER EFFECTS ON THE YIELD AND MALTING QUALITIES OF BARLEY (Hordeum vulgare L.) NADIR, STANLEY WALUCHIO Barley (Hordeum vulgare L.) is a cereal crop that grows over a wide range of environments and in Kenya it is grown primarily for malting. Barley requires adequate nitrogen (N) for good grain yields and quality malting, but the balance between adequate and excessive N is important therefore an experiment was set up between July 2011 and July 2012 to address the problems of N fertilizer use and soil moisture effects on grain yield and malting qualities. The experiment was conducted at medium altitude at University of Eldoret (Chepkoilel) (2185m asl) and at high altitude in Mau-Narok (2740m asl). The objective was to evaluate effects of nitrogen fertilizer rates, liming and varying soil water on the grain yield and malting qualities of barley. The experiments were done in the field and in the greenhouse. For the field experiment, nitrogen as C.A.N fertilizer was applied at 5 levels 0, 30, 40, 50 and 60Kg N/ha, all at planting. Phosphorus inform of TSP at 45 Kg/ha as P205, and potassium in form of muriate of potash at 35 Kg/ha as K20, were applied both as blanket in plots with nitrogen treatments, and as a treatment. Lime was applied at 2 levels (0 & 1.5 t/ha). Split plot arrangement in RCBD design was used in the field. Two different experiments were conducted in the greenhouse; the first one being a simulation of the field experiment which had similar treatments as those in the field. The second greenhouse experiment was a split-split arrangement in CRD design, with 3 soil water contents (field capacity, 80% field capacity and 50% field capacity) applied in 4 nutrient types (nitrogen, phosphorus, lime and control having all combined) tested on the two site soils. The results indicated the soils of the two sites were acidic and deficient in phosphorus. Mau-Narok site had more soil N than University of Eldoret. The effect of Nitrogen on grain yield was highly significant (P 0.001). Increasing N rates beyond 40Kg N/ha increased the grain protein content beyond the malting range. Effect of lime on grain yield in the field was significant at (P 0.01) while (P 0.05) in the greenhouse for both site soils. Lime treatments had higher grain protein contents than non-limed ones but not significantly different. Lime-nitrogen interaction on kernel weight was highly significant (P 0.001) but not significant for grain yield. The differences in grain yield, kernel weight and biomass due to soil type were highly significant (P 0.001).There was a significant relationship (P 0.001) between soil moisture content and lime on barley growth. Limed treatments of both site soils utilized less water to produce mature grains compared to the un-limed ones. The effect of soil moisture levels on biomass and tillering was highly significant (P 0.001). Application of lime in combination with N rates at 30 and 40 N Kg/ha produced best results for grain yield (>7 t/ha for both field and green house), biomass, kernel weight and grain crude protein (10-13.5 %) with soil moisture contents of between field capacity and 80% field capacity being ideal for barley growth on both soils. Nitrogen rates at 30N and 40 N Kg/ha produced highest grain yield, highest kernel weight and ideal maltable grain protein content for both site soils and therefore was recommended as optimum agronomic rates for both sites. In addition, liming was recommended for Chepkoilel while increase in phosphorus use for Mau-Narok.

EFFECT OF HARVESTING METHODS AND NPK FERTILIZER ON SOIL pH, SOIL AND LEAF MAJOR NUTRIENTS CONTENTS AND YIELD OF TEA IN TANZANIA

2021-11-12T06:50:35Z

EFFECT OF HARVESTING METHODS AND NPK FERTILIZER ON SOIL pH, SOIL AND LEAF MAJOR NUTRIENTS CONTENTS AND YIELD OF TEA IN TANZANIA MAKWETA, AMOS JOEL Tea (Camellia sinensis, (L), O. Kuntze crop in Tanzania has been traditionally harvested by hand. In recent years, high cost and shortage of labour have compelled tea growers to opt for mechanical harvesting. Mechanical harvesting is becoming very important and is considered vital for survival of the tea industry. However tea growers have reported decline in yield after some years of mechanical harvesting and there is a notion that nutrients lost through the harvested crop differ from hand harvested tea. Thus there is need to replenish nutrients lost through harvested crop which is different from hand harvested tea, however to replenish soil nutrients in mechanical harvested tea, growers are applying the same fertilizer rates as in hand harvesting method. The objective was to determine the effect of tea harvesting methods (hand and mechanical) and NPK fertilizer on soil pH, major nutrients (NPK) uptake, tea yield components (shoot weight, shoot type composition) and yield. The study had two parts. First a survey was conducted on tea estates (Ngwazi, Itona and Itambo) where both hand and mechanical harvesting had been practiced for more than three years. Soil and leaf samples were collected for soil pH, soil and leaf major nutrients (NPK) analysis. Yield data were used to compare yield trend in hand and mechanical harvesting. In the second part, two experiments were set at the Tea Research Institute of Tanzania stations (Marikitanda and Ngwazi) using randomized complete block design (RCBD) with split-plot arrangement. Experiments were conducted for 10 and 8 months at Marikitanda and Ngwazi respectively. Hand and mechanical (shear) harvesting formed the main plots and the six fertilizer rates (0, 50, 100, 150, 200, 250 kg N/ha) the sub-plots. NPK 25:5:5 fertilizer was applied once. Soil and leaf samples were analyzed for soil pH, soil and leaf major nutrients (NPK) contents. Yield, shoot count and shoot weight data were recorded. Results showed that, tea in mechanical method had higher soil pH and K uptake by tea plants. Tea plants in hand method had higher uptake of N and P. Mechanical method had significantly (p<0.05) lower shoot weight and had higher proportions of mature leaf and broken leaf (low quality greenleaf). Yield was significantly (p<0.05) higher in mechanical than hand method. The interaction between harvesting methods and fertilizer rates on shoot weight was not significant. Effects of fertilizer rates showed that, soil pH decreased with fertilizer rates, soil nutrients uptake increased with fertilizer rates but declined at high rates: At Marikitanda Tea Research Station, nitrogen declined at 250 kg N/ha, phosphorus at 250 kg N/ha and potassium at 150 kg N/ha. At Ngwazi Tea Research Station, nitrogen declined at 250 kg N/ha, phosphorus at 200 kg N/ha and potassium at 200 kg N/ha. Shoot weight increased with fertilizer rates but not significantly. At both experimental sites, shoot weight declined at 250 kg N/ha. Yield increased with fertilizer rates but declined at high rates: At Marikitanda Research Station, the yield declined at 200 kg N/ha, at Ngwazi Tea Research Station it declined at 250 kg N/ha. Only at Marikitanda did fertilizer rates showed significant (p<0.05) difference. There was no significant difference in fertilizer rates between hand and mechanical harvesting. The interaction between harvesting methods and fertilizer rates on yield was not significant. It is recommended that during the first few years (≤ 3) same rate of fertilizer should be applied in both hand and mechanical harvesting, this study should be continued in order to further assess the effects of harvesting methods on soil pH, nutrients uptake and yield

WHEAT RESPONSE TO PHOSPHORUS FERTILIZERS AND AGRICULTURAL LIME IN UASIN GISHU COUNTY, KENYA.

2021-11-11T07:30:24Z

WHEAT RESPONSE TO PHOSPHORUS FERTILIZERS AND AGRICULTURAL LIME IN UASIN GISHU COUNTY, KENYA. SIMATWO, PERES RACHAEL When water is not limiting, soil acidity, deficiencies of phosphorus (P) and nitrogen (N) amongst others are considered to be the major causes of low wheat yields in Uasin-Gishu County, Kenya. In this County, average annual wheat grain yields have always been low with an average of 2.34 t ha-1 but small scale farmers get much lower yields of as low as 0.7 t ha-1. The study aimed at investigating response of wheat growth pattern, grain and straw yields, and soil chemical properties as influenced by liming at 2 t ha-1 (main plots), P sources 23:23:0 (NPK), (DAP) 18:46:0, and 0:20:0 (SSP) - (sub-plots) and, P rates (sub sub-plots) P0; 0 kg P ha-1, P1; 8.8 kg P ha-1, P2; 17.6 kg P ha-1 and P3; 26.4 kg P ha-1. A split-split plot arrangement laid out in a RCBD experiment was set up in two sites; Chepkoilel and Kipsangui in 4 m2 plots, replicated 3 times. Data collected on soil (pH, available P, SOC, and exchangeable K, Ca, Mg, Na), plant height, grain, straw yields and plant total P and N were subjected to ANOVA using SAS 9.1 for Windows 2012 statistical package. Lime application increased the soil pH thus likely making P more available in the acidic soils in the two sites and generally increased exchangeable cations K, Mg, Na and Ca thus improving soil fertility. Phosphorus rich fertilizer application resulted in a significant (p≤0.05) increase in P and soil nutrients content during plant growth, heading and maturity stages. ANOVA showed lime application had a significant (p≤0.05) rise in the wheat grain yield in both sites. Fertilizer application and liming significantly (p≤0.001) improved grain yield in both sites. Rates of applied P also significantly (p≤0.001) influenced wheat grain yields in the two sites. Use of compound fertilizers with balanced ratios of nutrients resulted into increased wheat grain yields. Phosphorus application plus lime at 2 t ha-1 had a significant (p≤0.001) influence on the straw yield in Chepkoilel and Kipsangui. Lime at 2 t ha-1 significantly (p≤0.05) influenced straw yields in Kipsangui and Chepkoilel sites. NPK (23:23:0) fertilizer recorded higher wheat straw means in Kipsangui and Chepkoilel, with DAP giving the lowest yields. Grains’ total N in Kipsangui was higher under SSP (1.80 %). There was no significant difference (p≤0.05) in the level of total N in grain using DAP and 23:23:0 in Kipsangui and Chepkoilel respectively. P uptake was high under P3 application rate plus liming. P uptake was high in both sites. The study recommends 23:23:0 fertilizers at a rate of 26.4 kg P ha-1 for Chepkoilel and Kipsangui plus lime at 2 t ha-1 as most productive and economical. The study also recommends further research on fertilizer use to further increase wheat grain yields from 5.39 t ha-1 to the optimum of 7.2 t ha-1, as the study only managed a 43.0 % wheat grain increase.