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  Rice husk biochar for carbon sequestration, soil fertility and plant health improvement: A review

  (African Phytosanitary Journal, 2024)

  Wachira, Ephraim

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  Yegon, Rebbecca

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  Njiruh, Nthakanio P.

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  Carbon dioxide (CO2) is considered one of the ozone layer gases that contribute to climate change. As the area under agricultural use expands, the level of CO2 from soil as an agricultural by-product increases in the atmosphere. Burning rice husks in open air, decomposing plant materials among other activities release CO2 directly to the atmosphere. Rice husks as a by-product of rice production in Kenya has both the potential to be a source of greenhouse gas (GHG) and production of biochar. Production and deposition of rice husk biochar (RHB) into soil is thought to be one of the viable options for permanent carbon storage with related benefits to soil fertility. This review seeks to consolidate information from various studies that highlight the innovative way of using RHB in combating climate change, improving soil fertility, plant health and crop yields. Studies that have demonstrated beneficial use of RHB were evaluated to prepare this review. When RHB is used as a soil amendment, it has the ability to increase soil carbon storage, mitigate 10% of the current anthropogenic carbon emissions, improve pH and raise Cation Exchange Capacity (CEC), increase available plant nutrients, enhance inherent plant immunity, increase crop yields and improve water quality by increasing retention of nutrients and agrochemicals for plant utilization. A review of the benefits of RHB use in agriculture and climate change mitigation will enhance its adoption. The review further emphasizes the usefulness of pyrolysis in turning organic waste into bioenergy, compost and other beneficial products while protecting the environment.

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  Heterosis in chickpea for grain productivity in Embu county, Kenya

  (Journal of Experimental Biology and Agricultural Sciences, 2021-11)

  Wafula, Judith K.

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  Njoka, Fredrick M.

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  Njiruh, Nthakanio P.

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  Mosioma, Jeremiah O.

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  Mukono, Simon T.

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  Chickpea is a major source of proteins especially in arid and semi-arid areas of Kenya. However, its average yield per hectare is low when compared to neighbouring countries. This research was carried out to determine the levels of hybrid vigour on yield in the F1 generation. To obtain the F1s, reciprocal crossing between Mwanza 2 and Chaina I was carried out with controls being the parental lines. The experimental layout was a randomized block design replicated thrice for three seasons. A spacing of 50x20cm was used in plants, while all other agronomic practices were maintained constant. Data on grain yield and biomass per plant was obtained by measuring the weight, then subjecting it to a one-way ANOVA in SAS 9.4 software. Mwanza 2 expressed the highest biomass (2.56g), while both parents attained a maximum grain yield of 1.69g per plant. Chaina I x Mwanza 2 hybrid expressed maximum means of F1s for biomass (2.31g) and grain yield (1.4g) per plant. Chaina I x Mwanza 2 hybrid recorded the highest biomass and grain yield in better parent heterosis with 14.36% and 330% respectively. Mid-parent heterosis means were also highest at 24.53% and 405.88% for biomass and grain yield respectively. Further, the heritability was maximum for biomass under Mwanza 2 x Chaina I, varying from 93.1% to 100%, while Chaina I x Mwanza 2, expressed maximum grain yield and harvest index. Better parent heterosis and mid-parent heterosis was highest in Chaina I x Mwanza 2 than its reciprocal, Mwanza 2 x Chaina I.

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  Nodulation and protein content of selected chickpea varieties as impacted by spacing and n-fertiliser rates in Eastern Kenya

  (African Journal of Agricultural Research, 2021-05)

  Wafula, Judith K.

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  Njoka, Fredrick M.

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  Njiruh, Nthakanio P.

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  Mosioma, Jeremiah O.

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  Mukono, Simon T.

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  Chickpea is a major legume grown in Kenya. The agronomic performance, nodulation ability and grain crude protein are not fully exploited. Field experiments were conducted at Embu, Kenya to determine the effect of plant spacing and N-fertilizer rates on nodulation and protein content of selected chickpea varieties. A split-split plot design was used and replicated three times. Treatments consisted of main factor, variety in four levels (Saina K, Mwanza 2, Chania I, Chania III), sub factor, spacing in three levels (S1: 50 x 10; S2: 50 x 20; S3: 50 x 30 cm), and sub-sub factor, nitrogen fertilizer rates in four levels of (0; 30; 60; 90 kg ha-1). Data on nodulation and CP was subjected to GLM. Spacing and N-fertilizer rates significantly affected nodule numbers, fresh weight and their sizes. Mwanza 2 x 50x10 cm x N30 posted highest nodule numbers while Chania III had highest protein content. Interactions of VS, VN, SN and VSN had no consistent pattern under nodule factors but were highly significant in percent CP. Hence, optimal interactive effects of VSN can improve nodulation factors and CP of chickpea. The information will help growers make informed decisions, and researchers in developing improved varieties.

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  Arbuscular Mycorrhizal Fungi Colonization in the Rhizosphere of Aspilia pruliseta Schweif. ext Schweif in the Semiarid Eastern Kenya

  (Air, Soil and Water Research, 2020-09)

  Muchoka, James Peter

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  Mugendi, Daniel N.

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  Njiruh, Nthakanio P.

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  Onyari,Charles

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  Mbugua,Paul Kamau

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  The use of arbuscular mycorrhizal fungi (AMF) to enhance soil phosphate uptake is a biological technique considered to cure phosphate deficiency in soils. This study investigated association of Aspilia pruliseta Schweif shrub with AMF in Kenya. The study aims at profiling a tropical shrub with multiple ecological benefits that could reduce addition of chemical phosphatic fertilizer into the soil and reverse negative consequences of eutrophication. Sampling was purposive to have areas with or without Aspilia pruliseta vegetation growing. A small amount (10 g) of the soil from 27 composite samples was used for spore count determination and a similar amount for next generation sequencing. Spore counts varied significantly among soil textural types, sample locations, and soil depth. Sandy loam had the highest spore counts with a mean average of 404 spores. The spore count decreased significantly (P < .05) with the depth of soil from a mean of 514 spores to 185 along the rhizosphere. The intensity of spore morphotypes was significantly higher at P < .05 for soils whose vegetation was covered with Aspilia pruliseta than those without. Aspilia pruliseta vegetation used together with sandy loam soil could culture commercial mycorrhiza fungi production for use in agrisystems.

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  Agronomic Benefits of Shubhodaya-Mycorrhizal Bio-Fertilizer on Banana Production in Embu County, Kenya

  (Journal of Agronomy, 2020)

  Gichimu, Bernard Mukiri

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  Muthee,Arphaxard Ireri

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  Njiruh, Nthakanio P.

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  Background and Objective: Banana (Musa spp.) fruit yields in Kenya ranges from 4.5-10 tons per hectare per annum compared to the international levels of 40-50 t. This low production is attributed majorly to poor soil fertility management. This study was carried out to evaluate the effect of shubhodaya-mycorrhizal bio-fertilizer on banana productivity in Embu County. Materials and Methods: The experiment was set up in 5 sites distributed in different agro-ecological zones within Embu County. Application of treatments was preceded by soil chemical analysis to determine the soil fertility status. There were 6 treatments designated as T1: 5 g of NPK (13:2:44) fertilizer (control), T2: 5 g NPK+20 g bio-fertilizer, T3: 5 g NPK+30 g bio-fertilizer, T4: 5 g NPK+40 g bio-fertilizer, T5: 5 g NPK+50 g bio-fertilizer and T6: 50 g bio-fertilizer alone. The experiment was laid out in a randomized complete block design with 4 replications. A tissue culture banana cv. Gal was used as the test crop. Results: Soil analysis results indicated low soil fertility status characterized by acidic pH and low levels of macro and micronutrients. Treatment T5 produced the highest growth rate and weight of first bunch. Sole application of the bio-fertilizer at a rate of 50 g produced better results than when integrated at lower rates with the inorganic fertilizer. Conclusion: Shubhodaya mycorrhizal bio-fertilizer can serve as alternative eco-friendly source of plant nutrients in banana production.

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