Short Rains Season Research Articles

Combined inorganic and organic fertilizers improved soil microbial biomass and nitrogen dynamics in Upper Eastern region of Kenya

Soil microbial biomass elements and mineralization processes are essential in replenishing soil nutrients. Yet, the effect of fertilization on the microbes is still not well-defined. This study aimed to determine the effect of integrated soil fertility inputs (inorganic and organic) on microbial biomass, carbon (MBC), nitrogen (MBN), phosphorus (MBP), nitrogen (N) mineralization, and N use efficiency in a field experiment. The treatments were: control (no fertility input), sole inorganic fertilizer, and different combinations of inorganic and organic inputs in a randomized block design. The results showed that Conventional tillage + maize residue + goat manure + Dolichos lablab intercrop (CT4); minimum tillage + maize residue + Tithonia diversifolia + goat manure (MT5); and minimum tillage + maize residue + goat manure + Dolichos lablab (MT4) intercrop increased microbial C, N, and P by 78 %, 48 %, and 41 %, respectively compared to control (CT0). Compared to CT0, N mineralization significantly varied (p < 0.0001) among the treatments at planting and on the 15th, 30th, 45th, and 60th days after planting during the 2020 short rains season. It also differed significantly (p = 0.0018, 0.0028, < 0.0001, and 0.0028,) on the 45th, 60th, 75th, 90th, and 105th days, respectively, relative to CT0 after planting during the 2021 long rains season. The CT4 had 5.11 and 52.80 kg N ha−1 higher apparent nitrogen recovery and partial factor productivity N, respectively. Similarly, MT4 greatly enhanced N apparent recovery efficiency by 57.5 % relative to CT0. Integrating fertility inputs improved soil biological fertility and mineralized N. Therefore, technologies that integrate organic inputs, either solely or with inorganic fertilizers, should be harnessed and promoted as medium and long-term technologies to advance soil biological fertility, and mineral N and N use efficiency in smallholder farmers.

Exploring seasonal variability in water quality of Nyabarongo River in Rwanda via water quality indices and DPSIR modelling.

Understanding seasonal variations in water quality is crucial for effective management of freshwater rivers amidst changing environmental conditions. This study employed water quality index (WQI), metal index (MI), and pollution indices (PI) to comprehensively assess water quality and pollution levels in Nyabarongo River of Rwanda. A dynamic driver-pressure-state-impact-response model was used to identify factors influencing quality management. Over 4years (2018-2021), 69 samples were collected on a monthly basis from each of the six monitoring stations across the Nyabarongo River throughout the four different seasons. Maximum WQI values were observed during dry long (52.90), dry short (21.478), long rain (93.66), and short rain (37.4) seasons, classified according to CCME 2001 guidelines. Ion concentrations exceeded WHO standards, with dominant ions being and . Variations in water quality were influenced by factors such as calcium bicarbonate dominance in dry seasons and sodium sulfate dominance in rainy seasons. Evaporation and precipitation processes primarily influenced ionic composition. Metal indices (MI) exhibited wide ranges: long dry (0.2-433.0), short dry (0.1-174.3), long rain (0.1-223.7), and short rain (0.3-252.5). The hazard index values for Cu2+, Mn4+, Zn2+, and Cr3+ were below 1, ranging from 8.89E - 08 to 7.68E - 07 for adults and 2.30E - 07 to 5.02E - 06 for children through oral ingestion, and from 6.68E - 10 to 5.07E - 07 for adults and 6.61E - 09 to 2.54E - 06 for children through dermal contact. With a total carcinogenic risk of less than 1 for both ingestion and dermal contact, indicating no significant health risks yet send strong signals to Governmental management of the Nyabarongo River. Overall water quality was classified as marginal in long dry, poor in short dry, good in long rain, and poor again in short rain seasons.

Influence of organic fertilization on growth and yield of strawberry (Fragaria × ananassa) in Kabete and Mbooni areas, Kenya

Strawberries are a valuable crop in Kenya with the potential for significant economic contributions. However, strawberry production in the country has been facing considerable challenges, impacting its economic potential. This study examined the influence of organic manure on strawberry growth and characteristics in Kabete and Mbooni areas in Kenya. The study used a randomized complete block design (RCBD) with three replications. Treatments included livestock manure (well composted mixture of chicken, goat, and cow manure), bokashi manure, and a control, coded as LivManure, BokManure and Control, respectively. Growth parameters including leaf area, number of white flowers and number of runners, as well as yield parameters such as the number and weight of strawberries were assessed from the 3rd to 10th week after transplanting, during the short rain season of 2021. Using R statistical software, linear models were fitted to datasets from both study sites and analyzed using one-way ANOVA, followed by post-hoc tests for multiple comparisons. The rigorous analysis of the Kabete and Mbooni datasets provided insightful revelations about the influence of different treatments on strawberry characteristics, and geographical disparities between the two regions. The analysis of variance (ANOVA) outcomes unveiled significant treatment effects in both sites, with F(2,69) = 62.57, p < 0.001 for Kabete and F(2,69) = 49.02, p < 0.001 for Mbooni, highlighting distinct influences of treatments on log values within each group. Post hoc analyses, including Tukey tests and bootstrap comparisons robustly validated the significant differences among the three treatments in each site, supported by p-values <0.001. Effect sizes were also employed to reinforce the findings, and planned contrasts were set to gain more power in the analysis of variance. Comparison between Kabete and Mbooni indicated a significant difference of 9.78 units, with Mbooni area exhibiting significantly higher strawberry characteristics compared to Kabete. The results showed that LivManure treatment had the highest mean in both sites, followed by BokManure and Control treatments, respectively. These findings have important implications for agriculture, and highlight the potential benefits of using LivManure treatment to improve strawberry characteristics in similar agroclimatic settings. These observations can be attributed to the beneficial effects of livestock manure on soil health, which include buffering of the soil reaction, provision of essential plant nutrients and enhancement of soil faunal activities. Balanced use of livestock manure is recommended to enhance soil macro and micronutrients, and soil reaction for improved growth and yield of strawberry.

Integrating Entomopathogenic Fungi into Different Crop Management Practices for Fall Armyworm Management

The study was carried out to identify crop management practices favouring entomopathogenic fungi of fall armyworm (Spodoptera frugiperda J. E. Smith). An experiment was set up with 24 maize plots measuring 6 m x 5 m in Siaya, JOOUST Campus field during the September to December 2021 short rain season for identification of crop management practices favouring entomopathogenic fungi of fall armyworm. Morphological and Molecular characterization was done to estimate the diversity of entomopathogenic fungi offal armyworm larvae specimens from the treatment plots. Each plot was separated by 2 m occupied with Brachiaria CV Mulato to counter the possibility of fall armyworm migration from one treatment plot to another as recommended by the ICIPE’s fall armyworm push-pull technology. The results showed that weeding was statistically significant (0.044) on fall armyworm larvae collected while only 2 species of entomopathogenic fungi were isolated for this crop management practice. The case was different with intercropping, though not statistically significant, over 50% of the isolated species were from this management practice. This could mean that intercropping is likely to reduce FAW larvae infestation whilst increasing fungal activity. This study therefore concludes that the threat that S. frugiperda poses also calls for the need for the development and adoption of good crop management practices such as intercropping, adequate fertilization, and weeding

Evaluation of a regional crop model implementation for sub-national yield assessments in Kenya

CONTEXTCropping system models can be used to both assess regional food security and to monitor and predict agricultural drought. Agriculture in Kenya is extremely important to both the economy and food security of the country. OBJECTIVEThis study evaluated a regional implementation of a widely used crop model, the Decision Support System for Agrotechnology Transfer (DSSAT), within a coupled modeling framework, the Regional Hydrologic Extremes Assessment System (RHEAS), over Kenya. The goal of this study was to assess the ability of RHEAS to simulate the annual variability of maize yields at the county level and evaluate the uncertainty inherent in the model and inputs. METHODSThe RHEAS system implements a stochastic ensemble approach to account for field scale variabilities in crop management practices and underlying soil and weather conditions. Satellite-derived datasets were used to evaluate the land surface component of the system and seasonally disaggregated yield for 5 years was used to assess the performance of the cropping system model. RESULTS AND CONCLUSIONSThe median correlation between RHEAS and satellite-derived soil moisture and evapotranspiration estimates were 0.78, and 0.51, respectively, indicating that the model is able to capture the key drivers of the hydrological budget. Overall, RHEAS simulated yearly yield variations with a median correlation of 0.7 with reported yields, with the best performance in the short rains season. However, across both seasons, the RHEAS model was positively biased on the order of ∼1.6 MT/ha. The overall median unbiased RMSE was 0.66 MT/ha. The RHEAS system shows skill at simulating extreme departures in anomalies, and a majority of the time (62.5%) the reported yields fall within the interquartile range of the simulations. SIGNIFICANCEOne of the most important areas of improvement for the next generation of agricultural data and models is to better understand and communicate the inherent uncertainties. This is especially critical in data-limited regions. Here we present a modeling system and its implementation that begins to address these concerns. We demonstrate the ability to simulate broad trends in yields at the county level for sub-annual yields with skills that commensurate previous national/annual level studies.

Effects of soil amendments on growth and biomass yield of early generation seeds of sweet potato (Ipomoea batatas (L.) Lam) grown in net tunnels.

Early generation sweet potato vines are multiplied on nursery beds with high densities using soil medium within insect-proof net tunnels to inhibit the entrance of virus-transmitting insects (aphids and white flies). However, the rapid multiplication beds require suitable soil amendments to support vigorous growth of vines. To this end, farmyard manure, wood ash, sawdust, compost, coffee husk and control (soil only) were evaluated using Randomized Complete Block Design with three replications during the belg and meher seasons of 2016 to 2017 in the Chefe testing site of Hawassa Agriculture Research Center. Results also showed that the soil pH was higher by 8.9% and 1.4% due to the application of wood ash and sawdust whereas there was 9.3, 5.9 and 0.9% decrease in soil pH due to the use of compost, coffee husk and farmyard manure, respectively. All soil amendments enhanced soil moisture conservation compared to the control. A 47.0%, 31.2%, 30.3% and 26.5% increase in cation exchange capacity was observed by the end of second year due to use of coffee husk, wood ash, sawdust and farmyard manure, respectively. The potassium content was increased by 47.0%, 45.5% and 35.9% due to the use of wood ash, farmyard manure and coffee husk, respectively. The pencil root length, pencil root width and below-ground biomass were not affected significantly (P < 0.05) by differences in soil amendments (P < 0.05) in this experiment. The percentage increment in above-ground biomass due to the farmyard manure, coffee husk and compost was 62.01%, 53.56% and 49.87%, respectively higher than the control. Sawdust suppressed vine growth compared to the control. Coffee husk and farmyard manure medium produced higher number of branches (23 branches / plant) during meher whereas coffee husk produced the same during belg (14.4 branches / plant). Significantly (P < 0.05) higher number of vines was obtained due to farmyard manure (4686 vines/m2) and coffee husk (4602 vines/m2) compared to the control (2683 vines/m2). Significantly longer internodes were recorded due to the farmyard (100.6% greater) compared to the control. Thus, 50% farmyard manure, 50% coffee husk or 50% compost are recommended for better growth of pre-basic sweet potato vines in net tunnels. This study proclaimed possibility of nursery bed vine multiplication through use of local organic residues at the level of small holders and research sites during short and long rain seasons.

Trends and Variability in Temperature and Related Extreme Indices in Rwanda during the Past Four Decades

Analysis of the trends and variability of climate variables and extreme climate events is important for climate change detection in space and time. In this study, the trends and variabilities of minimum, maximum, and mean temperatures, as well as five extreme temperature indices, are analyzed over Rwanda for the period of 1983 to 2022. The Modified Mann–Kendall test and the Theil–Sen estimator are used for the analysis of, respectively, the trend and the slope. The standard deviation is used for the analysis of the temporal variability. It is found, on average, over the country, a statistically significant (α = 0.05) positive trend of 0.17 °C/decade and 0.20 °C/decade in minimum temperature, respectively, for the long dry season and short rain season. Statistically significant (α = 0.05) positive trends are observed for spatially averaged cold days (0.84 days/decade), warm nights (0.62 days/decade), and warm days (1.28 days/decade). In general, maximum temperature represents higher variability compared to the minimum temperature. In all seasons except the long dry season, statistically significant (α = 0.05) high standard deviations (1.4–1.6 °C) are observed over the eastern and north-western highlands for the maximum temperature. Cold nights show more variability, with a standard deviation ranging between 5 and 7 days, than the cold days, warm nights, and warm days, having, respectively, standard deviations ranging between 2 and 3, 4 and 5 days, and 3 and 4, and, especially in the area covering the central, south-western, south-central, and northwestern parts of Rwanda. Temperature increase and its variability have an impact on agriculture, health, water resources, infrastructure, and energy. The results obtained from this study are important since they can serve as the baseline for future projections. These can help policy decision making take objective measures for mitigation and adaptation to climate change impacts.

Predicting extreme floods and droughts in East Africa using a deep learning approach

The East African region is highly susceptible to severe floods and persistent droughts, which greatly impact the livelihood of millions of people. Early warnings, at least a few seasons in advance, would help implement mitigation measures. However, most prediction systems using dynamical models perform poorly at long lead times. In this study, we propose a statistical deep learning approach based on a convolutional neural network (CNN) to predict extreme floods and droughts during the short rains season (October–December). The proposed CNN model captures the phase of extreme floods and droughts two to three seasons ahead, except for a few cases. By diagnosing the model’s skills using heatmaps, we find that predicted extreme floods and droughts are linked with the sea surface temperature anomalies of the Indian Ocean Dipole at shorter leads and with western and southern Indian Ocean, equatorial Pacific, and southern Atlantic Ocean at longer leads. Although there were a few poorly predicted exceptions, the superior skill of our CNN-based predictions at longer leads provides a significant advantage in developing mitigation measures.

Tied-ridging and soil inputs enhance small-scale maize productivity and profitability under erratic rainfall conditions in central Kenya

Deficits in soil moisture and low soil fertility are the major constraints to smallholder farming systems in the SSA (sub-Saharan Africa) region. This study evaluated the effects of tied ridging and selected soil fertility inputs on; soil water content at different depths, maize yields, and economic returns. The treatments were: Tithonia diversifolia + inorganic fertilizer, manure + inorganic fertilizer, inorganic fertilizer, and control with or without tied ridging as the soil water conservation factor. Data were subjected to analysis of variance, and the means were separated using LSD at p ≤ 0.05. Treatments with Tithonia diversifolia or manure combined with inorganic fertilizer with or without tied ridging consistently affected soil water content positively. The effect of tied ridging on soil water content was greater during the short rain season compared to the long rains. In addition, there was evidence that tied ridging and organic soil inputs resulted in greater soil moisture conservation during the critical silking and tasselling maize phenological stages during the short rain season. Treatments had significant effects on grain and stover yields during the long rain 2016 season (p < 0.0001 and p = 0.0477, respectively) and the short rain 2016 season (p < 0.0001 and p = 0.0035, respectively). The highest (4.87 Mg ha−1) maize grain yield was recorded in Tithonia diversifolia plus inorganic fertilizer under tied ridging in the long rain 2016 season, while manure + inorganic fertilizer without tied ridging gave the highest yields (1.27 Mg ha−1) in the short rain 2016 season. The highest net benefits of US$ 1229.90 ha−1 and US$ 171.57 ha−1 were recorded under Tithonia diversifolia plus inorganic fertilizer with tied ridging during the long and short rain seasons, respectively. Overall, the best-performing treatments in yields and profitability were those that combined organic and inorganic fertilizers, regardless of the presence or absence of tied ridging. Climate-smart agricultural strategies combining tied ridges and organic inputs should be an integral component of farmer management if losses related to soil fertility and water stress are to be minimized under erratic rainfall regimes in the semiarid farming systems of the SSA region.

Cost-Benefit Implications of Conservation Agriculture with Trees in the Dry Lands of Machakos County, Kenya

The adoption of conservation agriculture and agroforestry has been cited as the solution to the degradation and low profitability challenges in the drylands. The two systems have been known to result in high profitability through the improvement of yields and lowering of crop production costs. The study was carried out as part of ongoing experimentation established in the short rains (SR) season of 2012 by the World Agroforestry Centre in an on-station site at the Agricultural Training Centre (ATC) in Machakos County, Kenya. The trials were based on a split plot arranged in a randomised complete block design with two farming systems (conventional and conservation agriculture) serving as the main blocks, 10 treatments and three replicates, summing to a total of 60 plots. In the fields, three shrub species (Calliandra calothyrsus Meissn., Cajanas cajan (Pigeon pea), and Gliricidia sepium Jacq.) were planted in three different spacing (1.5 x 1 m, 3 x 1 m, 4.5 x 1 m) for maize-legume intercrops. The costs of production were recorded consistently in each season (LR 13, SR 13, and LR14). The maize and legume yields were valued at the market selling price from the local market, and a cost-benefit analysis was done through the calculation of benefit-cost ratios (BCR). The data was statistically analysed using ANOVA and means were separated using LSD at p &lt;0.05. Results showed significantly high BCR under conservation agriculture (p &lt;0.0001) in all seasons with sole CA having the highest BCR of 9.9 in LR 2014. The BCRs were lower in the first season due to high initial production costs, but this increased steadily in the succeeding seasons. The study concludes that conservation agriculture both with trees and as the sole is beneficial to the farmer, with higher net benefits compared to conventional tillage

Plant Diversity and Honeybees’ Foraging Preferences: An Implication for Honeybees’ Conservation

Identification of honeybees’ preferred plant species is paramount for sustainable conservation, especially when honeybees are reported to be declining globally. The study assessed plant diversity in potential beekeeping areas in Northern Tanzania and determined the foraging preferences of honeybees across two rainy seasons of 2021/2022. We established quadrats of 5 x 5m (shrubs and forbs) nested with 1x1 m (grasses) at each of the four transects of 5 km distance to assess plant diversity and identify the most preferred plants in two study areas. The dominant plant families were Poaceae, Malvaceae, Commelinaceae, Acanthaceae, Amaranthaceae, Polygonaceae, Asteraceae, and Lamiaceae. There was a significant difference in plant diversity between short and long rain seasons in both study areas (t = 2.60, p = 0.01, and t = 2.27, p= 0.03). Grewia bicolor, Terminalia brownii, Ziziphus mucronata, Combretum schumannii, and Cordia monoica were the most visited plants by 2761, 2528, 1966, 1163, and 662 visits, respectively, during the short rain season, while Acacia mellifera, Hoslundia opposita, Ocimum bacilicum and Acalypha fruticosa were the most visited plant species by 1638, 788, 340, and 38 visits, respectively, during the long raing season. This study has highlighted important information on honeybees’ foraging preferences and their diversity that shades a way for sustainable honeybees’ conservation in the area and elsewhere. We recommend further identification and re-planting of honeybees’ forages; awareness campaign to enlighten local people in beekeeping potential areas on the impact of activities that reduce plant diversity, negatively affecting honeybees.

First Report of Cucurbit Aphid-Borne Yellows Virus Infecting Groundnut in Kenya

Cucurbit aphid-borne yellows virus (CABYV, genus Polerovirus, family Luteoviridae) causing cucurbit aphid-borne yellows disease (CABYD) in groundnut ( Arachis hypogaea) is characterized by interveinal yellowing symptoms in leaves. CABYV is transmitted by Aphis gossypii, Myzus persicae, and Macrosiphum euphorbiae. CABYV causes up to 80% yield loss, but there is no information available on its occurrence and serological and molecular characteristics in groundnuts. Two disease diagnostic surveys were conducted during the short and long rains seasons of 2020 and 2021 in Bungoma, Busia, Kakamega, and Siaya counties growing groundnut. Disease incidence and severity were scored, and collected data were analyzed using R software. Serological bioassays were performed using TAS-ELISA, and positive samples were pooled and processed with the transposon-based chemistry library preparation kit (Nextera XT, Illumina). Phylogenetic analyses and comparisons were performed using the MEGA X software. In the short rains season higher incidence (73.61%) was recorded than in the long rains season (42.65%). The CABYV isolates from Kenya clustered with other poleroviruses variedly. CABYV6-2 showed 94.5% nucleotide identity with CpPV2 isolate KX599164.1 from Burkina Faso and 83.4% identity with CABYV isolate MG257902.1 from Korea. This research provides evidence for the first report of CABYV infecting A. hypogaea relevant for development of better plant health management technologies for increased groundnut yield.

On the Predictability of the Extreme Drought in East Africa During the Short Rains Season

AbstractMany parts of East Africa experienced extremely dry conditions during the short rains season of October–December 2021. It was predicted a few months before by the ensemble seasonal prediction system based on the SINTEX‐F climate model. The analysis of co‐variability of inter‐member anomalies has revealed that the 2021 negative Indian Ocean Dipole was responsible for these unusually dry conditions over East Africa. We also show that a hybrid statistical‐dynamical framework is more skillful than the SINTEX‐F model at predicting drought in East Africa on longer lead time, which may help people to take necessary mitigation measures to reduce the devastating impact of the drought.

Host and Seasonal Effects on the Abundance of Bean Leaf Beetles (Ootheca spp.) (Coleoptera: Chrysomelidae) in Northern Uganda.

Simple SummaryBean leaf beetles (Ootheca spp.) (Coleoptera: Chrysomelidae) are endemic in Africa and are pests of cropped legumes (Fabales: Fabaceae). On common beans (Phaseolus vulgaris L.), the beetles cause leaf and root damages, leading to losses sometimes exceeding 50% in northern Uganda. Additionally, legumes are often grown in neighboring plots or in rotation season after season. This promotes the multiplication of pests and thus complicate their management. We conducted field trials to assess the seasonal variations in the abundance of the Bean Leaf beetles on common beans, cowpea (Vigna sp. Walp) and soybean (Glycine max L.), which are major legumes grown in northern Uganda. The beetles were most abundant during the long rainy season of 2018 and on cowpea, but also present during short rainy seasons of 2017 and 2018. Pupae remained in the soil after the harvest of the first season’s crops and were detected during the second season as well. Ootheca spp. preferred cowpea for foraging and development. Our study indicates that management strategies should be designed to target the above- and below-ground stages of Ootheca spp. in both seasons. Bean leaf beetles (BLBs) (Ootheca spp.) are serious legume pests in Uganda and sub-Saharan Africa, but their ecology is not well understood. We planted host plants, viz., common bean, cowpea, and soybean, in an experiment in the hotspot areas of Arua and Lira districts in Northern Uganda in order to assess their influence on the density of adults and immature stages of BLBs in different seasons. Overall, the number of adults, larvae, and pupae were higher in cowpea than common bean and soybean plots. The number of adults were highest in cowpea (29.5 adults/15 plants) in Arua during the long rainy season (2018A). The number of adults did not differ significantly during short rains (season B) in 2017 and 2018. Similarly, in Lira district, the highest number of adult BLBs was in cowpea (4.6 beetles) compared to the common bean (2.7 beetles) and soybean plots, with a peak at four weeks after planting (WAP). During 2018A, larvae of BLBs first appeared at five WAP and seven WAP and peaked at 13 WAP and 11 WAP in Arua and Lira, respectively. The pupae were present in the soil after the harvesting of crops during 2018A, but peaked at seven WAP and eight WAP in 2018B season in Arua and Lira, respectively. The occurrence of below-ground adults in 2018B followed the peak abundance of pupae, although this was delayed until six WAP in Arua compared to Lira. We conclude that cowpea is the most preferred by adults and larvae compared to common bean and soybean. Similarly, the first rain season (2018A) attracted higher abundance and damage than the second rain season. Management of the BLBs should thus take into consideration avoidance of host crop rotation and dealing with the below-ground stages.

Fanya juu Terraces Improve Maize (Zea mays L.) and Bean (Phaseolus vulgaris L) Grain Yields on Hardsetting Soils of Semi-arid Eastern Kenya

Aims: Fanya juu terraces are constructed by digging a ditch and throwing the soil up-slope with the sole purpose of maintaining an embankment to slow down runoff flow. The effect of the terraces on crop yields along the slope varies with the soil type. The aim of this study was to determine the effect of Fanya juu terraces on maize (Zea mays L.) and bean (Phaseolus vulgaris L.) yields and how these yields differ with slope positions and depth of the ditches.&#x0D; Study Design: Split-split plot design with four replications.&#x0D; Place and Duration of Study: The trial was established on Luvisols in Mua location, Machakos County in Eastern Kenya at 37o15’E 1o29’S and 37o15’E 1o29’S during both long rain (LR) and short rain (SR) seasons of 2014 and 2015 (February 2014 to March 2015).&#x0D; Methodology: Treatments consisted of three ditch depths (60 cm, 30 cm and 0 cm (control)) in the main plots and three cropping systems (maize/bean intercrop, sole maize and sole bean) in the sub plots. Grain yields were compared across the seasons at the upper, middle and lower slope positions of the terraces using analysis of variance and means separated using least significant difference at P≤0.05.&#x0D; Results: There were significant differences in maize grain yields in the interactions of ditch depth and slope position (P=0.004) and ditch depth and season (P&lt;0.001). Higher maize yields were realized when ditches were constructed than in the control. Yields increased from the lower to the upper slope position of the terraces with 30 cm ditch by 49.8% and in the 60 cm by 41.6%. Average yields from treatments with 30 cm ditch were significantly higher than from the control but non-significant from those in the 60 cm ditch. Significant differences (P=0.037) in bean grain yields were observed in interactions of ditch depth and slope position. Higher yields were obtained from the lower position of the 30 cm ditch than the middle and upper positions. Significant differences (P=0.033) were also found in interactions of ditch depths, cropping systems and seasons.&#x0D; Conclusion: The results indicate that Fanya juu terraces had a significant effect on crop yields on hardsetting soils. The study recommends construction of Fanya juu terraces with a ditch depth of 30 cm and intensive management of the lower slope position for improved maize and bean production on hardsetting soils in marginal areas.

IN-SITU WATER HARVESTING TECHNOLOGIES AND FERTILIZER RATES INCREASE MAIZE AND BEAN YIELDS IN THE SEMI-ARID KATUMANI, KENYA

&lt;p&gt;&lt;strong&gt;Background: &lt;/strong&gt;Crop production in the arid and semi-arid lands (ASALs) is constrained by erratic rainfall and poor soil fertility. Therefore, climate smart agriculture mechanisms such as &lt;em&gt;in-situ&lt;/em&gt; rainwater harvesting technologies and recommended fertilizer rates would be vital for ensuring food security.&lt;strong&gt; Objective&lt;/strong&gt;: To evaluate selected &lt;em&gt;in-situ&lt;/em&gt; water harvesting technologies and fertilizer rates on soil water content and yield of maize and beans at KALRO Katumani Research Center in Machakos County, Kenya during the 2019 and 2020 short and long rain seasons, respectively. &lt;strong&gt;Methodology:&lt;/strong&gt; The experiment was established in a randomized complete block design with a split-split plot arrangement, replicated three times, with &lt;em&gt;in-situ&lt;/em&gt; water harvesting technologies comprising of zai pits, ngolo pits, contour furrows and conventional tillage, as the main plots, whereas the split plots were varying rates of fertilizer inputs: Di-ammonium phosphate (DAP), goat manure and control. The split-split plots comprised of maize and beans cropping systems. Soil moisture content was assessed at 4, 8, 12 and 16 weeks after emergence, whilst nutrient uptake, use efficiency and crop yields at physiological maturity. Data was subjected to analysis of variance. &lt;strong&gt;Results: &lt;/strong&gt;Soil moisture, maize and beans yields, nutrient uptake and use efficiency were significantly (p&lt;em&gt; &lt;/em&gt;≤ 0.05) increased by &lt;em&gt;in-situ&lt;/em&gt; water harvesting technologies and fertilizer inputs. Highest soil moisture content was recorded under zai and ngolo pits and lowest in conventional tillage treatments. Ngolo pits recorded higher maize and beans grain yield. Application of DAP fertilizer increased maize and beans grain yield compared to control. Intercropping maize and beans increased grain yield significantly (p&lt;em&gt; &lt;/em&gt;≤ 0.05) compared to sole maize and sole beans. &lt;strong&gt;Implications. &lt;/strong&gt;There is need for promoting a combination of &lt;em&gt;in-situ&lt;/em&gt; rainwater harvesting technologies especially ngolo and zai pits with application of DAP+ manure in semi-arid areas where water is scarce coupled with poor soil fertility. &lt;strong&gt;Conclusion:&lt;/strong&gt; Ngolo and zai pits increased soil water retention capacity while application of DAP fertilizer led to increased crop yield and the study therefore recommends their adoption within the study area and extrapolation to areas of similar conditions. &lt;/p&gt;

Dry Matter Production and Carbon Sequestration Potential of Selected Indigenous and Introduced Grasses under Rangeland Ecosystems of South Eastern Kenya

This study determined dry matter production and carbon sequestration potential of three indigenous and two introduced grass species under rangeland ecosystems. The indigenous grasses were: - Masai love grass (Eragrostis superba), Foxtail (Cenchrus ciliaris), Bushrye (Entropogon macrostachyus) and the introduced grasses were: - Boma rhodes and Extozi rhodes. The study was in South eastern rangeland of Kenya and data was collected during peak growing period of short and long rain seasons from established pasture plots. Plant samples (above ground, below ground and litter) were harvested by randomly placing 1m2 quadrats in each plot in triplicate. Soil samples were randomly collected from each plot at a depth of 0-20 cm, air-dried and analysed for carbon content using Chromic acid digestion method from each plot under selected grasses, bulk density was determined. Harvested plant samples were oven-dried for 48 hours to stable mass at 65o C, ground (± 2mm size) and combusted in a muffle furnace at 550oc for 4 hours to determine organic matter concentration. The results revealed that indigenous grasses were 24% higher in dry matter production (17.3 vs 14.0tons/ha) and 23% higher in carbon stock (11.3 vs 9.2 tons) (p&lt;0.05). The implication of the results is that indigenous grasses would offer co benefit of higher dry matter production for livestock feeding and higher carbon sink capacity contributing to minimising emission and global warming potential. This is beneficial to mitigating climate change when increasing ruminant production under often degraded rangeland ecosystems. with this evidence, utilisation of indigenous grass species is highly recommended for sustainable rangeland livestock production supporting increased productivity while minimising carbon emissions.

Atmospheric and oceanic conditions associated with early and late onset for Eastern Africa short rains

AbstractTiming of the rainy season is essential for a number of climate sensitive sectors over Eastern Africa. This is particularly true for the agricultural sector, where most activities depend on both the spatial and temporal distribution of rainfall throughout the season. Using a combination of observational and reanalysis datasets, the present study investigates the atmospheric and oceanic conditions associated with early and late onset for Eastern Africa short rains season (October–December). Our results indicate enhanced rainfall in October and November during years with early onset and rainfall deficit in years with late onset for the same months. Early onset years are found to be associated with warmer sea surface temperatures (SSTs) in the western Indian Ocean, and an enhanced moisture flux and anomalous low‐level flow into Eastern Africa from as early as the first dekad of September. The late onset years are characterized by cooler SSTs in the western Indian Ocean, anomalous westerly moisture flux and zonal flow limiting moisture supply to the region. The variability in onset date is separated into the interannual and decadal components, and the links with SSTs and low‐level circulation over the Indian Ocean basin are examined separately for both timescales. Significant correlations are found between the interannual variability of the onset and the Indian Ocean dipole mode index. On decadal timescales the onset is shown to be partly driven by the variability of the SSTs over the Indian Ocean. Understanding the influence of these potentially predictable SST and moisture patterns on onset variability has huge potential to improve forecasts of the East African short rains. Improved prediction of the variability of the rainy season onset has huge implications for improving key strategic decisions and preparedness action in many sectors, including agriculture.

Nutritive value of forages and diets in some small-scale dairy farms in Kiambu County, Kenya in the short rains season

Sixteen selected small-scale dairy farms were investigated in Kiambu County (Kenya) during the short rains seasonto develop a snapshot of the types of rations fed, milk yields obtained and sources of fodder. On average farmers had1 ha of land and 2.2 lactating cows yielding 8.93 kg milk/cow/d with feed intake of 10.5 kg DM/d. Only 35% of feedconsumed was produced on farm. Boma Rhodes grass hay and green Napier grass were the main forage components(37.9 and 28.3% of total DM). Protein forages used were the herbaceous legumes lucerne and desmodium (19.9 and15.9% CP, respectively) and leguminous shrubs (Leucaena, Calliandra and Sesbania with 21.1% CP and 43.4%aNDFom, on average). Grasses had higher aNDFom digestibility (47.1%) than legumes (39.7%). Napier grass, BomaRhodes grass, lucerne and desmodium had fiber digestibility of 51.9, 48.6, 46.8 and 32.6%, respectively. The energyand protein balances (actual vs. requirements) of the cows were on average -19.3 and -16.4%, respectively, indicatingthat cows utilized body tissues to produce the levels of milk obtained. Mutiple correspondence analysis showed that amilk yield higher than 9.1 kg/d was associated with a level of Boma Rhodes grass &lt;5 kg DM/d, concentration of nonfibrous carbohydrates in the diet &gt;22.0% (DM basis), concentrate level &gt;2.63 kg/cow/d and CP% in the ration &gt;9.1%. To improve milk yields during this season farmers should harvest grass forage at a younger age, include leguminous forage in the diets and increase the level of concentrates fed. These strategies should be demonstrated on farms to show possible benefits.

Push-pull technology improves carbon stocks in rainfed smallholder agriculture in Western Kenya

Push-pull technology improves agricultural productivity. However, its long-term effect on biomass carbon and soil organic carbon (SOC) is not yet known. The aims of this study were: to assess the effect of push-pull technology on (1) biomass carbon and (2) SOC, considering climatic conditions and the length of time that push-pull had been practiced on a farm; and (3) to establish the relationship between biomass carbon and SOC on farms. Aboveground biomass carbon and SOC were measured on 36 farms in western Kenya, encompassing three contrasting sites (Bondo, Siaya and Vihiga) and six cropping systems (push-pull and five non-push-pull systems). Farms in western Kenya stock between 3.0 ± 0.3 and 4.0 ± 0.4 t C ha−1 in crop biomass and between 24.4 ± 2.1 and 37.0 ± 2.6 t C ha−1 in the soil for those practicing push-pull, and between 1.1 ± 0.3 and 2.1 ± 0.2 t C ha−1 biomass carbon and between 19.2 ± 2.1 and 31.1 ± 1.7 t C ha−1 soil carbon for those without push-pull. There was no correlation between biomass carbon and SOC. Adoption of push-pull offers opportunities to mitigate climate change through carbon sequestration in plants and soils in low-, medium- and high-rainfall environments in both long and short rain seasons.