DSpace Repository :: Browsing by Author "Gitari, Harun I."

Browsing by Author "Gitari, Harun I."

Now showing 1 - 20 of 24

Agronomic assessment of phosphorus efficacy for potato (Solanum tuberosum L) under legume intercrops
(Taylor & Francis, 2019) Gitari, Harun I.; Shadrack, Nyawade; Kamau, Solomon; Karanja, Nancy N.; Gachene, Charles K. K.; Schulte-Geldermann, Elmar
Phosphorus (P) is an essential element and its efficient use is of global importance. This study evaluated the effect of growing potato under legume intercrops on P uptake and use efficiency indices: P harvest index (PHI), P uptake efficiency (PuPE), P partial factor productivity (PPFP) and P partial balance (PPB). The experiment was carried out for four consecutive seasons with treatments comprising potato cultivated under legume intercrops: none (T1), dolichos (Lablab purpureus L) (T2), peas (Pisum sativum L) (T3) and beans (Phaseolus vulgaris L) (T4). Across the seasons, the mean haulm P uptake for T2 (6.7 kg P ha 1 ), T4 (5.5) and T3 (4.5) were 6%, 23% and 36% lower than that observed in T1 (7.1 kg P ha 1 ), respectively. On the other hand, tuber P uptake was highest in T1 (21.8 kg P ha 1 ) and T2 (21.3 kg P ha 1 ) and were significantly higher than 13.2 kg P ha 1 in T3 and 15.1 kg P ha 1 in T4. This had a profound effect on PuPE, which was equally highest in T1 (0.26 kg total P uptake kg 1 P supply) and T2 (0.25) and lowest in T3 (0.16) and T4 (0.18). Similarly, PPFP, PHI and PPB followed a similar trend, with highest values in T1 (57 kg tuber dry matter yield kg 1 P supply, 76.4 kg tuber P uptake kg 1 total plant’s P uptake and 0.20 kg tuber P uptake kg 1 P supply, respectively). Among the tested legume intercrops, dolichos competed least for P with the main crop (potato) hence it can be integrated into potato-based cropping systems without compromising potato tuber yield.
Castor Meal and Ground Hydrothermalized Phonolite Optimize Sweet Potato Nutrition, Yield, and Quality
(MDPI, 2024-07-23) Parecido, Renan J.; Soratto, Rogério P.; Fernandes, Adalton M.; Blanes, Mayara C.; Fidelis, Luis G.; Gitari, Harun I.; Dutra, Sérgio G.
To assess the effect of pure castor meal and a mixture of castor meal with ground hydrothermalized phonolite rock (CM+HP mixture) in providing nutrients, particularly N and K, and optimizing yield and quality of sweet potato, a field experiment was conducted using a randomized block design. Treatments were the absence and presence of synthetic N and K fertilizers (ammonium nitrate and KCl) combined with rates of organic fertilizers (1.2 and 2.4 Mg ha−1 of castor meal, 2.25 and 4.5 Mg ha−1 of CM+HP mixture, plus a treatment without organic fertilizers). The CM+HP mixture maintained adequate N and K status in plant leaves. Organic fertilizers increased the number of storage roots per plant and the sweetness of the storage roots, while synthetic fertilizers increased the storage root mean weight. Castor meal combined with synthetic fertilizers improved soil health (increased organic matter and enzyme activity in the soil). The combined application of synthetic fertilizerswith2.4Mgha−1 ofcastormealor4.5Mgha−1 of CM+HP mixture had the greatest benefit on storage root yield, with an average increase of 128% (10.9 Mg ha−1) on marketable storage root yield, and the nutrient removal compared with the sole application of organic fertilizers
Controlling soil erosion in smallholder potato farming systems using legume intercrops
(Elsevier B.V., 2019) Nyawade, Shadrack O.; Gachene, Charles K. K.; Karanja, Nancy; Gitari, Harun I.; Schulte-Geldermann, Elmar; Parker, Monica L.
Soil and nutrient losses due to soil erosion are pronounced in potato growing areas of East Africa due largely to the rugged topography and high soil disturbance associated with potato cultivation. This study intercropped potato (SolanumtuberosumL.)with three grain legumes: lablab bean (Lablab purperous L.), garden pea (Pisumsativa L.) and climber bean(Phaseolus vulgaris L.) in runoff plots and assessed their impact on soil and nutrient losses in central Kenya highlands. Bare plots and sole potato stands were included as controls. Vegetal cover was measured at different potato growth stages while runoff and soil loss were quantified at every runoff generating event and used for nutrient analyses. Yieldswere expressed as potato equivalents (PEY) at the end of each season. Mean cumulative sediment yield decreased from 169 t/ ha in sole potato plots to 50–83 t/ ha in potato-legume intercropping, representing a reduction of 51–70%. The eroded sediment exported in large quantity the SOC (16.6–39.5 kg C ha−1 yr−1), N (5.5–29.8 kg N ha−1 yr−1), P (3.9–16.4 kg P ha−1 yr−1) and K (5.2– 14.6 kg K ha−1 yr−1) and were consistently higher in sole potato plots relative to potato-legume intercropping. These losses occurred mainly at potato emergence following fertilizer application. Stronger associations of sediment nutrient enrichments was found with the micro-aggregates (250–50 μm) than with themacro-aggregates (N250 μm) pointing to the different degree of nutrient mobilization and distribution in eroded sediment. The PEY were significantly greater in potato-lablab bean systemthan in sole potato,while intercroppingwith garden pea and climber bean showed similar PEY to that of sole potato, suggesting that potato-lablab system may be preferred by the smallholder farmers. These results justify the need to intercrop potato with indeterminate legume intercrops, a strategy that must be done in a way guaranteeing high yield stability to the smallholder farmers.
Crop Water Productivity and Economic Return of Rain Fed Potato-Legume Intercropping Systems
(University of Montenegro, 2020) Gitari, Harun I.; Kamau, Solomon; Nyawade, Shadrack
Reliance on rain-fed potato-legume intercropping systems among resource constrained smallholder farmers is usually ineffective without considering their economic viability. A field experiment conducted at the University of Nairobi, Kenya, in the growing seasons of 2014 to 2016 evaluated the effect of intercropping potato with legumes on soil moisture content (SMC), evapotranspiration (ET), potato equivalent yield (PEY), net income and crop water productivity (CWP) based on PEY (CWPPEY) and economic returns (CWPE). The treatments comprised of pure potato (Solanum tuberosum L.) stand (PS), potato-dolichos (Lablab purpureus) (PD), potato-garden pea (Pisum sativum) (PG) and potato-bean (Phaseolus vulgaris) (PB). Results showed significantly higher SMC values at tuber initiation stage: 77, 69, 67 and 62 mm in PD, PG, PB and PS, respectively. Fresh tuber yield was highest in PS (36 t ha−1) and PD (35 t ha−1) and lowest in PG (29 t ha−1). PEY was higher under intercropping than monocropping systems. The lowest ET values that were recorded in PS (630 mm) and PG (631 mm) differed significantly from those in PB (636 mm) and PD (642 mm). Potato-dolichos was the most profitable cropping system with a net income of 9,174 US$ ha−1 and a BCR of 5.7 compared to PS (7,436 US$ ha−1) with a BCR of 5.1. CWPPEY varied significantly between cropping systems in the order of PD (6.2 kg ha−1 m−3) > PB (4.7 kg ha−1 m−3) > PG (4.3 kg ha−1 m−3) > PS (2.3 kg ha−1 m−3). A similar trend was observed for CWPE with values of between 1.3 US$ ha−1 m−3 for PD and 1.5 US$ ha−1 m−3 for PS. The study shows that dolichos is a viable legume crop that could be integrated into potato cropping systems to improve their CWP without compromising the tuber yield.
Effect of Cadmium Toxicity on Growth, Oxidative Damage, Antioxidant Defense System and Cadmium Accumulation in Two Sorghum Cultivars
(MDPI, 2020) Hassan, Muhammad Jawad; Raza, Muhammad Ali; Rehman, Sana Ur; Ansar, Muhammad; Gitari, Harun I.; Khan, Imran; Wajid, Muhammad; Ahmed, Mukhtar; Shah, Ghulam Abbas; Peng, Yan; Li, Zhou
Heavy metal stress is a leading environmental issue reducing crop growth and productivity, particularly in arid and semi-arid agro-ecological zones. Cadmium (Cd), a non-redox heavy metal, can indirectly increase the production of reactive oxygen species (ROS), inducing cell death. A pot experiment was conducted to investigate the effects of different concentrations of Cd (0, 5, 25, 50, 100 µM) on physiological and biochemical parameters in two sorghum (Sorghum bicolor L.) cultivars: JS-2002 and Chakwal Sorghum. The results showed that various concentrations of Cd significantly increased the Cd uptake in both cultivars; however, the uptake was higher in JS-2002 compared to Chakwal Sorghum in leaf, stem and root. Regardless of the cultivars, there was a higher accumulation of the Cd in roots than in shoots. The Cd stress significantly reduced the growth and increased the electrolyte leakage (EL), hydrogen peroxide (H2O2) concentration and malondialdehyde (MDA) content in both cultivars, but the Chakwal Sorghum showed more pronounced oxidative damage than the JS-2002, as reflected by higher H2O2, MDA and EL. Moreover, Cd stress, particularly 50 µM and 100 µM, decreased the activity of different antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT). However, the JS-2002 exhibited higher SOD, POD and CAT activities than the Chakwal Sorghum under different Cd-levels. These findings revealed that JS-2002 had a stronger Cd enrichment capacity and also exhibited a better tolerance to Cd stress due to its efficient antioxidant defense system than Chakwal Sorghum. The present study provides the available information about Cd enrichment and tolerance in S. bicolor, which is used as an important agricultural crop for livestock feed in arid and semi-arid regions.
Effect of lime and goat manure on soil acidity and maize (Zea mays) growth parameters at Kavutiri, Embu County- Central Kenya
(Academic Journals, 2015) Gitari, Harun I.; Mochoge, B. E.; Danga, B. O.
A greenhouse pot experiment was conducted to determine the effect of agricultural lime and goat manureon soil acidity and maize growth parameters using soils from Kavutiri-Embu County. Nitrogen and phosphorus fertilizers at the rates of 50 and 70 kg ha-1, respectively, and goat manure at three rates (0, 5 and 10 mg ha-1) and agricultural lime (CaCO3) at six rates (0, 2.5, 5, 7.5, 10, and 12.5 mg ha-1) were used for the study. The pot experiment was arranged in a complete randomised design and replicated three times. Maize, variety H513as test crop, was grown for a period of 8 weeks. The results were measured on maize crop parameters (plant heights, root lengths and dry matter biomass) and soil parameters (soil pH and exchangeable acidity). All the biophysical data generated were subjected to analysis of variance (ANOVA) and the difference between the treatments means separated using the Fischer’s least significant difference at 5% probability level. Linear correlation analyses were done using the Microsoft Excel 2010. Results generally showed that soil acidity decreased with increasing levels of manure and lime. The treatment with 12.5 Mg ha-1 of lime and 10 Mg ha-1 of manure had the best reducing effect on soil acidity and better maize yield performances reflected in the highest pH (6.3), highest root length (41.3 cm), plant height (150.3 cm) and dry biomass weight (755.4 kg ha-1) obtained.
Enhancing Climate Resilience of Rain-Fed Potato Through Legume Intercropping and Silicon Application
(Frontiers in Sustainable Food Systems, 2020) Nyawade, Shadrack; Gitari, Harun I.; Karanja, Nancy N.; Gachene, Charles K. K.; Schulte-Geldermann, Elmar; Sharma, Kalpana; Parker, Monica L.
A large portion of sub-Saharan Africa is situated in belts of uncertain rainfall and are characterized by low soil fertility with limited capacity to adapt to andmitigate the impacts of climate change. A field study was conducted in the semi-humid potato-growing belt of Kenya to test the effect of legume intercropping and water soluble silicon (orthocilicic acid) on soil erosion, and use efficiency of light and water. Potato (Solanum tuberosum L.) was grown singly and intercropped with dolichos (Lablab purpureus L.) or hairy vetch (Vicia sativa L.). Each cropping system was subjected to granular water-soluble silicon (Si) amendment at two rates [2.5 kg Si ha−1 (+Si) vs. 0 kg Si ha−1 (–Si)]. Plants receiving Si maintained significantly higher (p < 0.05) percent relative leaf water content (62–89% vs. 52–72% in controls) and exhibited higher concentrations of proline (1.99–2.91 vs. 1–1.19 umol g−1), soluble carbohydrates (28–59 vs. 10–28 umol g−1) and electrolyte conductance (1,409–3,903 vs. 746–2,307mS cm−1). Legume intercropping enhanced groundcover establishment and reduced soil and nutrient losses by 45–80% compared with sole potato. Crop yields were 2–3-fold greater in intercropping relative to sole potato and were significantly greater in treatments subjected to Si application. Land equivalent ratios were above unity in intercropping but less than unity in sole potato, and were 8–20% increased by Si application. Use efficiency of water (5.99–9.09 Kg ha−1 m−3) and light (1.98–2.98 g MJ−1) were significantly greater under legume intercropping compared with sole potato (1.13–3.23 Kg ha−1 m−3 and 0.77–0.98 g MJ−1, respectively) and increased with Si application. Integrative use of Si and legume intercropping presents the smallholder farmers an opportunity to increase productivity of potato while enhancing resource use efficiency and soil fertility in the semi-humid tropics.
Enhancing germination and seedling growth of barley using plasmaactivated water (PAW) with neutralized pH
(taylor & Francis, 2024-07-31) Seleiman, Mahmoud F.; Ali, Nawab; Nungula, Emmanuely Z.; Gitari, Harun I.; Alhammad, Bushra A.; Battaglia, Martin l.
achieving the highest seed germination and seedling growth rates is of paramount importance to maximize overall crop productivity. among different technologies aiming at increasing seed germination and early plant growth, cold atmospheric pressure plasma (Cap) and plasma-activated water (paW) are two of the most promising. however, Cap has been shown to decrease the ph of water, potentially constraining the utility of paW in applications involving ph-sensitive plants. here, we assessed the impact of magnesium addition to paW (Mg-paW), a potential mitigator of water acidity, on barley germination and growth compared to Cap technology without Mg (paW). although seed germination increased with both treatments compared to just Di water (control), the increase was higher when Mg-paW was added, increasing by 2.29 and 2.59 times on day 2 and day 3. application of Mg-paW also increased water absorption, seedling growth (both in terms of weight and length), concentrations of chlorophyll, carotenoids, total soluble protein and enzymatic activities compared to both the control and the paW treatment. the Mg-paW displayed a 1.8-fold higher total soluble protein level compared to paW alone. although both treatments reduced Malondialdehyde (MDa) content, a prominent stress marker in plants, Mg-paW application resulted in a 46% higher reduction in MDa content than paW alone. also, Mg-paW application increased superoxide dismutase (SoD) activity by 50%, and catalase (Cat) enzyme activity by 8% compared to paW alone. the implications of these discoveries extend to different agricultural applications, offering a promising avenue for improved early plant growth using Mg-paW technologies under neutral or near-to-neutral ph conditions.
Increasing potato equivalent yield increases returns to investment under potato-legume intercropping systems
(De Gruyter, 2019-11) Gitari, Harun I.; Nyawade, Shadrack O.; Kamau, Solomon; Gachene, Charles K. K.; Karanja, Nancy N.; Schulte-Geldermann, Elmar
In order to enhance sustainable intensification of potato-based cropping systems, especially in sub-Saharan Africa (SSA), there is a need to investigate the economic viability of investing in this lucrative venture. This study evaluated the economic returns under legume intercropping systems using value/cost ratio (VCR) and benefit/cost ratio (BCR) under treatments comprising of potato intercropped with dolichos (Lablab purpureus L.) (P-D), climbing bean (Phaseolus vulgaris L.) (P-B) and garden pea (Pisum sativum L.) (P-G), and a potato pure stand control (P-S). Across the seasons, tuber yield was not significantly (p < 0.05) affected by intercropping with P-D, whereas under P-B and P-G, it decreased by 19% and 16%, respectively compared to P-S. P-G, P-B and P-D recorded 6, 7 and 12% higher potato equivalent yield (PEY) relative to P-S. P-D was the most profitable intercropping system with VCR of 35 and BCR of 5.1 as compared to values recorded in P-S of 31 and 5, respectively. Regression of VCR against PEY resulted in a stronger coefficient (0.98) compared to that of BCR against PEY (0.82) implying that VCR is a simple tool that could be adopted for economic returns to investment studies such as potato-legume intercropping systems.
Insect frass fertilizer as a regenerative input for improved biological nitrogen fixation and sustainable bush bean production
(Frontiers, 2024-09-05) Chepkorir,Agnes; Beesigamukama, Dennis; Gitari, Harun I.; Chia, Shaphan Y.; Subramanian, Sevgan; Ekes, Sundayi; Abucheli, Birachi Eliud; Rubyogo, Jean Claude; Zahariadis, Theodore; Athanasiou, Gina; Zachariadi, Aikaterini; Zachariadis, Vasileios; Tenkouano, Abdou; Tanga, Chrysantus M
Bush bean (Phaseolus vulgaris L.) production is undermined by soil degradation and low biological nitrogen fixation (BNF) capacity. This study evaluated the effect of black soldier fly frass fertilizer (BSFFF) on bush bean growth, yield, nutrient uptake, BNF, and profitability, in comparison with commercial organic fertilizer (Phymyx, Phytomedia International Ltd., Kiambu, Kenya), synthetic fertilizer (NPK), and rhizobia inoculant (Biofix, MEA Fertilizers, Nairobi, Kenya). The organic fertilizers were applied at rates of 0, 15, 30, and 45 kg N ha−1 while the NPK was applied at 40 kg N ha−1, 46 kg P ha−1, and 60 kg K ha−1. The fertilizers were applied singly and in combination with rhizobia inoculant to determine the interactive effects on bush bean production. Results showed that beans grown using BSFFF were the tallest, with the broadest leaves, and the highest chlorophyll content. Plots treated with 45 kg N ha−1 BSFFF produced beans with more flowers (7 – 8%), pods (4 – 9%), and seeds (9 – 11%) compared to Phymyx and NPK treatments. The same treatment also produced beans with 6, 8, and 18% higher 100-seed weight, compared to NPK, Phymyx, and control treatments, respectively. Beans grown in soil amended with 30 kg N ha−1 of BSFFF had 3–14-fold higher effective root nodules, fixed 48%, 31%, and 91% more N compared to Phymyx, NPK, and rhizobia, respectively, and boosted N uptake (19 – 39%) compared to Phymyx and NPK treatments. Application of 45 kg N ha−1 of BSFFF increased bean seed yield by 43%, 72%, and 67% compared to the control, NPK and equivalent rate of Phymyx, respectively. The net income and gross margin achieved using BSFFF treatments were 73 – 239% and 118 – 184% higher than the values obtained under Phymyx treatments. Our findings demonstrate the high efficacy of BSFFF as a novel soil input and sustainable alternative for boosting BNF and improving bush bean productivity.
Intercropping Optimizes Soil Temperature and Increases Crop Water Productivity and Radiation Use Efficiency of Rainfed Potato
(Springer Verlag, 2019) Nyawade, Shadrack O.; Karanja, Nancy N.; Gachene, Charles K. K.; Gitari, Harun I.; Schulte-Geldermann, Elmar; Parker, Monica L.
Integrating crop species with different photosynthetic pathways has great potential to increase efficiency in the use of scarce resources. In order to tap the resource complementarity emanating from this mix, this study intercropped potato (Solanum tuberosum L.) with lima bean (Phaseolus lunatas L.) and dolichos (Lablab purpureous L.), and related soil temperature with radiation use efficiency and crop water productivity of rainfed potato in the upper midland (1552 m above sea level (masl), lowerhighland (1854 masl) and upper-highland (2553 masl)) agro-ecological zones of Kenya. Leaf area index (LAI), light interception, soil temperature and soil water contents (SWC) were quantified at different stages of potato growth and related with the radiation use efficiency (RUE) and crop water productivity (CWP) of potato. Intercropping increased crop LAI by 26–57% relative to sole potato stands and significantly lowered the soil temperatures in the 0–30 cm depth by up to 7.3 °C. This caused an increase in SWC by up to 38%, thus increasing RUE by 56–78% and CWP by 45–67%. Intercropping potato with legumes is coupled with optimum root-zone soil temperature and soil water content, thus potentially exerting additive relations in radiation interception and subsequent conversion into crop biomass.
Intercropping Potato with Grain Legumes for Enhanced Productivity and Climate Change Adaptation in Smallholder Farms, Kenya
(Regional Universities Forum for Capacity Building in Agriculture, 2018) Nyawade, Shadrack; Gitari, Harun I.; Karanja, Nancy N.; Gachene, Charles K. K.; Geldermann, E.; Parker, M.
This study evaluated the effect of potato-grain legume intercropping systems on best land equivalent yield ratios, crop water productivity and net profits in field trials conducted in three agro-ecologies of Kenya: upper highland with seasonal rainfall of 592 mm and altitude of 2550 m, lower highland (505 mm, 1879 m) and lower midland (356 mm, 1522 m) in 2017 rainy seasons. Shangi and Unica the most common potato variety in Kenya, and a drought and heat tolerant variety, respectively, were grown alone and intercropped with the deep rooting legumes, Dolichos (Lablab purperous) and Lima bean (Phaseolus lunatus). Whereas the potato varieties had similar yields in the traditional highland growing zone, the heat and drought tolerant Unica performed significantly better in a typical semi-arid midland agro-ecology. Intercropping systems with lima bean and Unica potato variety increased crop water productivity by 38% compared to the pure Unica cropping system and maintained soil moisture content above 33% during flowering and tuberization stages at all sites. This resulted in significantly higher dry matter equivalent yields of 3.21 ± 0.12 ha-1 compared to pure stands (1.98 ± 0.21 ha-1) and when intercropped with Dolichos (1.11 ± 0.23 ha-1) in the low midland zone. This system (Unica + Lima bean) recorded the highest net profits of USD 3,324 ± 143 ha-1 across the three agro-ecologies. These results reveal a strong effect of Unica potato genotype and environment interaction, and show that intercropping a heat and drought tolerant potato variety with lima bean is an excellent option for improved resource use efficiency in non-mechanized smallholder farming systems. This strategy can diversify potato production to mid-elevation agro-food systems and mitigate events of climate change in traditional growing regions.
Lime and Manure Application to Acid Soils and their Effects on Bio-Chemical Soil Properties and Maize Performance at Kavutiri - Embu County
(2014-02-22) Gitari, Harun I.; Danga, B. O.; Mochoge, B.O.
Soil acidity is widespread globally, accounting for about 40% of total arable soils. In Kenya, acid soils cover about 13% of total land area and are distributed widely in the croplands of central and western Kenya regions, covering over one million hectares. The main limitation of crop productivity in Kavutiri, Embu, is soil acidity and more specifically aluminium toxicity. The objective of this study was to determine the effects of agricultural lime in combination with farmyard manure (FYM) on soil properties (exchangeable acidity, pH, and microbial biomass) and maize growth. The treatments include: goat manure at 3 levels (0, 5 and 10 Mg ha-1) and agricultural lime (CaCO3) at 6 rates (0, 2.5, 5, 7.5, 10, and 12.5 Mg ha-1). The study was carried out in two phases. Phase 1 was carried out at the greenhouse with pots arranged in a complete randomised design (CRD) and replicated thrice while phase 2 was carried out on a farmer’s field at Kavutiri where the soil samples for phase 1 were taken. Only the best three performing treatments in phase 1 were selected and verified during phase 2 in a complete randomised block design (CRBD) with three replicates. In each phase, maize was the test crop and was grown for a period of 8 weeks. The biophysical data generated from the study was analysed using Analysis of Variance (ANOVA) in Genstat statistical package. Treatment means were compared at probability p< 0.05 using Fischer’s least significant difference (L.S.D). Results of this study indicate that soil acidity decreased with increase in manure and lime levels. The treatment M10L12.5 –with 10 Mg ha-1 of manure and 12.5 Mg ha-1 of lime - recorded the highest pH of 6.3 and 5.9 for greenhouse and field trials, respectively. Maize growth parameters (root length, height and biomass dry weight) were found to increase significantly as levels of manure and lime increased. Treatment M10L12.5 from greenhouse trial recorded the highest values for root length (41.3 cm), height (150.3cm) and dry biomass weight of 755.4 Kg ha-1. Microbial biomass was found to be higher in the field than in greenhouse trials with the highest value of 28.8 × 105 and 26.7 × 103 Colony forming units (CFU) for bacteria and fungi, respectively. This marked significant increases (P < 0.05) of 772.7 and 86.6% for bacteria and fungi, respectively above the control. From the study, it was concluded that combining 10 Mg ha-1 of FYM and 12.5 Mg ha-1 of agricultural lime could be a promising alternative amendment for acid soil management strategy for increased maize production at Kavutiri and other related soils in Kenya.
Optimizing soil nitrogen balance in a potato cropping system through legume intercropping
(Springer, 2020) Nyawade, Shadrack O.; Karanja, Nancy N.; Gachene, Charles K. K.; Gitari, Harun I.; Schulte-Geldermann, Elmar; Parker, Monica
Negative nitrogen balance represents a major factor causing low potato yield in potato growing areas of Kenya while its excessive surplus poses a significant environmental concern. In order to synchronize this tradeoff, a field trial integrating potato (Solanum tuberosum L.) with lima bean (Phaseolus lunatus L.) and dolichos (Lablab purpureus L.) in intercropping system was conducted in the upper midland [1552 m above sea level (masl), lower highland (1894 masl) and upper highland (2552 masl)] agro-ecological zones of Kenya. Nitrogen gains from mineralization, fertilization, biological fixation, and outputs from biomass accumulation, leaching, volatilization and soil erosion were quantified using standard procedures. Soil N balance ranged from - 10.7 to - 18.1 kg N ha-1 for sole potato, 4.1 to 6.6 kg N ha-1 for intercropping and 2.9 to 22.3 kg N ha-1 for sole legumes. The intermediate range of polyphenol and lignin contents in intercropping enhanced N mineralization with peak N release of 8 to 9 kg N ha-1 matching with peak N uptake by potato (19.9 to 31.2 kg N ha-1). Nitrate was leached below the active root zone in sole potato cropping (4.2 to 46.6 kg N ha-1), a process that was diverged by the deep root systems of legume intercrops. These results suggest that legume intercropping can provide a means of balancing the nitrogen retained in the biomass and soil, thus offering a mechanism for optimizing the soil N balance in smallholder potato farming systems.
Optimizing Sunflower Production Through the Use of GIS-Based Soil Fertility Management Strategy
(Taylor & Francis Group, 2024-08) Nungula, Emmanuely Z.; Massawe, Boniface J.; Chappa, Luciana R.; Nhunda, Daniel M.; Seleiman, Mahmoud F.; Ali, Nawab; Gitari, Harun I.
This study aimed to use a GIS-based approach in producing soil fertility maps and utilize the spatial data on achieving site-specific management of major nutrients in Morogoro, Tanzania. Soil samples were collected in six mapping units and analyzed for chemical properties such as pH, cation exchange capacity and electrical conductivity. ArcGIS 10.8 was used to produce nutrient variability maps of organic carbon, available P, total nitrogen and exchangeable K, Ca and Mg using the Inverse Distance Weight (IDW) interpolation method. The soil pH values ranged from 5.5 to 7.2. OC varied between 1.2 and 4.9g kg−1, TN ranged from low to medium (1.0 to 5.0g kg−1) whereas Av. P varied between l3.3 and 14.3mg kg−1. Exchangeable K, Ca and Mg had ranges (in cmol kg−1) of between 0.1 to 0.8 (low to medium), 3.8 to 15.6 (low to high) and 0.3 to 0.5 (low), cmol kg−1. The recommended amounts were 74, 44, 36, 35 and 12kg ha−1 for N, P2O5, K2O, MgO and CaO, respectively. Conducting soil analysis is key for monitoring the amount of nutrients that are available in the soil at time and space, to achieve site-specific nutrient management.
Optimizing sunflower production through the use of GIS-based soil fertility management strategy
(taylor & Francis, 2024-07-31) Nungulaa, Emmanuely Z.; Massaweb, Boniface J.; Chappac, Luciana R.; Nhundab, Daniel M.; Seleimand, Mahmoud F.; Alie , Nawab; Gitari, Harun I.
this study aimed to use a GiS-based approach in producing soil fertility maps and utilize the spatial data on achieving site-specific management of major nutrients in Morogoro, Tanzania. Soil samples were collected in six mapping units and analyzed for chemical properties such as ph, cation exchange capacity and electrical conductivity. arcGiS 10.8 was used to produce nutrient variability maps of organic carbon, available p, total nitrogen and exchangeable K, ......
Potato-legume intercropping on a sloping terrain and its effects on soil physico-chemical properties
(Springer International Publishing, 2019) Gitari, Harun I.; Gachene, Charles K. K.; Karanja, Nancy N.; Kamau, Solomon; Nyawade, Shadrack; Schulte-Geldermann, Elmar
Aims: To assess the effects of potato-legume intercropping on selected soil physical and chemical properties after four consecutive growing seasons (from the short rains in 2014 to long rains 2016). Methods: The experiment was laid out in a randomised complete block design with four replicates. The treatments were potato-dolichos (PD); potato-garden pea (PG); potato-bean (PB) intercropping systems, and a pure stand of potato (PS). After every harvest, crop residues were ploughed back and selected soil physico-chemical properties were assessed after two years of cultivation. Results: Potato-legume intercropping resulted in a significant increase down the slope for clay and silt under PS, PG and PB whereas, an opposite observation was made for sand and bulk density. Nonetheless, under PD, slope position had no significant effect on soil physical properties. In all cropping systems, a significant increase was observed down the slope for pH and cation exchange capacity. Similar observations were made for phosphorous, nitrogen and organic carbon under all the cropping systems except PD. Conclusions: This study has established PD as a viable intercropping system, which could be adopted by farmers for improved soil fertility.
Revisiting Intercropping Indices with Respect to Potato-legume Intercropping Systems
(Elsevier, 2020) Gitari, Harun I.; Nyawade, Shadrack O.; Kamau, Solomon; Karanja, Nancy N.; Gachene, Charles K. K.; Raza, Muhammad A.; Maitra, Sagar; Schulte-Geldermann, Elmar
Intercropping is gaining popularity in developing countries as a viable strategy for diversifying cropping systems to ease food insecurity, given that arable land is shrinking, and demand for food crops is increasing due to rapid population growth. A field experiment was conducted in 2015 and 2016, to examine the biological and economic viability of two intercropping systems (potato-dolichos and potato-bean planted in two potatoes to legume population density ratios: 1.1:2 and 1: 2.4) and their corresponding pure stands. Intercropping systems were also evaluated based on five competition indices: relative crowding coefficient (K), aggressivity (A), competitive ratio (CR), intercropping advantage (IA) and actual yield loss (AYL). Although biological feasibility revealed that intercropping decreased the yield of intercrops compared with respective monocultures; the economic assessment of different cropping systems indicated that intercropping resulted in a higher remuneration (gross and net income) than pure stands. Intercropping potato with a high population of legume (in 1: 2.4 patterns), resulted in not only higher system productivity but also potato equivalent yield compared to 1.1:2. Intercropping proved to be advantageous with AYL decreasing with increasing proportion of the legumes, whereas IA increased as the population of legumes increased. With regard to competition between the intercrops, the potato was more aggressive (A of potato was positive, and its CR > 1) in all cropping systems, and it dominated over legume (that had negative A values and CR < 1). Aggressivity and dominance capacity was higher in 1: 2.4 than 1.1:2 series. These results suggest that potato-legume intercropping may provide viable intensification options, especially for smallholder farmers.
Short-term dynamics of soil organic matter fractions and microbial activity in smallholder potato-legume intercropping systems
(Elsevier B.V., 2019) Nyawade, Shadrack O.; Karanja, Nancy; Gachene, Charles K. K.; Gitari, Harun I.; Schulte-Geldermann, Elmar; Parker, Monica L.
Continuous cultivation of potato (Solanum tuberosum L.) in monoculture systems represents the greatest factor deteriorating soil organic matter (SOM) in smallholder farms. With an aim to breaking this norm, a 2-year field trial intercropping potato with two legumes: lima bean (Phaseolus lunatus) and dolichos (Lablab purpureus), was conducted in the upper-midland (1552 meters above sea level (masl.)), lower-highland (1854 masl.) and upperhighland (2552 masl.) agro-ecologies of Kenya. Residues from each cropping system were quantified at the end of each season and incorporated back into the soil at start of the subsequent season. A combined physical and density fractionation was used to separate the soil in macro-aggregates (> 250 μm), micro-aggregates (250–50 μm) and silt plus clay fractions (< 50 μm), while SOM was partitioned into labile (density of 1.65 to 1.85 g cm−3) and stable (2.60 g cm−3) fractions. Microbial biomass contents were determined by chloroform fumigation while enzymatic activities were assessed by hydrolyses of fluorescein diacetate and dehydrogenase. Compared to sole potato, intercropping increased the contents of light fraction organic matter by 12–28%, dissolved organic matter by 7–21% and microbial biomass by 15–38%, thus stimulating enzyme activities. Trends in soil microbial respiration followed those of enzyme activity and were 20–34% higher in intercropping than in sole potato. Intercropping ensured high residue returns which got short-term residence within the macroaggregates, thus ensuring steady supply of substrates to the soil microbes. These results affirm legume intercropping as a possible entry point to restoring the impoverished soil quality in smallholder potato farming systems.
Silicon Exerts Additive Effects on Phosphorus Acquisition by Potato Intercropped with Chickpea
(University of Montenegro, 2020) Nyawade, Shadrack; Gitari, Harun I.; Kamau, Solomon
The role played by silicon (Si) and legume intercropping in nutrient acquisition by potato crop has been neglected in most studies. A field trial integrating potato (Solanum tuberosum L.) with chickpea (Cicer arietinum L.) in intercropping system was conducted over six (6) growing seasons in the upper midland (1552 m above sea level) agro-ecological zone of Kenya. The intercropped chickpea secreted enzyme phosphatase into the rhizosphere (5.1–27.1 mol g–1 fwt h–1) thus mobilizing organic (4.2–18.9 mg kg–1 soil) and inorganic phosphorus (6.9–42.8 mg kg–1 soil). This increased phosphorus availability and acquisition by the intercropped potato. Chickpea took up more cations than anions, resulting in net proton efflux (43–105 mmol kg soil–1) with a significant decrease in rhizosphere pH. This acidic medium enhanced Si solubilization, increasing Si+ ions, which competed with Fe3+ and Al3+ ions for specific soil phosphorus sorption sites. Provision of sustainable seed supply systems for chickpea and market linkages for water-soluble silicon are necessary for adoption of this innovation.

Browsing by Author "Gitari, Harun I."

Results Per Page

Sort Options