scholarly journals Evaluation on maturity and stability of organic fertilisers in semi-arid Ethiopian Rift Valley

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shiro Mukai ◽  
Wataru Oyanagi
Keyword(s):  
Rift Valley ◽  
Field Application ◽  
Sub Saharan Africa ◽  
Site Quality ◽  
Ethiopian Rift ◽  
Weed Seeds ◽  
Probable Presence ◽  
Organic Fertilisers ◽  
Sub Saharan ◽  
Semi Arid

AbstractCase studies that have comprehensively examined local organic fertilisers (OFs) for their maturity and stability are rare in sub-Saharan Africa. Farmers in the semi-arid Ethiopian Rift Valley use indigenous compost (kosi) and household wastes for OFs. With the entry of fast compost that was introduced by the administration, maturity and stability of these OFs were assessed. Their maturity was assessed by: monitoring pile temperature and volume, pH, organic matter and total nitrogen contents, and carbon to nitrogen ratio; determination of NO3– to NH4+ ratio; and respirometric measurement of CO2 evolution. Their stability was assessed by weed seed germination tests and phytotoxicity bioassays. Weed seeds that were originally contained in the feedstock of the kosi and fast compost samples became inactive during the composting process. The CO2 evolution tests and phytotoxicity bioassays indicated a probable presence of some phytotoxic compounds in the kosi. Mature kosi and immature kosi in a kosi pile should be mixed before the field application. Some samples (15%) of the household wastes contained weed seeds. The combination of several assessment methods used in this study and determination methods for nitrogen components using RQ-flex is considered to be effective for on-site quality assessment of OFs in sub-Saharan Africa.

scholarly journals Decomposition characteristics of indigenous organic fertilisers and introduced quick compost and their short-term nitrogen availability in the semi-arid Ethiopian Rift Valley

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Shiro Mukai ◽  
Wataru Oyanagi
Keyword(s):  
Organic Matter ◽  
Rift Valley ◽  
Nitrogen Availability ◽  
Sub Saharan Africa ◽  
Ethiopian Rift ◽  
Soluble Nitrogen ◽  
Nitrogen Mineralisation ◽  
Short Term ◽  
Analysis Methods ◽  
Organic Fertilisers

Abstract Case studies on the assessment of local organic fertilisers (OFs) in their quality (decomposition characteristics and nutrient availability for crops) are few in sub-Saharan Africa (SSA). This study assessed the quality of local OFs from the Ethiopian Rift Valley. The decomposition characteristics were assessed by acid detergent fibre analysis methods, while the short-term nitrogen availability was assessed by a combination of laboratory incubations and inorganic nitrogen and acid detergent soluble nitrogen determinations. A commercial hand-held reflectometer (RQFlex) was used for determining nitrogen components. The mean acid detergent soluble organic matter contents exceeded 250 mg g−1, indicating the OF feedstock contained much of the readily decomposable organic matter. Some of the indigenous compost (kosi) samples showed net nitrogen immobilisation during the initial period of incubation, followed by net nitrogen mineralisation in one month of incubation with 4% of the nitrogen mineralisation rate. Kosi should be applied to a field one month before seeding. Short-term nitrogen availability from kosi was too low to substitute for inorganic fertilisers. The combination of the simple analysis methods shown in this study is a quick, cost-saving, and accurate quality assessment approach for OFs, which can be useful in the field and at experimental stations in SSA.

scholarly journals A Strategy for Technology Development for Semi-Arid Sub-Saharan Africa

1998 ◽  
Vol 27 (3) ◽  
pp. 157-161
Author(s):  
John H. Sanders ◽  
Barry I. Shapiro ◽  
Sunder Ramaswamy
Keyword(s):  
Development Strategy ◽  
Water Availability ◽  
New Technologies ◽  
Technology Development ◽  
Organic Fertilizer ◽  
Sub Saharan Africa ◽  
Inorganic Fertilizers ◽  
Strategy Evaluation ◽  
Sub Saharan ◽  
Semi Arid

This article proposes a strategy for agricultural technology development for semi-arid West Africa. The strategy evaluation consists of two aspects: a) a review of the successes in the region; and b) analysis with mathematical programming of the potential impacts and constraints to various new technologies tested in the region. The technology development strategy indicates how further productivity gains can be made by responding to the two principal constraints of water availability and soil fertility. These constraints must be simultaneously resolved but the strategy needs to be adapted for different soil characteristics and economic environments. The major emphasis is on the importance of the rapid introduction of inorganic fertilizers combined with techniques to increase water availability; organic and inorganic fertilizers need to be considered complements in the semi-arid regions. Farmers are already introducing labour intensive variations of these techniques in the most degraded regions. The policy concern is to encourage government policymakers to put a high priority on fertilizer and increase the availability of inorganic fertilizer while research efforts continue to develop improved methods for complementary use of organic fertilizer.

Focused groundwater recharge in a dryland environment: hydrometric and isotopic evidence from central Tanzania

2020 ◽  
Author(s):  
David Seddon ◽  
Japhet J. Kashaigili ◽  
Richard G. Taylor ◽  
Mark O. Cuthbert ◽  
Lucas Mihale ◽  
...  
Keyword(s):  
Groundwater Recharge ◽  
Surface Waters ◽  
Poverty Alleviation ◽  
Managed Aquifer Recharge ◽  
Sub Saharan Africa ◽  
Aquifer Recharge ◽  
Ephemeral Stream ◽  
Groundwater Levels ◽  
Sub Saharan ◽  
Semi Arid

<p>Groundwater, and its replenishment via recharge, is critical to livelihoods and poverty alleviation in drylands of sub-Saharan Africa and beyond, yet the processes by which groundwater is replenished remain inadequately observed and resolved. Here, we present three lines of evidence, from an extensively-monitored wellfield in central semi-arid Tanzania, indicating focused groundwater recharge occurring via leakage from episodic, ephemeral stream discharges. First, the duration of ephemeral streamflow observed from daily records from 2007 to 2016 correlates strongly (R<sup>2</sup> = 0.85) with the magnitude of groundwater recharge events observed and estimated from piezometric observations. Second, high-resolution (hourly) monitoring of groundwater levels and stream stage, established in advance of the 2015-16 El Niño, shows the formation and decay of groundwater mounds beneath episodically inundated adjacent streambeds. Third, stable-isotope ratios of O and H of groundwater and precipitation as well as perennial and ephemeral surface waters trace the origin of groundwater to ephemeral stream discharges. The identification and characterisation of focused groundwater recharge have important implications not only, locally, for protecting and potentially augmenting replenishment of a wellfield supplying the capital of Tanzania through Managed Aquifer Recharge but also, more widely, in understanding and modelling groundwater recharge in dryland environments.</p>

Green biomass and rainfall in semi-arid sub-Saharan Africa

1988 ◽  
Vol 15 (3) ◽  
pp. 245-252 ◽  
Author(s):  
H.E. Dregne ◽  
C.J. Tucker
Keyword(s):  
Sub Saharan Africa ◽  
Sub Saharan ◽  
Semi Arid

scholarly journals Effect of legume intercropping on N<sub>2</sub>O emissions and CH<sub>4</sub> uptake during maize production in the Great Rift Valley, Ethiopia

2020 ◽  
Vol 17 (2) ◽  
pp. 345-359
Author(s):  
Shimelis Gizachew Raji ◽  
Peter Dörsch
Keyword(s):  
Rift Valley ◽  
Crop Production ◽  
Growing Season ◽  
Maize Yield ◽  
Sub Saharan Africa ◽  
Ethiopian Rift ◽  
N2o Emissions ◽  
Mineral N ◽  
Total N ◽  
N Input

Abstract. Intercropping with legumes is an important component of climate-smart agriculture (CSA) in sub-Saharan Africa, but little is known about its effect on soil greenhouse gas (GHG) exchange. A field experiment was established at Hawassa in the Ethiopian rift valley, comparing nitrous oxide (N2O) and methane (CH4) fluxes in minerally fertilized maize (64 kg N ha−1) with and without Crotalaria (C. juncea) or lablab (L. purpureus) as intercrops over two growing seasons. To study the effect of intercropping time, intercrops were sown either 3 or 6 weeks after maize. The legumes were harvested at flowering, and half of the aboveground biomass was mulched. In the first season, cumulative N2O emissions were largest in 3-week lablab, with all other treatments being equal to or lower than the fertilized maize mono-crop. After reducing mineral N input to intercropped systems by 50 % in the second season, N2O emissions were comparable with the fully fertilized control. Maize-yield-scaled N2O emissions in the first season increased linearly with aboveground legume N yield (p=0.01), but not in the second season when early rains resulted in less legume biomass because of shading by maize. Growing-season N2O-N emission factors varied from 0.02 % to 0.25 % in 2015 and 0.11 % to 0.20 % in 2016 of the estimated total N input. Growing-season CH4 uptake ranged from 1.0 to 1.5 kg CH4-C ha−1, with no significant differences between treatments or years but setting off the N2O-associated emissions by up to 69 %. Our results suggest that leguminous intercrops may increase N2O emissions when developing large biomass in dry years but, when mulched, can replace part of the fertilizer N in normal years, thus supporting CSA goals while intensifying crop production in the region.

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