scholarly journals Effect of legume intercropping on N<sub>2</sub>O emission and CH<sub>4</sub> uptake during maize production in the Ethiopian Rift valley

2019 ◽  
Author(s):  
Shimelis G. 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 three or six weeks after maize. The legumes were harvested at flowering and half of the above-ground biomass was mulched. In the first season, cumulative N2O emissions were largest in 3-week lablab, with all other treatments being equal or lower than the fertilized maize monocrop. After reducing mineral N input to intercropped systems by 50 % in the second season, N2O emissions were at par with the fully fertilized control. Maize yield-scaled N2O emissions in the first season increased linearly with above-ground 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 and 0.11 to 0.20 % of the estimated total N input in 2015 and 2016, respectively. 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 global warming potential by up to 69 %. Our results suggest that high yielding leguminous intercrops entail some risk for increased N2O emissions when used together with recommended fertilization rates, but can replace part of the fertilizer N without compromising maize yields in the following year and thus support CSA goals while intensifying crop production in the region.

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.

scholarly journals Closing maize yield gaps in sub-Saharan Africa will boost soil N2O emissions

2020 ◽  
Vol 47 ◽  
pp. 95-105 ◽  
Author(s):  
Sonja Leitner ◽  
David E Pelster ◽  
Christian Werner ◽  
Lutz Merbold ◽  
Elizabeth M Baggs ◽  
...  
Keyword(s):  
Maize Yield ◽  
Sub Saharan Africa ◽  
N2o Emissions ◽  
Yield Gaps ◽  
Sub Saharan

scholarly journals The interaction of seasonal rainfall and nitrogen fertiliser rate on soil N2O emission, total N loss and crop yield of dryland sorghum and sunflower grown on sub-tropical Vertosols

Soil Research ◽  
2016 ◽  
Vol 54 (5) ◽  
pp. 604 ◽  
Author(s):  
G. D. Schwenke ◽  
B. M. Haigh
Keyword(s):  
Crop Yield ◽  
Crop Production ◽  
Field Experiments ◽  
N2o Emission ◽  
N2o Emissions ◽  
N Loss ◽  
N Losses ◽  
Total N ◽  
Tropical Regions ◽  
The Impact

Summer crop production on slow-draining Vertosols in a sub-tropical climate has the potential for large emissions of soil nitrous oxide (N2O) from denitrification of applied nitrogen (N) fertiliser. While it is well established that applying N fertiliser will increase N2O emissions above background levels, previous research in temperate climates has shown that increasing N fertiliser rates can increase N2O emissions linearly, exponentially or not at all. Little such data exists for summer cropping in sub-tropical regions. In four field experiments at two locations across two summers, we assessed the impact of increasing N fertiliser rate on both soil N2O emissions and crop yield of grain sorghum (Sorghum bicolor L.) or sunflower (Helianthus annuus L.) in Vertosols of sub-tropical Australia. Rates of N fertiliser, applied as urea at sowing, included a nil application, an optimum N rate and a double-optimum rate. Daily N2O fluxes ranged from –3.8 to 2734g N2O-Nha–1day–1 and cumulative N2O emissions ranged from 96 to 6659g N2O-Nha–1 during crop growth. Emissions of N2O increased with increased N fertiliser rates at all experimental sites, but the rate of N loss was five times greater in wetter-than-average seasons than in drier conditions. For two of the four experiments, periods of intense rainfall resulted in N2O emission factors (EF, percent of applied N emitted) in the range of 1.2–3.2%. In contrast, the EFs for the two drier experiments were 0.41–0.56% with no effect of N fertiliser rate. Additional 15N mini-plots aimed to determine whether N fertiliser rate affected total N lost from the soil–plant system between sowing and harvest. Total 15N unaccounted was in the range of 28–45% of applied N and was presumed to be emitted as N2O+N2. At the drier site, the ratio of N2 (estimated by difference)to N2O (measured) lost was a constant 43%, whereas the ratio declined from 29% to 12% with increased N fertiliser rate for the wetter experiment. Choosing an N fertiliser rate aimed at optimum crop production mitigates potentially high environmental (N2O) and agronomic (N2+N2O) gaseous N losses from over-application, particularly in seasons with high intensity rainfall occurring soon after fertiliser application.

scholarly journals Identifying maize yield and precipitation gaps in Uganda

2021 ◽  
Vol 3 (5) ◽  
Author(s):  
Terence Epule Epule ◽  
Driss Dhiba ◽  
Daniel Etongo ◽  
Changhui Peng ◽  
Laurent Lepage
Keyword(s):  
Cropping Systems ◽  
Growing Season ◽  
Maize Yield ◽  
Sub Saharan Africa ◽  
World Bank Group ◽  
Precipitation Data ◽  
Yield Data ◽  
Yield Gaps ◽  
Maize Yields ◽  
Growing Season Precipitation

AbstractIn sub-Saharan Africa (SSA), precipitation is an important driver of agricultural production. In Uganda, maize production is essentially rain-fed. However, due to changes in climate, projected maize yield targets have not often been met as actual observed maize yields are often below simulated/projected yields. This outcome has often been attributed to parallel gaps in precipitation. This study aims at identifying maize yield and precipitation gaps in Uganda for the period 1998–2017. Time series historical actual observed maize yield data (hg/ha/year) for the period 1998–2017 were collected from FAOSTAT. Actual observed maize growing season precipitation data were also collected from the climate portal of World Bank Group for the period 1998–2017. The simulated or projected maize yield data and the simulated or projected growing season precipitation data were simulated using a simple linear regression approach. The actual maize yield and actual growing season precipitation data were now compared with the simulated maize yield data and simulated growing season precipitation to establish the yield gaps. The results show that three key periods of maize yield gaps were observed (period one: 1998, period two: 2004–2007 and period three: 2015–2017) with parallel precipitation gaps. However, in the entire series (1998–2017), the years 2008–2009 had no yield gaps yet, precipitation gaps were observed. This implies that precipitation is not the only driver of maize yields in Uganda. In fact, this is supported by a low correlation between precipitation gaps and maize yield gaps of about 6.3%. For a better understanding of cropping systems in SSA, other potential drivers of maize yield gaps in Uganda such as soils, farm inputs, crop pests and diseases, high yielding varieties, literacy, and poverty levels should be considered.

scholarly journals Smallholder African farms in western Kenya have limited greenhouse gas fluxes

2015 ◽  
Vol 12 (18) ◽  
pp. 15301-15336 ◽  
Author(s):  
D. E. Pelster ◽  
M. C. Rufino ◽  
T. Rosenstock ◽  
J. Mango ◽  
G. Saiz ◽  
...  
Keyword(s):  
Greenhouse Gas ◽  
Crop Production ◽  
Crop Yields ◽  
N Uptake ◽  
Ghg Emissions ◽  
Sub Saharan Africa ◽  
N2o Emissions ◽  
Vegetation Types ◽  
Western Kenya ◽  
The Impact

Abstract. Few field studies examine greenhouse gas (GHG) emissions from African agricultural systems resulting in high uncertainty for national inventories. We provide here the most comprehensive study in Africa to date, examining annual CO2, CH4 and N2O emissions from 59 plots, across different vegetation types, field types and land classes in western Kenya. The study area consists of a lowland area (approximately 1200 m a.s.l.) rising approximately 600 m to a highland plateau. Cumulative annual fluxes ranged from 2.8 to 15.0 Mg CO2-C ha−1, −6.0 to 2.4 kg CH4-C ha−1 and −0.1 to 1.8 kg N2O-N ha−1. Management intensity of the plots did not result in differences in annual fluxes for the GHGs measured (P = 0.46, 0.67 and 0.14 for CO2, N2O and CH4 respectively). The similar emissions were likely related to low fertilizer input rates (≤ 20 kg ha−1). Grazing plots had the highest CO2 fluxes (P = 0.005); treed plots were a larger CH4 sink than grazing plots (P = 0.05); while N2O emissions were similar across vegetation types (P = 0.59). This case study is likely representative for low fertilizer input, smallholder systems across sub-Saharan Africa, providing critical data for estimating regional or continental GHG inventories. Low crop yields, likely due to low inputs, resulted in high (up to 67 g N2O-N kg−1 aboveground N uptake) yield-scaled emissions. Improving crop production through intensification of agricultural production (i.e. water and nutrient management) may be an important tool to mitigate the impact of African agriculture on climate change.

scholarly journals Estimating the Effect of Climatic Variables and Crop Area on Maize Yield in Ghana

2012 ◽  
Vol 3 (9) ◽  
pp. 313-321
Author(s):  
Henry De-Graft Acquah
Keyword(s):  
Climate Change ◽  
Linear Regression ◽  
Regression Model ◽  
Crop Yield ◽  
Crop Production ◽  
Growing Season ◽  
Maize Yield ◽  
Climatic Variables ◽  
Non Linear ◽  
Crop Area

Climate change tends to have negative effects on crop yield through its influence on crop production. Understanding the relationship between climatic variables, crop area and crop yield will facilitate development of appropriate policies to cope with climate change. This study therefore examines the effects of climatic variables and crop area on maize yield in Ghana based on regression model using historical data (1970-2010). Linear and Non-linear regression model specifications of the production function were employed in the study. The study found that growing season temperature trend is significantly increasing by 0.03oC yearly whereas growing season rainfall trend is insignificantly increasing by 0.25mm on yearly basis. It was also observed that rainfall is becoming increasingly unpredictable with poor distributions throughout the season. Results from the linear and non-linear regression models suggest that rainfall increase and crop area expansion have a positive and significant influence on mean maize yield. However, temperature increase will adversely affect mean maize yield. In conclusion, the study found that there exists not only a linear but also a non-linear relationship between climatic variables and maize yield.

scholarly journals Smallholder farms in eastern African tropical highlands have low soil greenhouse gas fluxes

2017 ◽  
Vol 14 (1) ◽  
pp. 187-202 ◽  
Author(s):  
David Pelster ◽  
Mariana Rufino ◽  
Todd Rosenstock ◽  
Joash Mango ◽  
Gustavo Saiz ◽  
...  
Keyword(s):  
Greenhouse Gas ◽  
Crop Production ◽  
Crop Yields ◽  
N Uptake ◽  
Sub Saharan Africa ◽  
N2o Emissions ◽  
Vegetation Types ◽  
Smallholder Farms ◽  
Sub Saharan ◽  
Ch4 And N2o

Abstract. Few field studies examine greenhouse gas (GHG) emissions from African agricultural systems, resulting in high uncertainty for national inventories. This lack of data is particularly noticeable in smallholder farms in sub-Saharan Africa, where low inputs are often correlated with low yields, often resulting in food insecurity as well. We provide the most comprehensive study in Africa to date, examining annual soil CO2, CH4 and N2O emissions from 59 smallholder plots across different vegetation types, field types and land classes in western Kenya. The study area consists of a lowland area (approximately 1200 m a.s.l.) rising approximately 600 m to a highland plateau. Cumulative annual fluxes ranged from 2.8 to 15.0 Mg CO2-C ha−1, −6.0 to 2.4 kg CH4-C ha−1 and −0.1 to 1.8 kg N2O-N ha−1. Management intensity of the plots did not result in differences in annual GHG fluxes measured (P = 0.46, 0.14 and 0.67 for CO2, CH4 and N2O respectively). The similar emissions were likely related to low fertilizer input rates (≤ 20 kg N ha−1). Grazing plots had the highest CO2 fluxes (P = 0.005), treed plots (plantations) were a larger CH4 sink than grazing plots (P = 0.05), while soil N2O emissions were similar across vegetation types (P = 0.59). This study is likely representative for low fertilizer input, smallholder systems across sub-Saharan Africa, providing critical data for estimating regional or continental GHG inventories. Low crop yields, likely due to low fertilization inputs, resulted in high (up to 67 g N2O-N kg−1 aboveground N uptake) yield-scaled emissions. Improvement of crop production through better water and nutrient management might therefore be an important tool in increasing food security in the region while reducing the climate footprint per unit of food produced.

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 Nitrogen-use efficiency of organic and conventional arable and dairy farming systems in Germany

2021 ◽  
Author(s):  
Lucie Chmelíková ◽  
Harald Schmid ◽  
Sandra Anke ◽  
Kurt-Jürgen Hülsbergen
Keyword(s):  
Nitrogen Use Efficiency ◽  
Crop Production ◽  
Dairy Farms ◽  
N Balance ◽  
N Fixation ◽  
Mineral N ◽  
Nitrogen Use ◽  
Yearly Average ◽  
N Input ◽  
Use Efficiency

AbstractOptimising nitrogen (N) management improves soil fertility and reduces negative environmental impacts. Mineral N fertilizers are of key importance in intensive conventional farming (CF). In contrast, organic farming (OF) is highly dependent on closed nutrient cycles, biological N fixation and crop rotations. However, both systems need to minimise N balances and maximise nitrogen-use efficiency (NUE). NUE of organic and conventional crop production systems was evaluated in three regions in Germany by analysing N input, N output and N balance of 30 pairs of one OF and one CF farm each from the network of pilot farms for the period 2009–2011; indicators were calculated using the farm management system REPRO. CF had higher N input in all farm pairs. In 90% of the comparisons, N output of CF was higher than OF, in 7% it was the same and in 3% lower. NUE was higher in 60% of the OF, the same in 37% and lower in only 3%. The NUE of crop production in OF was 91% (arable farms: 83%; mixed/dairy farms: 95%) and the NUE in CF was 79% (arable farms: 77%; dairy farms: 80%). N balance was lower in 90% of the OF. The yearly average N balance was four times higher in CF (59 kg N ha−1 a−1) than in OF (15 kg N ha−1 a−1). The results show a huge individual variability within OF and CF. Organic mixed/dairy farms had the lowest N balances and the highest NUE. A further expansion of OF area can help to reduce high N balances and increase the NUE of crop production.

scholarly journals N<sub>2</sub>O emission from organic barley cultivation as affected by green manure management

2012 ◽  
Vol 9 (2) ◽  
pp. 2307-2341 ◽  
Author(s):  
S. Nadeem ◽  
S. Hansen ◽  
M. Azzaroli Bleken ◽  
P. Dörsch
Keyword(s):  
Green Manure ◽  
Management Strategies ◽  
Growing Season ◽  
Barley Grain ◽  
Manure Management ◽  
N2o Emissions ◽  
Mineral N ◽  
N Yield ◽  
Cereal Production ◽  
Biogas Residue

Abstract. Legumes are an important source of nitrogen in stockless organic cereal production. However, substantial amounts of N can be lost from legume-grass leys prior to or after incorporation as green manure (GM). Here we report N2O emissions from a field experiment in SE Norway exploring different green manure management strategies: mulching versus removal of grass-clover herbage during a whole growing season and replacement as biogas residue to a subsequent barley crop. Grass-clover ley had small but significantly higher N2O emissions as compared with a non-fertilized cereal reference during the year of green manure (GM) production in 2009. Mulching of herbage induced significantly more N2O emission (+0.37 kg N2O-N ha−1) throughout the growing season than removing herbage. In spring 2010 all plots were ploughed (with and without GM) and sown with barley, resulting in generally higher N2O emissions than during the previous year. Application of biogas residue (110 kg N ha−1) before sowing did not increase emissions neither when applied to previous ley plots nor when applied to previously unfertilized cereal plots. Ley management (mulching vs. removing biomass in 2009) had no effect on N2O emissions during barley production in 2010. In general, GM ley (mulched or harvested) increased N2O emissions relative to a cereal reference with low mineral N fertilisation (80 kg N ha−1). Organic cereal production emitted 95 g N2O-N kg−1 N yield in barley grain, which was substantially higher than in the cereal reference treatment with 80 kg mineral N fertilization in 2010 (47 g N2O-N kg−1 N yield in barley grain).

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