Adams, S.

Gillespie, A.

Kimaro, A.

Outtara, B.

Peak, D.

Saidou, K.

Schoenau, J.J.

English

eCommons@USASK

Long–term effect of fertilizer microdosing on soil fertility in Sahelianwest Africa

University of Saskatchewan Research Archive

Long –Term Effect Of Fertilizer Microdosing On Soil Fertility In Sahelian West AfricaAlexis Adams, Adam Gillespie, Koala Saidou, Anthony Kimaro, Badiori Outtara, Jeff Schoenau, Derek PeakIntroductionSahel and Food Security1 http://mapsof.net/map/map-sahel• Highest population food insecure people globally• Population in Sahel increasing at rate of 3.1% per year• Crop production increasing at only 1% per year • 24% Canada’s avg cereal yield▪ Unstable climate▪ Low inherent soil fertility▪ Competition for organic inputs▪ Feed, fuel, building materials▪ Low fertilizer use2Why is Crop Production So Low?Introductionhttp://urbanext.illinois.edu/soil/orders/soiord.htmLow Fertilizer Use: Less than 10 kg/ha! ▪ Fertilizer expensive• 4x Canada’s prices▪ Smallholder farmers• Low access to capital• Risk averse▪ Difficult to access• Weak infrastructure and input sectorE. Bachmann3IntroductionMicrodosing: Step in Intensification • Microdosing• Reduced rate of fertilizer, applied more preciselyhttp://www.idrc.ca4IntroductionMicrodosing Research▪ Focus on short term yield response▪ Lack of focus on sustainability• No long-term research• Few studies measure soil propertiesD. Peak.5Introduction▪ Determine sustainability of microdosed rate of fertilizer by analyzing:• Yield trends• Soil chemical properties• Carbon speciation▪ Explore sustainability of soil management practices as a wholeObjective6Research ObjectiveEffect of Rates: SadoreLong-Term Research Site Experimental design▪ Yield data from 1998 to 2013▪ Continuous millet ▪ No difference between high and low fertilizer rate in applicationRate Fertilizer Manure Crop residuekg/ha kg/ha kg/haControl 0N, 0P 300 300Low 15N, 4.4P 900 900High 30N, 13.2P 2700 27007http://www.dmpafrica.net/Experimental design8WRB Soil Code SUSTAINABILITY OF REDUCED RATE OF FERTILIZERhttp://www.oneacrefund.org0100200300400500600700800900Control Microdose RecommendedGrain yield (kg/ha)Figure 1. Average yield 1998-2013 by fertilizer rateControl Low Rate High RateCBA9Sustainability Microdosing- Yield10Yield Regression over Time0200400600800100012001400160018001995 2000 2005 2010 2015Grain Yield (kg/ha)YearFigure 2. Yield Trend by Fertilizer RateHigh RateLow RateControlLow RateR2=0.32High RateR2=0.37Sustainability Microdosing- YieldTable 1. Effect of fertilizer rate on soil properties at SadoreFertilizer Rate pHElectrical ConductivityOrganic CarbonTotal P Available P Total N CECmS/cm % mg/kg mg/kg mg/kg cmolc/kgControl 5.3a 0.048 0.24b 144.1c 5.9c 96.1c 0.7Low Rate 5.1b 0.053 0.26a 161.8b 10.9b 104.5b 0.6High Rate 5.0c 0.052 0.27a 172.9a 22.9a 127.0a 0.6SEM 0.02 0.0048 0.005 2.76 0.88 2.7 0.04p<0.05, SEM= standard error of meanFertilizer Rates and Soil Properties 11Sustainability Microdosing- Soil PropertiesTable 1. Effect of fertilizer rate on soil properties at SadoreFertilizer Rate pHElectrical ConductivityOrganic CarbonTotal P Available P Total N CECmS/cm % mg/kg mg/kg mg/kg cmolc/kgControl 5.3a 0.048 0.24b 144.1c 5.9c 96.1c 0.7Low Rate 5.1b 0.053 0.26a 161.8b 10.9b 104.5b 0.6High Rate 5.0c 0.052 0.27a 172.9a 22.9a 127.0a 0.6SEM 0.02 0.0048 0.005 2.76 0.88 2.7 0.04p<0.05, SEM= standard error of meanFertilizer Rates and Soil Properties 12Sustainability Microdosing- Soil PropertiesTable 1. Effect of fertilizer rate on soil properties at SadoreFertilizer Rate pHElectrical ConductivityOrganic CarbonTotal PAvailable PTotal N CECmS/cm % mg/kg mg/kg mg/kg cmolc/kgControl 5.3a 0.048 0.24b 144.1c 5.9c 96.1c 0.7Low Rate 5.1b 0.053 0.26a 161.8b 10.9b 104.5b 0.6High Rate 5.0c 0.052 0.27a 172.9a 22.9a 127.0a 0.6SEM 0.02 0.0048 0.005 2.76 0.88 2.7 0.04p<0.05, SEM= standard error of meanFertilizer Rates and Soil Properties 13Sustainability Microdosing- Soil PropertiesCarbon Speciation14Sustainability Microdosing- C SpeciationCarbon Speciation15▪ No difference in C species between fertilizer rates▪ Microdosing does not change C speciationSustainability Microdosing- C SpeciationSustainability of Microdosed RateCompared to the high rate, the microdosed rate has:▪ Lower average yield but similar rate of yield decline over time▪ No indication mining N or P▪ No difference in amount or type of organic C 16Sustainability MicrodosingSUSTAINABILITY OF SOIL MANAGEMENT PRACTICEShttp://agra-alliance.orgImproving Organic Carbon0.2250.230.2350.240.2450.250.2550.260.2650.270.275300 900 2700Organic Carbon (%)Amendment Rate (kg/ha)Figure 3. OC with OM AmendmentManureCrop Residueb BabBa A17Improving Organic Carbon0.2250.230.2350.240.2450.250.2550.260.2650.270.275300 900 2700Organic Carbon (%)Amendment Rate (kg/ha)Figure 3. OC with OM AmendmentManureCrop Residueb BabBa A17Improving Organic Carbon0.2250.230.2350.240.2450.250.2550.260.2650.270.275300 900 2700Organic Carbon (%)Amendment Rate (kg/ha)Figure 3. OC with OM AmendmentManureCrop Residueb BabBa A17Fertilizer, Cropping, and Cultivation EffectTable 4. Effect tillage, cropping, and fertilizer application on soil propertiesTreatment pHElectrical ConductivityOrganic CarbonTotal PAvailable PTotal N CECmS/cm % mg/kg mg/kg mg/kg cmolc/kgControl 5.5a 0.035 0.26 163.0a 4.0bc 79.4b 0.4bLow Fertilizer 5.2ab 0.045 0.26 190.2a 6.8b 89.8b 0.3bHighFertilizer5.3ab 0.043 0.26 194.4a 24.5a 133.9a 0.5bSEM 0.14 0.0239 0.028 9.82 0.77 9.51 0.06Uncultivated 5.0b 0.052 0.21 82.3c 3.0c 131.0a 0.8aSEM 0.09 0.0147 0.017 6.01 0.47 5.82 0.04p<0.05, SEM=standard error of mean.Sustainability Soil Management- Cultivation/Cropping18Carbon Speciation19Sustainability Soil Management- Cultivation/CroppingCarbon Speciation20▪ Main difference is between cropped and uncultivated soil▪ Cropping/cultivation largest influence on C typeSustainability Soil Management- Cultivation/CroppingConclusionConclusions▪ Nutrients required in these soils▪ Microdosed rate of fertilizer no less sustainable than recommended rate at Sadore▪ Is the cropping system as a whole sustainable?• Overall yield decline• Little OC buildup even with OM amendment• Loss of total N with cultivation• Cultivation changing C type▪ Recommendations:• Combine no-till, microdosing, and OM amendmentSolution must fit in socioeconomic context to be effective21ACKNOWLEDGEMENTS• Supervisors: Derek Peak and Jeff Schoenau• Integrated Nutrient and Water Management team (INUWAM)• Funding organizations• International Development Research Centre • Foreign Affairs, Trade, and Development Canada• Natural Sciences and Engineering Research Council• Augustine Osei and Gourango Kar for lab work• Canadian Light Source• Peak Lab Group

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Long–term effect of fertilizer microdosing on soil fertility in Sahelianwest Africa

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