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1 Pre-ssessment of the Africn Nitrogen Cycle: A Summry Mteete Bekund IITA Arush, Tnzni Coordintor, The Africn Nitrogen Centre of the Interntionl Nitrogen Inititive Presenttion outline Reson for the pre-ssessment N in Afric s tmosphere N in Afric s qutic systems Anthropogenic influence on N in terrestril systems Present nd future coping mechnisms An nnouncement Note: Summry of RAP workshop report in the process of publiction 1

2 N t u r l Atmosphere NOx N C s c d e Nr Aqutic Ecosystems Terrestril Ecosystems NH x Norg Humn ctivities INI Phse 1: Assessment of knowledge IDAF Study Sttions Atmospheric N blnce (kg/h/yr) Ecologicl zone Deposition Emmission Blnce Dry Svnn Wet Svnn Forest Atmospheric N deposition & emission in Afric. Source of dt: surfce mesurements, stellite, modeling Processes: dry & wet deposition, biogenic emissions, biomss burning, voltiliztion, domestic fires 2

3 N flows nd storge in inlnd wter systems (L. Victori) Bsin re: 283,168 sq. km Cropped lnd: 40 % (2006) Inlnd lke N flows & blnce (kg/h/yr) N source In flow Domestic wste 0.5 Industril Source 0.1 Rivers/swmps 7.2 Cropped lnd 3.3 Uncultivted lnd 4.3 Wet Deposition 9.1 Dry Deposition 5.7 N - BNF? Out flow River Nile 5.8 Fishery 0.6 Denitrifiction 0.4 Lod Blnce 23.4 Studies of nutrient flows in Africn terrestril ecosystems show mssive nd continuing depletion A B Stte of nutrient depletion (Stoorvogel nd Smling, A), nd Annul Soil nutrient depletion (Heno nd Bnnte, B) Figure 1 Fig 3

4 Anthropogenic influence (model) Inherent Nr Applied Nr Crop N Processing wste Food & feed N Food wste Cons ume d N Humn wste Not tken up by plnts Pre-ssessment to Identify chllenges, solutions Attching numericl vlues (IN) Dt not redily vilble! Inherent reserves: very vrible; contributes bout 40% vilble to crops kg N h -1 pplied to griculturl lnds in 2007 from externl sources of which: 2.2 kg N h -1 ws from minerl fertilizers 0.3 kg N h -1 from livestock mnures Reminder minly from BNF 4

5 Attching numericl vlues (OUT) N removed through crop hrvests in 2007 ws 18.0 kg N h -1 Annul Estimtes of N depletion from combined processes vry: 22 kg h -1 (Snchez et l, 1997) 34 kg h -1 (Sheldrick nd Lingrd, 2004) 17.4 kg h -1 (Tn et l, 2005) Coping mechnisms: Synthetic fertilizers preferred Rnking of nutrient sources ccording to gender nd resons for preference (Mpfumo et l, 2001) Nutrient resource Rnking by women men Fctors (restrictions) Synthetic 1 2 Immedite & relible results (Cost prohibitive) Animl mnure 2 1 Long lsting in soil (Ownership of substntil livestock) Compost 3 4 Processed from locl mterils (Lbor intensive) Termite mounds 4 3 Redily vilble in fields (Lbor intensive) 5

6 Coping mechnisms: Improve Fertilizer N mngement technologies Technology type Process nd comments Pre-plnt ppliction Adjust fertilizer type, rte, technique to locl conditions Topdressing Identify suited fertilizer, need, rte, timing PKS blends Reinforce N limiting conditions ISFM Mximise input interctions, investment, productivity, sustinbility Coping mechnisms: Empowering frmers N wreness ttribute Empower frmers to: Effective empowerment indictors N deficiencies N cycling Identify N deficiency symptoms Acquire N inputs; reduce N losses Adjust N mngement to erly deficiency symptoms Dignostic test strips nd djust N mngement N fertilizer use Apply N fertilizer Appliction methods, bsed on return to investment & nture conservtion HH protein mngement Complement crbohydrtes with legumes & greens Consumption of nutritionlly complete diets 6

7 Summry Externl N use in Africn griculture is extremely low Prctitioners consider synthetic N sources priority; developed coping mechnisms for low N Green revolution for Afric focuses on incresing fertilizer inputs to help restore soil fertility Studies re necessry to predict nd mnge unintended impcts of the greening of Afric To know nd contribute more on these issues, follow the Announcement For more informtion: 7