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Soil Health in Southern Africa and implications on sustainable intensification 2014 L Desta et al
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Soil Health in Southern Africa and implications on sustainable intensification: How much is the gap? World Congress Soil Science 2014 L Desta et al

Soil Health in Southern Africa and implications on sustainable intensification: How much is the gap? World Congress Soil Science 2014 L Desta et al

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Soil Health in Southern Africa and implications on sustainable intensification 2014 L Desta et al Soil Health in Southern Africa and implications on sustainable intensification 2014 L Desta et al Presentation Transcript

  • Lulseged  Tene1*,  Andrew  Sila2,  Job  Kihara3,  Gi<  Ndengu1,  Powell  Mponela1,  Keith  Shepherd2,   Markus  Walsh4  and   Deborah  Bossio3   www.ciat.cgiar.org   Eco-­‐Efficient  Agriculture  for  the  Poor   Soil  health  in  Southern  Africa  and   implica3on  on  sustainable  intensifica3on:   how  much  is  the  gap?   Lulseged  Tamene1,  Andrew  Sila2,  Job  Kihara1,  Gi<  Ndengu1,   Powell  Mponela1,  Keith  Shepherd2,  Markus  Walsh3  and   Deborah  Bossio1   1CInternaLonal  Center  for  Tropical  Agriculture,  2World  Agroforestry  Center,  3CThe  Earth  InsLtute     20th  World  Congress  of  Soil  Science   June  8-­‐13,  2014,  Jeju.  Korea  
  • Source:  INED   u SSA  countries  will  grow  the  fastest  –  pressure  on   resources   Background   PopulaLon  increase  
  • Background   This  will  lead  to:      -­‐  ReducLon  in  farm  size   -­‐  Expansion  to  steep   slopes  and  marginal   areas     -­‐  More  degradaLon   -­‐  Low  yield     There  is  a  need  to  produce   more  from  small  areas     Sustainable   IntensificaLon   View slide
  • Input  (type,  diversity)   ProducLvity  and  yield   Cost  of  input   Risk   Background   In  areas  low  income   households  and   high  environmental   risk,  implemenLng   sustainable   intensificaLon  may   be  a  challenge   View slide
  • Evaluate  soil  nutrient  deficiency  levels       Assess  soil  health  status  and  its  spaLal   variability       Gain  preliminary  picture  of  the  ‘gap’  that  should   be  replenished  to  improve  soil  health  and   achieve  “sustainable  intensificaLon”     Suggest  possible  opLons  to  enhance  sustainable   intensificaLon  under  prevailing  SSA  smallholder   circumstances   Objec3ves  
  • Study  Area  and  Sites   AfSIS   CRP1.1   Africa  RISING   v  6  Countries   v  29  Sites   v  464  Clusters   v  4640  Plots   v  18560  Sub-­‐plots   v  9280  soil  samples   Study  focuses  in  six  countries  of  Southern  Africa  
  • •  Take  advantage  of  data  collected  for  different   projects  across  southern  Africa     •  Soil  and  landscape  aeributes  data  collected  based   on  spaLally  straLfied  random  sampling  approach   Approaches   Sub-plot = 0.01 ha Site = 100 km2 Cluster = 1 km2 Plot = 0.1 ha Sub-plot = 0.01 ha Site = 100 km2 Cluster = 1 km2 Plot = 0.1 ha 0.01  ha   Site = 100 km2 Cluster = 1 km2 Site = 100 km2 Cluster = 1 km2 Plot = 0.1 ha Sub-plot=0.01ha Site=100km2 Cluster=1km2 Plot=0.1ha Sub-plot=0.01ha Site=100km2 Cluster=1km2 Plot=0.1ha
  • Figure  (a)  Near-­‐infrared  spectrometer  and  (b)  raw  and  derivaLve  spectra   used  to  calibrate  predicLon  models   Approaches   ² Over  9000  top-­‐  an  sub-­‐   soil  samples     ² NIR/MIR  spectral   analysis   ² 10-­‐20%  wet  chemistry   data  for  calibraLon  
  • Results   (%)   (mgkg-­‐1)   (mgkg-­‐1)   (mgkg-­‐1)   (gkg-­‐1)   (CmolcKg-­‐1)  
  • The  majority  of  the  sites  experience  low  soil  nutrient  content     ü  All  sites  have  zinc  limitaLon     ü  About  95%  of  the  sites  suffer  from  nitrogen  deficiency     ü  70%  of  the  sites  are  phosphorus  deficient     ü  65%  of  soils  have  poor  soil  structure     ü  About  40%  of  the  sites  have  low  potassium  level     ü  About  40%  of  the  sites  have  poor  SOC     q Overall  soil  ferLlity  status  is  beeer  in  Malawi   Results:  overall  soil  condiLon      
  • Total  N  (%)   Results:  Prevalence  es3mates  and  cri3cal  limits  
  • Results:  Prevalence  es3mates  and  cri3cal  limits   ApplicaLon  of  P  is  most  of  Malawian  soils   may  not  be  effecLve  –  even  it  may  lead  to   environmental  risk  due  to  P  leaching  into   water  bodies?   P  (mg  kg-­‐1)  
  • Results:  spa3al  variability  within  &  between  countries  &  sites   In  addiLon  to  the  observed  gap,   there  spaLal  variability  at  site,   cluster,  plot  levels     Example  K  for  one  site  and  cluster   in  Botswana   Country:  Botswana   Site:  Shoshong     Country:  Botswana   Site:  Shoshong   Cluster:  9  (variability  within  a  cluster,   between  plots     Cluster   Plot   ImplicaLon  on  ferLlizer   recommendaLon:  fine-­‐tune   to  local  soil  condiLons  
  • EsLmate  gap  between  current  soil  nutrient  status  in  relaLon   to  maize  nutrient  requirement   Ø  N  (114  kg  ha-­‐1)  and  P  (17  kg  ha-­‐1)  show  the  ‘widest’  gap  for   maize  producLon     Ø  Botswana  followed  by  Mozambique  show  large  N  gap     Ø  Malawi  and  Zimbabwe  low  (113  kg-­‐ha-­‐1)  N  gap       Ø  Botswana  (30  kg  ha-­‐1)  followed  by  Angola  (27  kg  ha-­‐1)   widest  P  gap     Ø  Malawi  has  no  P  gap  –  subsidy?     Results:  gaps  in  relaLon  to  maize  nutrient  requirements  
  • Approximate  cost  required  to  replenish  the  observed  gap   Depending  on  countries  and  household  status,   farmers  may  be  able  to  pay  for  ferLlizer  but  not  to   fill  the  whole  ‘gap’   Results:  Overall  cost  of  input  N  and  P  input  to  replenish  gap   0   50   100   150   200   250   Angola   Botswana   Malawi   Mozambique   Zambia   Zimbabwe   Cost  of  nutrient  (US$  per  ha)   Nitrogen   Phosphorus  
  • Considering  the   limited  income  of   smallholders  and  the   vulnerability  of   agriculture  to   different  kinds  of   stresses,  it  maybe   difficult  for  some   farmers  to  fill  the   ‘gap’  with  ferLlizer   input.         q AlternaLve  opLons   needed     Households  ordered  by  their  total  annual  income  (USD$)   Total  annual  income  ($USD)   Results:  Overall  cost  of  input  N  and  P  input  to  replenish  gap  
  • Results:  Overall  cost  of  input  N  and  P  input  to  replenish  gap   Alterna3ves  such  as  organic  inputs,  intercropping,  fer3lizer   crops,  CA  can  help  supplement  inorganic  input     Need  to  ‘encourage’  farmers  to  use  those  op3ons!   Supplement  with:  credit,  insurance,  subsidy,  …  
  • Conclusion     ü  Evidences  show  that  key  nutrients  are  limiLng  in  SSA   ü  Input  use  is  low  and  generally  ‘blanket’  approach  is  used   ü  ‘Site-­‐specific’  informaLon  needed  to  guide  implemenLng   targeted  intervenLon     ü  Price  of  ferLlizer  is  high  (8X  where  it  is  sourced  from)  –   encourage  and  enhance  local  producLon,  reduce  tax,   improve  complementary  inputs  +  ’green  opLons’   ü  Farmers  have  limited  ‘economic’  capacity  and  knowledge   to  use  adequate  input  sustainably:  incenLves,  credit  facility     ü  Farmers  contemplate  technology  use  –  risk  aversion.   Insurance,  subsidy,  Lmely  informaLon