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UEM/FAEF

WATER & NITROGEN MANAGEMENT ON SALT-AFFECTED SOILS IN THE CHÓKWÈ IRRIGATION SCHEME, MOZAMBIQUE - ------- - Progress Report - ------- -. by Paiva Munguambe. Prof. John Annandale (University of Pretoria) Prof. Rui Brito (University Eduardo Mondlane)

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UEM/FAEF

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  1. WATER & NITROGEN MANAGEMENT ON SALT-AFFECTED SOILS IN THE CHÓKWÈ IRRIGATION SCHEME, MOZAMBIQUE ---------Progress Report --------- by Paiva Munguambe Prof. John Annandale (University of Pretoria) Prof. Rui Brito (University Eduardo Mondlane) Dr. Martin Steyn (University of Pretoria) Prof. Richard Stirzaker (CISRO) UEM/FAEF Final Scientific Workshop – CP 17 JHB, 15 to 18 June 2009

  2. Introduction

  3. Introduction… • Some features of the CIS • Designed in the 50s… drainage was not so relevant….!! • Water from Massingir & Macarretane Dams (Gravity) • HICEP…… • 30,000 ha ( 1,000 ha salinazed& only  6 to 7,000 ha effectively cultivated) • 12,000 farmers (Small <4 ha; Medium 4 to 15 ha; big > 20 ha) • Private company (MIA) • Water Users Association • Rice (summer crop) : 2 to 4.5 ton/ha • Vegetables + maize (winter crops): tomatoes up to 60 ton/ha; • Heavy clay soils (low infiltration & transmissivity rates) • Good irrigation water ( 0.5 dS/m) • Poor crop and irrigation water management (Irrigation Efficiency < 30%) • Poor infrastructure management (State & farmer's management)

  4. Introduction… • Research questions, hypotheses & objectives • How to leach salts but conserve nitrogen on salt-affected soils of the CIS? • Hypothesis 1:Improved irrigation water and nitrogen management strategies will increase water and nitrogen use efficiency in salt-affected soils. • Hypothesis 2:Shallow water-table in salt-affected soils affects the saltdynamics in the root zone. • Hypothesis 3: Current irrigation water management under heavy clay textured soils with a shallow water table contributes both to nitrogenlosses and low water use efficiency.

  5. Methodology • 3  Saline Sites (Non-S, Mod-S & Saline) • Trial Layout (2X2 Factorial; 3 Rep; CRBD):2007; 08; 09 • Wtreatments- Calendar & SWD to FC • Ntreatments – 100 kg/ha ( 5 on/ha) & 200 kg/ha (>10 ton/ha) • WFD – drained water (N & Salt Analysis) at  depths • Monitoring (eg., climate & parameters, yields, etc.) • ? Modelling exercise!!?

  6. Methodology… Instrumentation & Monitoring

  7. Preliminary Results EC & N03 drained water (WFD): 3 Sites Dry Season NoSaline ModSaline

  8. Preliminary Results… EC & N03 drained water (WFD): 3 Sites Dry Season Saline

  9. Preliminary Results… EC & N03 drained water (WFD): 3 Sites Wet Season NoSaline ModSaline

  10. Preliminary Results… EC & N03 drained water (WFD): 3 Sites Wet Season Saline

  11. Preliminary results… Yield (Maize PAN 67): Dry & Wet Seasons

  12. Preliminary Results… Salt accumulation process: ModSaline & Saline Sites

  13. Preliminary Results… Salt accumulation process – Saline & ModSaline sites Rep 1 Rep 2 Rep 3 Irrigation canal waterlogging WT (1.2 m to 0.90 m) 20 m

  14. Challenges & On-going Activities • REGIONAL & in situ HYDROLOGY AFFECTS SALT DYNAMICS • WHAT MODELLING APPROACH CAN BETTER SUIT? • Modelling processes…. understanding the causes & effects (Micro scale) … • Modelling better future management scenarios (Macro scale) … Water vs. N & Salts • ARE THERE APPROPRIATE MODELS? • Water, Salts & Nitrogen Management (Saltmed; APSIM; etc.)

  15. Challenges & On-going Activities… • INPUTS • Field Trials Results • Soil data • Texture; Soil Layers; Saturated Hydraulic Conductivity; Infiltration Rates; • Climate data • ETo & Rainfall • Irrigation & drainage data • Depths; Timing & EC; Irrigation Water Management • Groundwaterdata • Depth & EC • Crop data • Planting date; Yield, etc. SOUND ENVIRONMENTAL SCENARIOS OUTPUTS Recommendations Improved Irrigation Water and Nitrogen & Salt Management Practices WATER & NUTRIENTS MODEL HYROLOGICAL MODEL INTEGRATED MODELLING FARMER’S PERSPECTIVES CROP MODEL

  16. Challenges & On-going Activities… • AGREED ON THE CHAPTERS (THESIS) • WRITING UP • HOPEFULLY TO SUBMIT BY THE END DECEMBER 2009

  17. Thank you!

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