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

Introduction

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 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)

Introduction … Research questions, hypotheses & objectives (i)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 salt dynamics in the root zone. Hypothesis 3:Current irrigation water management under heavy clay textured soils with a shallow water table contributes both to nitrogen losses and low water use efficiency.

Methodology 3  Saline Sites (Non-S, Mod-S & Saline) Trial Layout (2X2 Factorial; 3 Rep; CRBD):2007; 08; 09 W treatments - Calendar & SWD to FC N treatments – 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!!?

Methodology … Instrumentation & Monitoring

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

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

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

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

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

Preliminary Results … Salt accumulation process: ModSaline & Saline Sites

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

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.)

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

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

Thank you!