Upload
dominick-marshall-davidson
View
214
Download
0
Tags:
Embed Size (px)
Citation preview
IS DUAL CROPPING UNDER CENTRE PIVOTS A JUSTIFIABLE IRRIGATION PRACTICE?
Leon Van Rensburg, JH Barnard, JB Sparrow, ATP Bennie and CC Du Preez
Department of Soil, Crop and Climate Sciences
BACKGROUND
• WRC (Report No K5/1647, 2012): MANAGING SALINITY ASSOCIATED WITH IRRIGATION AT ORANGE-RIET AND VAALHARTS IRRIGATION SCHEMES
* Calibration and validation of the SWAMP model
* Crop selection
* Soils
* Crop production
* Irrigation scheduling
*Best management practice
R
U
Northern Cape
Eastern Cape
Free State
North West
Western Cape
Northern Province
KwaZulu-Natal
Mpumalanga
Lesotho
Gauteng
Vaal
Orange
Riet
Harts
32°0'0"E
32°0'0"E
28°0'0"E
28°0'0"E
24°0'0"E
24°0'0"E
20°0'0"E
20°0'0"E
21°0'0"S 21°0'0"S
24°0'0"S 24°0'0"S
27°0'0"S 27°0'0"S
30°0'0"S 30°0'0"S
33°0'0"S 33°0'0"S
36°0'0"S 36°0'0"S
Ü0 160 320 480 64080
Kilometers
Legend
R Orange-Riet Irrigation Scheme
U Vaalharts Irrigation Scheme
Rivers
Lower Vaal WMA
Upper Orange WMA
BACKGROUND
ORANGE-RIET
VAALHARTS
VAALHARTS
VAALHARTS
CASE STUDY: VAALHARTS (V6 & V7)
VAALHARTS
IS DUAL CROPPING UNDER CENTRE PIVOTS A JUSTIFIABLE IRRIGATION PRACTICE?
Soil properties
Soil depth
0- 0.3 0.3-0.6 0.6-.9 0.9-1.21.2-1.5
1.5-1.8 Mean
Clay content (%) 5 6.5 8 9 9 10.5 8
Bulk den (kg m-3) 1605 1653 1626 1627 1654 1656 1636
Ksat (mm h-1) 39.8 34.5 - - - 24.3 32.9
pH (H2O) 7 7.5 7.8 8.1 8.1 8 7.7
CEC (cmolc kg-1) 2.9 3 2.5 2.5 2.8 3 2.8
ECe (mS m-1) 73 83.3 77.1 84.4 79.7 88.5 81
SAR 1.25 1.74 1.71 1.81 1.88 2.08 1.74
MATERIAL AND METHODS: Soil information
Agronomic practices (East)
Season 1 2 3 4
Crop rotation Wheat Maize Fallow Groundnuts
Cultivar Duzzie Pannar 6126 Aqua
Planting date 12 June 2007 15 Dec 2007 5 Nov 2008
Harvesting date 29 Nov 2007 12 June 2008 25 July 2009
Planting density
150 kg ha-1 80 000 plants ha-1 114 kg ha-1
Total kg N ha-1 222 225 104
Total kg P ha-1 40 33 33
Total kg K ha-1 50 50 52
Pest management
- Eptam
TreflinTemikHarnas
Hammer
Cultivation practices
Plough, tiller & plant
Bale, plough, disc, till & plant
Disc, plough, till, & plant
Agronomic practices (v6, west)
Season 1 2 3 4
Crop rotation Peas Groundnuts Wheat Cotton
Cultivar Solara Aqua Duzie -
Planting date July 2007 Dec 2007 June 2008 Dec 2008
Harvesting date 14 Nov 2007 May 2008 1 Dec 2008 25 July 2009
Planting density
120 kg ha-1 120 kg ha-1 150 kg ha-1 18 kg ha-1
Total kg N ha-1 93 168 209 247
Total kg P ha-1 17 30 38 33
Total kg K ha-1 50 40 50 52
Pest management
Galliant -BuctrilMCPA
TreflinTemik
RoundupMetamidofos
Cultivation practices
Burn, plough, wonder till & plant
Bale, burn, rip & plant
Burn, wonder till & plant
Bale, burn, rip & plant
Gain of water:Rainfall and Irrigation
Evaporation and transpiration
Salts will accumulate
Leaching
Drainage effluent(Degrading ground and surface waters)
MATERIAL AND METHODS: Water balance
MATERIAL AND METHODS: Measurements
Rainfall
Irrigation
Soil water
Water table depth
East
Rainfall
Irrigation
Soil water
Water table depth
West
RESULTS ON SWB: EAST (V7)
Crop ∆W R I E T D
Wheat 61 204 441 66 497 -21
Maize 11 350 266 41 417 -147
Fallow 21 121 0 46 0 -54
Groundnuts 36 260 402 43 281 -302
RESULTS ON SWB: WEST (V6)
Crop ∆W R I E T D
Peas 13 202 344 41 496 4
Groundnuts 72 334 543 34 436 -335
Wheat -36 29 752 68 435 -315
Cotton -23 273 501 70 362 -365
RESULTS ON YIELDS: EAST (V7)
CropSeed (kg ha-1)
Biomass (kg ha-1)
Actual Pot Actual Pot
Wheat 5432 8000 15520 20000
Maize 9896 14500 17062 26500
Fallow
Groundnuts 2619 4500 7483 14500
RESULTS ON YIELDS: WEST (V6)
CropSeed (kg ha-1)
Biomass (kg ha-1)
Actual Pot Actual Pot
Peas 3428 4000 7617 9500
Groundnuts 3971 4500 11346 14500
Wheat 5845 8000 14256 16000
Cotton 0 6500 14084 18500
Season Pivot Dual crops Peak period(days) ET rate (mm day-1)
1West Peas 50 5.9
East Wheat 50 6.2
2West Groundnuts 70 5.5
East Maize 45 7
3West Wheat 50 6.5
East Fallow
4West Cotton 50 6
East Groundnuts 70 4
CONCLUSION
Thank you