Improving irrigation practice for growing vegetables on sandy soils

1. Improving irrigation practice for growing vegetables on sandy soils Rohan Prince and Robert Deyl

2. Background Efficient irrigation is required to maximise yield, water and nutrient use efficiency and therefore, often profit An irrigation system is only as efficient as the way it is operated Many tools are available to help predict the water movement in soil e.g. Dripgame and Wetup (CSIRO or CRC for Sustainable Sugar Production) Our sandy soil have an average of 95% coarse sand.

3. Root zones of crops Crops have an effective root zone where they remove the majority of water and nutrients This root zone is determined by crop type, soil type and structure, and cultural practice Pictures courtesy of DAFWA

4. Water movement Water movement is influenced by soil types, structure, irrigation method and volume and cultural practices What happens on the surface is not what always happens below the surface Blue dye test shows you the movement of water through soil Zwart, P, 2007. ‘Tracing Irrigation Water with Blue Dye and a Shovel’ Ministry of Agriculture, Food and Rural Affairs. Ontario.http://omafra.gov.on.ca/english/crops/hort/news/hortmatt/2007/20hrt07a3.htm Simonne et al, 2004. ‘How to Conduct an On-farm Dye Test and Use the Results to Improve Drip Irrigation Management in Vegetable Production’. Horticultural Sciences Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences,University of Florida HS980. http://edis.ifas.ufl.edu

5. On the soil surface the spread of the dye looked good 0.3 L water applied resulted in 20 cm radius from the dripper 2.0 L applied resulted in 30 to 40 cm radius indicated 4.0 L applied resulted in 40 to 60 cm radius indicated But this result was only skin deep Results on sandon the surface

6. Results on sand below the surface Depth and spread of dye in 2010-11 trial

7. Scheduling using evaporation Crop factor curve for irrigating tomatoes on sand Daily water application (mm) = Crop factor x Epan Weather data from DAFWA remote weather station network

8. The Vegetable Irrigation Scheduling System (VISS)

9. 2011-12 tomato demonstration crop irrigation Scheduling using evaporation Proportion of Evaporation replacement Weeks after planting

10. Tools

11. Soil moisturemonitoring Fine tuning, not scheduling Depth 0–15 cm 15–30 cm 40–70 cm Soil Moisture (%) Good Practice Grower Practice

12. 2 weeks after transplant 4 weeks after transplant 2011-12 Demonstration trial Good Practice scheduled using VISS left of each picture Vs Grower Practice right 6 weeks after transplant 8 weeks after transplant

13. Nutrient applications Grading and pack out

14. Similar yields 108 t/ha compared with 105 t/ha 40% less water applied 983 mm compared with 1651 mm 73% less drainage 250 mm compared with 950 mm Similar plant water use 733 mm compared with 701 mm 45% less leaching of nutrients 265 kg/ha compared with 477 kg/ha 2011-2012 Demonstration ResultsGood Practice compared with Grower Practice

15. Thank you and the funding bodies