Irrigate More Efficiently Using the Salt Balance
0 likes106 views
The document discusses the need for efficient water irrigation practices in agriculture due to climate change, population growth, and water scarcity impacts on food supply. It emphasizes managing salt concentration in soil to avoid stress on crops and outlines tools and measurements, such as the Teros 12 sensor and Zentra cloud, for monitoring soil moisture and electrical conductivity. Ultimately, it highlights the importance of understanding water and salt balance to maintain crop productivity sustainably.
Irrigate More Efficiently Using the Salt Balance
- 2. IRRIGATE MORE EFFICIENTLY USING SALT BALANCE Gaylon S. Campbell, PhD METER Group, Inc. USA Pullman, WA USA
- 3. • “Climate change, population growth, and increasing water scarcity will put pressure on our food supply.” (IPCC) • “Most of the freshwater (about 70 per cent on average) is used for agriculture.” • “It takes between 2000 and 5000 liters of water to produce a person’s daily food.” (FAO) WATER IN THE NEWS
- 4. • Minimize waste • Maximize water-use efficiency • Help implement and use sustainable practices WHAT CAN WE DO TO HELP?
- 5. Rootzone water content – too fast Salt in groundwater and rivers – too slow Salt concentration near the bottom of the root zone – just right STIRZAKER’S GOLDILOCKS PRINCIPLE
- 6. Inputs: Precipitation, Irrigation Losses: Transpiration, Evaporation, Drainage Storage:Change in soil water content THE WATER BUDGET TEROS 12 soil moisture, EC, temperature sensor ATMOS 41W Microenvironment Monitor
- 7. • Salts are in all irrigation water • Salts and water enter soil • Water leaves, but salts remain THE SALT BUDGET
- 9. • Fertilizer is applied to crops, some stays • Water and salts flow upward from shallow water tables • Water leaves, but salts stay ADDITIONAL SALT SOURCES
- 10. Measure salt as concentration, electrical conductivity, or osmotic potential
- 11. Total water potential of soil depends on salt concentration (osmotic potential) and soil matric potential HIGH SALT CONCENTRATIONS STRESS PLANTS
- 12. CORN GRAIN YIELD RESPONSE TO SALT STRESS Hoffman, G.J., E. V. Maas,T. L. Prichard, and J. L. Meyer (1983) Salt tolerance of corn in the Sacramento-San Joaquin Delta of California. Irrig. Sci. 4:31-41
- 13. CROPS VARY IN THEIR SENSITIVITY TO SALT Sensitive Moderately Sensitive Moderately Tolerant Tolerant almond alfalfa red beet sugar beet apple broccoli safflower cotton avocado cabbage olive date palm bean tomato soybean Bermuda grass carrot lettuce wheat barley grapefruit corn ryegrass orange cucumber wheatgrass lemon grape wildrye okra peanut onion potato strawberry radish peach rice plum sugarcane
- 14. CROP YIELD RESPONSE TO SALT Sensitive Moderately Sensitive Tolerant
- 15. • Bulk ECb – The EC measured by in situ sensors • Pore water or soil solution ECw - What the plant “sees” • Saturation extract ECe – Saturate the soil with distilled water, extract the water, and measure its EC – directly proportional to the salt content of the soil THREE MEASURES OF ELECTRICAL CONDUCTIVITY TEROS 12 Water Content EC & Temperature
- 16. To get pore water EC • Suck water out of soil with suction cup and measure its EC • Measure bulk EC and bulk dielectric and calculate with Hilhorst HOW DO YOU GET ECw? 𝐸𝐸𝐶𝐶𝑤𝑤 = 𝐸𝐸𝐶𝐶𝑏𝑏 𝜖𝜖𝑤𝑤 𝜖𝜖𝑏𝑏−𝜖𝜖0 ECw = pore water EC ECb = bulk EC εw = water dielectric εb = bulk dielectric ε0 = dry dielectric
- 17. SOME TOOLS ES-2 Water EC & Temperature ATMOS 41W TEROS 12 Soil Water EC & Temperature ZL6 Logger Connected to ZENTRA Cloud
- 18. • The irrigation water EC • The ECw in the root zone so you can avoid stressing the crop • The ECw below the root zone so you can compute the rate of drainage NOW WE CAN CONTINUOUSLY KNOW
- 19. • Defined as the ratio of drainage water to applied water: LF = Dd/Di • Can use it to compute drainage required for a particular irrigation water quality: LF = ECi/ECw • If ECi were 0.6 dS/m and ECw were 3 dS/m, then LF would be 0.2; 1/5 of the water would need to drain to maintain productivity MAINTAINING SOIL PRODUCTIVITY LEACHING FRACTION
- 20. • The TEROS 12 measures water content and bulk EC (ECb ) • ZENTRA Cloud converts that to pore water EC (ECw ) • ECw at bottom of root zone is Stirzaker’s Goldilocks measurement Gives • Crop suitability • Crop loss from salinity WHAT CAN WE DO WITH THIS?
- 21. GRACE, ID: WHEAT
- 22. • The TEROS 12 measures water content and bulk EC (ECb ) • ZENTRA Cloud converts that to pore water EC (ECw ) • ES-2 measures irrigation water EC (ECi) • Rearrange leaching fraction equation to give Dd=Di(ECi/ECw) so, from the EC measurements and knowing depth of water applied, you can calculate the depth of drainage WHAT ELSE CAN WE DO? Dd – depth of drainage water Di – depth of irrigation water ECi – irrigation water EC ECw – pore water EC in soil
- 23. • Correctly managing water for irrigation requires a knowledge of soil water content and soil salt content • The pore water EC within and below the root zone is “just right” as the long-term management tool for irrigated agriculture • METER provides the right measurements for modern irrigators to choose the right crops and manage water sustainably CONCLUSIONS
- 24. QUESTIONS? Thank you for your time