Irrigation Management of Perennial Forages Alfalfa and Timothy Hay Shelley Woods Soil and Research Scientist Irrigation Management Branch Irrigation & Farm Division Alberta Agriculture and Forestry Irrigated Crop Production Update January 20, 2016 Lethbridge, AB
Outline Basics of Irrigation Management Factors affecting irrigation Impacts of excess/insufficient water Soil physical properties Best management practices Specific Issues for Irrigating Forages Alfalfa Timothy
Factors Affecting Irrigation Management Crop Characteristics Type and variety (effective root zone) Stage of growth and plant population density Target yield (fertility) Crop quality requirements Soil Characteristics Soil water content Available water holding capacity Infiltration rate (saturated and unsaturated) Climate Precipitation Potential evaporation rate (temperature, radiation, wind) Disease risk
Potential impacts of insufficient or excess irrigation Insufficient water stress during reproductive stage (fewer seeds) Premature ripening/light kernel weight Reduce stem numbers/stand vigor Excess water Restricted root growth (insufficient soil air) Promotion of crop disease (moist conditions) Lodging (excess forage production) Environmental/Economic issues Wasted water (runoff, evaporation, drainage) Nutrient loss Unnecessary cost (water, energy) Public perception
Soil Physical Properties Texture Plant available water (AW) Permanent wilting point (WP) Field capacity (FC) Saturation Gravitational water Unavailable water Infiltration rate
Gravitational Available Soil Minerals,, and Air Field Saturation Field Capacity Wilting Point Unavailable
Bucket Model Runoff Rain and Irrigation Surface Storage Evaporation Saturation Field Saturation Field Capacity e.g. Soil Content 28% by volume 60% AW 40% Depletion Wilting Point Infiltration Gravitational Available Unavailable Drainage 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Soil Content (% volume) 40% 30% 20% 10% 0%
FC and WP vs Soil Texture Clay Loam Loamy Sand Field Capacity Wilting Point Gravitational Available Gravitational Available Gravitational Soil Content (% volume) 40% 30% 20% Unavailable Unavailable Available Unavailable 10% 0% Soil Content 23% by volume
FC and WP vs Soil Texture Clay Loam Loamy Sand Infiltration Rate = 0.6 6.8 60 mm/hr Field Capacity Wilting Point Gravitational Available Gravitational Available Gravitational Soil Content (% volume) 40% 30% 20% Unavailable Unavailable Available Unavailable 10% 0% Soil Content 50% of Available
Best Management Practices for Irrigation Applications Suitable crops, healthy seed and correct fertilizer rates Know your plant-available water and infiltration rate, specific to soil texture Know your water needs based on crop, variety, growth stage Control weeds Irrigation scheduling Source: Beneficial Management Practices: Environmental Manual for Crop Producers in Alberta, AAFRD, 2004
Alfalfa 540-680 mm Issues: High water use forage: deep perennial roots, produces large biomass, and long growing season Peak daily water use 9 mm (late-june) First cut has greatest yield (40%) and water use eff. Short, frequent irrigations to establish crop For optimum forage production, irrigate to stimulate vegetative growth (early spring and after cutting)
Alfalfa Use by Depth 40% 30% 20% 10% 0 cm 30 cm 60 cm 90 cm 120 cm After the third cut, bring soil moisture to 70% of available water to minimize winter kill or winter injury
Daily water use (mm) Timothy 500-550 mm Issues: Greatest demand is prior to first cut (>7 mm/day) and in late August (6 mm/day) Critical periods also early spring and immediately after cutting to stimulate crop re-growth Timing of irrigation can affect crop disease/quality Light, frequent irrigations for stand establishment Effective rooting zone for mature crop is 0-50 cm
Timothy After the second cut, bring soil moisture to field capacity Use by Depth 40% 30% 20% 10% 0 cm 15 cm 30 cm 45 cm USDA-NRCS PLANTS Database / Hitchcock, A.S. (rev. A. Chase). 1950. Manual of the grasses of the United States. USDA Miscellaneous Publication No. 200. Washington, DC. 60 cm
Alberta Agriculture Publications Irrigation Management Manual Irrigation Scheduling Fact Sheets Irrigation Management Field Book http://www.demofarm.ca
Alberta Agriculture Services Irrigation Management Climate Information Network (IMCIN) http://www.imcin.net Alberta Irrigation Management Model (AIMM) http://agriculture.alberta.ca/acis/imcin/aimm.jsp Irrigation Scheduler App http://weather.wsu.edu/is/ Irrigation Training Courses
Contact information: Shelley Woods Research Scientist Soil & Irrigation and Farm Division ARD, Lethbridge Phone: 403-381-5839 shelley.a.woods@gov.ab.ca