Irrigation Workshop Brad Rathje, AquaSpy Inc. brathje@aquaspy.com, 402-740-3687
Capacitance Probes Capacitance Sensor measures the surrounding soil as a capacitor. The sfu ( scaled frequency unit) changes as the moisture and air levels in the surrounding soil changes. Measures dielectric constants Pure water 80 sfu s Soil Solids 3-7 sfu s Air 1 sfu Size Matters: Larger diameter sensors have larger spheres of influence
Proven capacitance technology Sensor every 4 inches 20 / 40 / 60 Probe lengths Continuous data graphs Turn-key managed solutions
Apply water based on Crop Use Potatoes
Sugar Beet Water Use Curve
Strategic Irrigation Management Over Irrigation Poor root structure Less able to handle stress Under Irrigation Potential Yield loss Poor quality Corn water use curve Common grower practice By overwatering in the early part of the season, the plant root system does not develop adequately to keep up with water use requirements during peak demand.
Crop Dynamics Waterlogging Peak Water Use Day Night Day Night Stepping shows daily plant water use. Lower stress level from too little water than too much water Moisture Stress
Nebraska Corn
Agronomic Impact GOAL: Match plant available water with crop water need to develop maximum root zone UNDERSTAND IRRIGATION EFFECT: Optimize applications, to provide potential for reduction in irrigation events MONITOR WATER USE: More water is available in deeper root zone reservoir LET S USE IT!! Bottom Line: Typically experience $3-$4k per Center Pivot A SMARTER WAY TO GROW
Precise Information for each location Agronomic information based on current crop stage Depth of active Root Zone Soil Moisture levels at 4 increments
Consistent Sensor Spacing provides: Accurate understanding of active root zone Which depth moisture is being pulled How much more depth is available to grow Timely information on soil moisture levels Provides understanding of soil moisture dynamics Remaining Soil Moisture
Irrigation Management Tools Separate Layer Graph Drainage & Infiltration rates Root Activity Moisture Stress by Layer Summed Graph When To Irrigate How Much Daily Water Use Rate Irrigation Effectiveness Upper & Lower Limits
Irrigation Template - Corn Irrigation matched to growth stage Optimize rooting structure early on Manage last irrigation for optimum crop maturity V5 V10 Emergence Root Growth Tassel through Dent Maturity Seedling Establishment Save Water Maximize Root Depth Maintain good moisture levels during peak water use period Save Water
Irrigation Summary provides one view to see when each field needs to be irrigated again
Varietal Rooting Differences Active roots @ 60 on 7-Jul Corn Variety A Active roots @ 60 on 7-Aug Corn Variety B No Irrigation Rain only No Irrigation Rain only Two different corn varieties, side-byside No irrigation - Rainfall only Corn Variety B reaches 60 about 30 days earlier than Corn Variety A Corn Variety B has higher rate of root growth (deeper, faster)
Varietal Rooting Differences Dep th Day of Year 19-May 2-Jun 16-Jun 30-Jun 14-Jul 28-Jul 11-Aug 8 12 16 20 24 28 32 36 40 44 48 52 56 60 24 day difference 14 day difference 24 difference ~4 stored moisture Two different corn varieties, side-by-side No irrigation - Rainfall only Corn Variety B roots down deeper, faster Variety B has access to extra 24 soil (~4 of stored moisture) during peak demand Each inch of available water could equate to 10-20 bushels (depending on timing and level of stress)
QTV: Sweet Corn in Georgia The Plots 3 Irrigation regimes varied using VRI Variable Rate Irrigation AquaSpy Managed (7.23 applied) KanSched Software Managed (8.77 applied) Grower Managed (10.10 applied) 3 Replications AquaSpy Probes in 2 out of 3 Plots All 9 Plots Field Scout Data Irrigation rates were verified with 2 separate catch cup tests Hand Harvested 100 or 200 ears per plot Weighed, sized Graded for Quality (defects)
Jun 12, 2010: System Setup to Skip AS (0%), KS (80%), Farmer (100% =0.60 ) 9 Plots, 3 trials, 3 Reps KanSched Controlled AquaSpy Controlled Other areas managed by grower AquaSpy Probes in 2 out of 3 Replications
AS Plots with minor stress Afternoon leaf roll, recovering after sunset, does not affect yield when it happens prior to Tassel (June 16, 2010)
Sum graph for entire season Leaf curl occurred during very hot period Due to VRI system not working properly, working within the grower s irrigation schedule, and rainfall, moisture levels did not reach refill level Tassel refill set to level prior to visible afternoon leaf curl (day-night steps start to flatten out)
Preliminary Results All nine plots were hand harvested on July 9, 2010. There was no significant difference in yield or quality. The AquaSpy plots received a total of almost 3 inches less irrigation (2.93 inches saved) More could have been saved had the VRI system been working properly during the entire project.
Conclusion Allowing minor stress to occur prior to Tassel does not affect sweet corn yield or quality. True Allowing minor stress to occur prior to Tassel promotes a deeper root system. No significant difference in rooting depth. (The VRI system did not work well during the entire project and allowed more irrigations on the AS plots than desired.) Georgia sweet corn growers tend to over water. True. The AS plot saved almost 3 inches of irrigation water. (More would have been saved had the VRI system worked properly.)
UNL-ARDC 2007 Irrigation Regimes Large depletion of soil moisture Drying Down Rainfall = 13.6 Rainfall = 13.6 Irrigation = 8 Wetting Up Rainfall = 13.6 Irrigation = 10 + Small depletion of soil moisture Rain Fed Controlled Irrigation Continuous Irrigation
Overwatered Irrigation Drainage & Leaching Irrigations
Controlled Irrigation Optimum Date Irrigations No Drainage 40 Active root zone
Applying More Water Doesn t Mean More Water is Utilized
Marginal water applied at proper time provides significant yield increases 150 bu Corn 5.94 in 189 bu Corn 7.11 in
Wausa NE. actual yield demonstrates results of stress 150 bu. Corn Full Line Refill Line Stress Line 189 bu. Corn Full Line Refill Line Stress Line
Reduce Leaching of Fertilizer
Fertility
Basic economics Typical irrigation cost s range from $8-12.00 per acre inch One acre in of water with 19 ppm nitrate @ 50 cents per pound equating to $13.30 per acre Each acre inch of over application results in a minimum $21.30 per acre loss
The AquaSpy Solution AquaSpy does it all Installs Maintains AquaSpy Telemetry Delivers AquaSpy Probe Irrigation Template