Irrigation Templates for Florida Citrus Using AquaSpy Multi-Sensor Capacitance Probes and Graphical Software Marcos Bengolea – International Sales Manager 2 nd Symposium on Soil Water Measurement – October 30, 2007

C-Probe TM – Florida Citrus

4 th generation C-Probe TM A sensor every 4” (10cm) provides a more complete picture of soil water dynamics Completely buriable design allows installation in a wider range of crops 1 meter AquaSpy probes, with 10 sensors, are now about 40% of AquaSpy’s market in Florida citrus Most AquaSpy probes in Florida are connected to a GPRS telemetry unit and data is uploaded to AgWISE

AquaSpy TM Data Node & Display

350+ Probes Installed in Florida Since 2001

Florida Soil Types Central Highlands (Ridge) –Deep sandy soils, rolling topography, naturally well drained Coastal Lowlands (Flatwoods) –Shallow sandy soils, flat topography, poorly drained with impermeable subsurface soil layers –Require artificial drainage Florida Sand has a very low field capacity –Field Capacity is 9% –Wilting Point is 2% –Available Soil Moisture is 7% The impermeable hardpan layers (or organic stain) saturates at around 40%* * According to Dr. Kelly Morgan, University of Florida

CandlerTavaresAstatula Ridge Soils – Entisol – well drained sands

ImmokaleeOldsmarWabasso Flatwoods Soils – Spodosol – poorly drained

ImmokaleeOldsmarWabasso Flatwoods Soils – Spodosol – poorly drained

Bedded Citrus Groves for Drainage

Flatwoods Rooting Depth: 30-50cm

AquaSpy TM Raw Values w/ Offsets (stacked) (Curser is set to close to field capacity – Flatwoods Soil)

Default AquaSpy TM Calibrations Applied w/ Offsets (stacked) (Curser is set to close to field capacity – Flatwoods Soil)

Default AquaSpy TM Calibrations Applied w/ Offsets (stacked) (Cursor is set to close to field capacity – Flatwoods Soil)

All Sensors set to same scale 0-50

Setting Up Irrigation Templates By using continuous soil moisture monitoring and graphing, the citrus grower does not need to know much about soil properties or calibration. By examining the shape of the graph lines at the various levels and relative differences in crop use, the sum graph can then be setup to keep soil moisture at desired levels. Growers use the following technique to set up templates for different times of the season.

Separate Layer Graph –through drainage & infiltration rates –where most root activity occurs –soil moisture stress at each layer Summed Graph –daily water use rate –irrigation effectiveness –when to irrigate –how much to irrigate –establish upper & lower limits Irrigation Management Concepts

Separate Layer Graph Day-night stepping indicates root activity at 4, 8, 12 inches No root activity at 20 & 36-inch levels (no stepping) Rain 4-inch dries out Rain 6 hrs.4 hrs.

Separate Layer Graph Day-night stepping indicates root activity at 4, 8, 12 inches No root activity at 20 & 36-inch levels (no stepping) Rain 4-inch dries out Rain 6 hrs.4 hrs.

Summed Graph w/ Irrigation Template Refill point Full point for top 12 inches Early stress Repeatable

Time to Irrigate Below Refill Point

Irrigation Prediction Trendline

Improving Fruit Quality Many growers over irrigate in the Fall and Winter Over irrigation reduces the brix (sugar) content of oranges. (Over 92% of Florida oranges are grown for the juice market. Growers are paid based on brix and juice content or pounds solids per box.) In South Florida, citrus often does not receive enough chilling hours to induce a good bloom for the next season. (Need about 1,100 hours below 68° F.) Practicing deficit irrigation, or inducing mild drought stress in the Winter, enhances the bloom for next season, without reducing yield, and increases brix.

Keeping oranges dry (mild stress) in winter increases brix and induces a better bloom for the spring Multiple Stage Irrigation Template - Ridge

Multiple Stage Irrigation Template - Flatwoods Keeping oranges dry (mild stress) in winter increases brix and induces a better bloom for the spring

ROI Example: Orange Grove March–April: Bloom – Provide adequate soil moisture for good fruit set May–August: Provide adequate soil moisture for cell expansion to size up the fruit, while providing proper drainage during the rainy season (June–October) November–January: Reduce soil moisture levels in the winter, allowing afternoon wilt, to prevent vegetative growth and induce bloom for the next season, thus increasing the brix (sugar) and pounds solids per box of fruit Practicing this regime for the past 3 years.

Grove Template – 1,002 Days 2004 Rainfall 54”2005 Rainfall 82.5”2006 Rainfall 50.5”2007 Rainfall 32.5” 14 Yr Avg 60.5”

Increasing Rooting Depth – Regeneration Increasing rooting depth >>

2.5 Acre Valencia Orange Grove State Yield Valencia Oranges: 72.7 million boxes (down from original est. due to Hurricane Wilma damage, Oct. 2005) Yield: 587 boxes (down slightly due to Hurricane Wilma damage) 7.1 pounds solids per box (State average = 6.1) Price: $1.10 per p.s. Total Net income after harvesting cost: $5, State Yield Valencia Oranges: 63.3 million boxes (down 13%, due to lingering effects of hurricanes & drought) Yield: 817 boxes (up 28%, due to deficit irrigation management) 7.6 pounds solids per box (State average = 6.3) Price: $2.25 per p.s. Total Net Income after harvesting cost: $10,902

Examples of Growers’ Use Growers reduce duration of irrigations to reduce excessive leaching and over watering On the Ridge, growers use probes to help practice Best Management Practices (BMP’s) to prevent leaching nitrates into the water table; by only irrigating down to 20 inches Night time irrigation proves to be more efficient; less evaporative loss Many growers over irrigate with drip; up to 70% reduction possible

AquaSpy Data Node & Viewer

Reduced Irrigation Duration 40-Inch AquaSpy Probe in Valencia on Swingle (Flatwoods Soil) Grower changed irrigation duration from 6 to 4 hours every other day; a 33% reduction in water use

Irrigation Draining below 12 inchesOver Irrigation Reduced 40-Inch 40-Inch AquaSpy Probe in Valencia on Swingle (Flatwoods Soil) Grower changed irrigation duration from 6 to 4 hours every other day; a 33% reduction in water use

Spring 2003Summer Rains 2003Fall 2003Winter Spring 2004 Irrigate only to 20” to prevent leaching fertilizer Ridge Citrus BMP’s

Switch from Daytime to Nighttime Irrigation – Micro Sprinklers Nighttime Daytime Reduced water use by 50% Grower eventually changed from irrigating 4 hours every other day to 3 hours every 3 days

Over Irrigation with Drip Year 1: 10 hrs every-other day Year 2: Reduced to 5 hrs every 2-3 days Reduced water use by 70% In Year 2, grower cut his electric bill in half (between drip and jet irrigated blocks combined)

Benefits of Soil Moisture Monitoring Reduce Water Costs Reduce Pumping Costs Reduce Fertilizer Leaching Reduce Fertilizer Costs Increase Yield Increase Quality Increase Profits

AquaSpy ® AquaSpy ® Slurry Installation

Single sensor soil moisture Rugged robust design Fully sealed Maintenance free Large sphere of influence Accurate volumetric soil moisture For continuous monitoring Very affordable Includes a temperature sensor Works in porous media mixes AquaSpy Sensor TM

AquaSpy Sensor in Containers Used machete to slice roots and potting soil Sensor connected to AquaSpy Data Node Pushed sensor in and covered up with potting media 2.5 gal Pittosporum

AquaSpy Sensors at Coastal Nurseries, Indiantown, FL MetSpy Weather Station w/ 5 AquaSpy Sensors AquaBlu with Regulator attached to field irrigation valve – controlled based on container moisture levels TerraCom w/ 5 sensors AquaSpy Sensors

3.26 in. Rain1.42 in. Rain Template with all ten sensors with weather

University of Florida BMP Trial At Coastal Nurseries, there are 10 AquaSpy sensors 5 sensors in 3 gal. Ixora Nora Grant 5 sensors in 3 gal. Jasmine Peat based media In each group, there is one pot treated with 0.5 lb rate of Zeba and one pot treated with 1.0 lb. rate of Zeba soil amendment by Absorbent Technologieswww.zeba.com

Jasmine 3 gal Orange: Untreated – Green: Treated with Zeba

Ixora Nora Grant 3 gal Red: Untreated – Green: Treated with Zeba

2 Chilean Case Studies in Blueberries

Lomas de Quinchamalí Blueberries on very sandy soil. Drip irrigation. Irrigation management was based on ET calculations with specific crop coefficients applied. An average of 3 mm/day was applied in daily irrigation runtimes of 2 hrs. After a few days of monitoring it was evident that deep drainage was occurring. Waste of water and electricity. A reduction to 45 min runtimes, plus irrigation “on demand” resulted in 64% savings, excellent yield and quality. An extra 3 has were planted without the need of another irrigation head.

Daily Irrigation runtimes of 2 hrs Deep drainage!! 45 min daily irrigations No deep drainage Crop water use only through 30 cm Blueberries in very sandy soil

Daily irrigations 2 hrs Daily irrigations 45 min Irrigations every 2 nd day 45 min Leaves drop, no more water use

2005 – 2006 Daily Irrigations 2 hrs “Based on ET tray and Kc about 3 mm per day” Average Irrigations of 45 min every 2nd day “Precision Irrigation about 1mm/day” 64% Water Savings = Energy and fertilizers

Eto 7.43 mm/day Eto 2 a 3 mm/day Frequency = 5 days Frequency = 1 día “On demand” irrigation scheduling Early Stress

Agrícola El Trumao (Driscoll’s) Blueberries on heavy soil. They were planted on leveled ground and the beds were made in the 3rd year. This explains the deep root system. Drip irrigation. Irrigation runtimes of 1.5hr/day were not reaching 40 and 50 cm, where most of the root activity was observed The strategy was changed to 7 hr irrigation every 4 or 5 days according to plant demand. Water and energy savings were marginal (around 10%), but the better management produced a record crop.

Blueberries in deep heavy soil Beds were made in the 3rd year Daily irrigations of 1.5 hr don’t reach deep enough Moisture decreasing Crop water use in depth.

Change of irrigation strategy From 1.5 hr/day t 7 hrs/5 days