Strawberry: Drip Irrigation and Fertigation

Transcription

1 Strawberry: Drip Irrigation and Fertigation Erick D. Smith The University of Georgia Dept. of Horticulture, Tifton Campus January 10, 2014 SE RFVC Strawberry Educational Session Rm 205

2 Water Irrigation Critical for plant development Strawberry has shallow roots and sensitive to water stress Amount applied and when is critical Too much = nutrient leaching + disease + yield reduction Too little = drought stress + loss of production Studies have shown, only 5 days after a soaking rain strawberries can require irrigation (especially sandy soils) Supplemental irrigation can increase yields from 40 60%

3 Irrigation Two systems of production Matted Row Overhead irrigation Annual Hill Drip under plastic mulch Preferred method» Out paces disease» Good Fruit Quality

4 Water Irrigation Annual Bed/Hill System 7 month production process Bed preparation in fall (hopefully already ordered plants) Installation of mulch and drip line or tape» Irrigation placed on soil surface under mulch» Or buried 1-2 in the bed Strawberries planted through holes in the mulch And watered in with overhead irrigation immediately Utilize overhead for a few days until the plants are established Switch to drip

5 Water Annual Bed/Hill System Irrigation Spring Crop Water usage 0.2 per day or 5,431 gal/a/day Drip is 80-85% efficient Pumping capacity should be able to deliver 6,390 6,789 gal/a/day Two commonly used emitter products Drip tape thin walled» Single season use Drip line thick wall» Multiple season use

6 Water Annual Bed/Hill System Irrigation Various emitter spacings and choice is soil type dependent Sandy soils 8 Heavier soils 12 Lateral Flow Rate affects overall flow rate

7 Water Annual Bed/Hill System How to calculate lateral flow rate example: Drip tape flow rate = 0.4 gpm/100 ft Bed spacing = 5 ft x 100 ft 100 ft rows/a = [43560 ft 2 /(5ft x 100 ft)] = 87.1 Let s say 80% efficiency = 6,789 gal/a/day(gpad) 6,789 GPAD/87.1 (100 ft rows/a) =78 gal/100ft/day 87.1 (100ft rows/a) x 0.4 gpm/100ft =34.8 gpm/a

8 Water Annual Bed/Hill System How to calculate lateral flow rate example: 87.1 (100ft rows/a) x 0.4 gpm/100ft =34.8 gpm/a If production is on multiple acres: for example - 8 A 8 A x 34.8 gpm/a = gpm» If too much demand upon pump capacity, divide into zones 2 A x 34.8 gpm/a 69.6 gpm» Length of time to irrigate 2 acres 78 gal/100 ft 0.4 gpm/100 ft = 195 min or 3 hr 15 min 4 zones x 3 hr 15 min 13 hr to irrigate 8 A

9 Layout

10 Layout Pumps (20-25 psi at field entrance) (10-12 psi at drip tape) Gravity Prime mover (fuel, electric) Portable Stationary Self-Priming bigsprinkler.com barnyardsupply.com

11 Backflow Prevention Prevents reverse flow of water to source Protects water sources from chemigation practices Mandatory and regulated States, Counties and Districts may have specific codes» Consult County Agent or regulatory agency before construction to determine appropriate rules Common Devices Air Gap Atmospheric vacuum breakers (AVB) Pressure-type vacuum breakers (PVB) Double-check valves Double Backflow Prevention Assembly AVB PVB

12 Flow meters Measures water consumption Accurate flow measurements can: Efficiently manage nutrient, pesticide and fungicide applications Determine pump outlet flow and watering time on the crop Another Calculation Gallon per Minute (gpm) Applied Water in inches = [gpm x irrigation time (hrs)]/[acres x 449] (100 gpm x 1 hr)/(1 A x 449) = 0.22 inches of water applied to an acre Propeller Flow Meter (image by Kansas Department of Agriculture) Magnetic Flow Meter

13 Pressure gauges and filtration Filtration minimizes emitter clogs Manufactures of drip line will not guarantee products without filtration Shown disc filter system Pressure gauges used to indicate need for cleaning Filter on Drip Irrigation System (photo by Benjamin Shute of Hearty Roots Community Farm)

14 Pressure gauges and filtration Importance of water analyses! Factor Plugging hazard based on level Adapted from Pitts et al., 2003 Slight Moderate Severe ph < to 7.5 >7.5 Dissolved solids (mg/l) < to 2000 >2000 Manganese(mg/L) < to 0.5 >0.5 Iron (mg/l) < to 0.5 >0.5 Hydrogen sulfide (mg/l) < to 2.0 >2.0 Hardness (mg/l CaCO 3 ) < to 300 >300

15 Pressure Regulation Drip tape requires a specific water pressure 10 psi works well Higher than 15 psi can cause ruptures Maintain optimum pressure to ensure appropriate distribution regardless of pressure fluctuations at the pump head

16 Air Relief Valves Allows air to escape as the system fills or allows in after the system is turned off ELEVIATES AIR HAMMER Placed at the highest elevated point in the system or at the end of long runs where air accumulates xtremehorticulture.blogspot.com

17 Closing the system Heavy drip line Bend and clamp Connectors Splice connectors very important! Valves, T s, adaptors, etc.

18 Chemigation/Fertigation Equipment Venturi Bypass (Mazzei) Negative Pressure (suction) Various venturi sizes to accommodate area irrigated Positive Displacement Reciprocating action Accurate Does not require a bypass Mazzei Injector System Dosatron Tim Coolong, UGA

19 Fertilization and Fertigation Strawberry: 150 lb N/A/season Pre-plant Sample Soil Apply 33% of N (by soil analyses report) Apply P and micronutrients Fertigation The application of plant nutrients through the drip line Custom blends available, dependent upon nutrient analyses and soil type

20 Fertilization and Fertigation Liquid Fertilizer Preferred for drip systems Dissolved nutrients ready to be metered to the crop Granular Fertilizer Can be used, needs to be thoroughly dissolved before injected If done improperly can cause clogging

21 Fertilization and Fertigation Source material NO 3 or NH 4 Strawberry soil ph NH 4 is soil acidifying NO 3 /NH 4 ratio 50:50 at minimum Favor NO 3 Petiole sap-testing identifies ppm of NO 3

22 Fertilization and Fertigation Soil moisture monitoring Best Management Practice Minimizes nutrient leaching Avoids excess irrigation Types Tensiometers Measures soil moisture tension

23 Fertilization and Fertigation Types of soil moisture monitors Electrical Resistance Blocks Also known as gypsum blocks Inexpensive and simple Useful for providing information on irrigation timing But do not provide information on amount vfd.ifas.ufl.edu aesop.rutgers.edu Courtesy of Jack Rabin

24 Fertilization and Fertigation Types of soil moisture monitors Neutron Probe Meters (radioactive Americium 241 pellet) Not suitable for short term cropping such as hill system strawberry Expensive Operator training Licenses Regulatory inspections

25 Fertilization and Fertigation Irrigation Scheduling Soil moisture dependent on Time of year Rainfall Temperature Monitor soil moisture Tensiometer example (recommended) Place 4 to 6 inches in actively growing root zone Place offset of drip tubing Maintain 10 to 20 centibars Close monitoring in sandy soils gcrec.ifas.ufl.edu

26 Fertilization and Fertigation Irrigation Scheduling Do not allow more than 20% depletion of soil moisture Dependent upon soil type

27 Fertilization and Fertigation Fertigation Scheduling Timed to soil moisture and crop water demand Two suggested timings for applications Six-day Two-day Fertilizer Analysis Total Recommendation Pre-plant N (33%) Injected N and K2O Pre-plant K lb N 50 lb N 100 lb N (1:1 ratio) 160 lb K 2 O 100 lb K 2 O 60 lb K 2 O

28 Fertilization and Fertigation Fertigation Scheduling Two-day per week Method Five acres Density of 7-0-7: 10.5 lb/gal Application 7 lb/week/acre 0.07 x 10.5 lb/gal = 7 lb/ 2d = (3.5 lb)/(0.735lb/gal) = 4.76 gal/a x 5 A = lb/gal 3.5 lb/d 4.76 gal 23.8 gal Fertilizer Analysis Total Recommendation Pre-plant N (33%) Injected N and K2O Pre-plant K lb N 50 lb N 100 lb N (1:1 ratio) 160 lb K 2 O 100 lb K 2 O 60 lb K 2 O

29 Fertilization and Fertigation Fertigation Scheduling Six-day per week Method Five acres Density of 7-0-7: 10.5 lb/gal Application 7 lb/week/acre 0.07 x 10.5 lb/gal = 7 lb/ 6d = (1.17 lb)/(0.735lb/gal) = 1.59 gal/a x 5 A = lb/gal 1.17 lb/d 1.59 gal 7.95 gal Fertilizer Analysis Total Recommendation Pre-plant N (33%) Injected N and K2O Pre-plant K lb N 50 lb N 100 lb N (1:1 ratio) 160 lb K 2 O 100 lb K 2 O 60 lb K 2 O

30 Fertilization and Fertigation System Calibration Three factors Flow rate Flow meter» Gallons per minute or hour Injection rate Volume of material injected per unit time» Use a known volume, put the suction line of the injector, time how long it take that volume to enter into the system System pass-through time A calculation of flow rate and linear feet of tubing

31 Irrigation Scheduling Currently available Available both at the Google Play Store and Apple App Store for Android and ios operating systems.

32 Weather Networks

33 References Thank you Commercial Strawberries php Fertilization of Strawberries in Florida Southeast regional strawberry plasticulture production guide Guides/2005culturalguidepart1bs1.pdf