Managing Irrigation water: Lyndon Kelley MSU Extension / Purdue University Irrigation Management Agent WWW.msue.msu.edu - find St. Joseph Co. - then hit the Irrigation button

Size , Scale and Make-up Indiana 313,000 acres Michigan – 452,000 acres County Irrigated Acres % LaPorte 32,400 10.4 Knox 24,600 7.8 Elkhart 23,500 7.5 LaGrange 21,700 6.9 Jasper 20,600 6.6 St. Joseph 19,500 6.2 Pulaski 19,200 6.1 Kosciusko 19,100 Fulton 16,200 5.2 Starke 11,100 3.5 Bartholomew 9,100 2.9 County Irrigated Acres % St Joseph 104,000 23.0 Montcalm 47,000 10.4 Branch 39,300 8.7 Kalamazoo 29,600 6.6 Cass 25,400 5.6 Van Buren 23,900 5.3 Berrien 19,200 4.2 Allegan 15,300 3.4 Ottawa 13,500 3.0 Calhoun 10,400 2.3 Tuscola 5,800 1.3 Summarized from 2002 Agricultural Census 11 Counties = 73.8 % of total 11 Counties = 69.2 % of total

Needed Irrigation 5.5” Normal rainfall 34.6 Crop need 15.6” total

Estimated rainfall recharge Scientific Investigations Report 2005–5284 U.S. Department of the Interior U.S. Geological Survey

Water Quantity Needed Irrigation water replaces the plant water use (removed from soil) Water use is directly correlated to light interception 50% light interception results in about 50% of the maximum water use Maximum water use mid-July early August, full light interception, highest temperatures brightest and longest days. Evapotranspiration (ET) = fn (net radiation) + fn (temperature) + fn (wind speed) + fn (air humidity)

Weighing Lysimeter Rain and Irrigation increase weight Evapotransporation decrease weight

Soys Potato Alfalfa Alfalfa Soys Corn Field beans Corn Field beans From Minnesota Extension bulletin “Irrigation Scheduling”, assuming temperature 80-89

Three factor reducing effective water application 2. Lack of system uniformity 5-35% loss in effectiveness Three factor reducing effective water application Sprinkler overlap with end gun 1. Irrigation Runoff (comparing irrigation application rate to soil infiltration rate) 0 -30 % loss 3. Evaporative loss to the air Minimal loss in our humid area 0 – 6% Estimated 4-6% loss in Nebraska

Average application efficiency Desired Inches of effective application Necessary application rate to achieve effective evapo-transportation rates at various application efficiencies Average application efficiency Desired Inches of effective application 70% 75% 80% 85% 90% 95% 0.16 0.21 0.20 0.19 0.18 0.17 0.23 0.22 0.26 0.25 0.24 0.29 0.28 0.31 0.30 0.34 0.33 0.27 0.36 0.35 0.32 0.39 0.38 0.42 0.40 0.37

Quantity Needed Maximum water use for most crops is .27 - .32 in./day 3 gal/minute/acre pump capacity = 1”/week 5 gal/minute/acre pump capacity = .25 in./day 7 gal/minute/acre pump capacity =.33 in./day, 1”every 3 days 500 gal/minute pump can provide 1” every 4 days on 100 acres

Think of your soil as a bank Soil type : Heavier soil can hold more water / foot of depth than light soils Water holding capacity: The soil (bank) can hold only a given volume of water before it allow it to pass lower down. Intake rate: Water applied faster than the soil intake rate is lost. Deletion: Plants can pull out only 30 - 60% of the water Rooting depth: The plant can only get water to the depth of it’s roots. Water lost from the bottom of the profile can wash out (leach) water soluble nutrients and pesticides.

Calculating Water Holding Capacity Soil Name Depth Inches Available water holding capacity Average Available water holding capacity Ave. Available water holding capacity ( 24 in.) ( 36 in.) Oshtemo 0 - 14 14 – 35 35 - 60 0.10 – 0.15 0.12 – 0.19 0.06 – 0.10 0.125 0.155 0.08 14” x 0.125=1.75 10” x 0.155=1.55 ----------------------- = 3.3 14” x 0.125= 1.75 21” x 0.155= 3.26 1” x 0.08 = 0.08 = 5.09 Spinks 0 – 10 10 – 26 26 - 60 0.08 – 0.10 0.04 – 0.08 0.09 0.06 10” x 0.09= 0.9 14” x 0.09= 1.26 = 2.16 16” x 0.09= 1.26 8” x 0.06= 0.48 = 2.64

Calculating drought capacity Crop ET. was 0.30 in./day Available water capacity of 03.0 in. (AWCI Irrigation system can apply 0.20 in./day. Started irrigating when the AWC was 1.0 in. down 3.0 in. (AWC) - 1.0 in. = 2.0 in. available capacity 2.0 in. available capacity / 0.10 daily deficit = 20 days 20 days of drought capacity- Not Considering down time

Limited water supply Irrigation Management Diversify the crops sharing the water supply between high and low water use. Stager planting date to stager peak water need times. Plant part of irrigated area to a sacrifice crop to neglect during extended drought. Start irrigating early to bank water ahead. Stager forage crop cutting dates to avoid simultaneous peak use.

20 acres 30 acres 20 acres 30 acres 1320’ Field #10 1109’

SW 1/4 6-1-08 corn 3.0 36” 50 1.5 Available 2.00 1.85 1.70 1.52 1.34 1.94 1.79 Jun 21 Jun 22 Jun 23 Jun 24 Jun 25 Jun 26 75 85 .15 .18 -0- 0.75

Mendon Estimated Evapotranspiration (ET) for July 4, 2008 Irrigation scheduling links: Historical E.T. for this site MSU Scheduler IS 4 MichIana Irrigation Scheduler MSU Scheduler Excel MSU Paper check book system Explanation of estimated E.T.. Corn – 105 day maturity emerging on the listed date in 30” rows. Soybean – for grow 3.0 emerging on the listed date. E.T. have been estimate for two days in the future based on future weather forecast. Date- July 1 Stage/ ET.Estimate July 2 Stage/ ET.Estimate July 3 July 4 July 5 July 6 Corn Emerged May 1 .19 1st. Tassel .20 full tassel .22 May 7 .17 10 leaf May 14 .15 8 leaf .16 Soybean 6th. Trifolliate .18 First flower .21 4th. Trifolliate Grass -reference crop 4” standard 4” standard .20 4” standard .17

www.agry.purdue.edu/irrigation/IrrDown.htm

MichIana Irrigation Scheduler: Purdue Agronomy web site –Est. From High / Low temp. & date

MichIana Irrigation Scheduler – out put

Irrigation Scheduling Checkbook Challenges ?? Soil Moisture ?? Errors will accumulate over time -Weekly ground truthing needed Rainfall variability is more than often considered Only "effective” rainfall and irrigation should be considered - Only water entering root zone uniformly is "effective” Corn crop mature in program by calendar, not heat

Methods to Estimate Soil Moisture Feel an Appearance Electrical resistance – electrodes on blocks in soil Tensiometers – measures soil moisture tension

                                                                                                                     

Qualitative evaluation of soil water monitoring devices.   DEVICE NP TDR GS AP AQ TM GB WB INITIAL COST 3 1 8 2 7 FIELD SITE SETUP REQUIREMENTS 10 6 OBTAINING A ROUTINE READING 4 INTERPRETATION OF READINGS 5 ACCURACY MAINTENANCE 9 SPECIAL CONSIDERATIONS COMPOSITE RATING 49 52 48 42 47 41 A score of 1 is least favorable while a score of 10 is most favorable. NP - Neutron Probe TDR -Time Domain Reflectometry GS - Gravimetric Sampling AP - Troxler Sentry 200-AP AQ - Aquaterr Probe TM - Tensiometer GB - Gypsum Block WB - Watermark Block

Gravimetric Sampling Wet weight – Dry weight of a know volume of soil. Often refered to as a “can test”

Have you seen yield map patterns that match the irrigation system configuration?

Sprinkler overlap with end gun WWW.msue.msu.edu/St Joe /Irrigation Sprinkler overlap with end gun Tower 1 Tower 3 Tower 5 Tower 7 Tower 8

Greatest improvement needed End gun stop adjustment Water supply over or under design End gun orifice, too little or too much Wrong sprinkler or tip Leaks, plugs and no turn sprinklers

Water supply over or under design supply over design yield tail up, supply under design yield tail down Example of Water supply under volume for sprinkler design

330’ 495’ 660’ 990’ 2 acres 18 acres 31 acres 49 acres 71 acres 96 acres 126acres 10 acres 13 acres 22 acres 25 acres 30 acres Total Acres 4145’ 3109’ 2072’ 5181’ 6217’ 7253’ 8290’ circumference Over and under application issue affect the majority of the application area 8 acres 6 acres 165’ 825’ 1155’ 1320’ Feet from center

Most system apply within 85% of the expected application Application is 4 % under expectation

Measure flow at desired pressure prior to ordering sprinkler package Poor performance: Ask dealer to measure flow at peak water use season and compare to design parameters.

Assure the best plant stand possible Irrigate, if necessary, to make sure to get maximum germination and uniform emergence. Wet down 2.5” within five days of planting, ½” in most irrigated soil Maintain a moist surface,0.10” to 0.20” applications, till spike. Are you ready to irrigate the day you plant?

Using irrigation to get the most from pesticides and nutrients Timely application of irrigation water: Improves incorporation of herbicides. Improves activation of herbicides. Improves activation/reactivation of insecticides. Reduces nitrogen volatilization. Maximizes yield to utilize the resources.

Do not apply this product through any type of irrigation system. If available, sprinkler irrigate within 2 days after application. Apply ½” -1” of water. Use lower water volumes (½” ) on coarse-textured soils, higher volumes heavier soils (1”) on fine-textured soils.

Are appropriate backflow prevention devices in place and properly maintained if fertigation or chemigation is used? Backflow prevention safety devices are used and properly maintained if fertigation or chemigation are used. 2.9 Irrigation Management Practices

Are appropriate backflow prevention devices in place and properly maintained if fertigation or chemigation is used? Distance requirements between well and contamination, and agricultural chemical/fertilizer storage and preparation areas are at least 150 feet from the well. 2.11 Irrigation Management Practices

Irrigation management to Protect Groundwater Backflow protection with Air gap and vacuum relief -required for chemigation and fertigation - good idea for all systems. -Interlocks between nitrogen pump and irrigation pump. -Backflow protection between injection point and supply tank.

Chemigation / Fertigation Systems - Safety Interlock

Are split applications of nitrogen fertilizer used when nitrogen is used in irrigated field? Split applications of nitrogen fertilizer are used when nitrogen is used in an irrigated field. N application does not exceed MSU recommendation. 2.8 Irrigation Management Practices

Chemigation – Application of pesticide via irrigation water. Fertigation – Application of fertilizer via irrigation water.