Louisiana: Highlights from Irrigation Workshop

    Farmers can improve irrigation efficiency by understanding the environmental factors that affect their operation and by using technology to make better decisions, experts with the LSU AgCenter and National Resources Conservation Services said at a workshop held Dec. 8-9.

    The workshop at the LSU AgCenter Red River Research Station in Bossier City was the first of three that the AgCenter is hosting to educate farmers, consultants and others in the agriculture industry about sustainable irrigation practices.

    The next workshops will be on January 21-22 in Winnsboro and February 16-17 in Marksville. To register, visit here.

    Temperature, humidity, solar radiation and wind speed all affect how much water plants consume, so farmers must consider those environmental factors when irrigating to make sure they adequately provide water to their crops, said AgCenter weed scientist Josh Copes. Soil type, which affects how water infiltrates, is another factor.

    Farmers must pay close attention to the growth stage of their crops when making irrigation decisions, Copes said. Grain sorghum and corn, for example, grow faster as weather gets hotter. Plants become stressed if they don’t have enough water at key growth stages.

    With soybeans, the most important time for water is during pod development. Just six days of wilting from drought can cost farmers 20 percent of yields, Copes said.

    “One year is not going to be like another year, so that’s why it’s critical to monitor plant growth and moisture,” he said.

    As crops near maturity, farmers should check that the soil profile is full of water before stopping irrigation, Copes said.

    Scheduling irrigation minimizes soil and nutrient losses and improves yields, said AgCenter irrigation engineer Stacia Davis. Farmers should be familiar with their soil type, which affects how water moves. The NRCS’s Web Soil Survey can identify how much sand, silt and clay is in a certain area.

    “Sand has much larger particles, resulting in larger pore spaces, so it can’t hold much water because it’s going to move through very quickly,” Davis said. Silty loam and clay soils hold water for a longer time.

    Farmers should irrigate according to how much water their plants need rather that totally saturating the field, which promotes leaching. Flow meters, which monitor how much water flows through the pipe, are useful tools, Davis said.

    “If you don’t know how much water you’re putting out, you can’t say ‘I’m not over-irrigating.’ You don’t know when you’re inefficient if you’re not measuring it,” she said.

    Soil moisture sensors can also help farmers decide if they need to irrigate. Many different types are available, including some whose data can be viewed remotely online or using a smartphone app.

    Irrigation efficiency can be improved by choosing equipment best suited for a farmer’s operation, said NRCS engineer Biff Handy.

    “We want to maximize the volume of irrigation water pumped while at the same time minimizing the amount of fuel used during pumping,” Handy said.

    Surface water is usually less expensive to pump, Handy said. But not everyone has easy access to a body of water and instead must draw groundwater from a well.

    Some surface water bodies, like bayous, fluctuate more than others. When the water level is lower, it must be pumped up a greater distance, which uses more energy, Handy said.

    A handheld tachometer, or RPM gauge, is a valuable tool for testing pump efficiency.

    “It’s very important that you know the actual speed you’re operating that pump at,” Handy said. For example, running a pump slower than it was designed for is inefficient.

    In furrow irrigation, the number and size of holes in poly pipe affect efficiency, too. Davis told attendees about computerized hole-selection software, including PHAUCET and Pipe Planner, that determines the best way to punch holes using data that farmers upload.

    Although technology can be helpful, it is still important for farmers to get out in the field and know the conditions they’re dealing with, said Bruce Garner, AgCenter agent in West Carroll Parish. In many cases, experience is the most useful tool in making good irrigation decisions.

    AgCenter economist Naveen Adusumilli talked about financial tools producers can use to determine how much value they’ll get from various equipment investments. It is important to be familiar with cash flows and to be aware that markets and costs vary.

    NRCS agronomist Chris Coreil said NRCS offers financial assistance to producers who want to try new practices and technologies, including tailwater recovery systems, surge valves and cover crops.

    Salinity in irrigation water is a growing problem in Louisiana, said AgCenter water quality specialistChangyoon Jeong. Using saline irrigation water is a concern for crop quality and soil health.

    Salt comes from minerals in the soil, saline water tables, fertilizers and soil amendments like gypsum and lime.

    In clay soils that hold water, salt accumulates on the surface at the beginning of the irrigation period, which harms soil health. In sandy soils, the salt leaches into the ground and pollutes groundwater.

    Farmers can send soil samples to the AgCenter soil lab on the LSU campus to determine how much salt it contains.

    James Hendrix, AgCenter northeast area agent, said the Louisiana Master Farmer program helps producers voluntarily implement practices that reduce runoff and make more sustainable management decisions. Agriculture has been listed as a leading cause of water pollution over the years, so it is important for farmers to be responsible.

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