Study Looks into Alfalfa in Drier State29 November 2013
US – South west Kansas farmers are asking whether alfalfa is still an economical crop given arid conditions and a depleting Ogallala aquifer.
Kansas agronomists say that arid Kansas plains are not the ideal situation for alfalfa, a crop with high water requirements.
To help farmers evaluate the potential economic returns of growing alfalfa in that region even as the water supply is diminishing, Kansas State University researchers conducted a five-year study to better understand how alfalfa would fare with a limited water supply.
“Alfalfa creates the most economic return by far, compared with other crops for irrigators when water supplies are adequate for full irrigation,” said recently retired K-State Research and Extension water resources engineer, Norman Klocke , who cited consistent demand from the dairy and beef cattle industries, in particular.
“As water resources in this region decline, the question is whether or not alfalfa production is possible with limited irrigation – especially when the crop is stressed because of a lack of water during part or all of the growing season.”
Mr Klocke along with researchers Randall Currie and John Holman designed a field study conducted at the Southwest Research and Extension Center in Garden City. The experiment was intended to reflect the declining ability of the aquifer to supply water for irrigation and also to reflect the constraints of water rights and irrigation management.
What they found was that yield response to the same amount of irrigation was highest during 2007 when the maximum yield was 9 tons per acre and lowest in 2011 when the maximum yield was 4.5 tons per acre. These maximum yields came from 24 inches of irrigation applied in all years.
Dryland yields were 4.5 tons per acre in 2007 and zero yield in 2011. The drought in 2011 certainly impacted yield, but precipitation filled the soil profile in 2006 and alfalfa benefited from this extra water in 2007 because its roots extended to a depth of at least 8 feet. After that, precipitation could not fully replenish the soil.
Mr Klocke also compared alfalfa yield results from 2007-2011 with results from a study conducted at Garden City from 1921 through 1930.
Like Mr Klocke and the team, F.A. Wagner, a professor and early scientist with Kansas State, was also looking for the response of irrigation to different amounts of water. Back then irrigation was applied to the surface before irrigation pumps were available.
“The results from both experiments were similar, which tells us that conversion of atmospheric energy to plant dry matter through photosynthesis has not changed in alfalfa over all those years,” Mr Klocke said.
Results of the study have been published in Transactions of the American Society of Agricultural and Biological Engineers. More information is available at:here.
“The bottom line is that alfalfa produces good economic returns when it has plenty of water, but yields fall off over years when stored soil water is depleted due to less than optimum water from irrigation,” Mr Klocke said.
“Using yield results from this experiment, producers can make comparisons of the profitability of alfalfa and other irrigated crops.”
K-State’s Crop Water Allocator, which can be accessed at www.mobileirrigationlab.com, also helps producers evaluate economic returns, not only from alfalfa but also corn, wheat, sorghum, soybeans, and sunflowers getting zero to 24 inches of irrigation.
“Results show alternatives through crop selection and irrigation management to compensate for less irrigation, but water is still essential for crop production and unfortunately less water means smaller yields,” Mr Klocke said.
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