November 26, 2008


High nitrates in water seen as beneficial for agriculture

Nitrates in water from the Seymour Aquifer can be as high as 40 parts per million, which could benefit agricultural producers who use it for irrigation, according to Texas AgriLife Research scientists.


About 90 percent of the water from the Seymour Aquifer in Texas counties of Knox, Haskell, Baylor, Wichita, Wilbarger and Fisher, is used for irrigation, said Dr. John Sij, who had studied nitrate levels in irrigation water from the Seymour Aquifer for the past three years with Dr. Cristine Morgan and Dr. Paul DeLaune.


For agricultural producers, the nitrates could serve as a source of nutrients that could reduce fertiliser costs.


Sij suggests that subsurface drip irrigation systems should be installed so as to improve water quality by reducing nitrates, and to allow crop producers to use the benefits of the nutrients supplied in the irrigation water.


Drip irrigation is an efficient delivery system for nutrients, said Delaune.


"At nearly US$1 per pound for fertiliser nitrogen these days, 55 'free' pounds of nitrogen can add up to significant cost savings, about US$55 per acre or more, for producers who irrigate their crops with high nitrate ground water," DeLaune said.


However, farmers need to know the level of nitrogen both in the soil and water before planning their fertiliser programme, said Sij, adding that other nutrients such as potassium and phosphorus must be adequate to take advantage of nitrates in the irrigation water as well as any applied fertiliser nitrogen.


Producers should have their irrigation water analysed for nitrate annually and make allowance for this free nitrogen source when determining crop fertiliser needs, Sij said.

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