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Sprinklers don't boost contamination

Concerns that center pivot irrigation of pastures could lead to increases in groundwater contamination have been proven false, thanks to extensive research conducted in New Zealand.

The original concern was that microbial contamination could be leached into groundwater with sprinkler irrigation involving either center pivots or traveling volume guns. Bacteria capable of living in both animals and humans are commonly found in cow manure.

Sprinkler effects small

Researchers from the Institute of Environmental Science and Research in New Zealand studied the transport of microbes from two sprinkler-irrigated dairy pastures in that country.

Those scientists found that when irrigation applications were increased to simulate irrigation plus heavy rainfall, there was a small increase in some forms of bacteria, notably E. coli, in ground- water. But other common bacteria were only detected at very low levels when fresh cow manure was subjected to this treatment. The results of the study indicate a minimal impact on dairy farm pastures in microbial quality of groundwater as a result of sprinklers.

Flood irrigation an issue

Previous studies of the issue involved the flood irrigation method. That research did find that flooding fields was shown to cause high levels of groundwater contamination since that irrigation method applies much more water less efficiently.

The New Zealand research effort detected no differences between a traveling volume gun and center pivot. The researchers suggest that converting from flood irrigation to sprinkler irrigation of pastures would reduce microbial contamination of groundwater and, thus, minimize environmental health risks.

Early Planted Cotton Yields More but Only With Irrigation

Cotton growers can produce more cotton if they plant early – but only if they use irrigation. Early planting increased cotton production in two of the four years of the study with irrigation. Nonirrigated plots never saw increased production from early planting, and they even saw a 13% decrease in yield one year.

Those findings come from a four-year study conducted by Bill Pettigrew, a scientist with the USDA-Agricultural Research Service (ARS) in Stoneville, Mississippi. Pettigrew compared the performance of cotton under irrigated and nonirrigated plots. Half of those plots were planted the first week of April; the other plot was seeded in the more traditional time period around the first week of May.

Previous research indicated that planting earlier certainly boosted cotton yields. This yield increase is likely because the peak blooming period shifts closer to the longest day of the year (in June), avoiding the typically drier months of the year, July and August. The additional sunlight associated with longer days also allows the plants to take in more sunlight during their growing season.

However, most of this original field research was completed on irrigated crops.

Pettigrew's study found that while early planting does increase yields, it does so only with irrigation. The implication here, Pettigrew says, is that cotton producers in the Mississippi Delta region who don't have irrigation capabilities should probably not adopt an early- planting strategy.

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