Archived Issues

Efficient application

Article Images (Click for larger view) 

Kentucky revises nitrogen recommendations, giving some growers a shot at saving more money.

TFQ Staff Report

University of Kentucky tobacco researchers have revised their recommended fertilizer rates for burley and dark tobacco growers in the state. Compared to last year’s recommendations, the new rates may allow growers to apply less nitrogen—approximately 50 pounds per acre less in certain situations.

Bob Pearce, University of Kentucky Extension tobacco specialist, says state researchers tweaked their recom-
mendations earlier this year so that growers could be more efficient in their operations.

The revised recommendations provide growers with economically sound nitrogen rates, allowing them to produce good yields and quality while minimizing over-application. In addition to potentially saving growers some money, the new rates also help growers avoid excessive nitrogen applications that may result in high nitrosamine levels in cured leaf.

The table below shows the revised rates based on soil drainage and crop history. The extra 50 pounds per acre for continuous tobacco has been removed from the recommendations. In addition, the rates for well-drained soils have been separated from those for soils that are only somewhat well drained, allowing recommendations for lower nitrogen rates on soils with good drainage.

Research over the last decade has repeatedly shown that farmers can achieve high yields while using these recommended rates of nitrogen with a good crop rotation program. In most growing seasons, weather, disease or other factors will lower leaf yield before nitrogen becomes a limiting factor.

Recommendations regarding the practice of sidedressing have also been updated. Sidedressing is recommended on problem soils, including sandy soils and soils with poor drainage. Sidedressing improves fertilizer use efficiency by placing the fertilizer near the root zone just prior to the time of most rapid nitrogen uptake. Sidedressing a high rate of nitrogen fertilizer, however, may increase late-season nitrogen uptake and contribute to leaf levels of nitrogen that are higher than desired. If sidedressing is practiced on well-drained soils, growers are en-
couraged to reduce the total nitrogen rate by 15 to 25 pounds of nitrogen per acre.

For more information, please see the “Lime and Fertilizer Recommendations” publication at your local Extension office or check it out online at: www.ca.uky.edu/agc/pubs/agr/agr1/agr1.pdf

On the Web
University of Kentucky Extension tobacco specialists are concerned about increasing fertilizer efficiency in coming years, and not just because of increased fertilizer costs and lower leaf prices. Ammonium nitrate, currently the dominant source of nitrogen for tobacco, may soon be in shorter supply. Because of homeland security concerns, the government is putting increasingly burdensome regulations on the transport, storage and sale of ammonium nitrate. Some manufacturers have already begun limiting production, and some dealers are stocking lower quantities.

To address this potential problem, the University of Kentucky Cooperative Extension Service has made “Alternative Fertilizer Nitrogen Sources for Tobacco Production” available to growers on the Web. The document helps growers understand what alternate sources of nitrogen are available for tobacco production and how they may differ from ammonium nitrate. Check out the document at: www.uky.edu/Ag/Agronomy/Extension/ssnv/newsviews.htm