|Eckhoff, Joyce -|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: January 7, 2009
Publication Date: January 12, 2009
Citation: Stevens, W.B., Eckhoff, J. 2009. Managing Nitrogen Inputs to Optimize Grower Returns [Meeting Abstract]. 31-32. Technical Abstract: Nitrogen management has been a topic of great interest among sugarbeet growers and researchers for decades because of the balancing act required to achieve high sucrose yield without excessively sacrificing sucrose content and extractability. While many field studies have been conducted over the years questions continue to arise as other management factors such as irrigation methods, tillage practices, genetics and fertilizer technology change to meet the ever evolving sugarbeet industry. A good example of changes that are occurring is the accelerating conversion from furrow irrigation to flood irrigation. This conversion is being driven by a variety of non-fertilizer factors including increasing labor costs but will likely have a substantial impact on N management because of the close relationship between water movement in the soil and N leaching. Research was conducted by Montana State University researchers at the Eastern Agricultural Research Center comparing N response with overhead sprinkler irrigation with that under furrow irrigation. Results confirm that optimum production can be achieved with sprinklers at a lower N application rate than with furrow irrigation on clay soil. Analysis of nitrate-N content of groundwater show higher groundwater N concentration with furrow irrigation, suggesting that the reduced N requirement under sprinklers is due to less N being lost from the root zone. Another example of evolving management practices that may affect N management is development of new sugarbeet cultivars, including the herbicide-tolerant varieties that are now widely grown. Traditional and molecular breeding techniques have been observed to affect the amount of top produced per pound of root mass. Since the top can be a significant N sink, this and other genetic characteristics may result in different N response patterns for different varieties. Results indicated that some small differences may exist, but they do not justify adjusting N recommendations accordingly. However, the study provides recent data that emphasizes the impact over-application has on sucrose content and extractability while providing only a limited increase in root yield. When compared to commonly accepted N recommendation algorithms, the data support the use of current formulas to optimize sucrose production. Finally, reduced tillage systems such as strip tillage alter the way fertilizer is applied and how N in crop residues and soil organic matter is released. A study to compare N availability and uptake within the two tillage systems showed that while there are some small differences, in general the sugarbeet response with strip till was similar enough to that with conventional tillage that we concluded that productivity could be maintained using current N recommendation. However, our studies were not designed to find out if the N rate can be reduced with strip tillage because of the potential for increased N use efficiency resulting from the banded application. Results from N placement studies under conventional tillage suggest such an increase in efficiency may be expected with optimum fertilizer band placement.