Submitted to: Proceedings of Great Plains Soil Fertility Conference
Publication Type: Proceedings
Publication Acceptance Date: November 27, 2007
Publication Date: March 4, 2008
Citation: Stevens, W.B., Iversen, W.M., Evans, R.G., Jabro, J.D., Kim, Y. 2008. Strip tillage for sugarbeet and its implications for N fertilizer management. Proceedings of Great Plains Soil Fertility Conference. 12:54-60. Interpretive Summary: Strip tillage (ST) is attractive as a means to reduce fuel and labor costs associated with sugarbeet (Beta vulgaris L.) production, but seedbed preparation, fertilizer management, and weed control are concerns. A field study was conducted near Sidney, MT with objectives to (i) compare the effect of tillage system [conventional tillage vs. strip tillage] on yield and quality, and (ii) compare N uptake and availability with the two tillage systems under sprinkler irrigation. Most sugarbeet yield parameters were nearly identical in 2004, regardless of tillage system. The only difference was that root sucrose content was 0.5% higher for strip tillage than for conventional tillage. This was probably the result of differences in N availability during the mid to late growing season. Petiole NO3-N concentration was lower for strip tillage than conventional tillage in 2005 while there was no difference in the 2006. Despite the lower N status in 2005, sucrose yield with strip tillage was either equal to or greater than with conventional tillage in all three years. Available N (NO3-N) in the top 18 inches of soil was greater with conventional tillage than with strip tillage at 80 days after planting, but was similar at sampling dates thereafter. Considerable downward movement of fertilizer N occurred with both tillage systems, but the movement was greater with strip tillage. Spatial distribution of available N (NO3-N + NH4-N) in the top 24 inches of soil suggested that seedlings may temporarily be N deficient with strip tillage because of a N-depleted zone between the seed and fertilizer band. It was concluded that yield and quality of sugarbeet grown with strip tillage was similar to sugarbeet grown with conventional tillage. It was further concluded that, while N uptake and availability were slightly lower with strip tillage that with conventional tillage early in the growing season, negligible effects on yield and quality suggest that adjustments to application rate and fertilizer band location are not warranted. However, use of starter fertilizer may be beneficial with strip tillage to compensate for low NO3-N concentrations in the top 2 inches of soil.
Technical Abstract: Strip tillage (ST) is attractive as a means to reduce fuel and labor costs associated with sugarbeet (Beta vulgaris L.) production, but seedbed preparation, fertilizer management, and weed control are concerns. A field study was conducted near Sidney, MT with objectives to (i) compare the effect of tillage system [conventional tillage (CT) vs. ST] on yield and quality, and (ii) compare N uptake and availability with the two tillage systems under sprinkler irrigation. For ST, 12-inch strips spaced 24 inches apart were tilled in the fall into small grain straw residue using a modified parabolic shank strip tiller. Dry N and P fertilizers were banded about 3 inches below the seed row. The same fertilizer materials and application rates were used in both ST and CT. Results suggest that root yield and sugar production are similar with the two tillage systems under typical conditions; however, root sucrose content was higher with ST than with CT in two of three years suggesting greater end-of-season N depletion with ST. Midseason petiole nitrate concentrations show that ST sugarbeet exhibits a delay in N absorption compared to CT sugarbeet. Spatial analysis of soil NO3-N concentrations showed that at planting fall-applied N had moved downward but remained within 24 inches of the soil surface. There was a zone of low NO3-N between 0 and 2 inches with ST. Results suggest that seedlings may temporarily be N deficient with ST because of a N-depleted zone between the seed and fertilizer band. Starter fertilizer may be beneficial with ST to compensate for low NO3-N in the top 2 inches of soil.