Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: 8/8/2007
Publication Date: 11/7/2007
Citation: Stevens, W.B., Jabro, J.D., Evans, R.G., Iversen, W.M. 2007. In-season movement of fertilizer nitrogen in conventional and strip till sugarbeet systems. American Society of Agronomy Meetings.
Technical Abstract: Strip tillage represents a lower input alternative to conventional tillage sugarbeet (Beta vulgaris L.) production. A one-pass strip till system significantly reduces fuel use while enhancing soil conservation. Nitrogen use efficiency with strip tillage should also be greater because fertilizer is banded directly below the seed row rather than broadcast and incorporated as with conventional tillage. Research was conducted at Sidney, MT to determine if fertilizer distribution in the soil during the growing season is more favorable with strip tillage than with conventional tillage. A vertical grid sampling scheme was implemented utilizing a linear transect perpendicular to and centered on the crop row. A soil core 1.7 cm in diameter and 60 cm in length (depth) was extracted every 5 cm along the transect using a hand-operated sampling device that encased the core in a plastic sleeve. The resulting data were then used to construct two-dimensional graphical representations of the soil NO3-N concentration of a vertical cross section (60 x 60 cm) of the crop row in the early, mid and late growing season. Soil NO3-N concentrations at planting showed that fall-applied N remained within 60 cm of the soil surface, but that substantial amounts had leached to a depth of 50 cm with strip tillage and 40 cm with conventional tillage. By mid season, soil NO3-N concentrations in the 5 to 40 cm depth range had been depleted to about 3 mg kg-1. Concentrations were higher in the 45 to 60 cm depth range indicating that N was leaching out of the 60 cm sampling zone. One month prior to harvest most of the sampling zone was relatively depleted of NO3-N, with average concentrations less than 4 mg kg-1. Concentrations were somewhat higher in the top 5 cm, due presumably to mineralization of organic N residues.