422-5 Nitrogen Dynamics in Conventional Versus Twin Row Silage Corn.
See more from this Division: SSSA Division: Soil & Water Management & ConservationSee more from this Session: Management Impacts on Soil Properties and Soil C and N Dynamics: II
The objective of this study was to compare the N usage efficiencies of manure-fed, conventional row corn (CRC) versus twin row corn (TRC) management systems on a tile drained soil in Atlantic Canada at the same N application rate. In the first year of the study, three major N loss components were determined, namely removal of N in the silage harvest, nitrate leaching and denitrification losses, while a fourth, ammonia volatilization in the period subsequent to manure application, was estimated using a model. Silage yield and quality was used to measure of economic sustainability. Our hypothesis was that the twin row system with a higher plant population and greater rooting density per unit volume of soil would utilize N more effectively than its conventional row counterpart, but without reductions in yield and silage quality.
The two corn systems were grown in a randomized complete block experiment with three replications. Liquid dairy manure (LDM) was applied uniformly to all plots at a target rate equivalent to 150 kg N ha-1 and incorporated with tillage. A further 50 kg of fertilizer N was applied as a side dress at planting. The CRC and TRC systems were planted at 78,450 and 96,800 plants ha-1, respectively. A conventional 30" row spacing was used in the case of CRC and a twin row 7" apart and centred on a 30" spacing was used for the TRC system. Cumulative denitrification losses during the 2013 growing season (GS) were not significantly different, amounting to 25.2 and 18.5 kg N ha-1 for the CRC and TRC systems, respectively. Nitrogen leaching losses via tile drainage during the same period amounted to 15.9 and 16.9 kg N ha-1 for CRC and TRC, respectively. Subsequent nitrate leaching losses during the 2013-14 non-growing season (NGS) amounted 22.0 and 21.5 kg N ha-1, respectively. Leaching losses were not significantly influenced in either period by cropping system. Silage yields of 28.3 and 32.5 metric tons ha-1 for the CRC and TRC systems with N removals of 107.6 and 102.5 kg N ha-1, respectively were also not significantly different. Placement and relative availability of side dress N fertilizer in the two systems may have been a complicating factor in evaluating N usage efficiency and will have to be addressed in subsequent growing seasons. Further evaluation of these systems is required before conclusions can be drawn.
See more from this Session: Management Impacts on Soil Properties and Soil C and N Dynamics: II