|Grisham, Abbey - University Of Wisconsin|
|Akins, Matthew - University Of Wisconsin|
|Remick, Elizabeth - University Of Wisconsin|
|Su, Huawei - University Of Wisconsin|
Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/6/2017
Publication Date: 6/25/2017
Citation: Grisham, A., Akins, M., Remick, E., Su, H., Ogden, R.K., Coblentz, W.K. 2017. Nitrogen fertilization effects on sorghum forage yield and quality. Journal of Dairy Science. 100 (suppl. 2):68.
Technical Abstract: The study objective was to determine the effect of nitrogen fertilization on yield and quality of photoperiod sensitive (PS) and non-PS forage sorghum, sorghum-sudangrass, and sudangrass compared to corn. This study was a randomized complete block design with treatments arranged in a 4 x 8 factorial with 3 replicate blocks. Within each block, N rates (0 kg N/ha, 56 kg N/ha, 112 kg N/ha, 168 kg N/ha) were randomized with 7 kg N applied as urea (46-0-0) by hand at planting and the remaining N applied at the 4-6 leaf stage. The 0 kg N/ha application rate did not receive pre-plant N. Within each N rate, varieties (corn, PS forage sorghum, PS sorghum-sudangrass, forage sorghum, BMR forage sorghum, sorghum-sudangrass, BMR sorghum sudangrass, PS BMR sudangrass) were randomly assigned. The plots were planted June 3, 2016 and harvested at 1/3 to 1/2 kernel milk-line for corn, soft to hard-dough for sorghum, or after a killing frost. Data were analyzed using MIXED procedure of SAS 9.4. The interaction of variety and N rate was not significant (P=0.67). Nitrogen rate affected yield (P=0.02) with reduced yield for 0 kg N/ha plots compared to 56 kg N/ha, 112 kg N/ha, and 168 kg N/ha plots (11375 vs 17199, 16627, 18981 kg DM/ha respectively). However, no significant differences in yield were found across N rates of 56, 112, and 168 kg N/ha (P>0.21). Yield was affected by variety (P<0.01) with PS varieties, forage sorghum, and BMR forage sorghum having greater yields than BMR sorghum-sudangrass, sudangrass, and corn. Overall, some sorghum varieties can provide excellent yields of forage with modest N fertilization.