The study objective was to determine the effect of N fertilization on yield and quality of photoperiod sensitive (PS) and non-PS sorghums compared with corn. This study was done in a randomized complete block design with treatments arranged in a 4 × 8 factorial with 3 replicate blocks. Within each block, N rates (0, 56, 112, and 168 kg N/ha) were randomized with 7 kg N applied as urea 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, brown midrib (BMR) forage sorghum, sorghum-sudangrass, BMR sorghum sudangrass, PS BMR sudangrass) were randomly assigned. 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. The interaction of variety and N rate was not significant (P = 0.67). Nitrogen rate affected yield (Table 1; P = 0.02) with reduced yield for 0 kg N/ha plots compared with 56 kg N/ha, 112 kg N/ha, and 168 kg N/ha plots (11375 vs 17199, 16627, 18981 kg DM/ha respectively). However, there were no significant differences in yield across N rates of 56, 112, and 168 kg N/ha (P = 0.21). Yield was affected by variety (Table 1; 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 in central Wisconsin. Table 1. DM yields (kg/ha) for sorghums and corn using nitrogen rates in WI in 2016

Variety1	Nitrogen rate (kg/ha)
	0	56	112	168
Corn	12,391	11,499	14,127	15,717
PS forage sorghum	9,983	21,399	21,885	25,118
PS sorghum-sudan	11,715	18,726	21,302	23,647
Forage sorghum	13,410	20,660	19,130	20,250
Sorghum-sudan	13,836	17,278	15,269	20,085
BMR forage sorghum	14,205	24,289	17,226	21,332
BMR sorghum-sudan	8,609	14,859	12,566	13,306
PS BMR sudangrass	6,854	8,885	11,514	12,395
SEM	3,181
Variety × Irrigation (P-value)	0.67

¹PS = photoperiod sensitive; BMR = brown midrib.