Seeding Date for Different Forage Brassicas in North Dakota.

Forage brassicas are useful to produce high quality feed for livestock, when most traditional forages are not available. This study was conducted to determine the best seeding date for different forage brassica species in North Dakota. Four forage brassicas were evaluated including: kale (Brassica oleracea L. cv. Maris Kestrel), swede (Brassica napobrassica (L.) Mill. cv. Major Plus), turnip (Brassica rapa L. cv. Purple Top), and winter canola (Brassica napus L. cv. Riley), in three different seeding dates. The experiment was conducted in 2012 at two research sites in Prosper and Fargo, ND. The experiments were established in 2, 15, and 30 May in Prosper, and 25 April, 9, and 30 May in Fargo. Harvest dates were 12 and 25 October, in Fargo and Prosper, respectively. At harvest, 1 m² of fresh material (leaves + stem/roots) and dead material were collected and weighted. The fresh material was divided in leaves and roots/stems, and then dried. The experimental design was a randomized complete block in a split-plot arrangement with three replicates. Seeding dates were the main plot and species the subplot. The total forage dry matter (DM) production was greater in the first seeding date in Fargo. Swede and kale total forage was 11.2 and 10.5 Mg ha^-1, respectively. In Prosper, the same trend occurred, but with lower forage yield; 8.4 and 5.8 Mg ha^-1 for swede and kale, respectively. Leaves were the major component of the total forage DM. The total biomass production (forage DM + dead material) for swede and kale were 14.4 and 13.6 Mg ha^-1 in Fargo, and 13.1 and 9.7 Mg ha^-1 in Prosper, respectively. The seeding date affected forage DM and total biomass production in species with a longer growth period, such as swede and kale.