Summer Annual x Fertility Rate Trial

Warm season grasses are high yield and quality forages best grown during the hot and dry summer months. They can provide quality pasture in the summer months when common cool season grasses are not as productive. Warm season grasses can also be harvested for stored feed. As with any crop though, summer annuals have their advantages and disadvantages. Some advantages include fast germination/emergence, rapid growth, high productivity and flexibility in utilization. Some disadvantages include high cost of annual establishment and high nitrogen (N) requirements. Summer annuals such as sorghum, sudangrass, sorghum x sudangrass and millets are heavy N feeders and require up to 150 lbs of N per season. Supplying high levels of N fertility in organic systems can be difficult. The primary source of N is manure on most farms. Timing manure application to coincide with crop N demand can be difficult as N mineralization rate is impacted by many environmental factors. Lack of N can also lead to lower protein and FA concentrations in forage. The goal of this study was to determine manure application rate appropriate to meet the N requirements of two summer annuals grown in Vermont