Cool-Season Grasses: Established Stand Management
A soil test is the best guide for proper fertilization. In the absence of a soil test, refer to the typical plant nutrient recom- mendations listed in Table 1.2-5.
Nitrogen is extremely important for grass production. Economic returns usually can be achieved with an application of 50 pounds of N per ton of yield split at least three times during the year: 1⁄3 of the total annual N in early spring when the grasses first green up and the remaining N divided after each cutting.
Grass tetany is an animal condition caused by low blood magnesium levels. It usually occurs in the spring, when high-producing animals such as lactating cows are consuming primarily grass, and their demands for magnesium exceed the supply. This situation can be aggravated by excessive soil potassium levels. To reduce the possibility of tetany from grasses to be harvested for hay or silage, do not apply potash in early spring except when recommended by soil test. After the first harvest, however, apply needed fertilizer to maintain a balanced soil fertility program. It may be helpful to give livestock high-magnesium supplements during spring.
Generally, the best compromise between yield and quality is obtained when the first cutting is made at early head emergence from the boot (Table 1.8-2). Timothy and smooth bromegrass are particularly sensitive to harvests made before this stage of growth. Harvesting cool-season grasses beyond the early head emergence stage leads to dramatic declines in forage quality (Table 1.8-1).
Except for certain species and varieties, later cuttings of cool-season grasses usually are vegetative (all leaf material) and normally can be cut 6 to 7 weeks after the first harvest.