Second harvest timing and cut height of forage crops in Central Alaska
Proper timing of second harvest is critical for good yields and long-term sustainability of perennial hay crops in high latitude environments. We studied effects of second harvest timing and height on yield and forage quality for smooth bromegrass (Bromus inermis Leyss.), alfalfa (Medicago sativa L.), and cicer milkvetch (Astragalus cicer L.) in central Alaska. Second harvest treatments occurred every 2 wk starting approximately 3 wk after the initial mid-June harvest and ending in late September at stubble heights of 5, 10, and 15 cm. Yields increased with increasing time to second harvest and decreasing height of cut. Forage quality decreased with increasing time to second harvest while the effect of cut height was variable. For subsequent year first harvests, yields of all crops were lowest for previous year second cuts done 30 to 40 d after initial harvest, and then increased with length of time to second harvest, but were still significantly reduced when second harvests were made as much as 8 wk after the initial harvest. There was little effect of second harvest timing on subsequent year forage quality. Second harvest cut height had little effect on subsequent year yield or forage quality. Our results showed that smooth bromegrass and alfalfa can be harvested late in autumn in central Alaska without adverse effects on subsequent year growth, but a second harvest earlier in the season reduces subsequent year first harvest forage yields. Cicer milkvetch died out before the end of the study and is likely not a suitable crop for central Alaska.