May 5, 2011

Are spring oats, new alfalfa, and other spring plantings growing painfully slowly?

It’s been a frustrating spring for anyone with new hay or pasture plantings. Oats, turnips, and pasture grasses are barely growing and new alfalfa stands are struggling to emerge.

Blame the cold conditions and cold soil. April and early May were relatively cold and cloudy, and when rain occurred, it generally was a cold rain. Fortunately, soil temperatures started to increase last weekend.

For seeds, the physiological processes that activate germination and control emergence are temperature dependent. Seedlings that burst out of the ground at 50°F may barely grow at 45°F.

Established plants may not have exactly the same problems, but cold soils release nitrogen very slowly, failing to stimulate plant growth. You can see this readily if you look at hay and pasture fields. Brome pastures might be growing slowly, but urine spots often are deep green and twice as tall. These areas have plenty of extra nitrogen. We also see less stress on pastures that were heavily fertilized early or have lots of legumes. This nitrogen effect becomes even more evident when you see that alfalfa, which produces its own nitrogen, is growing quite normally.

Sunny warm days and timely rains should speed growth of these spring plantings.

Bruce Anderson
Extension Forage Specialist