Site search
sponsored by
News
ENLARGE
Shelby Filley
Every year producers wait for spring forage growth on their pastures; every year wishing the grass would come earlier than it usually does.
What can be done to stimulate earlier growth? How can we use our resources more efficiently? These questions come from the reality that pasture forage for grazing livestock is usually lacking early in the growing season and livestock producers must provide costly harvested forages during this time.
Traditional timing of mid-spring nitrogen fertilizer comes when growth rate is already accelerated, but does not help with the lack of feed very early in the growing season.
Research during the 1980s in Great Britain showed that early nitrogen application can be advantageous for providing early-season forage. A method called T-SUM 200 was developed to determine the date of that first application to a pasture. The fertilizer was put on when pasture plants started to grow in mid- to late winter, and stimulated more pounds of feed during the first part of the grazing season. Research in Douglas County and elsewhere in Oregon found T-SUM 200 to be useful for providing early forage here also.
The T-SUM 200 method is an accumulation of heat units starting from Jan. 1, until a total of 200 heat units are reached. The first application of nitrogen should be applied on or soon after the date that 200 heat units are accumulated. A heat unit is the average of the high and low temperature for the day, in degrees centigrade.
Jan. 1 is the chosen starting date for the accumulation of heat units. It isn’t some magical date after which plant growth starts, but it happened to be a convenient and easy starting point. It is based on the assumption that cool or cold winter temperatures in December or January have caused plant growth to slow down or cease and that plant growth is initiated about 200 heat units after the first day of the year. The 35-year average for western Oregon is late January to mid February.
Using this January’s actual temperature, plus projected temperatures based on historical data, the estimated T-SUM 200 for this year in the Roseburg area is Feb. 5. However, because meteorologists are forecasting freezing temperatures for the upcoming week, that date will most likely be delayed. For detailed information on the T-SUM 200 method and calculations, see Oregon State University publication EM 8852, “Early Spring Forage Production in Western Oregon Pastures.”
I hope you can use this information to provide early season forage. The most important caution about using the T-SUM 200 method is that it will not fit every pasture. To minimize loss of nitrogen, fertilizer should not be applied to very wet soils, especially ones with some standing water. Also, use caution on sandy soils due to the potential for nitrogen loss early in the growing season.
Additionally, producers should not turn livestock out onto pastures until the soils are firm, as this can cause long-term damage from hoof action on softened ground. Use lighter weight animals (stocker cattle or sheep and goats) for these early grazing opportunities.
What can be done to stimulate earlier growth? How can we use our resources more efficiently? These questions come from the reality that pasture forage for grazing livestock is usually lacking early in the growing season and livestock producers must provide costly harvested forages during this time.
Traditional timing of mid-spring nitrogen fertilizer comes when growth rate is already accelerated, but does not help with the lack of feed very early in the growing season.
Research during the 1980s in Great Britain showed that early nitrogen application can be advantageous for providing early-season forage. A method called T-SUM 200 was developed to determine the date of that first application to a pasture. The fertilizer was put on when pasture plants started to grow in mid- to late winter, and stimulated more pounds of feed during the first part of the grazing season. Research in Douglas County and elsewhere in Oregon found T-SUM 200 to be useful for providing early forage here also.
The T-SUM 200 method is an accumulation of heat units starting from Jan. 1, until a total of 200 heat units are reached. The first application of nitrogen should be applied on or soon after the date that 200 heat units are accumulated. A heat unit is the average of the high and low temperature for the day, in degrees centigrade.
Jan. 1 is the chosen starting date for the accumulation of heat units. It isn’t some magical date after which plant growth starts, but it happened to be a convenient and easy starting point. It is based on the assumption that cool or cold winter temperatures in December or January have caused plant growth to slow down or cease and that plant growth is initiated about 200 heat units after the first day of the year. The 35-year average for western Oregon is late January to mid February.
Using this January’s actual temperature, plus projected temperatures based on historical data, the estimated T-SUM 200 for this year in the Roseburg area is Feb. 5. However, because meteorologists are forecasting freezing temperatures for the upcoming week, that date will most likely be delayed. For detailed information on the T-SUM 200 method and calculations, see Oregon State University publication EM 8852, “Early Spring Forage Production in Western Oregon Pastures.”
I hope you can use this information to provide early season forage. The most important caution about using the T-SUM 200 method is that it will not fit every pasture. To minimize loss of nitrogen, fertilizer should not be applied to very wet soils, especially ones with some standing water. Also, use caution on sandy soils due to the potential for nitrogen loss early in the growing season.
Additionally, producers should not turn livestock out onto pastures until the soils are firm, as this can cause long-term damage from hoof action on softened ground. Use lighter weight animals (stocker cattle or sheep and goats) for these early grazing opportunities.
Shelby Filley is the Regional Livestock and Forages Specialist for OSU Extension Service of Douglas County. Shelby can be reached by e-mail at shelby.filley@oregonstate.edu or by phone at 541-672-4461.
