 Hi I'm Miranda Meehan, the NDSU Extension livestock environmental stewardship specialist. Today we're going to be talking about monitoring and determining grazing readiness for a range in pasture land. Pasture turnout is one of the most important decisions that land managers make. Land managers need to monitor their forage to make sure that it is ready to be grazed before livestock turnout. Starting grazing too early reduces plant leaf area for photosynthesis that is needed to replace carbohydrates and root reserves. If the plant is unable to replace these carbohydrates and root reserves, plant vigor is reduced, plant stands are thinned, and we have a reduction in total forage production. We can actually have a reduction of up to 60% in total forage production if we graze too early. Also increases our susceptibility to weed and insect invasions. Grazing too early can be costly in terms of forage production during the entire grazing season. Grazing before the plants reach grazing readiness can cause a reduction of herbage production by as much as 60% which reduces stocking rates and animal performance. Pasture and range that are damaged by grazing too early may take several years of deferment or even rest before they stand regains productivity. On the other hand, starting grazing too late increases forage losses through waste and trampling our reduced palatability. In the northern Great Plains the increased presence of exotic cool season grasses such as Kentucky bluegrass and smooth brome grass can occur if we graze too late. Land managers typically base grazing readiness off of calendar dates. This may be the right decision in some years but each year is different with respect to earlyness or lateness of spring. So the calendar date method may not always coincide with the best time to graze. For example, Oliver County western wheatgrass was at the three and a half leaf stage on May 9th in 2017 and at the one and a half leaf stage May 14th in 2018. The timing of grazing readiness depends on a number of factors including the species of grass, available moisture, weather and past management. As a result exact timing of grazing readiness can vary across the state. We recommend that grazing readiness be based off of plant developmental stage. The first thing we do when we go out to pasture or rangeland is we determine what our key species are. In this pasture our key species are smooth brome grass and Kentucky bluegrass. So we look at this smooth brome grass to determine our developmental stage we're going to simply count the number of leaves. We're going to even if there's dead leaves we'll count those because they would have been developed this year for example this bottom leaf here. So we start at the bottom and we have one two three four five six and this one's not all the way quite all the way extended so we're probably six and a half almost seven leaves on this. So that would be the stage of development that we're at. For our team pasture species in North Dakota we recommend the grazing readiness is at the three leaf stage. These species would include smooth brome grass, metal brome grass and crested wheat grass. Our native rangelands our species need to be at the three and a half leaf stage before they to reach grazing readiness. Common rangeland species would be western wheat grass, green needle grass, blue grama. Air temperature is the main factor that determines the rate of plant development. Each leaf produced on a stem requires a specific amount of accumulated heat or heat units. The temperature when plants initiate development or the base temperature is 32 degrees Fahrenheit for cool season grasses and 40 degrees Fahrenheit for warm season grasses. So our cool season grasses would be our tame pasture species smooth brome grass, crested wheat grass and also the native range species such as western wheat grass and green needle grass. Warm season grasses would include blue grama. The temperature or heat units that a plant needs to accumulate to produce a leaf can be expressed in growing degree days. For any calendar day the number of growing degree days for that day is the average of the hour minimum and hour maximum temperatures in the same 24 hour period minus the base temperature. So the formula to calculate that would be the daily maximum temperature plus the daily minimum temperature divided by two minus the base temperature for that species. So 32 degrees Fahrenheit for cool season species and 40 degrees Fahrenheit for warm season species. The time that we start accumulating growing degree days is on the first day after March 15th that the average daily air temperature exceeds 32 degrees Fahrenheit for five consecutive days. This is based off of research conducted at the USDA Research Center in Mandia, North Dakota. The number of growing degree days to reach grazing readiness varies from species to species. For example, crested wheat grass needs 443 growing degree days and green needle grass needs 1209 growing degree days. Using the growing degree day approach to determine grazing readiness can minimize guesswork of when grazing can begin on a pasture. Because the spring season and grazing readiness vary from year to year the growing degree day approach will help you determine the best state to begin grazing. However, the most reliable method of monitoring grazing readiness is getting out and monitoring plant developmental stage. For more information on grazing readiness in your area contact your local extension agent or check out this publication.