Its warming up and row crop planting has begun in South Dakota.
On average, corn requires approximately 90 to 120 growing degree days to emerge; however, planting date and environmental conditions can cause required GDDS to change.
Corn growing degree days are calculated by taking the average daily temperature minus the base temperature (50F in the case of corn). Use the following equation to calculate corn GDDs: [(maximum daily temperature + minimum daily temperature)/2]-50F.
Corn growth and development typically happens between 50 and 86F. If the daily low or high temperature exceeds these values, the base development temperatures are substituted into the equation in place of the actual low or high daily temperature. For example, if the daily high was 70 and the daily low was 45, the growing degree days would be calculated like the following:
(70+45)/2= 57.5
57.5-50= 7.5 growing degree days
This equation can be used for many different crops by simply changing the base temperature to the appropriate value for the crop. Base temperatures are as follows: wheat, oat, rye, barley and canola- 40F; sunflower- 45F; corn, soybean and sorghum- 50F. Keep in mind that factors other than the air temperature can adjust GDDs (Table 1).
Rangeland conditions
In addition to affecting row crops, the dry spring has affected range plants as well. With early dry conditions affecting much of the state, range grass turnout may be delayed. Recent rains in some areas have greened things up, but allowing grass to become well-established is crucial for season production. Turnout dates vary depending on region, grass species, and conditions, but keep in mind that if pastures are grazed too early, before grasses are ready, seasonal forage production can decrease, causing reduced livestock performance.
Get to know your pastures: Are they dominated by native or tame grasses or by cool or warm-season species? If pastures are dominated by native grasses (like big bluestem, needlegrass, western wheatgrass, etc.) they will likely be slower to break dormancy than tame grass pastures and should not be grazed until late spring/early summer. If a pasture has more tame grass species (like crested wheatgrass, smooth brome, or Kentucky bluegrass) it will likely be ready to graze earlier in the spring.
Its also important to know if rangeland is dominated by cool or warm-season species. Pastures dominated by cool-season grasses are quite common in South Dakota. These grasses tend to be high in crude protein and total digestible nutrients early in the growing season, when temperatures are cooler. If managed well and moisture is adequate, fall regrowth may occur as well. Warm season grasses, however, have higher nutritional contents during the hottest time of the summer, so grazing timing is typically later than cool-season grasses in order to maximize forage production and quality.
Once familiar with your pasture plant communities, evaluate the readiness of the plants for grazing. You can do this by looking at growing degree days and actual forage growth stage. As a rule, native cool-seasons like western wheatgrass and green needlegrass, should not be grazed until the 3.5-leaf stage to avoid harm to the plant. When native grasses are grazed too early it may damage the plant and allow invasive species to enter. Tame, cool-season grassed like Kentucky bluegrass or smooth brome are ready for grazing at the three-leaf stage. Tame grass species typically reach maturity sooner and can take grazing pressure a bit better, making them more ideal for initial spring grazing.
Spring precipitation and temperatures play a huge role in determining spring forage growth (especially April-June). Research shows that precipitation during these months accurately predicts annual forage production in the northern Great Plains (Smart et al., 2020). If spring moisture is not sufficient, grazing livestock turnout times may need to be delayed. Keep in mind that previous grazing strategies always play a role in the following years regrowth. If pastures were overgrazed in years prior, they will likely need extra time to fully recover (sometimes up to a year).
Upcoming events
- Garden Hour Webinar: May 6, 13 (every Tuesday through Aug. 26) at 7 p.m. Register free here.
- International Farm Transition Network-Roadmapping Your Succession and Adding a Family Member to the Farm Business: May 15 at 10 a.m. online. $30 to register.
- Monitoring Range Conditions and Annual Forage Considerations on Cattle HQ Live: May 15 at 2 p.m. Free registration.
- Ag Economic Dialogues Webinar: May 16 at 10 a.m. Free registration.
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