Is it really drought? Or other caveats of weather and soil which affect plant growth?
We are in severe drought according to drought monitor which is based on departure from 20 yr rainfall averages for each month.
Available plant water is about 90% (~2.5-3") at 16" depth. At 32" depth, soil is much drier due to lack of high rainfall events over last 90 days...that is not a concern until June! Drought monitors do not take into account soil water storage capacity nor SOM levels.
I want you to remember this adage in terms of winter forage growth...."1 day in Sept and Oct is worth 2 days in Nov Dec and Jan!"
In pic above, soil water is ample for growth of winter annuals. Here is a pic of soil temperatures this last week. Soil microbial activity, root uptake of nutrients, photosynthetic capacity and plant growth are suppressed when soil temp is below 50F. This is called the 'dormant season' or 'period of slow plant growth'.
Two other factors are worth mentioning. Angle of sun to earth is least in Dec and growing degree days the shortest. Days are getting longer so that is a good thing come late Feb! Second, clouds reduce photosynthesis. When sun angle is low the more cloudy days you have the slower plant growth and longer plant recovery period after grazing. We had substantial cloud cover the last 30 days. Last year we had ample plant recovery in 70d for a second winter grazing. This year ~120 days will be required unless abnormally warm weather returns.
Do you have drought or do you have a soil potassium deficiency? The two are hard to separate. The best way to create a potash deficiency is to apply only N which spikes plant growth and creates lean times for uptake of other nutrients. That is why I always recommend 1 lb of K20 for every 1 lb of N applied....every time N is applied. Did you know the cow excretes 1.5-2x potassium as she does N? What about deer which consume a higher quality diet than the cow? Do you see the pattern there?
Both pictures below are from the same pasture with 20 days recovery since last grazing. 49 days of recovery is about twice the height but still below the 6-8" height needed for a second grazing.
Growth of rye/triticale on a well drained loam soil. Soil test potash was 330 lb/ac (optimum+) a few years ago. Dormant warm season thatch and full soil cover is a Godsend when it's dry and or cold! Yes, cereal rye and triticale are able to grow when soil is quite cold (down to about 30F)....but that is slow growth and may not supply sufficient regrowth for more than 2 grazings in winter (either with cattle or with deer....with deer can be even slower than with cattle since deer tend to graze plants more severly).
Mixed winter annuals in a long term cattle loafing area.....1000 lb/ac potash. Fastest recovery in winter will occur here....the area can be monitored from the truck seat! That is if deer let it regrow! I don't recommend 1000 lb/ac potash levels in soil.....'optimum plus' on the soil test should suffice!
Google 'potassium plant water relations' and all sorts of articles discussing how low potassium levels accentuate drought can be found. Here is one example with tomato:
https://www.jstor.org/stable/42938634?seq=1#page_scan_tab_contents
Contingency plan for the cow is to graze stockpiled native rangeland until late Feb when cool season forages on tame pasture break dormancy and provide ample forage for grazing. Forage in this pic is 280 days of regrowth since last prescribed fire. Note the biomass of stockpiled green as that is what cows will seek first. Keep in mind prescribed fire adds a lot of potassium back to the soil in the form of wood ash....and we never need to apply N to these native soils!
Drought? In June, I will make that decision!
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