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'Normal' Hard to Define When it Comes to Rain

Posted Mar. 12, 2007

We lived through a significant drought in 2006. Some much-needed winter precipitation has lessened our fears, but some forecasts still call for drier than "normal" weather starting in May. Normal? Who knows what "normal" is? We've been surviving drought, at least seasonally, since 1995. I moved to Oklahoma in 1986, and, from then until 1994, all it did was rain. Producers had abundant forage and hay was cheap. So was fertilizer, compared to today's prices. As a result, stocking rates were increased.

I now believe that the period from the early 1980s to the mid 1990s was unseasonably wet. Look at Figure 1, which shows the total annual rainfall trends in south-central Oklahoma from the late 1800s through 2006.

I think the graph paints a pretty bleak picture. Look how wet we were during the period outlined in red. Then think about what's to come next...

Figure 2 is similar, but looks at spring (March-May) rainfall trends. This figure shows the drought starting in 1996, when we had our first dry spring following a dry fall in 1995. The good news is that spring rainfall should begin to improve in the near future. The bad news is that annual rainfall may still be declining. Do not base your stocking rates on the wet years from 1980 through 1994. Stock conservatively, continue to rest pastures seasonally, and be happy if you produce more forage than you have cows to eat it! Cow condition, conception rates and weaning weights will improve if you are conservatively stocked.

Following is a list of strategies, published by Hugh Aljoe and me nearly 10 years ago, that you should consider to avoid a crisis due to drought.

  • Adjust stocking rate to the carrying capacity of dry years.
  • Know your seasonal forage flow, and be prepared to adjust your stock flow accordingly.
  • Ensure access to large water reservoirs or well water if possible. Graze areas with limited water reserves first.
  • Add additional fencing to increase the number of paddocks, thus increasing your ability to effectively control the graze and rest periods.
  • Lengthen rest periods during slow or no growth. Plants can withstand severe grazing if followed by proper rest periods.
  • Know your critical dates, coinciding with seasonal temperatures and day length, for rainfall and for forage growth.
  • Establish "levels" of culling or dispersal: i.e., first level - open cows; second level - low or poor producers; third level - growing stock and large calves; fourth level - old cows and non-conformers, etc.
  • Consider early weaning to avoid poor conceptions the following year.
  • Establish a forage/grazing plan or calendar that outlines expected seasonal forage production.
  • Remember that it is usually more cost effective to move cattle to a location with abundant forage than it is to ship forage into a drought-stricken area.

 

Thanks to the Oklahoma Climatological Survey for providing the figures used in this article. Their Web site is at www.ocs.ou.edu.

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