Answer: Pecans tend to be "alternate bearing". That is, a heavy crop one year will use the available carbohydrates in the tree resulting in a lack of available carbohydrates for setting nut producing buds for the following year. This usually doesn't result in a complete crop loss the following year, by can cause a dramatic reduction.
Some varieties have a greater tendency toward alternate bearing than others. In addition to this, stress factors such as drought can accentuate the problem. Alternate bearing can be remedied by thinning some of the nuts from the tree during the summer months in a heavy cropping year. Such a practice is rather impractical however and therefore seldom done.
Your tree should have a good crop next year and with some periodic watering during summer droughts should level out a bit in the future.
Thanks for the question!
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