First a correction from last week regarding double-cropping called to my attention by a reader of the column.. I referred to fall planted wheat after corn or beans as double-cropping. A better description is continuous cropping. Double cropping would be soybeans or milo planted after wheat harvest. For the purpose of this column it’s not a huge deal but if you’re in government programs or need crop insurance, it’s important. Generally, double-cropping isn’t an “accepted” practice while continuous cropping would be, so double-cropping as defined by certain agencies falls outside government programs and isn’t able to be insured. I apologize for the error and am happy someone actually reads the column. Back to the description of our climate and what it means.
Rather than dazzle everyone with terminology, it’s more useful to describe our climate.
• We live in a typical continental climate. In English, we experience wide daily and seasonal temperature fluctuations. We experience cold winters from frequent outbreaks of Polar air but winter normally lasts only from December through February. Spring and fall are typically short with warm summer temperatures (around six months per year) resulting in a fairly long growing season. During a typical year the range in temperatures can be 110 degrees.
• We live in the rain-shadow of the Rocky Mountains and are typically west of the flow of moist Gulf of Mexico air. Long-term this means that moisture is often yield limiting for traditional crops and prevents the production of others in spite of our long growing season. Our climate results in around 26 inches of annual precipitation. Normally 75 percent (19 inches) falls from April through September, however, this often comes as severe weather and extremely heavy rains which results in the moisture actually available for crop production being much lower. PET (see last week’s column) is our next major bullet point but first a couple of climate items that interact with it and our available moisture and temperature.
• We receive lots of sunshine, especially in the summer. In fact we receive 75 percent of the possible sunshine in summer and over 60 percent in winter.
• And as most of us have observed, it’s windy and our prevailing wind, particularly in spring and summer is from the south.
• So what do the above bullet points mean for cropping? Temperatures, length of growing season, and our seasons define what we can possibly produce. It is also key in understanding available water, water use, and PET (Potential EvapoTranspiration).
• In crops and soils, terminology is used to describe how much moisture an area receives, its distribution, and how much PET is possible. The traditional Corn Belt on average receives more moisture than it loses from evapotranspiration, more uniform moisture distribution throughout the year; doesn’t experience drought conditions and typically has a net gain in soil water storage, an “udic” moisture regime. That’s why they don’t have dryland agriculture.
• The short description of our moisture is that it isn’t the previous bullet point. We are an “ustic” moisture regime. Our moisture distribution is uneven, our PET is normally much greater than what we receive as precipitation, we can expect periods of drought during the growing season, and over the long term we do not gain in soil moisture.
Net week we’ll wrap this up and try to put together climate, weather and what is means for agriculture.
Dr. Victor L. Martin is the agriculture instructor/coordinator for Barton Community College. He can be reached at 620-792-9207, ext. 207.