In less than a month thousands of square miles of the central plains states, TX north to ND, go throughthis progression starting in the south and moving north.
1) Tall green (grass) wheat shading the earth and giving off water vapor helping to cool the atmosphere.
2) Wheat matures, plant dies and grain berries dry, the earth is still shaded from sun light by the standing wheat.
3) Harvesters cut the plant save the berries leaving short stubble and straw, with almost all shade removed the soil and air temperatures in the field rise.
4) To speed the composting of the straw and prevent weeds, plowing and disking of the fields soon follows, leaving soil fully exposed to the sun, temps increase further.
This is the farming method for wheat in the central plains states. So far as I know there is no fault in this process, it's what my family has participated in for a century, I explain it only to inform you of something few people are aware of. When hundreds upon hundreds of square miles of farm land goes from respiration of cooling water vapor to bare earth the temperature of the region begins to rise. It is a seasonal solar produced rise for sure as days grow longer accelerated by our farming of wheat on a massive scale. But as barefoot kids and dogs know well the sunny day rule, walking in grass and walking on blacktop are not the same.
But, 2012 could be a scorcher, my theory, we had a warm winter, record spring highs, high soil temps, we are on pace to harvest wheat 3 weeks earlier than ever before. Kansas will be cutting wheat in mid May. As the pictures show examples of the 8 million acres will soon be without shade in Kansas alone. The temperature feed back loop will have a 3 week jump start to a long hot summer in the plains states.
When I was a kid we cut wheat at the very end of June, now it's 45 days earlier, and the summers are hotter.
Temperature variations: grass over blacktop or white roof over black roof, in the range of 40°f.
This is disturbing... Is there any way to mitigate this? Dry-land cover crop, or mulch of some sort? If this keeps up, the midwest is going to look like the Gobi in a few decades.
ReplyDeleteCynthianne, THis is a tough one to mitigate as you ask. No till farming practice is the best I think. It leaves the stubble and straw, which provides a little cover and minimum shade. The problem is it requires a spray to kill the weeds and tree seedlings from sprouting, even in the drought conditions there are plants that grow. Allowing them to grow uses up some of the deep moisture in the soil that otherwise slowly finds it's way up and to the wheat when it is replanted in the fall.
DeleteThere are also a kind of knife plow that can be pulled, a horizontal long blade a few inches below the surface that cuts the roots of weeds, it doesn't disturb the stubble and straw but it does not get the shallow root weeds or thing just beginning. It is not used much in this area.
A cover crop as you ask about is a problem, end of May here is not a good time to be starting most grasses or ground covers , or if it uses more nutrients than it leaves thats not good. Some do a double crop, the minute the wheat is cut you plant milo, a hot weather grain that matures a month before you replant the wheat. This comes up and shades the earth, it's green, looks like little corn, used to feed animals. This would if used widely possibly reduce the temperature a tiny amount, but it ruins the soil to take crops off it in rapid succession more than once every few years in my area.
I am for doing all we can to slow the slide to global warming, but bread has to be part of our food stream, and so far as I know the most grain can be grown currently using these practices. The great plains states are perfectly suited to raise winter wheat, which came to us from the same type of area and climate in Russia. Again, my purpose was inform people why it is that temperatures jump at the beginning of summer so suddenly most years as a combination of the solar gain pattern of longer days as well as the sudden denuding of millions of acres.
Darrel,
DeleteWhat role does the inclement spring weather patterns have on that - I know that Wichita has been pounded with storms?
Ron
Ron, the storms that came through did no real damage to wheat, it was young enough it didn't blow down, and if there was flooding it was so local it didn't get reported, it didn't impact futures so what ever it was must have been slight. Now the wheat has berries forming and will begin to dry soon if the warm weather holds.
ReplyDeleteAs always it is at risk from hail, hard wind, floods, and to a lesser extent some years it can mold or rot in the head if we get extended wet humid periods.
Actually there was storm damage of an unusual type, those big ones 2 weeks ago blew "rust" out of Texas and south Oklahoma. Those damn bible thumpers wheat has a disease called rust. The spores blew in and some areas are seeing damage from that.