This week’s article returns to reducing tillage and crop rotations, specifically what broadleaf crops can we rotate with our traditional dryland crops of wheat, grain sorghum and corn. And what will it take for a crop to be successful in our area. While choices may seem limited, over the next decade options should expand to include choices suited to the climate of the area. What is driving the process is the increasing role of agriculture in not only food and fiber but also fuel and the increasing demand for heart healthy oils. Added into the mix is a growing world population and an increasing level of income in many parts of the world, especially in Asia demanding more and better quality food options. And even though as apparent in Western Kansas as say in Wichita, the population in the United States is becoming more culturally diverse resulting in a greater diversity in the demand for foods.
What traits will make a broadleaf crop a dryland rotational crop here? First, let’s define where here is. The long-term viable options change in Kansas as you move from east to west, north to south, and southeast to northwest. What is a viable crop in Barton County may fit poorly Ness or Lane County. Dryland soybeans are pretty reliable in Harvey County but much iffier in our area.  There are two primary reasons both revolving around climate.
The most obvious is precipitation. Rainfall in Southeast Kansas averages close to forty inches per year while Southwest Kansas receives on average only sixteen inches. Barton County is on the twenty-four inch isoline.  It’s obvious that how much rainfall you receive determines what can be grown but some less obvious factors are involved too. Almost as important as the amount is when the precipitation falls and how it falls. Our area may receive four inches of rain in July but there is a big difference in the effectiveness of that moisture if it spread over several events instead of one downpour. In this area, our most useful moisture normally occurs from late March through mid-June. This is the reason why winter wheat works better here than say oats or spring wheat. The other part of the precipitation equation we deal with is termed PET, Potential Evapotranspiration, the amount of moisture “potentially” lost to the atmosphere directly from the soil and through plants.  Typically in our area our PET is greater than precipitation received meaning less water is available than necessary to supply the PET demand for the production of many, if not most crops. Or in English, plants are water stressed and yields suffer because of this deficit.
The other climate/weather factor is length of growing season/temperatures. This area is on the edge of several summer broadleaf crops because, believe it or not, our summer growing season is too short, temperatures could be higher, and the crops don’t even like a 55 degree night in August. On the other extreme for fall planted crops, we get too hot during late spring and early summer. On the plus side, we normally receive adequate solar radiation and our lower humidity helps suppress many diseases.
Next week will include a description of other traits we need to look for in a rotational crop. Not just its growth habits but what can you do with it and what will it take in terms of machinery, storage, time, and labor to produce.