The 2007 crop year continues to throw challenges at area producers.
Wheat harvest is around the corner, and yields could be anywhere from poor to decent.
Some of the corn crop is looking very good, but part of the crop is showing some signs of nutrient deficiencies. There was also some “rootless” corn in areas this spring, mostly the result of planting and weather related conditions.
Many soybeans are already in the ground and looking pretty good. If beans are not yet planted, however, should producers start thinking about changes in management strategies for soybeans? Should a shorter-season variety be substituted as planting dates move into late June?
As planting is delayed, the situation begins to resemble double-crop soybean production. The soybean crop following wheat is usually planted 2 to 6 weeks later than the optimum date for highest yields. Since planting is delayed, often until the end of June or early July, there is a tendency to switch to a shorter-season variety to ensure the crop will mature before frost.
While planting a variety that is too late in maturity will increase the likelihood of frost damage, switching to a substantially earlier maturing variety should be resisted. This is for two reasons:
• First, early maturing varieties planted late in the season will usually have limited vegetative development, short stature, and low yield potential.
• Second, any given variety will have fewer days to flowering, pod development, and maturity when planted late compared to earlier planting dates.
As planting dates get later into June, the day length has begun or will soon begin to shorten and nights will start getting longer. This causes plant development to speed up. Consequently, there is not a one-for-one relationship between the number of days difference in planting dates and the number of days delay in maturity. As a general rule, for every three days delay in planting, maturity is delayed by only one day.
Since soybean development is hastened in later plantings, the highest yields in a late-planted or double-cropped system are often achieved by using the same variety or one only slightly shorter in maturity as what is used in full-season production.
Other management practices can be affected by late planting, however. Because late planting shortens the period for vegetative growth and reduces canopy development, increasing the seeding rate alone or in combination with narrow row spacing can help the crop compensate by providing the opportunity to produce more pods in the canopy.
Seeding rates can be increased by 30 percent to 50 percent in high-rainfall environments if planting is delayed until late June or July. Although past research has demonstrated no consistent benefit for narrow row spacing (less than 30 inches) in Kansas, narrow rows may have an advantage in late plantings in our area of the state.
• Additional information is available from the Lyon County Extension Office at 341-3220, the Soybean Production Handbook, Publication C-449. Brian Rees is a Lyon county Extension Agent with the K-State Research and Extension and can be reached at brees@k-state.edu.