Winter wheat after summer full season crops

In central Oklahoma continuous wheat is the predominant cropping system. However, nowadays it is not rare to find fields with summer crops. Full season summer crops such as corn, soybean and sorghum are usually planted from late March to early May and harvested in late August to September. Afterwards, winter wheat is usually planted. At this moment we usually have the dilemma whether this following winter wheat will have lower yields compared to wheat after fallow, due to starting with drier soil profile.

In a study that compares the adoption of several crop species in 2-yr cropping systems, we have observed that the soil profile after full season crops is considerably drier than a soil profile coming from a fallow period (about 4 months in the typical continuous wheat systems of central Oklahoma). Nonetheless, at this point wheat does not require much water. Wheat water needs may be satisfied by few fall precipitation events that recharge the first 30-40 cm, even when the rest of the soil profile remains dry.

Later measurements of plant available water at the beginning of April did not show significant differences between these cropping systems. Winter wheat grain yield after grain sorghum and corn was similar than wheat after a follow period. This shows that initial water content may not play an important role as it does precipitation distribution according to crop needs.

Field Day at Stillwater Agronomy Farm – Oct. 1st

The field day will give kids and their parents a better idea about plant and soil sciences and the different subjects involved. There will be booths set up where college students within Plant and Soil Sciences will teach various subjects such as; learning how new varieties of wheat or soybeans are made, why herbicides are effective tools when used properly, or how plants and soils work together to produce seed. Feel free to visit anytime between 10am - 2pm on Saturday October 1, 2011. We will have food and drinks available throughout the day.

Planted First Trial of 2011

Planted the first corn plots last Friday (3/18) of the year in NC Oklahoma under ideal conditions. The trial is designed to evaluate starter fertilizer rates and placement methods. Placement option included: in-furrow, 2x2, 2x4 and rate from 10 lb N/ac to 150 lb N/ac. We felt the need to collect some data in Oklahoma for the use of starter fertilizer. From others states, data often shows a response to starter being applied when planting summer crops early, especially corn into cool soils. Even though we have warmer temperatures in the southern US, our no-till soils still remain cool during early planting of corn and even grain sorghum. The trial is located near Covington, so we have been lucky to catch some timely rains.

Foliar Feeders in Oklahoma Soybean Fields

We are starting to see an increase in defoliation from insects in some soybean fields around the state. Basically these insects can be broken down into two distinct groups; “foliar feeders” and “pod feeders”. Fall army worm has been observed in some fields. The distinct identifying characteristic of fall armyworm is the inverted “Y” on the head capsule. Fall armyworm can quickly do damage that results in yield loss. The general rule of thumb for fall armyworm and other foliar feeders is the following:

Treatment is recommended when foliage loss is around 15-20% during pod fill. However, if pods are filled defoliation losses can be 35-40% before the treatment threshold is reached.

The other insect that has been observed in some fields is corn earworm, which can feed directly on pods and greatly reduce yield potential. Control of corn earworms is suggested if you find two or more per row-foot.

With the high yield potential we still have in some of our soybean fields and the price of soybean make sure you continue to scout for pest problems.

Treatment information can be found at the following link:
http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-2347/EPP-7167web.pdf

Relying on glyphosate only applications is not good

Over the last 6 months I have been in several soybean fields around the state and more often than not we see developing weed control problems. These problems seem to be centered on the continual use of glyphosate with no other tank mix partners. I’m not saying we have glyphosate resistant weeds but with continual applications of glyphosate only we may not be far from developing resistant populations. In some cases, 3 to 4 applications of glyphosate only have been made within a single cropping season. This is simply not a good practice, I realize it may be the most economical in a single year but long-term the economics of controlling glyphosate resistant weeds will not look so good.

Combining herbicide chemistries is very important to ward off resistance, especially rotations that are dominated by glyphosate resistant crops. Using pre-emerge products can reduce the number of glyphosate applications in season to as few as one. Plenty of good herbicide options are available for RR soybean production, non-RR soybean production, and Liberty Link beans. All of these require careful attention to detail and a well thought out plan. A well thought out herbicide program will pay long-term.

Do we rely on glyphosate too much for weed control?

Is the era of glyphosate only weed control over?

Double cropping decisions

As we move into the first part of July, producers possibly need to re-think double-cropping decisions. In the case of soybean, it is not recommended planting past July 10. Planting after this date greatly reduces yield potential.

Grain sorghum can be planted until July 15-19 in most areas. Planting after this date reduces the chances of properly maturing before the first frost.

The only grain crops that can be planted after this date is sunflower and sesame. Both of these crops can be planted until July 25 and even as late as Aug. 1 in the southern part of the state.

What drives the decisions for double cropping, is it soil moisture, time of year, crop rotation, or some combination of these? I realize it varies in different parts of the state and some areas simply to not get enough precipitation to double crop. I would like to hear what drives the decision making process.

In my opinion if you have the moisture available after wheat harvest you should use it because soil water retention during summer fallow periods in Oklahoma is not efficient in storing water. Only about 20% of water is stored during a summer fallow period.