You want to maximize your yield potential by optimizing soil management practices. If you create soil compaction or other problems in the spring, the corn or soybean crop will have to live with those problems all year.
Weather conditions and wet soils cause anxiety and concerns for late planting, especially for corn. Spring weather this year definitely creates challenges in preparing fields and getting certain field operations done on time, such as tillage, anhydrous injection, manure application, etc. Decisions to do these operations need to be made carefully regarding soil moisture conditions. The current soil moisture status makes soil conditions susceptible to compaction, low soil temperature and soil erosion. These problems can be yield robbers.
You need to look at them individually and be patient in entering fields. Waiting a few days may pay off significantly. The following recommendations come from Mahdi Al-Kaisi and Mark Hanna of Iowa State University Extension. Al-Kaisi is an agronomist who specializes in soil management and Hanna is an ag engineer with considerable soil management experience.
Soil compaction can decrease yield potential more than you realize
Soil compaction can occur when soil moisture is at field capacity, where the soil retains the maximum amount of water as dictated by soil texture and natural drainage of that particular soil. The best way to determine if your soil is at field capacity is to check your tile drain. If it is still running your soil is saturated and you need to consider waiting before entering the field.
However, once the tile stops running then the soil is at field capacity. As a rule of thumb when soil is at field capacity, it is advisable to wait one to two days before entering the field, because at such conditions soil compaction and side wall compaction (when soil smeared by anhydrous knife or seed bed-openers) can be very significant and much deeper than at dry soil conditions.
The reason for a high level of soil compaction at such moisture conditions is that soil aggregates will easily break down under a heavy load. The compression of soil particles will reduce soil porosity and reduce aeration that is essential for root growth and development and ultimately reduce yield.
Check planter settings often as soil conditions change in fields
One study documented 18 to 27 bushel per acre losses when corn was planted into wheel tracks of a susceptible wet soil during spring field work. Although yields over time may be reduced 4 to 6 bushel per acre for corn and 2 to 3 bushel per acre for soybeans, yield due to severe soil compaction from can range from 10% to 30% or more depending on the level of soil compaction. These conditions can encourage shallow root formation.
Another problem that may be associated with wet soil conditions at planting is the proper seed depth, which should be on average a 2-inch planting depth to ensure best corn root formation. Therefore, you should check planter settings often and keep in mind proper closing of soil over the seed in the seed furrow is essential to ensure a uniform plant stand.
Lower soil temperature can result from excessive soil moisture
Excess soil moisture can significantly affect soil temperature, especially in poorly drained soils. The moisture conditions at the end of April 2011 and the saturated soil profile in many fields caused significant drop in soil temperature from two weeks prior, when the temperature was warmer.
Ideally, for optimum soil conditions to allow for seed germination, the soil temperature should be approximately 50 degrees F or above in the top 2 inches of soil. Some of the risks of planting corn in cold soils include a delay in germination and exposure of seeds to soil borne diseases that can have considerable impact on yield potential.
Beware of soil erosion problems this time of year, if you do tillage
Soil erosion is always a concern during this time of the year when soil, especially in conventionally tilled fields, is most vulnerable to loss. That's because there isn't any plant cover growing yet in these fields, and there is little crop residue cover in tilled fields that are exposed to intense rains.
Working soils during wet conditions can accelerate soil erosion due to soil compaction that reduces water infiltration and increases surface runoff. These freshly tilled soils are most susceptible to top soil loss during heavy rain events. It has been documented that reduction of top soil depth (A-horizon) by 2 inches caused a corn yield loss by as much as 2 and 5 bushels per acre for loess and till-derived soils, respectively.
Operating field equipment in suitable moisture soil conditions is essential. You want to maximize your yield potential and avoid unnecessary soil compaction that can cause nutrient loss and deficiencies of nutrients such as potassium, and ultimately can result in yield loss. Even delaying a field operation part of a day to allow surface drying can make a big difference. Modern agricultural technology and equipment can make a difference in compensating for loss of time.