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On May 23, 2018

To Prevent Sidewall Compaction

During planting season, it is difficult to try and fit everything in, especially when trying to dodge rainstorms that seem to be common this spring. With the pressure to get all fields planted, it can be tempting to go into a field that is less than ideal for planting. However Extension Agronomist Claire Coombs reminds us if the soils are too wet, they can be easily compacted and there will be an increased risk for sidewall compaction.

Sidewall compaction can refer to any and all soil compaction and/or soil smearing in and around the seed furrow. It is often caused by planting when too wet, planting too shallow and setting too much down pressure on the gauge wheels and closing wheels. Sidewall compaction can be especially damaging if a dry spell occurs after planting, resulting in an open seed well. It is critical to assess if the soil is dry enough for planting and this can easily be done in the field. The following are two methods to assess soil moisture by hand:

The first method is to collect soil from the top 2-3 inches in your hand and make a small ball (slightly larger than a golf ball) in your hand. Throw the ball in the air as if you were throwing a baseball. If the ball of soil reaches the ground intact, it is probably too wet to plant. If the ball breaks apart in mid-air, it may be dry enough to plant

A second way is to collect soil from the top 2-3 inches and form a ball in your hand. Squeeze the soil between your thumb and forefinger to form a ribbon of soil. If the soil creates a ribbon longer than 3 inches before breaking, it is probably too wet to plant.

While soil moisture will be critical to preventing sidewall compaction, it is also important to ensure the seed furrow is closed while using minimal down pressure in the closing wheels. With too shallow of planting, there is an increased risk of the closing wheels not functioning correctly which can result in an open seed furrow.

With a wet spring it can be difficult to wait for ideal planting conditions but it is important to ensure the soil is not too wet. Sidewall compaction cannot be fixed once it occurs and can have detrimental effects on crop performance and yield. Consequences of sidewall compaction include reduced germination, poor stands, uneven emergence and growth, and restricted root growth. All these consequences can have a negative effect on yield when harvesting in the fall.

For more information on all types of compaction, see our Avoiding Soil Compaction fact Sheet  https://extension.psu.edu/avoiding-soil-compaction

 

To Evaluate Switching Corn Hybrid Maturities?

Corn planting is lagging behind, but favorable weather should allow for planting to continue.  Extension Agronomist Dwane Miller asks should you stick to your original hybrids, or switch out to shorter season corn?

Looking at USDA’s Weekly Crop Progress as of May 20, planting progress is certainly behind where we would normally be on this date.  Statewide, corn is reported as 35% planted, compared to 56% in 2017, and 64% for the 5-year average.  The recent spell of wet weather has kept many planters in the shed, and some growers are beginning to question whether or not to switch out hybrids with earlier maturities.  It’s important to remember that planting date is only one factor when it comes to a successful corn crop.  Although timely planting is important, it is just as critical to avoid planting in poor soil conditions.  Sidewall compaction and poor seed to soil contact can result in less than desirable stands and substantially limit root growth.

According to the Penn State Agronomy Guide, in most areas, switching to a shorter than adapted hybrid maturity should not be considered until at least the last week of May.  If your hybrids are on the longer side of maturity for your area, these hybrids probably should have been in the ground by mid-May.  If you are analyzing your hybrids, or are considering switching, you must be able to approximate the number of growing degree days (GDD’s) left in the season before a killing frost.  While many growers and seed dealers discuss hybrid selection in the relative days to maturity (95 day, 108 day, etc.), you may also see GDD information on your seed tag, or in the seed catalog.  A corn hybrid with an approximate relative maturity rating of 90-95 days will require 1,600-1825 (GDD’s) to reach black layer formation.  Compare that with a 111-115 day hybrid which requires about 2,500-2,724 GDD’s.

A good reference tool when making a decision is the online reference map for corn hybrid latest planting dates https://extension.psu.edu/latest-planting-dates-for-various-corn-hybridsfrom Penn State.

So, are we there yet?  Is it time to pull the trigger?  If you’ve selected hybrid maturities that are within reason for your area of the state, and we have good planting conditions within the next week, Miller says stick to your guns.  Once we flip the calendar into June, if the seed isn’t in the ground yet, you may need to rethink your original hybrid decisions.

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