- Gary Shafer, Research Director
We’ve discussed soil compaction, poor drainage, and the negative effects of excess water for several decades. Several of the ISP products have very positive effects upon all of these potentially serious situations. These include MetaboliK HV-1, Phytogro Xtra, Pow’rPak, ReStore 3g, and even to a lesser extent MetaboliK SB. We used to walk fields of all soil types with penetrometers to measure resistance to soil penetration, and constantly recorded significantly less oil resistance where these products were being used. We also used to measure soil hydrophobia, or the reluctance of a soil surface to absorb water. Hydrophobia adds greatly to the problem of water runoff and pooling into lower areas. As with penetration, the time required to soak in one inch of water was greatly reduced where a biostimulant was applied.
With some of the recent growing seasons these water issues, and the resulting crop damage, has once again brought “water” to the forefront of many growers’ thoughts. Obviously, tile will greatly aid in reducing these problems, but even with tile the water still has to soak downward to reach the tile and leave the field. In soils with poor aggregation, this can be slowed dramatically, plus when the water does drain from the field it can carry a higher percentage of soil microparticles with it. That, of course is called erosion and will greatly reduce the productive potential in any field.
The use of ISP biostimulants, and the resulting increase in beneficial soil fungi and other microbes, will improve soil aggregation thus improve pore space, and will also aid in building soil organic matter. Improved aggregation and pore space of course leads to better drainage and less soil micro-particles being removed with the water itself. Aggregation is a basic aspect of soil biology, particularly soil fungi, and can be demonstrated by draining water through soil taken from a fence row compared to a tilled agricultural soil taken in close proximity. Cornell University demonstrates this quite graphically on their website.
Aside from the use of HV-1, PhytoGro Xtra or other products, water soak can be improved by leaving a little residue on the soil surface. If there has been any interaction between the soil and residue, it acts almost like a pipe or wick, allowing water to enter the surface much more rapidly, thus reducing the possibility of “pooling”. But even if you’ve laid tile, used biostimulants for years, and leave some residue on the surface, there are still going to be days where the soil is still too wet for tillage or planting. Obviously, this is just the way it is.
In several weeks, as you start watching the calendar and want to plant, you may realize that you could be headed into fields that are less than ideal for planting. Wet soils are easily compacted, and most everyone understands the negative effects from both surface compaction, or crusting, and subsoil horizontal compaction layers, or what is commonly referred to as “plow pans”. Less understood are the very negative effects of sidewall compaction. During planting this can be a problem, especially if the crop is “mudded-in” and a dry spell occurs after planting.
Sidewall compaction typically occurs when planting into soils that are too wet, planting too shallow and setting too much down pressure on the gauge wheels and closing wheels. Sidewall compaction is never beneficial and again, it will be the most detrimental when the soil becomes dry after planting.
Since it is difficult to quickly eliminate sidewall compaction once it occurs, it should be prevented whenever possible. The most effective way to prevent sidewall compaction is to wait until soil moisture conditions are suitable for planting. Of course, this is easier said than done given the calendar date and planting delays we often experience. Here are several simple methods for determining if the soil is too wet to plant.
Mark Hanna, agricultural engineer at Iowa State University, recommends the following methods for assessing planting conditions. Collect a handful of soil from the top 2 to 3 inches and form it into a ball. Then throw the ball of soil as if throwing a runner out at first base. If the ball stays mostly intact until it hits the ground, the soil is too wet to plant. Additionally, he says to take a sample in your hand and squeeze the soil in your fist. Use your thumb and forefinger to form a ribbon of soil. If the ribbon extends beyond 3 inches before breaking off, the soil is probably too wet to plant. Paul Jasa, agricultural engineer at the University of Nebraska, adds the following method: Take a similar soil sample and form it into a ball and drop it to the ground from about waist-high. If the ball remains mostly intact or breaks into only a few pieces, the soil is too wet.
You can also evaluate whether the soil is too wet by how the planting equipment is operating in the field. If soil is building up on the rubber closing wheels, the soil is too wet to plant. Inspect the sides of the seed furrow periodically for signs of soil smearing (smooth, shiny appearance). Check to make sure that the seed furrow is closed while using minimal down pressure on the closing wheels. Angled closing wheels are designed to perform best when planting at a depth of 2 inches. The risk of the seed furrow not being closed or opening up increases with shallower planting depths.
A good way to provide loose soil for closing the seed-vee is to close after the seed is placed in the furrow. Spoked closing wheels are available to replace the standard press wheels. These spoked closing wheels till in the sidewall around the seed. Less aggressive spoked wheels provide some seed-to-soil contact and reduced air pockets around the seed. More aggressive spoked closing wheels tend to dry the soil more. These typically require a seed firmer to provide seed-to-soil contact and a drag chan behind to level the soil.
Watch Down Pressure
Excessive down pressure is always going to create some root inhibition, but in wet soils this can be especially damaging. Again, be careful not to have too much down pressure set on some of these spoked closing wheels as they may “till” the seeds out of the seed-vee. To reduce the aggressiveness of the tillage and to provide some soil firming and depth control, some growers will run one spoked closing wheel and one standard wheel. This situation works well in a wide variety of situations.
While the seed furrow closing devices are important, too much down pressure on the depth gauge wheels will also create sidewall compaction as the disk opens the seed furrow. The disk openers may create some sidewall smearing while pushing the soil outward. If there is too much down pressure on the depth gauge wheels, they will pack the soil downward at the same time, causing compaction that may be too dense for the closing wheels to fracture. When this occurs, growers typically put more pressure on the closing wheels trying to close the seed-vee, making conditions worse yet. Down pressure on both the row unit (gauge wheels) and the closing wheels should be reduced in wet soil conditions.
Jasa provides some other excellent recommendations for reducing sidewall compaction when planting into less than ideal soil moisture conditions.
- If possible, wait for drier soil conditions before planting.
- Reduce down pressure in wet conditions to avoid compaction.
- Plant corn at least 2 inches deep of fracture the sidewall while closing the seed-vee.
- Evaluate seed-to-soil contact at seeding depth. Resist the temptation to increase down pressure to close the seed-vee.
- Leave residue over the row to reduce the seed zone from drying out and the soil from shrinking.
- Build soil structure using no-till, manure or cover crops. Soil with good aggregation is less likely to smear or compact.
- Level the planter front-to-rear, or even operate it slightly toil down, to improve seed-to-soil contact and closing the seed-vee.
- Use an attachment to till and loosen some soil for closing the seed-vee.
- Till in the sidewall with spoked closing wheels (need seed firmers for seed-to-soil contact).
- Use one spoked closing wheel and one standard wheel to close the seed-vee and firm the soil.
- If possible, stagger the angled closing wheels, one in front of the other, to reduce the seed-vee from opening back up as the soil dries. (If using one spoked wheel, place it in front.)
These are all positive recommendations, and to it we will add another. Apply one of the ISP biostimulants in the seed row at planting. If your planter is not set up to apply in the seed row, then the more common 2”X2” placement will be almost as good. Using MetaboliK SB, or Pow’rPak, etc., will create a little “hot area” of bio activity as well as providing some valuable organic acids and growth compounds. In addition, the root stimulants in these products will enable the seedling roots to push downward and outward with a little more strength so that if there is some sidewall compaction perhaps the root can push through it.
Combined with our 15-30-15, or 10-45-10 plant foods, these biostimulants provide a very strong “pop-up” nutrient package. Yield potential is determined very early, possibly at or just days after emergence, and this application will help you set a higher yield potential. Visiting with Nelson Martin, the ISP dealer servicing the Shiloh, Ohio area, I was told that one of his clients used this “pop-up” mix in parts of several corn fields this past season. The yield increase ranged from nine to fifteen bushels more corn per acre. This is not only good protection against excess soil moisture, but it’s also really profitable corn production. Anytime you can increase production at a cost of less then $1.00 per bushel of increase your making money. While commodity prices may at times be down somewhat, they are never that low. (For more information on ensuring early vigor, see the article on MetaboliK SB in this publication, or visit with your local ISP representative.)