CRUSTING AND CRUSTBUSTING
We may have good deal of soil crusting problems to deal with this year. Some folks planted deeper than normal in an attempt to find moisture. Others may have planted into soil that was too wet and/or may have received hard packing rains following cotton planting. For this reason, I thought I would share some ideas concerning crusting, many of which I have borrowed from Johnny Crawford and Gene Seigler from Georgia.
Most folks wait too long before deciding to break a crust. If you wait past 3-4 days past germination (not necessarily planting), you have probably waited too long. If a hard crust is evident when the seed sprout is approaching one inch long, you should break the crust quickly. You only have one or two days depending on soil temperature. The germination process can move so fast in warm soils that the root will grow enough to anchor the seedling between the time you make the decision and get into the field. Otherwise, the seedling will spend too much energy while pushing against the crust trying to emerge. This is evidenced by a swelling of the stem below the cotyledons.
Crustbusting is best accomplished by running a rotary hoe just deep enough to break the crust completely. No more than 10-20 percent of the seedlings should be completely uprooted or broken off. Pull seedlings gently to determine if they are anchored enough to survive. Crustbusting can also be accomplished with a rolling cultivator set with the gangs turned to run straight down the row. Preferably, the gangs should be moved in so that one runs on each side of the row with about a four inch gap between to straddle the row.
Georgia recommends a 0.3-0.5 inch irrigation as a way to reduce the effects of crusting for those with irrigation. A timely rain can accomplish the same thing.
Determining how much crust is too much is difficult for those with little experience with cotton on their soils. Research in Georgia suggests that soil strengths which give a soil penetrometer reading of 10 psi would be a candidate for crustbusting if the cotton is planted deeper than one inch.
There are various strategies that producers use to help prevent soil crusting problems. One strategy is to plant less than an inch deep (dust in) so it dries out before germination begins. Then a rain will bring it up uniformly and quickly. Some farmers South Alabama plant hill-drop cotton specifically to reduce the effects of soil crusting. Winter cover crops usually will reduce crusting also.
Planters with narrow, split press wheels, which press each side of the drill area and leave an unpacked ridge directly over the seed, are less likely to cause crusts than smooth flat wheels. Older planters with smooth rubber tires have been modified by splitting the rubber tire, slotting it, removing it or replacing it with older slotted type metal wheels.
One problem I have seen with the "grooved" type of rubber press wheels that leave a loose ridge is that a hard rain can knock the ridge down and leave the seeds on the surface if you plant too shallow.
Back to the 1997 and earlier Cotton Notes
Carolina Cotton Notes CCN-94-5b May, 1994