Between the Rows: A Review of Research
Greg Roth
Department of Crop and Soil Sciences
Penn State
March 1999
We spend lots of time doing research on corn production in our department and work hard to get the word out on what we've been up to. Hopefully many of you are somewhat aware of some of our findings. If you're not, let me share with you in this column a sampling of the projects we have been working on.
Last year in our project we spent considerable effort looking at response to plant populations and hope to do more of that in the future. In the 5 Acre Corn Club, there has been a trend for producers to increase plant populations by about 250 plants/year during the last 25 years. This year the final stands of the entrants averaged nearly 26000 plants per acre.
Population studies are difficult to conduct because the response often varies from year to year. You need to conduct them over time to get a handle on the response. We are basically finding that newer hybrids are responding to higher populations and that plant populations from 25 to 30,000 plants per acre (ppa) appear to be appropriate for many situations. In a population trial we conducted this year in Lebanon and Lancaster Counties, our best yields came at 28,000 plants per acre in Lebanon and 32,000 plants per acre in Lancaster. Not all of the hybrids stood well at 32,000, indicating that before you try higher plant populations check with your seed dealer to see if you have a hybrid that will take the increased population.
We have been running a similar trial in Schuylkill County under high yield (200 bu/A) conditions. In 1996 we didn't see a benefit from increasing plant populations above 27,000 ppa. That year the hybrid had stalk rot and was falling down in our 32000 treatment. We switched hybrids in 1997 to one with a better stalk and 1998 to a Bt hybrid and both have stood much better. In the last two years, we found a 8 bushel/acre advantage to the 32000.
I'm not recommending that everyone switch to 30,000 plants per acre. The optimum plant population is dependent on row width, soil productivity and hybrid. Wider rows, droughty soils and some hybrids may dictate lower plant populations. But our data does seem to support the national trend of increasing plant populations.
Another research project has been evaluating crop rotations for dairy farms. Some of you may have seen our video on this subject. As part of this research we have found that many fields following corn that have been scouted for corn rootworm will be above the threshold for corn rootworm. Third and fourth year fields we checked averaged about 80% above threshold. Also, about 39% of the third year alfalfa fields scouted in our project had less than 4 plants per square foot. Both of these factors indicate that on some farms long corn and alfalfa rotations can cost money. As a result of this project we showed that on some farms shortening the alfalfa rotation when dictated by scouting to three years can be profitable. Substituting soybeans for the 3rd year of corn for grain in a four year rotation was another was to reduce costs, improve yields and reduce the need for insecticides.
We are also starting a project to evaluate alternative starter fertilizers in corn on high P and K soils. Several other states have begun recommending starters with 1-1-0 or 2-1-0 ratios rather than the typical 1-3-1 analyses used in Pennsylvania. We conducted one study last year to look at these but the field we chose had low K areas that most of our fields don't have. As a result the 1-3-1 fertilizer performed well. The advantage of the 2-1-0 fertilizers would be lower cost and less P added to already high testing soils. Also, some of the N requirement would be placed near the seed at planting and not subject to volatilization. We plan on repeating our study again this year.
These are just a few of the trials we have on going currently. Our objectives are to try find way to produce corn at a lower cost in our region. Space doesn't permit a complete discussion of everything we have going on. If you have ideas on good research topics we are willing to listen. We will be putting most of our research on our internet site, so check there from time to time.