Planting Sets the Scene
When planting season gets tough, it is not the time to just roll on. In marginal conditions, planter down pressure settings become increasingly important.
Given the spring many experienced in 2008, it's no surprise down pressure is top of mind for farmers.
"The number of questions I get about appropriate levels of down pressure is growing," says Farm Journal Field Agronomist Ken Ferrie. "We can get by with more mistakes in good conditions, but with a year that was cold, wet and slow to get started, the margin for error was even smaller."
To show the importance of correct down pressure, Ferrie set up a demonstration plot for the 2008 Farm Journal Corn College.
Seedbed condition, planting speed and planter setup determine the level of down pressure.
"Striking the right balance is the key," Ferrie says. "Too little down pressure will cost planter performance and rob stands. But too much down pressure can overcompact the soil around the planted seed, which will sabotage uniform emergence and growth."
The demonstration plots included planter passes ranging from 400 lb. down pressure to 100 lb. down pressure. The rig planted seedbeds with the four types of tillage: moldboard plow, vertical tillage, strip-till and no-till.
"Different tillage practices requires different down pressure," Ferrie explains. "We set up this plot to show the extremes of where it wasn't enough and where it was too much."
In the moldboard-plowed ground, 100-lb. down pressure resulted in the greatest yield. The opposite occurred in the no-till plot. The row units needed more than 100-lb. down pressure to keep the planter in the ground.
In the plowed ground at 400 lb. the disk openers closed the slot but scored the sidewall, which led to cracks as the ground dried.
Any time the planter travels through the field, the row unit depth wheels leave a footprint that can tell an observer a lot about the necessary down pressure. Ferrie says when he goes to the field he focuses on the footprint, which should be uniform.
"In the 400 lb. portion of the no-till section of this plot you could see the planter footprint, but you could also see the open slot. At 100 lb. you couldn't see an open slot, but the planter footprint wasn't visible either. The pressure was too light, and we lost planting depth," he says.
Since demand on down pressure is partly determined by tillage, take into consideration these factors: In conventional tillage, it's important that the soil finisher leaves a uniform 3" to 4" soil density that should require no more than the weight of the row unit to maintain depth. In vertical tillage, the key is how well the primary tillage pass was done. In no-till, farmers are going up against wheel tracks and varying soil types from sandy to clay. In strip-till, settings rely on the quality of the strips and the planter staying on them.
Finding a balance in down pressure settings can be easier with infinitely adjustable pneumatic systems. The air bags make it possible to dial in settings and adjust them as conditions change from field to field and day to day.
"Air bags can be effective to find the sweet spot and keep the planter consistent. Farmers are more likely to make changes when they are easy, such as turning one knob for the entire planter," Ferrie says. "Pneumatic systems on a planter are just like air suspension on a semi truck that keep the axle on the asphalt whereas leaf springs will have more axle bounce."
Speed limit. Planting speed also impacts down pressure needs. "The row unit is like a water ski—the faster the speed, the more it will want to come out of the water," he says.
Ferrie has worked with many farmers who originally thought a field was too wet to plant due to sidewall smearing and the slot not closing. Slowing down and decreasing the down pressure showed the field was fit to plant.
How the planter is equipped with row cleaners and starter attachments also impacts down pressure needs. For example, fixed row cleaners require more down pressure than floating row cleaners. Starter attachments mounted to the row unit that engage the ground also need more down pressure.
Ferrie notes the operator should maintain proper planter bar height, and the parallel bars must run level for down pressure success.
"The bar might not run at its proper height due to mechanical issues such as wrong tire size or hydraulic malfunction," he explains. "To increase down pressure, farmers must transfer the weight from the bar to the row unit. The bar must have the weight to transfer or it will start floating up. This will be noticed by the parallel bars running uphill, in which case farmers need to add weight onto the bar."
There are some tools you can use to assist in setting down pressure levels. One is the Precision Planting 20/20 SeedSense monitor, which we've used in our plots since its prototype phase.
"A tool like the 20/20 SeedSense monitor will tell you if the planter hits a tough spot and wants out of the ground," Ferrie explains. "Then you increase the down pressure until it stays in the ground. When you maintain depth in the tough spots, ground truth in the field to see if you are smearing the sidewall anywhere else."
Monitor your down pressure settings throughout the entire season. As Ferrie warns, conditions change and farmers need to react, especially when pushing the limits.
Late Planting Reveals Row Spacings' Strengths
Farm Journal has studied soybean row spacings for 17 years. Our latest effort includes looking at row spacing and population's effect on yield and susceptibility to insects and diseases.
For four years we've had temperature and humidity sensors installed 6" off the ground in each row spacing and population. Our row spacings included 10", 15", 20" and 30" with populations of 120,000 plants per acre, 160,000 plants per acre and 200,000 plants per acre. Collecting this data has provided a fresh view on the role row width and population play.
"Once the canopies close, temperature and humidity are the same in like populations no matter what the row spacing is," Ferrie explains. "The high populations, across all row spacings, maintain higher humidity levels than the low populations. The temperature remains the same, so the actual humidity within the canopy increased."
Ferrie attributes this to higher populations having a higher quantity of plants, which cumulatively produce more humidity through respiration.
In 2008, the soybean row spacing test plots were planted the week of June 27. "We were planting when we would normally already have rows closing their canopies," Ferrie says.
With the later planting date, the wide rows didn't have as much time to close before the warmest part of the summer because late planting results in shorter plants.
"If you are planting beans late due to weather or double-cropping beans, I would advise that you push the population up and narrow the rows," Ferrie says. (See page 22 for results.)
This is the first year we've started to collect weather data within the canopy of twin-row soybeans. We'll continue our test plot with soybean widths in the coming year.
Series of Success
We've studied narrow-row corn in our test plot program for more than a decade. In our field trials, we've found a steady 7 bu. to 10 bu. advantage for narrow-row corn (twins and 20" spacings) compared with 30" rows.
In 2008, we used a 16-row Great Plains Yield-Pro planter and AutoFarm RTK system to plant a plot that compared 30" rows and twins 7½" apart on 30" centers. The guidance system made it possible to return and plant the twin rows among already planted 30" row strips.
At harvest, our field was divided into two yield zones. In one yield zone the twins outyielded 30" rows by an average of 7 bu. In the other, twins topped 30" rows by 9 bu.
"These yields are consistent with our data from 10 years of work with twin rows," Ferrie says.
You can e-mail Margy Fischer at email@example.com.
- March 2009