The farmer’s pass through the field with the planter is the pass that sets the yield, say planting experts.
How the seed is planted and the conditions in which it is planted have a direct effect on the uniformity of the stand. Under ideal conditions these aspects lead to a greater yield.
Why it matters: A lot of technology has gone into planters in the past decade, with farmers working to figure out the profitability of being more precise in the field.
The uniformity of crop emergence is crucial. Precision Planting found in trials that plants that emerge one to five days after the first plants can have an ear weight decrease of three to 33 per cent. They found that the plants that didn’t emerge until four to five days late didn’t have the same access to resources, and later in the plants’ life cycle the larger ones dominated the smaller ones as they canopied over.
Uniform emergence depends on seed depth, moisture level, seed to soil contact and fertilizer applied at planting.
A high percentage of seed singulation is important. Some programs on the market can count the skips and multiples in the field. These ensure less competition between plants and the proper population.
The depth that farmers plant their seeds varies greatly when comparing farmer to farmer and their soil types.
“The most common cause of uneven emergence is corn in dry soil, [farmers] want all corn to emerge in a 24- to 36-hour window,” says Justin McMenamy, a Precision Planting team member in the United States during a recent Precision Planting conference.
“It’s important for the growers to check the seeding depth when in a new soil and in a new field.”
Getting seeds to moisture
A corn seed needs to absorb 30 per cent of its weight in water to germinate properly. Without adequate moisture this isn’t possible.
Ben Rosser, OMAFRA’s corn specialist, adds that in practice, planting into moisture has the greatest influence on variability of corn emergence.
Germination is more determined by moisture and temperature than by seeding depth, said McMenamy. Dale Koch of Precision Planting said moisture will get the biological processes inside cells going, otherwise the seeds will remain dormant.
Growers also must ensure the temperature of the soil is sufficient.
“The seeds need to be warm to stretch out and use that 30 per cent moisture and if it’s not warm enough, the cell walls will rupture as they can’t stretch out,” says Koch.
Residue within a field is also key at the time of planting. Residue can act like a blanket around the seed.
“[The residue] is more hungry for moisture than the seed is,” says Koch.
Precision Planting found a 31-hour difference in germination among seeds when residue was present. This compared to a 10-hour difference in germination when no residue was present.They also found that every one per cent of residue beside a seed can lead to a 1.1 bushel per acre decrease in yield because it affects the seed’s ability to soak up moisture.
Close the trench
The proper closing of the trench is vital to ensure complete seed-to-soil contact. Sometimes, the furrow does not close completely leaving an air gap between the seed and the soil above. It’s the job of the closing system to lock in and maintain the moisture.
“Just because you did everything you did to get that seed at the right position, you need to ensure that you hold and keep that soil moisture in the soil by closing it in properly” says Jason Stoler, also with Precision Planting.
Variability of staging within a field has significant yield impact.
The University of Guelph has completed research showing a five per cent yield loss where one in six plants had a two-leaf delay in crop maturity and a nine per cent yield loss with one in six plants had a four-leaf delay, says Rosser.
Late-emerging plants may silk after the bulk of the field has pollinated. At this time, pollen supply may be low and the ears of these late-emerging plants may not fully fertilize.
Unfertilized silks may remain green for prolonged periods relative to fertilized silks, says Rosser. The prolonged period of receptive silks increases risk of silk-initiated mould establishment on those ears.
Variability within a field makes insecticide and fungicide management of the field more difficult in reference to mould and western bean cutworm infestations.
“The variability in your field is the villain in your field,” stresses Matt Bennett of Precision Planting.