Real-time soil moisture sensors to optimise planting success

The field crop yields that we depend on every year for our survival are in turn dependent on protection from diseases and pests, adequate precipitation, fertility – and to start it all off, high rates of seed germination and even plant stand emergence. New US-based technology is helping crop growers automatically ensure chances of germination are a high as possible.

Factors affecting germination

First, a quick review of the factors affecting germination. For a typical field crop seed to germinate, enough water must be absorbed over about three days. Soil moisture levels on any farm typically vary due to topography and differing soil types. Sowing seed deeper down in the soil where there is more moisture available is a good strategy to ensure germination and even seedling emergence, but it’s hard to know at what depth that moisture exists. In addition, planting seed deeper than needed can delay seedling emergence and impact seedling survival.

Soil moisture and seed-available moisture

In addition, we must distinguish between soil moisture and seed-available moisture. “You can have a wet soil, maybe it’s so wet that it’s even borderline too wet to plant, but it may be a soil type which holds onto water very tightly and the water is therefore not available for germination,” explains Bryce Baker, marketing manager at Illinois, US-based ag technology company Precision Planting. “We wanted to create a system that measures actual seed-available moisture.”

In the development of this unique planter-mounted moisture sensing system called SmartFirmer, the Precision Planting team studied germination of over 40,000 seeds of various crop types.

Reading of the seed bed

Besides measuring seed-available moisture in real time, SmartFirmer also gives reading of the seed bed in terms of temperature, furrow wall uniformity – whether the sidewall is caving or cracking – and soil organic matter level. (Baker explains however, that SmartFirmer soil organic matter readings are not meant to replace actual soil organic matter level tests, but rather are useful to show farmers where changes exist in soil organic matter level on their farms, with mapping capabilities.)

Precision Planting also offers the only planter attachment on the market that automatically adjust seed planting depth, called SmartDepth. The firm also believes it’s the only so far to offer real-time seed-available moisture measurement with instantaneous automatic corresponding adjustment of planter depth (SmartDepth). However, the systems can also be used independently.

Availability of platform

The company has sold both SmartFirmer and SmartDepth units so far in the US, Europe and South America, and the cost for each unit of either type is about $ 675 USD. Please note that they function on traditional planters, not those with ‘air seeders.’

And, to use one of these systems or both of them, a ‘20l20’ Precision Planting cab monitor system is required, along with Precision Planting control modules on every planter row. The ‘20l20’ monitor was not available in 2021 due to supply chain issues and neither so far this year, but they are expected to be available worldwide later in 2022.

High germination rates and even crop emergence are only one of the many factors that can affect yield throughout the growing season such as fertility, pest and disease pressures and in-season weather. But Baker notes that by making the best adjustment of seed depth to ensure seeds will germinate due to having adequate seed-available moisture, you are avoiding yield losses through lower germination and setting yourself up for the best yields through the most uniform emergence possible.

Planter customisation

Farmers are generally strongly encouraged to add precision technologies such as these according to their specific needs. A wide variety of precision plant attachments are now available that measure many factors that impact germination and seedling emergence. These include detection or automatic adjustment of seed spacing and singulation.

There are also row cleaners that move residue aside more effectively and create a smoother row unit ride, better seed-to-soil contact and faster planting speeds. Automated downforce control attachments ensure the same weight on the gauge wheels of every row. Furrow attachments better ensure the correct soil density around the seed and closing of the furrow. Still other attachments allow for placing various combinations of nutrients next to the seed in the future root zone.

Decisions about attachments should include an analysis of what’s hasn’t been going well for you in terms crop emergence and what you surmise may be negatively affecting your crop all the way through to yield. In addition, your cropping style, which crops you grow now, which you may grow in the future and other factors should be part of the decision.