Learn more about trends in cover cropping and conservation tillage adoption.
Q: Why do I see a large jump in the number of ND and MN cover crops in 2020, followed by a large decrease in 2021?
A: Regrow's cover crop KPI tracks cover crops that have a meaningful impact on soil carbon, rather than attempting to identify locations where cover cropping was attempted, but may not have thrived. Generally, this means we are looking for fields where a cover crop is well established and covers the majority of the field area.
The spike in observed cover crops in 2020 was due in large part to favorable growing conditions in the fall of 2019 and spring of 2020. During fall of 2019, the US Midwest had relatively normal temperatures and more than average precipitation, allowing recently planted cover crops to emerge and get established before the hard freeze and snowfall in the winter. After the snow melted and the weather warmed up in the spring, these conditions returned, with early rains and warm weather allowing the cover crops to re-emerge and thrive before they were terminated to make way for planting.
Compare this to 2021, and we see much drier conditions. During the fall of 2021 there was much less precipitation, making it harder for cover crops to get established before winter set in. A similar dry period in the spring limited the growth of any cover crops that overwintered, leading to less vigorous growth. The vegetation moisture status maps below compare the fall and spring conditions for both 2020 cover crops and 2021 cover crops, highlighting the differences in regional growing conditions, especially in the upper midwest and corn belt states.
Fall vegetation moisture status in 2019 and 2020. Note the wetter than normal conditions in 2019, and the drier than normal conditions in 2020.
Spring vegetation moisture status in 2020 and 2021. Note the wetter than normal conditions in 2020, and the drier than normal conditions in 2021.
Note: we see a similar spike in successful CC implementation acres in Illinois, Iowa, Indiana and other corn belt states in 2018. This is driven by similar favorable climate conditions - in this case warmer than average spring weather that allowed cover crops to grow rapidly for a month or longer before these cover crops were terminated in April. Source
Q: In the US Corn Belt, why do I see a decrease in conservation tillage acres in 2018, followed by a spike in 2019 and another drop in 2020?
A: Here are a few reasons:
- Increase planting of soybeans in 2018 due to prices (high soybean, low corn) - many acres “switched” from corn to soybeans - often after field work had been done in 2017 to prepare for corn planting. This field work often includes tillage. 2018 showed more acres planted to soybeans than normal.
- Cold weather in 2018 prevented planting of soybeans until later in the season. In an effort to warm solid more quickly, some growers may have tilled the soil to increase soil temps and enable planting.
- Abnormally wet weather in the fall of 2018 and the spring of 2019 prevented many growers from conducting field work, including tillage. Many growers reported using reduced or no-till systems in 2019 as they rushed to plant once the weather allowed them to get into the field.
- We see a similar 2018 decrease in no and reduced till and subsequent spike in regional agronomic data
https://origin.farmdocdaily.illinois.edu/2021/03/tillage-benchmarks-for-soybeans-in-illinois.html
Q: Why is there a declining trend in cover crop adoption in the Canadian regions of Manitoba and Saskatchewan from 10% in 2020 to 1% in 2023?
A: Regrow's focus on outcomes will result in lower cover crop estimates as some cover crops growers plant will fail to thrive.
Generally, the biggest driver of big YoY changes in CC is due to growing conditions in the field during the cover cropping period. Drought, early freezes, late snow melt, and flooding have historically caused significant decreases in cover crop acres from one year to the next. Each of these events can impact growth:
- Drought will cause cover crops to have weak / no emergence. or very limited growth due to lack of water.
- Early freezes or abnormally cool weather will result in limited / no emergence as the CC seed will not germinate.
- Flooding and late spring snows can kill a cover crop after it starts growing, causing the field to have no green cover after the flood / late snow.
We see the same thing in commodity crops, where weather events lead to large variations YoY in commodity crop yields - the CC data show the same pattern we see in crop yield data.
Cover Cropping on Oats in the Canadian Prairies
The data specific to oat fields has two factors contributing to the CC decline:
- Dramatic decrease in oat production in the Prairie provinces
- Decrease in cover crop performance on the remaining oat fields
Decline in oat production
- Saskatchewan decreased the acres seeded to oats by 50% between 2022 and 2023. Manitoba had a similar drop (we see a larger decline in the supply shed selected in SI)
- As you decrease the number of acres with oats, you decrease the number of fields that could have cover crop, increasing the impact of localized weather events on the fields that remain.
Decrease in cover crop performance on the remaining oat fields
The prairie provinces have experienced very dry conditions for the last few years, with drought conditions in Manitoba and Saskatchewan in the fall 2022 / spring 2023 - precisely when a cover crop would need water the emerge, grow, and establish a strong stand.
The image below shows the 3-month drought conditions as of April 30, 2023, covering the period when any cover crop growth in the spring would occur. The dry conditions here will directly impact CC growth, limiting the area Regrow classifies as cover crop.
Drought conditions impacted grain production as well, leading to decreased yields.
Without the ability for the cover crop to grow due to lack of water, even if growers planted cover crops, these seeds were not able to grow to the point that Regrow would classify them as cover crops.
In the image below, you can see that what Regrow counts as a cover crop (based on its SOC impact) is a well-established cover crop stand. Many fields that planted cover crops but were experiencing drought likely are classified as low / moderate green cover (ie Potential over crop), which Sustainability Insights does NOT display in the UI. Work to display the additional data sets is underway.
Q: Relative to NASS and anecdotal evidence from working with their growers, Sustainability Insights seems to have lower conservation tillage adoption.
A: The Sustainability Insights data was configured in a conservative nature (ie. it errs on the side of underestimation vs overestimation of conservation tillage practice adoption) to ensure our customers could utilize these metrics against Scope 3 reporting requirements where being cautious leads to much less scrutiny.
NASS data is based off of grower surveys on practices in general. It is:
- Not crop specific v. Sustainability Insights is specific to corn
- Reports farm-level data v. Sustainability Insights looks at field-specific data. Large and small farms are given the same weight in the NASS data.
- Based on % of farms adopting these practices and NOT precise % of acres
There are no great sources for field-level practice data. For IL for ex:
- USDA NASS survey: ~34% adoption on farms (not fields) across all crops
- Farmland Trust (utilizing field visits on a farm basis): 15% adoption
- Regrow Sustainability Insights: ~23% adoption across reduced & no-till