The variability we continue to see in our lab results has thrown a great big monkey wrench into our ability to assess progress using only our lab results. However, we can still assess the progress our growers have made in increasing their use of tried-and-true soil health practices, including:

• Increasing their Days of Living Cover
• Increasing their use of Cover Crops
• Decreasing their Tillage Intensity
• Increasing their Organic Matter Inputs

Our growers have made excellent progress incorporating 3 out of 4 of these soil health practices in the last 5 years.

We have 5 years of data on the 51 sites which have been in the project since the very beginning, with data on both their management practices as well as their soil testing results.  The average Days of Living Cover on these 51 sites has increased by 20 days since 2019.  Our growers have increased their Days of Living Cover by increasing their use of cover crops, converting annual crops to perennial systems, and incorporating more fall-planted small grains into their rotations.

Our growers have increased their days of cover crops on average by 25 days/site since 2019.  We examined the 200 sites for which we have cover crop data and found that our growers’ Cover Crop Use has increased for almost all our crop categories including Commercial Veg/Flower/Fruit, Commodity Row Crops, and Home Gardens. 

Two thirds of all our growers have planted cover crops in the last 5 years, with Commercial Vegetable and Commodity growers leading the way.  Only when a rancher inter-seeds a cover into an existing pasture or reseeds an annual field into a perennial crop do we credit a cover crop to that site, so we expect that cover crop use would be low for many of our established Perennial Hay/Alfalfa/Pasture sites.  Dryland grain sites, which depend on 420 days of fallow soil to store enough soil moisture for a biennial small grain crop, avoid cover crops because cover crops can deplete soil moisture.

When we examine just the 51 sites for which we have 5 years of data, we see that our growers have decreased their Tillage Intensity by 17 points over the last 5 years. This is very good news since lower tillage intensity is correlated with better soil health.  We use a Natural Resources Conservation Service soil erosion model to assign a soil disturbance score to all farm operations that compact or disturb soil.  For example, NRCS assigns a single pass with a subsoiler-chisel plow a score of 52.6, a disc harrow gets a score of 11.67, and hay cutting equipment gets a score of 0.15. We total all the scores from each implement used in a field in a calendar year to compute the tillage intensity score for each site.

When we examine the Tillage Intensity of the 191 sites for which we have tillage data and group them into their 5 crop categories, we see that 4 crop groups have made very good progress in reducing their Tillage Intensity, with Commercial Veg/Flower/Fruit sites and Dryland Grains making the most progress.  Perennial Hay/Alfalfa/Pastures have held steady with quite low Tillage Intensity scores.  Home gardens also have low tillage intensity scores, because many of our home gardeners use mostly hand tools, which disturb the soil less and have lower intensity scores.

A majority of all our growers have used organic matter inputs (manure, compost, mulches) on their sites in the last 5 years, with home gardeners leading the way.  We only count the organic matter inputs which are acquired off-site in this analysis.  Manure deposited by grazing animals on-site, or clippings from on-site cover crops, are not counted as organic matter inputs here.  Thus, perennial fields with aftermath grazing often appear to have no organic matter inputs, even though they may have many days of grazing animals depositing manure and urine there.

Organic Matter Input use has decreased by 13T/acre on average since 2019.  When we examine our successive years of data and divide our sites into their different crop categories, we see that only home gardeners have increased their Organic Matter Inputs in the last 5 years.  All other crop categories have seen a sharp decrease in Organic Matter Inputs.  Commercial Veg/Flower/Fruit growers have seen the biggest decrease.  Our growers identified several possible causes for this decrease. 

• An exceptionally wet May-June-July in 2023 meant growers had a hard time planting, cultivating and harvesting between storms.  They may not have wanted to or been able to get additional machinery into soggy fields to spread amendments.
• Fuel and hauling costs for amendments have tripled in recent years, putting amendments out of reach for many growers.  Several have switched to amending with more economical cover crops if they have the water to get them established.
  
• Some growers with excessively high phosphorus levels have decided to forego organic matter inputs and use cover crops instead, to avoid increasing their soil phosphorus to dangerous levels.
  
• Our very tight labor market meant growers struggled all season to fill vacant positions.  They may not have had enough workers to do things like spread amendments. Additionally, our tight labor market has increased labor costs sharply.  This has affected Commercial Veg-Flower/Fruit growers the most as their crop category is the most labor intensive.  Recent high labor costs may have consumed any profit that formerly paid for purchased amendments. 

These 4 graphs show that Home Gardens and Perennial Hay/Alfalfa/Pastures have the most variable soil health scores year-to-year.  Each site’s 3-5 years of soil health scores are represented by a column of 3-5 colored data points connected by a vertical black line (a blue square for 2019, red circle for 2020, green triangle for 2021, yellow diamond for 2022 and aqua diamond for 2023). Each square-circle-triangle-diamond-Blackline combo represents the Soil Health Scores for one site for 3-5 years.  Sites with the most variability have the tallest black lines between their lowest and highest scores.
Last year we showed that large amounts of organic matter inputs and more days of grazing animals increased variability.  This year we have shown that home gardeners apply the highest rates of organic matter to their sites, and we know that grazing animals are usually found in pastures.  It makes sense then that Home Gardens and Perennial Hay/Alfalfa/Pastures would experience the greatest variability in Soil Health Scores.

We continue to see a great deal of variability in our lab results when we compare sites with themselves year-to-year.  We divided our sites into 4 crop categories (Commercial Veg/Flower/Fruit; Commodity Row Crops and Dryland Grains; Home Gardens; and Perennial Hay/Alfalfa/Pastures) and examined each category’s variability.  These 4 graphs show that an examination of past practices can often explain some of the exceptionally big jumps in variability which we see in every crop group.

There are significant differences between our sites with the most variable soil health scores (our Swingers) and our sites with the least variable scores (our Parked sites).  The most significant difference between the 2 groups is that Swinging sites have 3 times the number of average grazing days as Parked sites. While Swinging and Parked sites have the same numbers of sites with grazing animals, Swinging sites have animals grazing on-site for a much longer period of time.  2/3rds of Swinging sites are pastures, and the majority of Swinging sites use conventional growing methods.  Swinging sites also apply an average of 7.5 T/acre of organic matter inputs, almost 50% more than Parked Sites at 5.6 T/ac.  These findings support our 2023 findings that more grazing animals and organic matter inputs increase variability.

In this graph, we compared our sites’ soil pH with their longitude (east-west location).  We found that sites further east out on the plains tend to have higher pH than sites closer to the Front Range foothills and up in the mountains.  This could be due to several things. 
Precipitation is higher in the mountains and foothills than further out on the plains.  Higher rainfall is associated with more acidic soil.  Also, a site’s original parent soil material is more acidic in the mountains and foothills than on the plains.  Furthermore, the pH of irrigation water can change soil pH with repeated applications.  Irrigation water becomes more alkaline as it travels further east away from the mountains, picking up tailwater, salts and minerals.  All this means that the location of a field might determine its soil pH as well as its soil health, since soil pH has a significant effect on soil health. (As pH increases and becomes more alkaline, soil health decreases.)

For each of our 7 crop groups, we calculated their average use of 6 different parameters that effect soil health: days of supplemental irrigation water, days of living cover, tons of organic matter added, number of grazing days, their tillage intensity score, and their soil Ph. 
We then examined those averages to see if we could predict which crop groups would have the lowest and highest soil health scores.  The graphs above show the average soil health practices for all 7 crop groups.  See if you can predict which crop groups will have the best and worst soil health scores, just by looking at their relative rankings on soil health practices.  Remember that you are looking for HIGH water days, HIGH days of living cover, HIGH organic matter inputs and HIGH grazing days, but LOW tillage intensity and LOW soil pH to predict the highest soil health scores. It’s just the opposite for the lowest soil health scores.

Perennial Hay/Alfalfa/Pastures: The Pasture group has the highest average soil health scores of these three crop groups.  Although the Pasture group has lower supplemental water days and lower organic matter added, their very high days of living cover and very high grazing days, along with their very low tillage intensity and lower soil pH seem to more than make up for their water challenges, in terms of soil health.
Commodity Row Crops: The Commodity crop group has the lowest average scores of these three groups.  Although they have done an excellent job of reducing their tillage intensity, that fact alone cannot make up for their high soil pH, lowest days of living cover and lowest organic matter added.  They have only 2/3rds of the water availability as the Commercial Veg/Flower/Fruit group, which explains their lower days of cover crops that often require fall seeding and fall water.  Inter-seeding cover crops aerially or when the main crop is still small are work-arounds but not always practical.  Low commodity prices mean the cost of additional organic matter inputs like compost and manure are hard to justify.
Commercial Veg/Flower/Fruit: The Commercial Veg group has the highest tillage intensity by far, but also triple the organic matter inputs of the other 2 groups.  These huge organic matter inputs, along with their longer water season, greater use of cover crops, and lower soil pH overpower their intense tillage and boost their average soil health scores above the commodity crops’ averages.  Their longer water season means they can plant more fall cover crops and string together succession plantings for a longer growing season.  Their high value vegetables mean that they can afford organic matter input costs and hauling fees.

In the top graph above, 71 sites with both grazing animals and organic matter inputs (OMI) are each represented by a quadruplet of data points connected by a vertical black line (a blue square for 2019, red circle for 2020, green triangle for 2021, and yellow diamond for 2022).  Each square-circle-triangle-diamond-black-line combo represents the Soil Organic Matter (SOM) values for one site for 4 years. According to the literature, SOM is supposed to be quite stable and very difficult to change, and yet we are seeing large swings in individual sites’ SOM data, especially when grazing animals are present or organic matter is imported to the site, as is the case in the top graph above.
We only have 12 sites in our study which have no grazing animals or imported organic matter for 3 or more years.  The second lower graph shows that the variability in SOM values for these 12 sites is much less than for sites with grazing animals or organic matter inputs.

We examined our 28 sites which have the most variability in their soil health scores.  We call these sites our “Swingers”, and they are evenly split between organic and conventional growing methods. 
Over half the “Swinger” sites are pastures with the rest split evenly between home gardens and commercial vegetable sites.  Their most common crop is grass hay with mixed vegetables coming in second. Their average water season is 127 days long.  “Swinger” sites have an average soil health score of 27.6, which is very high, especially for Colorado.  The growers of these “Swinger” sites are all Soiley Award winners or nominees.  They have adopted many soil health practices, as you can see in the following graph.

The lesson here seems to be that no good deed goes unpunished.  It seems that one result of adopting good soil health practices may be a great deal of variability in soil health lab results.  If you see your Haney test results bouncing around a lot, year-to-year, it does not necessarily mean that you are doing anything wrong.  It may mean that you are doing many things right!  We will explore this hypothesis further in coming years as we gather more data.

We sorted our sites into 3 groups and calculated the average variability for each group.  This bar graph shows that the groups which grazed animals or added organic matter to their sites for 2 consecutive years have approximately three times as much variability in their lab results as the group with NO grazing animals and NO organic matter inputs.

This graph shows the soil health practices which our growers could identify upon enrollment in the project, ranked from most to least commonly named.  Every grower could identify at least 5 practices as contributing to soil health, and many could identify far more.  There seemed to be a strong correlation between the soil health practices a grower could identify and the practices they were already using on their land.  It seems that most growers believe they are already improving their soil health.

Three quarters of our growers report making changes to their operations over the first 3 years of the project, as a result of information they have received about soil health. In the 21st century, we expect organizations and sectors to be nimble, able to rapidly adapt to new technologies and turn on a dime like a drone.  However, agriculture is NOT like a nimble drone, but rather is like a huge super tanker, taking an exceedingly long time to turn.  In agriculture, there is usually only one shot per year to try something new, and many reasons why that one shot might or might not work in that year, which then requires more years of testing, tweaking, and retesting.  That is why the CSSHP is a 10 year long project.  

In this graph, the green bars are the soil health scores of the sites that were sampled in the spring, and the orange bars are sites that were sampled in the fall.  The height of the bar shows the site’s soil health score.  Our spring soil samplers had a significantly lower median score than our fall samplers.
This is why it is important to test your soil health at the same time each year.  If you test soil in the spring, then apply a soil amendment and test again in the fall, you won't be able to really tell if the amendment affected your soil’s health.  Any increase in the soil health score may just be due to this seasonal variation we see here.  You must test your soil at the same time each year to really be able to assess changes in soil health.

This table shows that in 2021 only about half of our growers fully understand their soil testing results and use this information to drive management decisions.  The remaining growers prefer a different test, have found an outside advisor to assist them in management decisions, or are challenged to understand their test results.   
We see greater understanding of the confidential individualized year-end reports that we send to all growers.  Our year-end reports show growers how they compare with their peers on 10 important Haney and PLFA soil health indices, and three management practices.  The Year-End report contains more graphics and fewer categories to decipher than soil test results.  It is designed so that a grower can easily see if they fall into the top, middle or bottom of the pack.  This may explain why more growers understand the year-end report than their soil test results.