Archive - Citizen Science Soil Health Project

Published on: August 9, 2026

Characteristics of Fields with Increasing Soil Health

Graph of Change in sample depth VS change in soil organic matter

We identified the fields in our 6 different crop categories which are making the most progress improving their soil health. They are Stonebridge Farm (Vegetables, Flowers & Fruit), Olander Farms (Commodity Crops), Lehi Ranch (Commodity/Pasture rotation), Nine Mile Ranch (Pasture Grass & Hay), Longview Farm (Dryland Wheat), and Your Neighborhood Christmas Tree Farm (Home Garden). These 6 sites share 4 characteristics which have helped them improve their soil’s health.

Supplemental irrigation water: 5 out of 6 of these growers (all except Dryland Wheat) have supplemental irrigation water. More water means more varied and bigger plants, healthier roots and soil microbes, and the ability to grow fall cover crops and to water grazing livestock year-round.
Decreasing tillage intensity: All 6 growers decreased tillage intensity over 6 years, or maintained it at very low levels. Less tillage means more and healthier soil microbes, especially more fungi, which feed more nutrients to crops.
Organic Matter Inputs: All 6 growers have added or plan to add significant amounts of organic material to their soil, through imported amendments, grazing, cover crops and crop residues. It may not matter how you get more organic matter onto your soil, just that you get it there.
Starting with soils in the “Poor” to “Good” range: None of these 6 growers started with soils that were in the “Excellent” range, where soils may have reached their carbon saturation point. Some of our CSSHP growers who enrolled in the CSSHP with “Excellent” soils are discouraged because they aren’t seeing their soil health scores improve significantly, despite their best efforts. It may be that their soils have reached their carbon saturation point, and now they can only build deeper “Excellent” soil, just maintain and make more of, but not improve significantly, the “Excellent” soil they already have.

Published on: August 9, 2026

The Depth of a Soil Sample affects the Soil Organic Matter Value

Microbial life and organic matter are greatest in the top couple of inches of soil. When you collect a deeper soil sample, you add more soil from deeper down where there is much less organic matter. That tends to “dilute” the amount of microbial life and organic matter that is in the top couple inches of soil. That dilution from the deeper soil makes the lab’s reading of your soil organic matter drop. The inverse is also true. If you collect a shallower sample it makes the lab’s reading of your soil organic matter rise.differences-between-the-most-and-least-variable-sites-copy

Each data point in this graph represents the change in soil sample depth on one site over 2 consecutive years, plotted against the corresponding change in SOM. Most data points fall into the graph’s colored quadrants, where a later shallower soil sample has a higher SOM, and a later deeper soil sample has a lower SOM than the previous year’s sample. The red trend line confirms that sample depth affects our SOM values.

However, the data points in this graph are widely scattered, and 30% of the data points fall outside of these 2 colored quadrants. If sample depth were the only thing affecting SOM, you would expect to see all the data points much more closely clustered around the trend line, with very few data points in the two white quadrants. That is not what we are seeing. That means that other things besides sample depth (management, inputs, environmental factors, etc.) are also affecting changes in SOM.

Published on: March 16, 2024

Differences between the most and least variable sites.

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.

Published on: March 16, 2024

Past Practices can explain some variability.

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.

Published on: March 16, 2024

Variability is highest in Home Gardens and Pastures

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.

Published on: March 16, 2024

Organic Matter Input use has decreased.

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.

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