Documenting Soil Change using Dynamic Soil Properties and

Documenting Soil Change using Dynamic Soil Properties and Ecological Site Descriptions Skye Wills NCSS, 2011

Soil and Ecosystem Change • Soil Change Guide – Document change in soil function applicable over the entire extent of a soil series or component phase – When possible, Ecological Sites and associated State and Transition Models inform study design and interpretation – Dynamic soil properties collected concurrently with vegetation properties

Space and Time • Some conceptual model is needed to separate the soil component being evaluated into conditions that can be compared in space – Space for time substitution allows us to interpret change over time or caused by management system – Statistical inference: where can results be applied

Conceptual Model • Ecological Site with State and Transition Model

Begay DSP Project (Utah) • Used STM to separate ecological site (R 035 XY 215 UT) and the correlated soil map component phases into conditions for comparison – Reference State -Community Phase • 1. 1 Perennial grassland/shrubland – Alternative State -Community Phase • 4. 1 and 4. 2 Cheatgrass Dominated/Monoculture

Organic carbon % High and low values of reference state B to 25 cm 2 cm to base of A 0 -2 cm Bulk density PG-S = perennial grass-shrub; AG = Annual grass (cheat grass) n=4

Conceptual Model • Ecological Site with State and Transition Model • Add additional land uses – assume these represent different states and that we understand the dynamics at work between these land uses.

MLRA 77 C (TX) Amarillo DSP Project • Chose conditions for study based on past and current land use – Rangeland – ‘Degraded’ shortgass, shrub invaded (R 077 CY 034 TX; Shrub Dominant Community 3. 1) – Conservation Reserve Program – previously cropped, currently dominated by ungrazed introduced grasses – Cropland –Irrigated conventionally tilled cotton

CRP – variable conditions and past management difficult to fit within STM concepts Cropland – could conceivably be considered a separate state. However, the large energy inputs available could overwhelm any subtle ecological dynamics in the site.

Amarillo: Wet Aggregate Stability Standard Error Proportion > 0. 25 mm % Mean Weight Diameter mm Standard Error Mean Weight Diameter mm Mean Proportion > 0. 25 mm % Shrub (3. 1) 4. 81 a* 0. 25 0. 84 a 0. 04 CRP 2. 73 b 0. 22 0. 55 b 0. 03 Crop 0. 43 c 0. 22 0. 14 c 0. 03 * Means with same letter are not significantly different (P=0. 05) Ted Zobeck, personal communication 4/20/11

Conceptual Model • Ecological Site with State and Transition Model • Add additional land uses – assume these represent different states and that we understand the dynamics at work between these land uses. • Chose to evaluate management systems within one land use – Pasture – Forest – Crop

Idaho Threebear project • Chose to evaluate management conditions in forest land – Mature forest – Clear-cut and planted forest

Threebear Results

MLRA 106 (NE and KS): Kennebec Soil • Chose to evaluate management systems within cropland – Generally, corn/soybean rotation with • Conventional tillage system • No-till system • “organic” system – While this sounds like a straightforward comparison there are many variations of each of these management systems. Deciding what to compare and what to include in each was a major difficulty.

Total C stocks (Mg ha-1 to 40 cm) % WAS Kennebec Results

Using ESDs to Interpret Soil Change • An ESD and particularly the state and transition model provide context for making management recommendations and interpretations • It also segments a soil map unit component phase into conditions relevant for management – That is – this component with the same community phase present will likely have the same properties and respond to management in the same way

Using ESDs to Interpret Soil Change • Begay Project – the STM supplies contextual information about the ecological dynamics of the site • Amarillo Project – While the STM provides information about range and CRP land – it doesn’t tell us how broadly we can apply the results from the cropland or what processes are important for maintaining or restoring ecosystem function

Ongoing Projects • MLRA 133 A (GA)Tifton – Longleaf Pine/Wiregrass vs. Pasture – Data collection being done concurrently with ecological site data collection – Presents challenges …………but should allow us to interpret and infer ecosystem change • MLRA 80 A (OK and KS) Kirkland – Claypan Prairie Rangeland vs. Cropland – Conventional and no-till management systems within cropland use will be sampled

Acknowledgements • • • Arlene Tugel Cindy Stiles Ted Zobeck Laurie Kiniry Craig Bird Gerald Crenwelgie • • Dave Kohake Bruce Evans Judy Ward Brian Gardner