Location: Great Basin Rangelands Research
Project Number: 2060-21500-001-006-I
Project Type: Interagency Reimbursable Agreement
Start Date: Aug 1, 2021
End Date: Sep 30, 2025
Objective:
Hydrology and Erosion Dynamics following Compost Applications on Annual Grassland Rangeland throughout the world store approximately one-third of the terrestrial organic carbon pool. Degraded rangeland that have incurred excessive runoff and erosion can transition to an alternative state that has depleted organic matter. Although addition of organic soil amendments are common on pastureland (e.g., organic and synthetic fertilizers), this practice is not common on rangelands. Few studies have evaluated organic carbon and nutrient dynamics with soil amendments on rangelands. In agriculturally cropped soils, additions of soil organic matter have been related to enhanced soil water holding capacity, improved organic nitrogen and plant productivity, soil aggregate stability, decreased bulk density, and improved infiltration capacity.
A recent experiment involved applications of compost to annual grasslands in California which measured changes in soil carbon and nitrogen because of a single application of composted organic matter. The authors found that the addition of compost stimulated and increased both above- and belowground net primary productivity, net ecosystem carbon storage, and soil nitrogen.
The focus of this study would be to evaluate the addition of single surface applied application of compost on degraded annual grass dominated rangelands to determine impact on specie richness and productivity, soil organic carbon and nutrient levels within the soil and within surface runoff following application and then 3 years after application.
Approach:
I. Two rates of rainfall simulation application; three treatments (control, compost application rate 1, compost application rate 2); 3 replications on a single site. Rainfall rates will consist of 10-year return period storm on dry soil. Then wait 1 hour and apply 50-year return period storm. This will allow evaluation of soil erosion and water quality on dry storm following application. The second event would evaluate erosion and water quality on saturated soils under extreme conditions.
II. Rainfall simulations during Year 1 to quantify infiltration, runoff, soil erosion, sediment yield and water quality (sediment, organic carbon, Nitrogen, Phosphorus, and heavy metals) in runoff water.
III. Soil analyses (soil organic carbon, Nitrogen, Phosphorous, Heavy Metals). Sample before application to establish baseline, after rainfall simulation in year 1 to demine nutrient flux into the soil. In Years 2, and 3 sample soils to determine long-term impacts on nutrient distribution with the soil as contrasted to control.
IV. Evaluate biological integrity of plant community. Sample vegetation before applying compost to establish baseline. Sample vegetation in Years 1, 2, and 3 to determine long-term impacts on species diversity and productivity near peak standing crop each year.
V. In Year 4, write up experimental findings and submit final report.
