Starting a sustainable agriculture business comes with an abundance of challenges. When record drought is added to that equation, success seems impossible and is enough for even the most seasoned producer to call it quits. As young producers, the most recent drought (2011-2014) made us realize that water will be the greatest conservation concern we will experience in our lifetime.
One approach to the drought solution may be subsoiling and the concept of keyline design. Subsoiling could be an affordable and effective tool for our landscape.
In March 2013 we purchased a single shank subsoiler and began subsoiling a Kleingrass pasture that had been devastated by drought. The pasture was 100 percent bare ground in many areas, organic matter was extremely limited, and the hard pan topsoil would not allow water to infiltrate. The tool made 24″ deep slices approximately 10′ apart on contour with the land. Months passed and we received 6″ of rain. The results were incredible. When rains came the water no longer ran off our fields but soaked down deep into the soil. Grass grew in perfect lines on contour, exactly where the plow had cut.
We conducted vegetation surveys in March 2014, 2015 and 2016. Results were very positive, most notably the reduction in bare ground and increase in forbs and litter.
Based on our experiences, we propose that subsoiling is an effective, low cost, and easy to implement tool for water and soil conservation. We believe it can be adopted widely to help producers reduce runoff; increase water infiltration and soil moisture; aerate soils; build soil organic matter, nutrients and microbial life; reduce compaction; and ultimately improve forage production.
The Southern SARE grant would allow us to implement subsoiling across two pastures and design a survey to measure the effectiveness of this technique on a variety of soil types, plant communities, and pasture conditions.
- Spatial Reconnaissance of Pastures. Both pastures will be surveyed using a non-invasive electromagnetic induction instrument prior to subsoiling and any sample measurement.
- Vegetation Cover Survey. We will conduct vegetation cover surveys to determine relative abundance and presence of plant species in both the control and treatment pasture.
- Soil Nutrient. Soil samples will be collected prior to subsoiling for baseline nutrient analysis and repeated at the end of the study.
- Soil Compaction. Soil compaction will be measured in both control and treatment sites.
- Infiltration Test. Hydraulic conductivity of the soil surface will be measured using the single ring constant head method. Infiltration will be measured before the deep soil ripping and approximately one year after.
- Photo Point Survey. Permanent photo points will be established in each pasture in both the control and treatment areas. Landscape and ground level photos will be taken to document changes over time.
- Spatial Reconnaissance of Pastures (May 2018): Both pastures were surveyed using a non-invasive electromagnetic induction instrument prior to sub soiling and any sample measurement (Neely et al., 2016; Watson et al., 2017). This instrument created a high spatial resolution (5-m) map of how the soil varies to 1.2 m deep. The map was used to determine the experimental design of how to split each pasture into the treatment and control. This information has created a stronger experimental design as has assured us that the control and treatment are performed on similar soil variability. The collaborator, Dr. Morgan and her student provided the EMI instrument and performed the survey. The survey took take 4 hours and consume 1 4V battery (i.e. costs are minimal).
- Infiltration Test (May 2018: Hydraulic conductivity of the soil surface was measured using the single ring constant head method. Infiltration was measured before the sub-soiling and approximately one year after. Tests were timed to capture infiltration rates when the soil is at field capacity. Measurements were performed by collaborator, Morgan and student, using an infiltration trailer that is owned by the USDA NRCS Teas Soil Survey. Morgan will provide training on the trailer and will also perform any data analysis required to calculate Ksat (saturated hydraulic conductivity).
- Vegetation Cover Survey (May 2018 and Nov 2018): We conducted vegetation cover surveys to determine relative abundance and presence of plant species in both the control and treatment pasture. Using a m2 quadrat along, we estimated percent cover of bare ground, litter, grass, forbs, and woody species (60 samples per site, 30 in control and 30 in treatment).
- Photo Point Survey (May 2018 and Nov 2018): Permanent photo points were established at each site in both the control and treatment areas. Landscape photos were taken by setting the camera on top of the T-post and photographing the landscape in each cardinal direction. Three ground level photos within 10 feet of each T-post will be randomly designated with a m2 quadrat and marked by flagged rebar. We will take a photograph directly over the quadrant and identify cover type, and percent bare ground at each photo point.
- Soil Nutrient (July 2018): Soil samples were collected prior to sub soiling and send to the Texas Plant and Soils Lab for baseline nutrient analysis and will be repeated at the end of the study. Data will be sued to inform our nutrient management plan and vegetation production goals.
- Sub-soiled pastures (August 2018)
- Biomass Survey (Nov 2018): Using the Robel Pole Method, we took 60 measurements of biomass in each site (30 in control and 30 in treatment).
To be discussed
Educational & Outreach Activities
Completed in 2020