Soil Health Tips by Deborah Aller, Soil and Crop Sciences Section, Cornell University; Mina Vescera, Nursery and Landscape Specialist, Cornell Cooperative Extension of Suffolk County  Above: Soil compaction caused by an old construction driveway impacting the growth of a hedge. Photo by Mina Vescera According to the USDA, soil health can be defined as “the capacity of the soil to function as a vital living ecosystem that sustains plants, animals, and humans.” This definition emphasizes that soils are full of life and need a more holistic approach to management. A healthy soil system provides much of the water, air, and nutrients plants need to thrive, while simultaneously reducing fertilizer use and possibly pesticide inputs. Landscapes are heavily modified by human activities, however, landscape professionals and others in the plant care industry have the capacity to either degrade or improve the soil at a site based on management decisions.  Above: Don't guess, test! Boxwoods are susceptible to many pests, and poorly drained soils promote soil borne pathogens. Photo by Mina Vescera Know What You’re Working With - Soil Nutrient vs. Soil Health Testing Know before you act; the first step to good soil management is to evaluate the soil. Information about a site’s soil properties can be found online through the USDA-NRCS Web Soil Survey or SoilWeb platforms. These tools provide an aerial view of a location and access to soil maps for a selected area. While the information is less reliable for recently altered landscapes and urban areas, it is a useful place to start. Soil analyses are the next best tool, providing valuable information for both plant establishment and maintenance.  Soil chemical analyses focus on measuring soil pH, macro- and micronutrient levels, soluble salts, and other tests. These tests inform the amount of limestone and fertilizer that are needed to support plant health. Landscape soils should be tested, using the same laboratory, every three years for maintenance or as needed for new projects and troubleshooting.  Above: Infiltrometer testing is used to measure the rate of water infiltration into soil. Soil health testing emphasizes the integration of all three soil properties: physical, chemical, and biological. The Comprehensive Assessment of Soil Health test at Cornell University is the most widely used and commercially available soil health test today (Moebius-Clune et al., 2016), however, recently other soil health testing labs have been established. Soil health tests are more costly than nutrient tests ($56-130 vs. $13-18) but are recommended only every five to six years since changes in soil health are long-term compared to short-term changes that occur with fertilizer applications. No Cost On-Site Tests In addition to laboratory testing, simple ‘on-site’ tests can be done by landscape professionals to evaluate the soil and help inform management decisions. Collect soil at various locations and depths across the site. Observe the color to get a sense of organic matter (OM) levels (darker generally means more OM). Feel the soil to get an idea of the texture (e.g., sandy loam vs. silty clay). Smell the soil, as poorly drained soil has a foul odor. By simply using your senses you can better understand soil variability and issues across a site. Understanding water movement into and through the soil is crucial, especially before planting when compaction is likely a concern. An infiltration test measures how quickly water enters the soil. Slow infiltration often leads to surface ponding and waterlogged conditions. Fast infiltration can result in runoff, erosion, and rapid drying of soils. A percolation test is used to determine how water moves through the soil, providing insight into soil drainage. Ideal soil drainage is between 1-3 inches per hour for most plants. These easy, quick tests provide valuable insight into soil properties and can help guide site design. Management and Recommendations Organic matter is also central to healthy soil as it occupies the smallest fraction of the soil (4-6% in typical healthy landscape soils), but small changes have a big impact on overall soil functions. Both the quality and quantity of OM are important in soils and directly connected to soil texture with fine-textured (clayey) soils holding more OM than coarse-textured (sandy) soils. Organic matter can be added to landscape soils in many forms including compost, grass clippings, mulch, leaves, and biochar. Adding OM during site preparation is the best time to incorporate it into the soil profile, however, surface applications of OM are helpful too, and have benefits for reducing surface compaction and improving soil moisture. Every landscape is different, and management needs vary by site. By acknowledging the importance of soil and incorporating these simple on-site and lab testing methods into your overall landscape management program, you can foster a site that supports thriving landscapes.  |
