This fact sheet describes the importance of soil health and best soil testing practices

Alston, Diane G.

Cardon, Grant

Reeve, Jennifer R.

Thomsen, Esther

English

DigitalCommons@USU

October 2017             Horticulture/Soils/2017-02pr Simple Soil Tests for Onsite Evaluation of  Soil Health in Orchards Esther Thomsen, Research Assistant Jennifer Reeve, Soil Scientist  Diane Alston, Entomologist Grant Cardon, Soil Scientist The Importance of Soil Health  Soil health or quality is the ability of a soil to function as a suitable environment for root growth and to maintain water and environmental quality. Optimal soil health allows for water retention and infiltration, filtering of contaminants, buffering of pH, efficient recycling of nutrients, and maintaining a stable porous structure even under erosive pressures from water and wind. Healthy soil provides habitat for a diversity of soil life, and these diverse life forms can prevent soil borne diseases and help maintain soil  properties over a long period  of time.  The goal of simple on-site soil health tests is to enable a grower  or landowner to track the effects of soil management practices on  soil health. This can be achieved by comparing two different management approaches such as a tilled plot to an area covered in perennial vegetation in the same orchard, or testing the same orchard year after year to monitor long-term change in soil health. Keeping track of the physical and biological properties of soil as a complement to traditional measurements of soil fertility can be helpful to overall farm management decisions and may even save the grower money in the long-term through improved soil health. An example of an important soil physical property is aggregate stability, which is the ability of primary soil particles to remain attached under disruptive forces. Aggregate stability tests are specifically useful in addressing a soil’s potential for erosion (Kemper and Koch, 1966; Kemper and Rosenau, 1986). Soil organisms are important biological indicators of soil health as they are rapidly responsive to shifts in management practices (Pankhurst et al., 1997). Soil organisms affect the rate of nutrient decomposition, and can inform to prevent over application of nutrients in efficient systems (Guillard et al., 2015). Healthy Soils:  Filter contaminants Retain more water Resist erosion Provide habitats forbeneficial organisms Aid in prevention of soilborne diseases Save money andresourcesBest Soil Testing Practices For best results, choose soil test sites that represent the main soil textural type present in the orchard or field. It is important to test within the same  soil textural type as texture can have a greater effect on soil health than  management practices. Soils rich in clay form aggregates much easier than  soils rich in sand, and also tend to have greater biological activity as the  primary particles are of a size that store water and carbon more easily than  sandy soils (Franzleubers et al. 1996, Mulder et al. 2011).  Sandy soils may  show little to no structure at all, as larger primary particles are not as cohesive as smaller primary particles.  If possible choose a neighboring site on the same soil type that has a history  of long-term management in perennial vegetation as a comparison. Repeat tests at the same time every year, and preferably at least 2 days after  a rainfall or irrigation event to ensure similar soil moisture conditions.  Supporting soil health promotes long-term plant and tree health. These  tests will help you detect early signs of soil degradation so that remedial  actions can be taken in order to help avoid or reduce costs associated with  soil erosion and compaction, increased irrigation and nutrient inputs.  Reductions in pest management needs, and plant diseases may also be  noticed as soil health improves over the long-term. The following tests include physical and biological parameters.  Chemical evaluations of the soil, including N,P,K and pH are best  completed by laboratories as simple chemical test kits available on the  market are prone to inaccuracies. The following simple soil tests have  been tested for their ability to discriminate between soils of different known soil health. They all ranked high when compared to similar lab based tests and were evaluated for ease of use by growers in the field. Physical Soil Tests – Test # 1: Soil Slaking 1. Fill a large sieve to the rim with un-sievedsoil.2. Remove any rocks and large pieces oforganic material.3. Soak sieve with soil in a bucket of water for5 minutes.4. Raise the sieve out of the water to let drain,and then slowly raise and lower the sieve 5times into the water.5. Take note of the surface texture of the soil.6. Rate the soil from 1 to 10 (see Table 1)based on how much of the surface soiltexture appears to have remained the sameafter the repeated soaking, with 1 beong thelowest health indicator and 10 being thehighest.7. Take a picture,List location of test, general visual features of soil before and after the test under the observations column, and checkmark the number that best fits the test, from 1-10 with 1 being less than 10% surface aggregates visible after repeated soaking of the soil, and 10 being 100% surface aggregates visible after repeated soaking of the soil. Location Observations Soil Rating from 1-10Least desired 1 Mid- level 5 Most preferred 10 <10% surface aggregates visible 50% surface aggregates visible 100% surface aggregates visible Taking Soil Samples  Choose sites with arepresentative soil type forthe area Choose sites—same soiltype—under differingmanagement practices forcomparison Remove organic materialfrom the surface of the soilbefore taking the soilsample Take a shovel full 7-9” deepRating the Soil Slake Test Weaker soil structure typically shows less varied surface texture, displays qualities such as smoothness, shininess and glossiness. Strong soil structure typically shows a variety of shapes and sizes of soil aggregates (clumps of soil). Example Pictures 1. Least desired 5. Mid-level 10. Most preferredTest #2: Hose Test 1. Take the sieve filled with soil and bring it to a running water source, preferably a hose.2. Turn the hose on just above medium flow, but not the highest flow setting. It may be helpful to record thenumber of turns it took to reach the desired flow rate.3. Hold the sieve about two feet from the sieve and spray down the soil in the sieve using circular motions,maintaining an equal distribution of water flow over all surface points of the soil in the sieve.4. Record 1) the amount of time until all soil is washed away, or 2) the percentage of soil left in the sieve after 1minute of hosing.5. Record what is observed.The greater the percentage of soil remaining after hosing the stronger your soil aggregates. List location of test, general visual features of soil before and after the test under the observations column, and checkmark the number that best fits the test from 1-10, with 1 being less than 10% of soil volume remaining after spraying of the soil and 10 being 100% of soil volume remaining after spraying of the soil.  Loam soil from a peach orchard under tillage for 30 years Sandy loam from a peach orchard under conventional NPK and herbicide Loam soil from a peach orchard under long-term undisturbed grass cover  Biological Soil Tests Test #3: Soil Organism Biodiversity Test  At your selected soil test site, dig a 1’x1’x1’ cube of soil and placeinto a bucket. Examine soil out of the bucket one handful at a time. Count andrecord the number of different kinds of soil organisms (examplesinclude, earthworm, centipede, ant, spider, ladybug, etc.) you findbefore returning the soil to the hole. Record the total number of organisms found once all of the soil fromthe bucket has been examined.*Note-According to the NRCS if you have more than 10 earthworms inthis amount of soil, it is also good indicator.Location Observations Soil Rating 1-6Least Desirable 1 Mid- Level 3 Most Preferred 6 <1 visible soil organism 3 different soil organisms >6differentsoilorganismsSummary Less than optimal soil quality can promote erosion, poor water holding capacity and infiltration, and will likely need more inputs for optimal productivity. Soil quality tests can help land managers compare the effects of land management practices and gauge over a period of time whether soil health is being maintained, improved or depleted. Timely recognition of soil health problems can be recognized and corrected before soil health worsens to the point that significant negative impacts on crops occur.  Practices that are helpful for maintaining and improving soil quality or health are moderate additions of organic matter through mulch, compost or manure; reducing the frequency or extent of tillage; and incorporating cover crops and/or more perennials into a system. Cover crops can be planted after the main crops have been harvested as a fall/winter cover crop, and they can also be planted as buffer strips, companion plants or understory plants. Maintaining or improving soil health will improve the bottom line for growers in the long term by improving yields and reducing the need for inputs such as water and fertilizers.  Biologically Rich Soils…  Need fewer inputs, due tomore efficient breakdown oforganic residues and greaternutrient cycling Increase stable physical soilstructure, as residues fromorganisms help bind soilparticles together inaggregates, creating morepores for aeration, waterpassage and root access.Related Fact Sheets Preparing Garden Soil:   https://extension.usu.edu/files/publications/factsheet/HG_H_01.pdf Soil Testing Guide for Home Gardens:  https://extension.usu.edu/files/publications/factsheet/HG_H_05.pdf Understanding Your Soil Test Report:    http://extension.usu.edu/files/publications/publication/AG_Soils_2008-01pr.pdf Preparing and Improving Garden Soil:  https://extension.usu.edu/files/publications/factsheet/pub__8066784.pdf References Franzluebbers, A., J., Haney, R., L., Hons, F., M., and Zuberer, D., A. 1996. Active fractions of organic matter in soils with different texture. Soil Biology and Biochemistry, 28(10–11), 1367–1372. doi:10.1016/S0038-0717(96)00143-5 Kemper, W.D., and E.J. Koch. 1966. Aggregate stability of soils from the western portions of the United States and Canada. USDA Tech. Bull. 1355. U.S. Gov. Print. Office, Washington, D.C. Kemper, W.D., and R.C. Rosenau. 1986. Aggregate stability and size distribution. methods of soil analysis, part 1. Physical and Mineralogical Methods-Agronomy Monograph no. 9 (2nd Edition).Mulder, C., Boit, A., Bonkowski, M., De Ruiter, P. C., Mancinelli, G., Van der Heijden, M. G. A.,  Rutgers, M. 2011. A Belowground Perspective on Dutch Agroecosystems: How Soil Organisms Interact to Support Ecosystem Services. In Guy Woodward (Ed.), Advances in Ecological Research 44: 277–357. Academic Press. Pankhurst, C.E., Doube, B.M., and Gupta, V.V.S.R. 1997. Biological indicators of soil health: synthesis. P. 419-435. In C.E. Pankhurst (Ed.), B.M Doube (Ed.), and V.V.S.R. Gupta (Ed.), Biological Indicators of SoilHealth. New York, NY: CAB InternationalAcknowledgment This work was supported by funding from USDA-WSARE GW15-046, UT Dept. Ag. and Food 141622, USDA CREES 2009-51300-05533 and the Utah Agricultural Experiment Station. Utah State University is committed to providing an environment free from harassment and other forms of illegal discrimination based on race, color, religion, sex, national origin, age (40 and older), disability, and veteran’s status. USU’s policy also prohibits discrimination on the basis of sexual orientation in employment and academic related practices and decisions. Utah State University employees and students cannot, because of race, color, religion, sex, national origin, age, disability, or veteran’s status, refuse to hire; discharge; promote; demote; terminate; discriminate in compensation; or discriminate regarding terms, privileges, or conditions of employment, against any person otherwise qualified. Employees and students also cannot discriminate in the classroom, residence halls, or in on/off campus, USU-sponsored events and activities. This publication is issued in furtherance of Cooperative Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, Ken White, Vice President for Extension and Agriculture, Utah State University.  

Simple Soil Tests for Onsite Evaluation of Soil Health in Orchards

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Simple Soil Tests for Onsite Evaluation of Soil Health in Orchards

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