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Home , Agricultural lime, Soil test

AY-18

Soil Testing for Lawns

Zac Reicher and Clark Throssell Purdue University Turfgrass Specialists

Evaluating the status of your is MENDED. Most Indiana under an important step in developing a quality turfgrass do not need . If is turf. The best way to find out what your soil recommended, review the following guide- needs to nourish healthy turf is to have it lines before making the application. tested. Most soil testing labs recommend that • No more than 100 lb. of you check the status of your soil every three per 1,000 sq. ft. should be applied on to five years. You can obtain information, higher turf. forms, and sampling bags at your local county Extension Office. The following • Ground agricultural or ground should help you interpret your agricultural Dolomitic limestone are the results and provides guidelines to improving preferred forms of lime for use on all your soil’s nutrient status. turfgrass areas. Applying lime after an aerification will increase the rate of pH Taking a Soil Sample change. • Contact your county Cooperative • Lime is very slow acting, so the pH will Extension office or soil testing lab for not change quickly. the fee structure, mailing containers, and other information. • Lime does not replace a sound fertiliza- tion program. • Using a small shovel or soil probe, sample to a 3-inch depth. • The area should be retested in three years to check for a change in the pH. • Take approximately 10 to 15 samples per lawn and remove thatch and live plant • Hydrated lime should not be used on material. lawns. The material could severely burn grass at high rates. • Combine the samples to make one composite sample. Do not mix soils of Soil pH from 6.0 to 7.5 different texture and color, from areas It is unnecessary to adjust the pH. This is the differing sharply in elevation, or from optimum pH range for turfgrass growth. disturbed sites and undisturbed sites. Soil pH above 7.5 • Air dry the sample before sending. The only product recommended to reduce a high soil pH (alkaline) is . Unfortu- Soil Test Report nately, the success of adding sulfur to lawns After processing your soil sample, the soil to reduce a soil pH has been limited and is test lab will send you a soil test report. The not practical or economically feasible. To following are usually included in the report: compensate for high pH, increase the annual application rate of , , and Soil pH by 25%. A soil pH indicates whether the soil is acidic, PURDUE UNIVERSITY alkaline, or neutral. The concentration of soil Phosphorus (P) will vary depending on the soil pH. The soil test results represent the amount of COOPERATIVE phosphorus available to the plants from the Soil pH Below 6.0 soil. Phosphorus deficiencies are rarely EXTENSION SERVICE If a soil pH is less than 6.0 (acidic), then a observed in established turf in Indiana, lime index is calculated to help make a more WEST LAFAYETTE except on soils with very high pH. Table 1 is accurate lime recommendation. DO NOT a guide for determining the desired rates of APPLY LIME UNLESS IT IS RECOM- INDIANA 47907 phosphorus application for established turf. Table 1. Recommended annual phosphorus (P O) 2 5 When establishing or renovating an area, a applications for established turf based on soil test results. phosphorus application will help establish seedlings. A high in phosphorus Soil test results lb. P O/ 2 5 (also called a “starter fertilizer”) should be level lb. P/acre ppm P 1000ft2/year used for this application and should be low 0-25 0-13 3a applied at 1.5 pounds P O /1000 ft2 . 2 5 normal 26-50 13-25 2 Potassium (K) high 51+ 25+ 1 The soil test results represent the amount of

potassium that is available to the turfgrass aTo increase the amount of phosphorus applied plant. Potassium deficiencies are rare in turf while maintaining the same amount of nitrogen in Indiana soils except possibly on coarse- applied, use a fertilizer high in phosphorus for the textured, sandy soils. Muriate of potash (0-0- late fall application.The phosphorus (P) 60) can be used to increase soil potassium perecentage should be larger than the nitrogen (N) and potassium (K) percentage. An example levels. Muriate of potash can burn leaf would be 5-10-5 or 17-23-6. blades, so apply in cool, dry weather and water the area soon after application. Table 2 is a guide for applying the proper amounts of potassium. Table 2. Recommended annual potassium (K O) 2 applications based on soil test results. (Ca) and (Mg) Soil test results lb. K O/ Calcium and magnesium are rarely deficient 2 2 in Indiana soils when the pH is maintained level lb. K/acre ppm K 1000 ft /year above 6.0. Should a deficiency be noted, very low 0-50 0-25 6a calcium and magnesium can be added as low 51-100 25-50 4b dolomitic limestone. normal 101-150 50-75 2c Cation Exchange Capacity (CEC) high 151-200 75-100 1c This number represents a measure of your very high 200+ 100+ 0 soil’s capacity to hold nutrients. The higher the CEC, the more fertile the soil. It is used aApply 0-0-60 (muriate of potash) in the early spring and late fall at 2 lb. of fertilizer product per by the soil test laboratories in making certain 1000 sq. ft. for two years in addition to planned nutrient recommendations for your lawn. The nitrogen applications. cation exchange number of an established bRefer to the notes in (a) above. Only apply the lawn will not change significantly with time. muriate of potash for one year. In addition, it cannot be adjusted by adding c fertilizer or chemicals. Use a complete fertilizer containing nitrogen, phosphorus, and potassium twice per year. Nitrogen There is no reliable soil test for nitrogen. Therefore, other factors should be considered in planning a nitrogen program. The nitrogen More information and mentioned COOPERATIVE EXTENSION WORK IN program is the key to a successful turfgrass publications are available at AND HOME ECONOMICS, STATE OF INDIANA, PURDUE UNIVERSITY, fertility program. Refer to AY 22, Fertilizing www.agry.purdue.edu/turf AND U.S. DEPARTMENT OF AGRICULTURE Established Lawns, for more information. COOPERATING; H. A. WADSWORTH, DIRECTOR, WEST LAFAYETTE, IN. ISSUED IN FURTHERANCE OF THE ACTS OF MAY 8 AND JUNE 30, 1914. THE PURDUE UNIVERSITY COOPERATIVE EXTENSION SERVICE IS AN EQUAL OPPORTUNITY/EQUAL ACCESS INSTITUTION

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