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HOW TO TAKE A PLANT SAMPLE FOR PLANT ANALYSIS

(For more details, order our sampling guide for plant tissue analysis)Plant analysis assesses nutrient uptake while soil testing predicts nutrientavailability. The two tests are complementary as crop management tools. Plantanalysis will detect unseen hidden hunger and confirm visual deficiencysymptoms. Toxic levels may also be detected. If it is done early, plant analysiswill allow a corrective fertilizer application in the same season.A basic knowledge of plant structure is necessary before collecting samples. Aleaf is made up of a leaf "blade" and a "petiole". The petiole is the stalk attachedto the blade. A compound leaf may have several "leaflets" attached to it. Insome cases, only terminal "leaflets" may be sampled, as in the case of walnutsand pistachios. A common error in tomatoes is when only leaflets are sampledinstead of the whole compound leaf. This shows the importance ofunderstanding proper sampling technique.The most recent mature leaf (MRML) is the first fully expanded leaf below thegrowing point. It is neither dull from age nor shiny green from immaturity. Forsome crops, the most recent mature leaf is a compound leaf. The most recentmature leaf on soybean and strawberry, for example, is a trifoliate compoundleaf: three leaflets comprising one leaf.

For cotton, grape, potato and strawberry, petioles provide an additionalindication of nitrogen status. When sampling these crops, collect most recentmature leaves and their petioles. Detach leaves from petioles in the field tostop the translocation of nutrients. Put petioles in a separate bag. "Midribs" arethe middle ribs to large leaves such as corn, lettuce, and cabbage, and wouldequate to a petiole sampling.Deciding When to SampleTo monitor plant nutrient status most effectively, sample during the

recommended growth stages for your specific crop Take samples weekly orbiweekly during critical periods, depending on management intensity and crop

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value. However, to identify a specific plant growth problem, take sampleswhenever you suspect the problem.The best time to collect samples is between mid-morning and mid-afternoon.Nitrate nitrogen varies with time of day and prevailing conditions but generally

not enough to alter interpretation. Sampling during damp conditions is okaybut requires extra care to prevent tissue from decomposing during shipping.Keep samples free of soil and other contaminants that can alter results.The appropriate part of the plant to sample varies with crop, stage of growth,and purpose of sampling. When sampling seedlings less than 4 inches tall, takewhole plants from 1 inch above the soil line. For larger plants, the most recentmature leaf is the best indicator sample.Taking A Representative SampleProper sampling is the key to reliable plant analysis results. A sample canrepresent the status of one plant or 20 acres of plants. In general, a common-sense approach works well.When problem solving, take samples from both "good" and "bad" areas.Comparison between the two groups of samples helps pinpoint the limitingelement. Comparative sampling also helps factor out the influence of droughtstress, disease, or injury. Take matching soil samples from the root zones ofboth "good" and "bad" plants for the most complete evaluation.When monitoring the status of healthy plants, take samples from a uniformarea. If the entire field is uniform, one sample can represent a number of acres.If there are variations in soil type, topography, or crop history, take multiple

samples so that each unique area is represented by its own sample.Choosing Sample SizeThe actual laboratory analysis requires less than one gram of tissue. However, agood sample contains enough leaves to represent the area sampled. Therefore,the larger the area is, the larger the sample size needs to be.Sample size also varies with crop. For crops with large leaves, like tobacco, asample of three or four leaves is adequate. For crops with small leaves, likeazalea, a sample of 25 to 30 leaves is more appropriate. For most crops, 8 to 15leaves is adequate. For crops requiring petiole analysis, collect at least 15 to 20leaves.The tables below show the sampling guide for various crops.

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Submitting the Sample

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Send the completed information sheet and proper fee with each sample. Usepermanent ink or pencil on sample forms and bags Avoid numbering samplessimply as 1,2,3 as it may lead to confusion later. Give each sample a uniqueidentifier that will help you remember the plants or area it corresponds to-such

as HOUSE1, 15B, GOOD, or BAD. You can use up to six letters and/or numbers.Put the identifier on both the information sheet and the sample envelope. Payattention to detail when filling out the information sheet. Note any conditions-drought, disease, injury, pesticide or foliar nutrient applications-that might berelevant. Indicate the analysis desired and provide very specific informationon stage of growth and plant part if an interpretation is required. Thelaboratory does not automatically provide an interpretation, as some clientsprefer to make their own.Diagnostic interpretations require more details than predictive. When sendingmatching soil, solution, or waste samples, indicate the matching sample ID inthe designated areas on the information sheet. Be sure the grower name andaddress are exactly the same on all matching information sheets. Ship allmatching samples in the same container. Ship the tissue sample in a paperenvelope or cardboard box so it can begin drying during transport. Samples putin plastic bags will rot, and decomposition may alter test results.If samples are very wet, air-dry to a workable condition before packaging.Otherwise, decomposition or molding will occur. Include a completed plantanalysis information sheet or cover letter with instructions within the samepackage. Processing will be delayed if sent separately. Also, include payment if

you do not have an established account. Samples should be shipped by a carriersuch as UPS or FEDEX, or by first class mail.Interpreting the ReportSamples are analyzed the next day of their arrival. The prompt turnaroundmakes it possible for growers to take any corrective action needed to salvagethe current crop. The report can be emailed or post mailed to the growerGraphic Sampling Guides for some Common Crops

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