Coffee Leaf and Soil Sampling Instructions

UH-ADSC (Oahu) no longer accepts soil, plant, forage, feed, and food samples from the public, including farmers. Please see the CTAHR Interim Dean and Associate Deans' (June 8th) message at the end of this page.

Read the publication from the Associate Deans of Extension and Research: FAQ: Changes at UH CTAHR ADSC
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Contact the labs directly for information on soil and tissue submissions, transport, payment, permits, forms, etc. Tissue is likely to require drying at 70 degrees celsius (158 degrees fahrenheit) and possibly finely ground before mailing. The local CTAHR Extension offices will no longer assist with the packing and postage of soil and tissue samples. However, if you have insect, disease, and nematode samples, these can still be brought to the Extension Offices and you can specify to have insect, disease, and nematode samples submitted to the UH-CTAHR ADSC Lab in Hilo. 

Your other alternatives for submitting samples for analysis may be:​​
Learn How to Take Proper Soil and Leaf Samples for Coffee. 

​Typical soil samples are analyzed for pH, P, K, Ca and Mg. Typical plant leaf tissues are analyzed for total nitrogen, P, K, Ca, Mg, Fe, Cu, B, Zn, Na and Mn.

​If you are unsure your tree problems are related to nutrition or a plant pest or disease, here are some helpful hints for Collecting Plant Disease and Insect Pest Samples for Problem Diagnosis.
​What is adequate plant nutrition for coffee plants?

While it's easy to apply whatever fertilizers that are in your closets or garage, you may be wasting your time, money and fertilizers. Also, you can look at the green leaves and suspect that a coffee tree is healthy, but some plant nutritional symptoms are inconspicuous and difficult to identify visually, thereby causing a potential downhill slide in plant health, production and again, an inefficient use of time and money, if you are not providing the tree what it actually needs.

​A typical soil (S2) test can help to determine pH, total phosphorus, potassium, calcium and magnesium in the soil. However, this test does not tell you what nutrients are actually available to the plant in a form that can be absorbed by the roots. For this reason, it is recommended that proper leaf samples are submitted with soil samples on at least an annual basis. Testing for T1-total nitrogen and T2 are recommended for coffee tissue (leaf) samples.

​​Ex: some soil tests will show high levels of phosphorus (P). At low soil pH, but much of soil P it is not readily available to the plant. 
It may seem as though you have enough P to supply the plant, but in fact, the plant is deficient and the leaf tissue analyses will confirm this by showing low levels of P in the leaves when analyzed.

The "Growing Coffee in Hawaii" booklet (pages 14-17) will provide you with a general idea of why and when to fertilize your coffee trees and how much macronutrients (nitrogen, phosphorus and potassium) is required by coffee trees based on the amount of coffee cherry harvested per acre. Read about Coffee Nutritional Deficiencies and see photos of specific deficiency symptoms in this publication.

Click here to better understand the role of each essential (macro and micro) plant nutrient.

Other helpful publications:
Adequate Nutrient Levels in Soils and Plants in Hawaii (General Guide)
​Recommended Plant Nutrient Levels (for various crops)
Testing your Soil - Why and How to Take a Soil-Test Sample
Interpreting Soil Nutrient Analysis Data
Collecting Plant Disease and Insect Pest Samples for Problem Diagnosis
Learn how to best collect and submit disease, insect pest and nematode samples to the UH Agricultural Diagnostic Service Center (ADSC) for diagnosis. 
  • General directions on collecting samples  - Collecting Plant Disease and Insect Pest Samples for Problem Diagnosis
    • Submit at least 2.5 cups of roots and soil each for nematode samples
    • Submit at least 2 cups of soil for S1 (pH and salinity) tests ​
  • As of 8/16/23: ADSC Hilo analytical service fees for insect, disease, virus, fungi, and nematode.
    • GMO papaya testing of leaf tissue and seeds by the Hilo ADSC is available. The cost is $15 for the first sample and additional samples are $3.00 each up to 250 samples. 
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