Soil and Plant Sampling

Commercial Christmas Tree Plantings

1. Divide the field into "blocks" of trees of the same species, age, and general soil condition. Develop a number/letter code system to identify each "block" to be sampled and use this code each time samples are taken in the future.

2. Select 5 to 10 trees in each block, that is typical of the block. Mark these trees in some permanent manner such as plastic or aluminum tags or ribbons. These trees will become the "indicator" trees for the entire block. A composite soil and plant sample from these 5 trees will be taken for each block, and used to evaluate and fertilize the entire block.

3. Take 3 to 4 soil cores around the drip line of each tree (15 to 20 cores in total). Place the soil cores in a plastic bucket and mix them thoroughly. Fill a soil bag supplied by AgSource up to the line on the bag. These combined cores will become the soil sample for that block of trees.

4. There are some options in plant sampling, depending on pruning/shearing practices. The nutrient analysis of any part of the current season's growth is acceptable and the terminal or lateral growth is similar.  It is possible to sample older tissue, but the interpretation of the results will be less accurate.  From each of the same trees, take 3 to 5 laterals or terminals (a total of 15 to 20 for each block is enough). Do not sample current season's growth until it is hardened off. The best time to sample is after the tree has become relatively dormant from late summer into fall (typically October in the Midwest). During this time roots are dormant, the trees have produced most of their annual woody growth, and nutrient levels are relatively stable.  

5. Mark the soil bag and plant sample envelope with the number/letter code for that block, plus the other requested information. Put the sample bags in a secure shipping container such as the boxes provided by AgSource and send them to AgSource.

6. Record this identification and all other information such as sample data, treatments, measurements, close-up photographs, and other data in a log so you can evaluate the progress of the crop.

Note: If you want to identify or confirm suspected nutrient problems with individual trees, sample the single tree as described above. Remember to take the total required "current years growth tips" and soil cores from that tree. In this case, it would be helpful to take an additional set of tips and soils from a normal tree to compare with.