A lot of people who want to proceed with a soil or leaf tissue analysis ask us about the sample selection. And of course sampling is a very important part of an analysis, as it can affect the results and ultimately the assessment of the nutritional status of the field or plant. Depending on the crop, our answers can vary, but in this article we will try to answer some of the basic questions.
So let’s answer the most common and important questions about soil sampling.
The more samples the better but we would suggest you collect about 5 samples per 1 acre. Of course the samples should be from different parts of the plot and then for approximately every 0.5 acre you should collect another sample. You place the samples from all areas of the plot in one bag so they can get mixed up and we’ll handle them as one.
For the most part, 30cm is an appropriate depth for a soil sample.
The sampling season does not affect the results so much. It would make more sense, though, to conduct a soil analysis in winter/autumn in order to have a better understanding of the type of fertilization your crop needs.
Based on the results of the analysis, will we be able to determine exactly how much fertilizer we’ll need to add so the concentration each element will rise to the desired levels?
The answer is no. Soil analyses provide us with an estimation of the status of the nutrients in our field, not the exact concentration of the nutrient in question. Wherefore, we can figure out which element(s) are in shortage/excess, then proceed with appropriate fertilization and in approximately two years, when we conduct another analysis, we will see the results of our fertilization choices.
Ideally, every 2-3 years we should do another analysis if we want to optimize our crop production.
So these were the key questions for soil sample collection and testing. Let’s answer some questions about collecting leaves for leaf tissue analysis as well.
No, generally baby leaves are not what we need for a leaf tissue analysis. We need mature (dark green) leaves.
Yes, we need the stem of the leaves. So you need to collect the leaf with the stem
Unlike soil analysis, leaf tissue analysis helps us understand the immediate needs of the plant (which change depending the cultivation stage). In conclusion, this is a question that is not feasible to answer in order cover every crop. Generally speaking, the best time for this analysis is during the plant’s most productive season, when it needs help to cope and push the necessary nutrients to its fruits.
This question is difficult to answer given the diversity of the leaf size in plants. So it’s best to contact us directly. But some basic examples are:
- Grapes: we need about 30 leaves
- Fig tree: we need about 30 leaves
- Olive tree: we need about half a leaf
- Citrus fruits: we need about one bag
So these are some question and answers that we think will cover many of your questions. However, we would be happy to speak with you directly to address more specific questions you may have about your crop.