Fortunate owners of small greenhouses can run similar tests indoors during the winter to give a clue to treatments for the entire garden the following spring.
The testing of plant tissues, particularly leaves, for nutrient levels is usually carried out for farm operations rather than for the home garden, but occasionally a friendly county agent can be found who knows the technique and will "read" your feeding efficiency. Foliage tissue tests are particularly valuable because they show the rate at which food is being taken up by the plant. Such tests can detect a nutrient deficiency long before the plant itself begins to show it. (See Appendix for a fuller discussion of this testing method.)
An answer is given to the controversial question of "to test or not to test" the soil; excluding pH tests made with inexpensive home kits, the answer is "don't bother." There are too many variables involved in testing for nutrients and other conditions, and a non-scientific gardener can easily misinterpret the test results. Professional testing, of course, is costly but can be relied upon. Soil profiles and wash tests are practical ways for the home gardener to find out about his soil makeup.