- Author: Trisha Rose
A couple of years ago, I took the Soil Science class at Solano Community College. This was my last class in the series of courses required to complete a Horticulture Certificate. There are about 7 courses in this program with no particular order of completion required. Each course is taught over a semester with projects, tests and written assignments appropriate to the subject. It is strongly suggested that students begin their studies with the Introduction to Horticulture, an overview course that touches on a number of aspects of this very broad subject. A mini-version of this overview course was presented in the lecture series of my Master Gardeners training in 2010.
It took me a few years to get through all the courses due to my general lazy nature and the way the classes are scheduled, but as I approached the last course on my checklist I was glad to have spent my time delving into many of the aspects of horticultural science and art. So as the course, Soil Science, began, my curiosity was awakened, although the first bit on geology was a little dry, the discussions of the elements and how they influenced plant life were very interesting.
Finally, the mystery of what and how elements such as Zinc, Manganese, Copper, etc., influence plant health and growth were unveiled. Each of the 17 elements necessary for plant life was discussed. Carbon, Hydrogen and Oxygen are taken from the air and water surrounding our planet. The 14 soil born elements are grouped as either Primary, Secondary or Micronutrients. The Primary elements, N (Nitrogen), P (Phosphorus) and K (Potassium) are grouped together because they are the 3 most commonly deficient nutrients. This is the familiar NPK group listed on our Fertilizer containers. The Secondary Group nutrients are Calcium, Magnesium and Sulfur, fortunately they are less frequently found to be deficient in the soil so they are grouped as secondary.
The discussions about the Micronutrients caught my attention. These elements are used by plants in very small amounts but they are just as essential for plant health as those elements in the Primary and Secondary Groups. Zinc is an example of one of the Micronutrients. It is used as a supplement for many crops including tree fruits, nuts, beans, onions and tomatoes. Deficiency may appear as a decrease in stem length and rosetting of terminal leaves, reduced fruit bud formation, mottled young leaves shown as interveinal chlorosis and die-back of twigs after the first year.
The study of soil is fascinating, there is so much more to learn and understand. I found the readings, chemical experiments and discussions about the elements very interesting, and continue to go back and read about them and how they influence plant health and vigor.
The Western Fertilizer Handbook, second horticulture edition, 1995 and Soil Science Simplified, fifth edition 2008 available used on-line were the two books we used in our Soil Science class at Solano Community College.