Pennsylvania Flower Growers #187
Introduction Man has long been interested in controlling the yield and quality of products grown on his land. At first, crop growing was dependent on the natural fertility of the soil. Then it was discovered that decomposed or decomposing forms of plant and animal matter could be used to increase crop growth. Next it was found that inorganic chemicals could be used as fertilizers to change the nutritional status of the soil and thus improve crop productivity. The amounts of fertilizer used and the frequencies of fertilizer application have increased steadily through the years to the present day highs. Visual Analysis There are several approaches possible for deciding the amounts and kinds of fertilizers to use. One of the oldest and possibly one of the first used methods was diagnosis by visual plant symptoms. The grower looks at his crop and compares what he sees with his knowledge of what he expects a normal healthy plant to look like. However, experience and experiments have shown that such symptoms may be unreliable in pinpointing the element which is deficient. In some cases two different elements in deficient sup ply may give symptoms quite similar in appearance. In fact, often toxicity symptoms appear the same as symptoms created by deficiencies of the same element. Furthermore, growth, yield and quality may be seriously reduced without the development of recognizable deficiency symptoms. This situation has been called "Hidden Hunger" in many publications.
Keywords: Yield and quality Fertilization visual plant symptoms Essential Elements Plant Analysis