Even though people have known for more than two thousand years that adding mineral elements, such as plant ash or lime, to the soils can improve plant growth, the systematic study of plant nutrition is a relatively young science, considering humanity's long history of cultivating crops. About 250 years ago, farmers and gardeners started to ask the question, "What makes plants grow?" It was widely believed that soil humus, a brown or black organic substance resulting from the partial decay of plant and animal matter, provided plants with carbon for making sugar and starch, and substances such as saltpeter, lime, and phosphates simply helped the humus to be more useful. It was not until around 1840 that the German chemist Justus von Liebig (1803-1873) helped to compile and summarize the scattered information on the importance of mineral elements for plant growth, and plant nutrition began to be established as a scientific discipline. Since then, great progress has been made in the study of plant nutrition.
It is now known that, aside from carbon, hydrogen, and oxygen, which plants get from air and water, about a dozen other nutrients are needed for plant growth. They can be divided into three classes. The primary (or major) nutrients, including nitrogen, phosphorus, and potassium, are needed in larger quantities than are the secondary nutrients, calcium, magnesium, and sulfur. These in turn are required in greater quantity than the trace (or minor) nutrients iron, boron, manganese, copper, zinc, molybdenum, chloride, and nickel. These nutrients are contained in the minerals and organic matter in the soil. Many more elements are found in both soils and plants for instance, aluminum, cobalt, fluorine, iodine, and sodium. They may not be needed by all plants and may be either beneficial or toxic to plant growth. Silicon, sodium, and cobalt are beneficial to some plants.
Soil and Plant Nutrients
Soil is the natural medium in which crops grow. The nutrient content of a soil and the availability of the nutrients to crops are important factors that determine a soil's productivity.
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Coping with Nutrient Deficiencies
Based on knowledge of plant nutrition and experience accumulated over a long period of time, nutrient management practices have been established to enhance soil fertility and overcome crop nutritional problems by balancing the use of mineral fertilizers combined with organic and biological sources of plant nutrients.
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Overcoming Nutrient Toxicities
Soil can become acidified as a result of its own physical properties, microbial activity, climate, vegetation, and the addition of acidifying fertilizers.
Continue of the article: Overcoming Nutrient Toxicities
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