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The nutrient content of a plant can be assessed by testing a sample of tissue from that plant. These tests are important in agriculture since fertilizer application can be fine-tuned if the plants nutrient status is known. Nitrogen most commonly limits plant growth and is the most managed nutrient. == Most useful times== Tissue tests are almost always useful, since they provides additional information about the physiology of the crop. Tissue tests are especially useful in certain situations; * For monitoring the nitrogen status of the crop throughout the growing season. Soil tests are commonly performed before planting * In highly controlled environments, such as hydroponic production in greenhouses, crops require a constant feed of nutrients in their water supply. Even a transient lack of nutrients can reduce yields. In these controlled environments, soil testing is unlikely to be sufficient to manage crop nitrogen status. Soil testing is more suitable when growing crops in slow-release composts and manures * When there is a risk that the nutrient applications are toxic to the crop, such as during the application of poultry litter that contains micro nutrients such as copper. * To guarantee that nitrogen levels in the crop do not exceed a certain limit. High concentrations of nitrates has implications to human health because nitrates can be converted into nitrites in the human digestive tract. Nitrites can react with other compounds in the gut to form nitrosamines, which appear to be carcinogenic. Crops contain high concentrations of Nitrate when excess fertilizer is used. This is an issue in crops with high levels of nitrates, such as spinach and lettuce. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Plant tissue test」の詳細全文を読む スポンサード リンク
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