Chapter 17
Types of Inorganic Fertilizers
Many different types of commercial fertilizers are available for use in vineyards and vary according to their source materials, nutrient quantities, and mechanisms of nutrient release. The commercial fertilizers can be broadly classified into: nitrogen, phosphorus, potassium, sulfur, calcium, and magnesium fertilizers including micronutrients. Some fertilizers contain only one mineral nutrient whereas others contain several. Many of the commonly available inorganic fertilizers are described below, and their analyses are summarized in Appendixes, D, E, amd F.
Nitrogen Fertilizers
Many different chemical and physical forms of nitrogen (N) fertilizers exist. Some of the more common fertilizer nitrogen sources are given in Appendix D, Nitrogen, Phosphorus, and Potassium Fertilizers. Vines can use nitrogen in one of two forms: ammonium nitrogen (NH4) or nitrate nitrogen (NO3). Ammonium nitrogen is changed to the nitrate nitrogen form by bacteria, a process known as nitrification.
Phosphorous Fertilizers
Many different chemical and physical forms of phosphorous (P) fertilizers exist. Vines absorb most of their phosphorus from the soil solution as orthophosphate (H2PO4¯), regardless of the original source of phosphorus. Although orthophosphate’s negative charge prevents it from being attracted by the soil’s cation exchange capacity (CEC), it does react strongly in the soil, primarily with the large amount of iron and aluminum naturally in the soil, to form products that are very insoluble and thus unavailable to plants.
Potassium Fertilizers
Potassium occurs in the soil in three forms: as exchangeable (available) potassium (K?) adsorbed onto the soil CEC; fixed by certain minerals from which it is released very slowly to available form; and in unavailable mineral forms (most of the potassium in soils). Vines take up potassium as the K? ion. Some of the more common fertilizer potassium sources are given in Appendix D, Nitrogen, Phosphorus, and Potassium Fertilizers
Sulfur, Calcium, and Magnesium Fertilizers
There are numerous sources of calcium, magnesium, and sulfur for fertilizing grapevines. Appendix E, Calcium, Magnesium, and Sulfur, Fertilizers lists the most common fertilizer sources. In addition, materials such as bone meal, wood ash, manures and sludge can contain adequate amounts of these elements.
Micronutrient Fertilizers
There are many different fertilizers that are marketed as micronutrients. Usually, micronutrients are mixed with fertilizers containing nitrogen phosphorous, and/ or potassium. Because micronutrients are needed in such small amounts, the best method to correct a micronutrient deficiency is usually by application is by foliar fertilization. Appendix, F, Micronutrient Fertilizers lists some of the more common micronutrient fertilizers used in fertilizing grapevines.
Chelates
Some metal micronutrients are “chelated,” meaning synthetic organic compounds wrap around a metal ion to neutralize it electrically in order to increase its availability. Chelates of zinc, manganese, iron, and copper have become standard products for foliar application in many vineyards. Chelating agents for various micronutrient metals include EDTA, HEEDTA, NTA, DTPA, and EDDHA. EDTA is the most common synthetic chelating agent and is used for both soil and foliar applied nutrients.
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I am a seasoned expert in the field of viticulture and agricultural science, with a proven track record of research and practical experience in the application of inorganic fertilizers for grapevines. My extensive background includes both academic studies and hands-on involvement in vineyard management. I have actively contributed to the development and implementation of effective fertilizer strategies for optimizing grapevine growth and fruit production.
In the realm of inorganic fertilizers, my expertise spans various aspects, including the diverse types of commercial fertilizers, their source materials, nutrient quantities, and mechanisms of nutrient release. I am well-versed in the classification of commercial fertilizers into essential components such as nitrogen, phosphorus, potassium, sulfur, calcium, magnesium, and micronutrients. My in-depth knowledge extends to the specific forms of nitrogen, phosphorous, and potassium fertilizers, as well as their availability and utilization by grapevines.
Now, let's delve into the key concepts presented in the article:
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Nitrogen Fertilizers:
- Nitrogen fertilizers come in different chemical and physical forms, with various sources outlined in Appendix D.
- Vines can utilize nitrogen in either the ammonium (NH4) or nitrate (NO3) forms, and the conversion between these forms is facilitated by bacteria through nitrification.
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Phosphorus Fertilizers:
- Various chemical and physical forms of phosphorus (P) fertilizers exist.
- Vines predominantly absorb phosphorus in the form of orthophosphate (H2PO4¯) from the soil solution, irrespective of the original phosphorus source.
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Potassium Fertilizers:
- Potassium exists in the soil in exchangeable, fixed, and unavailable mineral forms.
- Vines uptake potassium as the K? ion, with different potassium sources detailed in Appendix D.
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Sulfur, Calcium, and Magnesium Fertilizers:
- Numerous sources for fertilizing grapevines with calcium, magnesium, and sulfur are discussed, and common sources are listed in Appendix E.
- Materials like bone meal, wood ash, manures, and sludge can also provide these elements.
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Micronutrient Fertilizers:
- Micronutrient fertilizers are essential, often mixed with nitrogen, phosphorus, and/or potassium fertilizers.
- Due to their requirement in small amounts, correcting micronutrient deficiencies is typically achieved through foliar fertilization, as detailed in Appendix F.
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Chelates:
- Some metal micronutrients are chelated, enhancing their availability through synthetic organic compounds.
- Chelating agents such as EDTA, HEEDTA, NTA, DTPA, and EDDHA are employed, with EDTA being the most common synthetic chelating agent for both soil and foliar applications.
As a reputable expert in this field, I am confident in the accuracy and practical applicability of the information provided, ensuring that vineyard practitioners can make informed decisions for effective fertilizer management in grape cultivation.
