Agronomy notes


U.S. Borax counts some of the world’s leading boron agronomists among its staff. These agronomy notes have been compiled in response to commonly asked questions about boron’s role in plant nutrition.
Boron deficiency symptoms

Boron deficiency symptoms

Plants initially may not exhibit obvious symptoms of boron deficiency. When moderate or severe boron deficiency occurs, most crops exhibit visible symptoms. Knowledge of boron-deficiency symptoms can help in diagnosing deficiencies.

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The role of boron in flowering and fruit, nut and seed formation

The role of boron in flowering and fruit, nut and seed formation

One of the important functions of boron in plant nutrition is its role in fostering pollen growth and development, which is important in seed set and the resulting fruit, nut and grain production.

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Boron mobility in various plant species

Boron mobility in various plant species

Plant uptake of boron (B) is a passive (non-metabolic) process and B is transported in the xylem vessels (transpiration stream) of all plant species. Therefore, B is mobile in the xylem system of all plants.

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Functions of boron in plant nutrition

Functions of boron in plant nutrition

Boron is a micronutrient required for all plant nutrition. The main functions of boron relate to cell wall strength and development, cell division, fruit and seed development, sugar transport, and hormone development. Some functions of boron interrelate with those of nitrogen, phosphorus, potassium and calcium in plants.

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Coastal bermudagrass: Boron applications

Coastal bermudagrass: Boron applications

Some coastal bermudagrass varieties may respond to applied boron, especially on sandy soils in high rainfall regions, or with adverse weather conditions during the growing season. Where needed, a preplant application of Granubor 2 with the early-season top-dressed NPK fertilizer generally will ensure an adequate supply of boron.

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Cotton: Boron applications for increased yields

Cotton: Boron applications for increased yields

Cotton requires an available supply of boron, especially during the boll development stage, or boll shed may occur which reduces yields. Multiple foliar sprays of Solubor applied alone or with insecticides will ensure an adequate supply of boron during flowering and boll development. Preplant soil application of Granubor 2 plus foliar sprays of Solubor during the season are recommended for soils testing low in available boron.

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Peanuts: Boron applications for improved quality and yields

Peanuts: Boron applications for improved quality and yields

Peanuts require boron, especially during the pod development stage, or “hollow heart” may occur, possibly reducing quality and yields. One or more foliar sprays of Solubor applied alone or with insecticides will help ensure boron supply during flowering and pod development. Preplant soil application of Granubor 2 plus foliar sprays of Solubor during the season are recommended for soils testing low in available boron.

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Apples: Boron applications for increased production

Apples: Boron applications for increased production

Apples require an adequate supply of available boron, especially during flower formation and fruit set. Foliar sprays of Solubor during the dormant season, pre-pink and early bud stages will ensure an adequate supply of boron during the critical stages of flowering and fruit development.

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Grapes: Boron applications for increased production

Grapes: Boron applications for increased production

Grapes require an adequate supply of available boron, especially during flowering and fruit set. Multiple foliar sprays of Solubor applied alone or with insecticides will ensure boron supply during the critical stages of flowering and berry development. Preplant soil application of Granubor 2 plus foliar sprays of Solubor during the season are recommended for soils testing low in available boron.

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Soybeans: Boron applications for increased yields

Soybeans: Boron applications for increased yields

Soybeans require boron, especially during flowering and seed development. Multiple foliar sprays of Solubor will ensure an adequate supply of boron during this stage of growth. Foliar sprays of Solubor can be combined with other field treatments, such as insecticides, to reduce costs. Preplant soil application of Granubor 2 plus foliar sprays of Solubor during the season are recommended for soils testing low in available boron.

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Corn: Boron applications for increased yields of high-yield field corn and sweet corn

Corn: Boron applications for increased yields of high-yield field corn and sweet corn

Boron aids in the transfer of sugars and nutrients from leaves to reproductive organs, and increases pollination and seed development. Corn requires a supply of available boron, especially during tasseling and silking.

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Forestry: Boron in forestry production

Forestry: Boron in forestry production

Boron deficiency is the most common micronutrient limitation in forest plantations. It occurs in many countries, particularly in exotic plantations of eucalypts and pines, but also in plantations and natural stands of native species on soils altered by macronutrient fertilization, liming, fire or erosion.

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Fruit tree foliar nutrient sprays

Fruit tree foliar nutrient sprays

Foliar nutrient sprays are commonly applied to fruit trees. Boron is immobile in most plant tissues so boron may not be readily transported to developing flower buds. Solubor can be effectively applied with dormant oil-insecticide sprays during the dormant stages of most fruit trees.

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Pistachios: Boron application for increased yields

Pistachios: Boron application for increased yields

Research in California has shown that foliar applications of Solubor increased pistaschio yields. The best time for foliar application is from the late dormant to the early bud stages. Soil applications of boron are not as effective as foliar applications in supplying sufficient boron for flowering.

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Soybeans

Soybeans

Boron fertilization of soybeans has shown to increase grain yield at locations across the world when the boron supplying power of the soil is inadequate even though soybeans are listed as tolerant to boron deficiency. University research has found soybean yield increases ranging from 2-17.91 bushels per acre due to application of boron to boron deficient soybeans.

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Boron reactions in soils

Boron reactions in soils

Organic matter is the storehouse for most of the available boron in soils. Boron deficiencies in crops are found mainly in low organic matter soils and in acid, sandy soils in humid regions.

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Does manure contain enough boron?

Does manure contain enough boron?

Animal manures contain varying concentrations of most plant nutrients.

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Effects of sodium in borax on soils and crops

Effects of sodium in borax on soils and crops

Sodium is found in all soils and crops. Soils in humid regions, where most boron deficiencies occur, contain about 50-150 lbs/acre of sodium in the surface 6-inch layer, but soils in drier regions may contain higher levels of sodium.

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Fertilize before boron deficiency symptoms occur for optimum yields

Fertilize before boron deficiency symptoms occur for optimum yields

Visual symptoms of boron deficiency may not occur until the deficiency has become moderate or severe. At this stage, slower growth may have reduced the yield potential for the crop. Use the results of soil tests and/or plant analyses to help assess the potential for boron deficiencies to ensure adequate boron supplies for the crop.

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Plant tissue testing for boron

Plant tissue testing for boron

Plant analysis can be a valuable tool in determining the general nutritional status of crops during the growing season. Accurate interpretation of plant analyses data requires that plant tissue samples be carefully collected and handled prior to shipment to the laboratory. Knowledge of the normal boron sufficiency range in a given crop helps to interpret the analytical results and to diagnose a possible boron deficiency.

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Soil tests for available boron

Soil tests for available boron

Soil testing is helpful in assessing the potential boron-supplying capacity of the soil. Recent research has shown that three commonly used soil tests, the Mehlich-1 and -3 tests and the DTPA test modified to include sorbitol, also may be used to determine available boron in soils.

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Differences in boron fertilizer sources

Differences in boron fertilizer sources

Growers should know the relative boron needs for each specific crop, as well as the water soluble available boron supply in the soil, to determine the optimum rate and method of applying sufficient boron for optimum yields.

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Solubility of Solubor in liquid fertilizers

Solubility of Solubor in liquid fertilizers

Solubor is an excellent boron source for inclusion in liquid fertilizers because it is readily soluble and does not react with other components of these fertilizers.

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Amounts of Solubor to mix into spray tanks to supply desired boron rates

Amounts of Solubor to mix into spray tanks to supply desired boron rates

Solubor is highly water soluble, and is commonly applied in foliar sprays. Because the season for the most effective foliar application of boron is short, foliar sprays must be prepared quickly and accurately.

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Relative plant tolerance to available boron supply

Relative plant tolerance to available boron supply

Boron nutrition is a special concern in crop production; growers want to ensure that the available boron supply is sufficient for optimum nutrition but not so high as to result in reduced yields from an over-supply.

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How much will increased pH affect pesticide efficacy?

How much will increased pH affect pesticide efficacy?

The efficacy of some pesticides may be affected by increased pH of the pesticide tank mixes. Inclusion of an appropriate buffer to control the pH of tank mixes is suggested for those pesticides whose efficacy is known to be reduced by increased pH.

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Alfalfa: Boron for profitable alfalfa

Alfalfa: Boron for profitable alfalfa

Alfalfa has a higher boron requirement than most crops. For optimum yields of high quality alfalfa, it is essential to maintain adequate supplies of available boron throughout the growing season.

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