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Understand your boron micronutrient levels this summer

Understand your boron micronutrient levels this summer

Understand your boron micronutrient levels this summer

Trace elements, or micronutrients as they are also known, are required in small quantities by plants and animals. A small deficiency can critically affect growth and development.

One micronutrient that is commonly observed as being deficient in many parts of New Zealand is Boron (B). B is often considered to only be required by plants for healthy growth, but research literature has shown evidence that it also influences metabolism and growth in animals.¹

In plants, B plays an important role in carbohydrate metabolism and protein synthesis. It also assists with the movement of calcium and sugars into growing parts of the plant. B is important for seed set and pollination and it is common practice to apply B to brassica and root crops to prevent conditions such as ‘brown heart’ and ‘hollow stem’.

A deficiency in legumes presents as the plant having a ‘bushy’ appearance due to the death of the stem tips and development of short stems. Leaves may be misshapen and crinkly. A deficiency is more likely to occur in soil types that are free draining, such as soils with a coarse and sandy texture with low organic matter, as these soils lose B through leaching in drainage water.

To determine a plant’s tissue B status, a plant herbage test should be taken for sampling and analysis. Plant analysis is an essential way to determine B status. Soil tests are less reliable indicators of potential plant utilisation and should not be used in isolation to determine a plant deficiency. Herbage tests are the most reliable tool to identify and confirm if visual symptoms are related to a B nutrient deficiency rather than related to fungal diseases such as 'dryrot' and Scelrotinia.

A plant tissue sample of clover is necessary due to the difference between B requirements of grass and of clover. Concentration of B is at its lowest in winter and early spring so the best time to test for B in clover samples is during summer when clovers are rapidly growing. It is also recommended to take a plant tissue sample of the youngest mature leaf in brassicas for analysis too.

If testing shows a B deficiency, prompt remedial action is required to mitigate the effects. Foliar applications of formulated B are a quick, accurate and cost-effective option that can be applied to the crop. B should always be included in starter fertiliser programmes for brassica crops.

Check your legume, brassica or seed crop plant tissue levels for boron in summer. For assistance taking a herbage test to analyse if there is a boron deficiency, contact your local PGG Wrightson Technical Field Representative.

¹ Cornforth, Ian. (1998). Practical soil management. Lincoln University Press and Daphne Brasell Associates Limited.