Identifying nutrient deficiency in a lawn

Nutrient deficiencies are rare in treated lawns. The soil of established lawns is usually quite good at holding nutrients however, there are occasions when a domestic lawn does need a top-up of one nutrient or another. Perhaps it’s a new-build struggling on poor soil, or maybe it’s a very sandy area that sees a lot of rain and the nutrients are being washed out too quickly. Knowing the signs will help you identify a problem and take action.

A quick note before we begin…

soil testsSolving deficiencies is not always straightforward. This is because having a deficiency in one nutrient may affect the uptake of another, so solving the deficiency of the latter will not solve the original problem. Soil pH can also cause nutrient deficiencies as certain nutrients become more or less available as pH changes. You also need to make 100% sure that the problem is not related to a different issue such as bad mowing practice, shading, general wear, drought stress, etc.

For a definitive answer, the best option is to send off a sample of soil for analysis. (GreenBest can help with this, get in touch with a member of the sales team if you would like more information.)


Nitrogen (N)

The lawn will have a mottled pale green to yellow appearance as the older leaves turn yellow. In extreme cases, the lawn will thin and struggle especially in shady areas or during winter.

Nitrogen leaches easily from the soil so it’s important to use a slow release nitrogen source where possible to keep lawns green and to keep applying some nitrogen all year round.

Phosphorus (P)

The lawn foliage will take on a reddish hue and can sometimes look purple. New growth will be limited causing the lawn to thin over time.

Most soil tends to have plenty of phosphorus but not always in available forms. We recommend that you apply ‘available’ phosphorus all through the year, for this reason, it appears in the majority of our SmartLawn fertilisers.

close-up-dew-field-72296Potassium (K)

The tips of the leaves will look burnt/scorched and older leaves may yellow in colour. The lawn will also wilt easily in the summer and does not recover well after drought conditions.

Potassium can be stored by the plant but since it has an important role in water management it should be applied all year round. It is included in nearly all of our SmartLawn fertilisers so that your lawns can be as green as possible all year round.

Magnesium (Mg)

The older leaves of each grass plant will turn red. We include enough magnesium in our spring and autumn feeds to prevent deficiencies of this nutrient.

Calcium (Ca)

Leaves go curly and brown and they will be very susceptible to disease. In chalky areas, a deficiency in calcium is very rare. We have recently added Ca to SmartLawn Ultimate to prevent deficiencies of this and improve disease resistance in treated lawns.

Iron (Fe)

The new leaves are yellow. Iron deficiencies are highly unlikely if the lawn has been treated with iron sulphate for moss in the past few years.

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