We get this question a lot and there is a straightforward answer… yes it does. But there is much more information that needs to be considered when using iron and iron is not the only thing that can assist in making your lawn greener.
Important things to consider prior to any applications are:
Before we consider the individual nutrients, it is important to talk about soil’s cation exchange capacity (CEC). The CEC is known as the buffering capacity and is a measure of the soil’s ability to store nutrients. This is the cornerstone measurement to understand soil analysis as it allows us to define target nutrient values for each particular soil.
Sands which have a low organic matter content have a low CEC, typically 1 to 4, while clay soils have a much higher CEC, normally in the range of 12 to 20.
There is no ideal CEC, a high value is beneficial as it enables you to get results from the fertiliser that you use. With a low value being less desirable, giving the soil less nutrient holding capacity, making the correct management technique the use of liquid feeds, controlled release fertilisers, or regular light applications of fertiliser.
pH levels of a soil is also of great importance as it affects the availability of the nutrients to be taken up by the turfgrass plant.
It’s essential to appreciate that nutrients do not stand alone and interact in the soil solution. These exchanges affect the availability of each nutrient within the turfgrass and is ideal to keep them in balance for overall turfgrass health and growth.
The below gives a little reference to the fore mentioned:
|A high level of the nutrient below||Reduces the availability of the nutrient in this column|
|Calcium||Boron, Iron, Potassium and Magnesium|
|Phosphorus||Zinc, Iron, Calcium, Aluminium|
The key ingredient you will find in increased amounts in most winter fertilisers is Iron. Iron helps to strengthen your grass and to improve leaf colour, making your lawn greener. Iron is also known to limit the impact of frost and is a common solution for killing off moss.
To ensure an Iron application is effective, you need to make sure your soil’s pH is 6 and below. Iron should not be used on an unhealthy lawn or outside of label instructions. It can very easily do more harm than good if overapplied and blacken/burn your grass. If you maintain good lawn care practices, particularly leading into winter, your lawn should have the nutrient it requires to retain reasonable colour in most areas especially in frost free areas.
If you are wanting to make your lawn really stand out in winter, you have a healthy lawn and consider yourself a bit of a lawn enthusiast, then you are ready to incorporate specific iron treatments into your lawn maintenance program.
There are a number of iron products out there, but in winter we recommend you use a liquid iron product like iron chelate and where possible use one with added nutrients like Magnesium…
Magnesium encourages winter hardiness and early growth. It is vital for nitrogen metabolism and chlorophyll synthesis and helps the turfgrass to utilise iron and phosphate. Turfgrass that is low in magnesium can have yellowing drooping leaves.
Magnesium interacts with both calcium and potassium so should be kept in balance with those. Ideally the calcium to magnesium ratio should be about 10:1.
Manganese is essential for nitrogen uptake, activation of enzymes, and photosynthesis. It may also play a part in protecting the turf from disease. Deficiency symptoms include spotted or mottled leaves. Manganese is often deficient in sandy soils, and is most available at pH 6 and below, but high pH reduces its availability greatly.
If manganese is in short supply, it is worthwhile to apply a manganese supplement to help vigour and disease control.
We cannot talk about green grass without mentioning Nitrogen. Nitrogen is largely responsible for leaf growth, but also plays a role in all areas of turfgrass growth including Stolons (runners), Rhizomes and roots. It is the most talked about nutrient for lawns and is usually the highest percentage of your NPK ratio. Nitrogen usually comes in the following forms: Ammonium, Controlled release (synthetic), Nitrate and Urea. Nitrogen helps with the formation of proteins that the cells within the grass needs to grow. Without sufficient Nitrogen, your lawn can suffer stunted growth and yellowing.
In winter, your lawn will have slowed in growth and will not require a high amount of Nitrogen, so it is important to not apply too much during this time. Overapplying Nitrogen to a lawn in winter can lead to disease issues and burning of the leaf. Knowing your soil type and temperature (time of year) has a big impact on the form of Nitrogen you should choose to maximise results.
For most lawns, a good quality slow release fertiliser will contain all the nutrients your grass needs to maintain health, including iron to keep your lawn greener, and will last for up to 12 weeks.
An application in Autumn, and then again in Spring when the grass is growing strongly again will be sufficient.
Trace minerals can be applied more efficiently as foliars due to the impact of soil pH and excess soil nutrients that can lock these out and reduce their uptake.