top of page

Protein & Nitrogen

in Pasture Grass

Grass sprouting after rain

Grass sprouting after drought breaking rain

fertilised grass

Certain fertilisers will make the clover power ahead.
The grass above was fertilised with Nutrigro. Compare that to the grass below, from the same farm which received no fertiliser and has a range of great grasses...

unfertilsed grasses
After spraying out the clover

In the two photographs above, the clover was sprayed out in spring with a broad leaf spray. As you see in the photo taken a couple of months later, the grasses have powered ahead unhindered by clover.

Once this grass seeds and hardens off, it will be perfect for the horses to graze.

Are Broadleaf Sprays Damaging to the Environment?

The use of broadleaf sprays is understandably an emotive subject.

To be clear broadleaf sprays are very different to RoundUp.

Of course, we would all prefer not to use sprays at all but proper research can put these concerns into perspective.

This following informations addresses the valid concerns of some people around the use of broadleaf sprays to eliminate plants like clover, plantain, cat’s ear which, when they become predominant in the pasture can severely impact the health and welfare of our horses.

The truth of the matter is, we see very healthy environments here where we have used broad leafs sprays every year for 12 years; an environment that is full of insects, birds along with thriving horses who are free from the troubles that used to be caused by the clover.

Timothy Dee; is a soil scientist in the environmental arena who chairs the contaminated land management sector group steering committee of Wasteminz.

Here is what Tim had to say…

“Firstly, this is a quick review of the available data and does not constitute a proper scientific review…

All pesticides, which includes herbicides have the potential to be evil, that's what makes them effective.

Copper and sulfur are ancient sprays (literally prehistoric); both used in excess will persist forever in the soil and change the ecology forever, yet they are both classed as 'organic' (this is a big part of why I find organic labelling so disingenuous).

DDT breaks down over a hundred years or so. So context can matter.

The active ingredient in Granstar appears to be tribenuron-methyl (TBM). This is a crystalline solid and is an organic chemical, meaning it's a carbon centric molecule.

There is a lot of available environmental information reflecting the effort of the supplier to demonstrate to regulators globally what the genuine risks are.

All of the bond types occur fairly commonly in nature and there are no *halogens in it.

TBM works by inhibiting the synthesis of amino acids – specifically valine and isoleucine, thereby preventing cell division and cell growth and studies have shown the ‘toxicity’ to be comparable in land animals, to table salt.

The product will move quickly in a wet environment and has an expected half-life of between 1 to 3 weeks (not years or decades).

Out in the real world that could translate to days or months but not years or decades.

Occasional use in dry conditions, away from water, with responsible controls, should not pose any significant environmental risk based on this information”.

Timothy Dee CChem. MSc(hons). BSc. MRSC.

To those who say that they have seen effects from broadleaf spray on their horses, we suggest that these effects are not from the spray itself but from the mineral imbalances inherent in green vegetative grass – as in the horse being ‘Grass Affected’. There is absolutely nothing in this spray that would cause anything to worry about unless, maybe, your horse drank it.

During 5 minutes of sitting in a patch of grass in one of Cathy’s paddocks she spotted the following …

An abundance of small Crickets

A Harvestmen spider hunting a fly

Grass Moths

A Red Admiral butterfly!

Dragon flies


Plus there are a variety of finches living there – Goldfinch, Chaffinch, Greenfinch, Red poll, Sparrows, all thriving on the seed heads produced by the mature grass, along with Thrush, Blackbirds, Starlings, Dunnocks, Waxeyes, Fantails, Grey Warblers, Magpies, and a family of Little German Owls.

The key to creating a great environment both for your horses and for other creatures who share this living space, is not to overgraze, but rather allow the grass to mature before grazing.

On a small (10 acre) block, this is best done by creating a dry area for the horses to live on, on hay, over Spring and Autumn and any other time the grass is not suitable for grazing.

What IS detrimental to the land environment is over grazing, constant harrowing and over fertilising.

What IS detrimental to your horse’s health is allowing them to graze on clover or any grass at a young stage of growth.

So yes, you can safely spray with a broadleaf spray in early spring every year if you have to. Your horses will thank you for it and the environment will not suffer.

*Halogens: Any of the elements fluorine, chlorine, bromine, iodine, and astatine, occupying group VIIA (17) of the periodic table. They are reactive non-metallic elements that form strongly acidic compounds with hydrogen from which simple salts can be made.

PHOTOS (right) : Some of the thriving birdlife on Cathy's Property

At certain times of the year (Spring & Autumn) and under certain climatic conditions (consecutive cloudy days, frosts or after a drought-breaking rain) Crude Protein levels in pasture can increase to levels which cause problems for horses.

Ingestion of excess nitrogen is a contributor to “Grass-Affected” syndrome along with other aspects we are aware of including potassium and sugar levels.

• All Forage and Feed Analyses will include a CP (Crude Protein) reading. Crude Protein in plants is comprised of both ‘true protein’ and ‘spare nitrogen’ or Non-Protein Nitrogen (known as NPN).

• ‘True protein’ is made up of long chains of amino acids all strung together. Nitrogen is required for protein synthesis. Grasses and legumes and certain other broadleaf plants will take up more nitrogen than they need when it is readily available to them.

• In Autumn and Spring, and under conditions mentioned above, CP levels can exceed 20 and even 30%, we have analyzed pasture where horses ran into trouble (laminitis and repeated bouts of colic) with CP levels of 36%!

• When horses consume more than their requirement of nitrogen or protein they will drink more water and urinate more. The urine will be ‘strong’ with a smell of ammonia which can be a problem if the horse is kept in a confined space. Or it may ‘burn’ the grass and leave brown patches in the pasture.

• Nitrogen in the form of Nitrates from plants can have the effect of ‘robbing’ the horse of precious calcium and magnesium, especially when there is a lack of sodium, (just one of the reasons to add salt to your horse’s feed).

• The CP concentration of legumes (Clover & Lucerne) is averagely much higher than grasses. There are other plants which are known ‘Nitrate Accumulators’ - to the point farmers are using them to reduce nitrogen leaching, more coming up on this subject.

• Cattle can utilise the excess NPN in the rumen and build it into true protein but horses cannot.
When CP readings are very high (as after drought-breaking rains or in spring and Autumn) nitrogen can significantly contribute to metabolic problems and be toxic to them. This is one of the reasons that it is difficult for horses to successfully share grazing that is meant for cattle. Their digestive systems are completely different.

• Horses, by choice, avoid consuming grass growing on high nitrogen areas (like where they drop their manure).

• Frequent harrowing of manure has the effect of spreading the nitrogen more evenly and turning it from ‘slow release’ into ‘rapid release’ nitrogen for uptake by the grass. Not saying you should never harrow but a lot of people do it often to keep things looking tidy. Think about whether it is appropriate in your particular grazing situation.

• Urea is another form of NPN. It is not a good idea to fertilise your horse pastures with it (or anything like it: chicken manure, poulfert or NPK).

• Generally speaking the younger and greener the grass the higher in nitrogen it is likely to be. Grass that sprouts after a drought-breaking rain is very potent in both potassium and nitrogen. More mature grass which has slowed down or finished growing tends to look yellower and is proportionately lower in nitrogen.

Zephyr and Merlot on perfect summer grass

Merlot and Zephyr out on their perfectly mature summer grass. This grass has zero concerns for grazing.

bottom of page