Have you experienced completing a tedious activity that turned out to pay off more than double your efforts? Your preparation was immense, and your execution was tiresome, and yet, the results showed it was all worth it. I'm sure you're a farmer who can relate. Even more so on the topic of topping pastures. In saying this, you might still have reservations with the question, is topping pasture worth it?

In this blog, we'll discuss the following:

1. What is topping pasture?

2. Benefits of topping pasture

3. Tips for topping pasture

Paddock cut for silage and a paddock a paddock recently grazed.

What is Topping Pasture?

Topping is the process of getting rid of the top of a pasture with a large formation of seed head by cutting it off. The main goal of topping is to induce growth and nutritional quality. By cutting off reproductive pasture, grass growth will be encouraged, and pasture quality will improve through the production of a vegetative sward.

The interesting thing with topping is that it should probably be called bottoming. Why? Because with topping, it is not only about removing the top. Instead, the mower used in topping is set low to be able to remove stalky growth, such as that of undesirable grasses and weeds. This practice is especially true when topping during spring and summer when the bottom of the pasture requires cleaning up.

The topping season usually transpires during mid-spring through mid-summer because this is the time when pasture growth is most abundant and reproductive. And when pasture growth rates are high due to the longer days, warmer temperatures, and high soil moisture. As for late summer, autumn, winter, and early spring, the pasture is primarily focused on growing leaves and is, therefore, in a vegetative state. This lifecycle means topping may not be a good idea for this time of year.

One standard method that you can use is topping paddocks post-grazing. This practice is to remove stemmy and stalky grass in the hopes of improving quality in the next grazing rotation. In saying so, topping pasture post grazing can be messy and result in lower pasture utilisation and animal performance compared to the of topping paddocks pre-grazing.

Recently topped pasture sitting scattered on the ground.

The Benefits of Topping Pasture

Topping hastens the regrowth of the pasture.

In farming, timing is gold. We're always looking for ways to enhance the regrowth of our pastures. Topping proves to be one of these ways. With the use of a topper or mower, growth rates of our grazing paddocks improve.

You may ask, what then if the grass growth increases?

Well, there are two benefits: the faster the growth of the grass, the quicker you can return your livestock to your paddock for proper nutrition and feeding. The second is, the quicker the growth of your pasture, the higher your potential stocking rate. Win-Win!

Topping reduces undesirable plants and weeds.

A topper mower can serve as a method of weed control. In the case of the Californian Thistle, one of the most undesirable weeds that can hamper your pasture growth, a topper mower can mulch and top this weed. This practice enables the grass to getaway. Meanwhile, the mulched thistles and the grass is consumed by your livestock.

Topping prevents your livestock from grazing the pasture too hard.

A topper mower can help prevent your livestock from grazing the pasture too much. A simple topping of the paddock will do this trick. Why would you want to achieve this? Several studies have shown that letting your livestock graze lower than 5cm will diminish your returns. However, it is you as a farmer who can determine the most fitting grazing approach for your farm.

Topping promotes an overall improvement of your pasture grazing.

Topping pasture has taught me one thing: it is THE way to improve your grazing paddocks quickly. Paddocks don't get fully grazed, no matter how many livestock you have. If you notice, there is always grass left behind by your herd, even though the grass seems healthily appetising. After every rotation, there is and will always be grass left, which we call clumps that congregate around dung. With a topper mower, you can clear out these clumps by cutting them and allowing for new grass to grow. Importantly, maintaining a vegetative sward of pasture, as your livestock graze into summer.

Pre-grazing topping can increase milk production.

Who knew a topper mower could be a crucial investment to produce more milk from your livestock? But don't be surprised because several studies have proved this. The regrowth of fresh, nutrient-laden grass for your livestock's consumption positively affects their milk production. It may not be the same for all farms, but this might make purchasing a mower worth considering.

Furthermore, topping at the point of pre-grazing can encourage your herd to consume higher volumes of unselected pasture. This method increases fibre, energy and protein intakes from the grass, which culminates in healthy and happy cows that produce more milk.

Dairy cows grazing pasture between the clumps that need topping.

Tips for Topping Pasture

Since topping is a machine-dependent process, the first step is to find the right kind of equipment for you to use. Many farmers will use their hay/silage mowers. This option is prevalent because topped pastures are meant to be consumed by livestock usually after it is wilted to make it more appealing to your cattle. As explained above, this method will increase animal performance and pasture utilisation.

Using a mower, you can take the progressive step of topping the paddock before any livestock goes in. Again, this will increase the consumption of pasture by your animals. Therefore, it also increases the utilisation of your pastures. Another thought-provoking practice is to mow only half of your paddock. This method can increase consumption because the herd can choose. The animals can either consume cut and wilted grass or be selective with the fresh standing grass. Either way, having options will also encourage consumption. In succeeding grazings, reverse the process topping the other half, with the earlier topped half already cleaned up.

Another topping technique that you can employ is light grazing your pasture. Then cut and dry this as a light crop of hay or silage from the heavy toppings. By the sheer combination of pasture control and forage conservation, you can take advantage of the crop's tendency to quickly dry. In case of rain or heavy moisture, you may also write the harvest off without much loss. Labour and operational costs such as fuel used, should be taken into consideration of the cost-benefit of this practice.

Aside from the classic field mower, you may choose to use a rotary slasher-type.

The slasher is your go-to when all that is left over is unpalatable grass. This type of machine will slash the pasture until it is like mulch, which will hasten its breakdown and integration into the soil organic matter. By doing this, you can avoid dealing with large proportions of cut grass that will hamper the regrowth of your paddock. Most of all, doing this will help spread the parts of the pasture with compost, which will, over time, help fertilise the soil. This process may, however, make cleaning the tractor afterwards another hassle to consider topping pre-grazing.

Rotary slashers prove to be more effective in situations where pulverising and scattering compost is required. Meanwhile, hay mowers are designed almost as if to ensure gentleness in cutting the grass cleanly.

As for cutting height, it is crucial to set the blades low, no matter what type of equipment you are using.

The top of your boot toe is approximately 1500 KgDM/ha — not a bad rule of thumb.

A rotary slasher is less complicated. If it goes over humps, you are reassured that the humps will be decapitated. This scalping effect does not have a positive impact on regrowth. This scalping leaves ground that is bare that does not readily recover and is very vulnerable to invasion and growth of weeds. You may think setting the blade higher will fix this problem, but doing so puts the whole topping process in vain.

If you want to carry out effective topping of pasture, another important tip is to make sure that you have sharp blades. In topping, you need to be able to make a clean-cut, and having sharp blades will do just this. If you use dull blades, you are creating a possibility of a bludgeoned pasture, where the grasses are tugged out of the soil instead of cut properly. This action weakens the root system of the grass, which it may find hard to recover, thus reducing the potential future growth.

Furthermore, using a high rev blade is very important. It's just as important as having sharp edges. Compared to grasses that have been bludgeoned instead of cut, a clean surgical cut ensures a quicker regrowth.

The best approach in topping is to focus on the benefits it brings to your operation. Some farmers choose to use their animals to eat hard into their pastures every round. I'll let you ponder on what this does to pasture utilisation and animal performance. By topping, you are already doing an excellent job of ensuring the quick and healthy regrowth of your pasture and promoting better animal performance — all with little effort other than organising the logistics around grazing intervals.

I do reply to every comment and would love to hear your experiences with ryegrass in the comments below.

Happy farming!

- Ollie Roberts, 4 September 2019