Controlling weeds and pests with surface tillage and harrows

Every year, pests and weeds cost agricultural producers a staggering four billion dollars.

That’s $4,000,000,000 if you prefer it in numerical format, which is perhaps a better way to aptly portray the devastation that weeds and pests have on our farmers. Every single year.

Thankfully, there are things every farmer can do to reduce the impact that weeds and pests have on their farms and the economy in general. This includes surface tillage and the use of harrows.

The $4 billion problem

The $4 billion annual price tag wrought by weeds and pests is the figure estimated by the Australian Government’s Department of Agriculture, Fisheries and Forestry.

It includes loss of livestock, disease transmission and controls that are put in place to eradicate and reduce weeds and pests. This includes the utilising surface tillage and harrows, which we will look at soon.

It should be said that this estimation took place back in 2017, so the figure is likely to be higher today. In 2018 the Centre for Invasive Species Solutions put the figure at $5 billion annually for weeds alone.

Whichever figure or figures you prescribe to, rest assured that the cost is huge.

Surface tillage and harrows part of the solution

There’s a lot of work going on to reduce the impact on Australian agriculture from weeds and pests. While some of this work originates from government levels and other organisations, farmers have a big role to play as well.

One of the ways that farmers are using to eradicate and reduce weeds and pests is through surface tillage and the use of harrows.

In case you’re not a farmer or unaware of what surface tillage is, it involves cultivating the soil to a relatively shallow depth. For example, to between five and 12 centimetres. This is opposed to deep tillage, which can involve cultivating the soil to 70 centimetres and in some cases even more.

While you might get away with conducting surface tillage in your home vegetable garden with a hand-held hoe or even a stick, on a farm you’ll want something a bit more specialised.

This is where equipment like harrows, pulled by tractors or other farm machinery, come into play. Other surface tillage equipment includes discs and chains, tined cultivators and rotovators.

Before motorised solutions, horse-drawn tillage equipment was used. In fact, this method is still used today in some developing countries and for people (like the Amish) who don’t believe in using modern equipment and tools.

Controlling Weeds With Surface Tillage & Harrows

The control of weeds is one of the biggest benefits of surface tillage practices.

Surface tillage using harrows and other tools uproots and shreds large and small weeds that are growing in the soil. Cultivation kills weeds by digging them up, burying them, breaking them apart and drying them out.

Surface tillage is often considered better than deeper cultivation since fewer weed seeds are brought to the surface. In any case, generally weed control by surface tillage is repeated throughout the year to reduce weeds and prevent the germination of weed seeds.

One weed that is affecting many parts of Australia currently, and many farmers, is fleabane. Some populations of fleabane have developed resistance to common herbicides, such as glyphosate, and are difficult to control using herbicides alone.

This is why most experts are recommending a strategic approach to the management of fleabane, targeting all parts of the weed’s life cycle.

Promising results have been shown with surface tillage work. For example, the Queensland Department of Agriculture and Fisheries says: “Research has also shown that tillage operations alter the distribution of flaxleaf fleabane seeds in the soil profile and consequently reduce the number of
seedlings emerging. One harrow operation reduced
emergence compared to zero till by approximately
90%.”

Controlling Pests With Surface Tillage & Harrows

The control of pests is another of the benefits of surface tillage practices.

Like with weeds, surface tillage disrupts the life cycle of insects and other pests. For example:

• Surface tillage using harrows and other equipment can expose pests to predators (e.g. birds and other wildlife) and the elements.
• Using surface tillage to break down the residue from the previous crop can provide organic material for the soil and improve its overall health. It can also destroy the habitat of pests that love to live and breed in crop residue.
• Cultivation of farm soils to a depth of around 10 centimetres has been found to destroy exit holes of moth pupae.
• Surface tillage can restrict the movement of crawling insects that may otherwise make their way into paddocks by creating a barrier of cultivated soil.
• Cultivation lowers the risk of slugs and snails impacting farming soils.

Other benefits of surface tillage

While the management of weeds and pests are two of the benefits of surface tillage, there are many more:

• Surface tillage promotes soil conservation by reducing soil erosion. By disturbing only the top layer of soil, surface tillage provides a protective cover that minimises water runoff and prevents the loss of valuable topsoil.
• It contributes to improved soil structure by minimising soil compaction, enhancing water infiltration, improving root penetration and, in general, providing a favourable environment for plant growth.
• Surface tillage increases the organic matter content of the soil, thereby improving soil fertility, water-holding capacity, nutrient availability and microbial activity.
• The practice aids in efficient water management by retaining soil moisture and reducing evaporation.
• Surface tillage contributes to nutrient management. The gradual decomposition of crop residues, by cutting it up and returning it to soil, releases nutrients over time, reducing the risk of nutrient leaching and promoting nutrient recycling within the soil ecosystem.
• It is also a time and cost saver compared with other practices.

Overall, surface tillage provides a sustainable and environmentally friendly approach to agriculture, benefiting soil health, water management, weed and pest control, nutrient cycling, and overall farm productivity.