Five ways drought helps weeds grow
SPONSORED CONTENT: Drought conditions means some plants don’t grow – and others do. Here are five things to look out for as autumn approaches.
Recent droughts have stressed almost the entire Australian agriculture industry, and farmers across the nation are still dealing with its knock-on effects.
While soil stress might not be the most noticeable of these effects, it is one farmers will do well to address as quickly and conscientiously as they do the other parts of their operations.
This is because stressed soils are more susceptible to environmental damage and weed overgrowth.
Neglecting soils can lead to losses in five pivotal areas of crop production during drought: space, nitrogen, moisture, compaction and money.
As we know, droughts can devastate existing vegetation – removing all competition for light, nutrients, moisture, and space.
But it can also offer a golden opportunity for weeds to take over once the rains come, taking advantage of any mineralised nitrogen already in the soil.
Droughts create dry soil conditions that prolong the viability of weed seeds – by being too dry for the fungi and bacteria that would normally break seeds down to function.
In dry soil, weed seeds do not break down, and remain completely viable, as if they have been kept in a paper bag in the cupboard.
According to the NSW Department of Primary Industries, up to 12 per cent of weed seeds can pass through the guts of animals and remain viable.
After a drought, weeds that are already on a property may spread to new areas, and weed densities can increase. As well as this, new weeds may have been introduced, by drought feed, contaminated visiting machinery or livestock either returning from agistment or bought in a restocking program.
After a drought, the nitrogen content of soil can vary wildly, even within the paddock. Because of the variable moisture from the drought year, the uptake ability of crops can leave pockets of richer soil.
At the same time, lack of downward water movement means any previously-applied additives can accumulate residually in the soil at higher levels than normal.
Conversely, areas with high weed growth during the drought can create nitrogen deficiencies along with high levels of weed seed banking within the soil.
Managing these variances can be tricky. A good rule of thumb when replanting or planning additives for soils following a drought is to thoroughly soil test throughout the paddock, as pockets of residual chemicals can exist. These pockets develop as a residual of the previous years’ crop and weed growth.
A larger sampling of soils can help identify the areas with higher nitrogen concentrations or weed-depleted deficiencies. Minimising application in high concentration areas can help alleviate over-application, run off, and other issues, while heavier application in depleted areas can help rebalance the overall growing ability of the paddock.
Water is Australia’s most precious resource – don’t waste it on weeds!
Root zone soil moisture is deficient across the majority of Australia, and while trees and other deep-rooted vegetation can access subsurface moisture down to about 6 metres, crops don’t have that luxury.
As a result, without accessible moisture reserves, crops are one ill-timed rainfall away from desiccation, so doing everything possible to protect and maintain moisture at shallower levels is imperative.
A lack of moisture also impacts the action of some types of herbicides, as some plants build up wax layers in dry conditions, making them less susceptible to the weed killer.
In this case, forgoing herbicide application or supplementing it with mechanical forms of weed control, like tillage, is an option.
This helps manage weed seedbanks and keeps them from competing with crops for already scarce moisture resources.
It may not be caused directly by drought conditions, but a lack of moisture can contribute to and exacerbate soil compaction – reducing the size of pore space available for air and water.
This means not only that water is less able to infiltrate the soil – it increases the potential for water to pond on the surface and to runoff – taking valuable nutrients with it.
It can also reduce crop emergence as a result of soil crusting, impede root growth and decreases the ability of crops to take up nutrients and water efficiently from soil – a situation that can lead to stunted, drought-stressed plants even when the weather is good.
When soils are dry, some form of tillage can help to physically break up compacted soils – but care should be taken to ensure that the soils are not too moist, to avoid exacerbating the problem.
Varying the depth and direction of tillage every time it takes place can also help to avoid compaction.
Adequate management of these steps makes a big difference in how much the fifth step – money – impacts your operation.
Farmers are always looking for ways to cut operational costs, and especially during times of drought.
Understanding the interplay between nitrogen, soil moisture, mechanical interventions, and cash outlay can help producers redeploy their financial resources, rather than looking for ways to cut them completely.
With the steps listed above, producers can minimise the need to purchase chemical additives, instead relying on tillage equipment to manage weeds until your soil moisture levels return to a more normal state.
K-Line Ag has a full range of tillage equipment with options available to suit your operation and applications. With deep Australian roots in farming, technology and manufacturing, Cowra-based K-Line Ag has made a name for itself as a trusted manufacturer of innovative and reliable tillage machinery.
A family-owned company, K-Line Ag designs and builds farm equipment to exacting standards, utilising a research and development team familiar with the demanding working conditions of Australian terrain.
Contact the friendly team at K-Line Ag on 1800 194 131 to discuss your tillage solutions or locate your closest dealer.
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