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Why Do Farmers Burn Stubble?

Why burn stubbles?.

From now until the end of May most crop stubbles in the district will be burned.

This is a spectacular operation, with lots of smoke by day and high flames lighting the sky at night.

It may look scary to the public but it is a very controlled operation requiring much preparation by the farmer.

There are strict guidelines for weather conditions, time of day, number of people and tankers, width of firebreak, and notifications.

The smoke looks bad for the environment, however it is worth the trouble and is not as bad as it looks. The crop used a lot of carbon from CO2 in the atmosphere to grow. It is not all lost when the stubble burns. One third goes to the roots or remains unburned on the moist soil, later to form humus in the soil. One third goes into the grain which is sold and eaten.

Of the one third that is burned half stays as ash on the soil and half goes as smoke and carbon dioxide, with much of the smoke particles being washed back to earth with the next rain.

So maybe only 10% of the carbon used to grow the crop goes as smoke. This and more is recaptured in the following year's crop.

The crops must be burned for several reasons. One is to kill the weed seeds for the following crop.

Fire also kills slugs and other pests. This reduces the need for chemical control.

Many chemicals need contact with the soil to be effective. If stubble is in the way then that chemical is ineffective.

When unburned wet stubble rots it produces CO2, methane and other chemicals which act as a poison for the following crop. The rotting process also ties up nutrients better used by the crop. Rotting stubble is also a wonderful home for slugs which eat the young crop.

Most suitable seeding machines cannot pass through heavy stubble without blocking up. This is not such a problem in the Wimmera where crops are lighter.

Stubbles can be grazed a little but it is not nutritious for long and sheep lose weight.

There is a market for some types of straw but it is limited and seldom profitable.

So there are no easy alternatives to burning stubbles!