Recovering from drought

MEDIA RELEASE

19 February 2009

Recovering from drought

Drought is affecting some parts of the country for the second year in a row now, and while drought can’t be prevented, there are several steps that can be taken once the drought breaks to help get the grass growing again.

Recovering from a drought requires effective and strategic use of fertiliser, especially if the drought has been prolonged and has affected farm incomes.

As soon as it rains, there is a temptation to apply nitrogen (N) fertiliser to lift pasture growth. This is not necessarily the best approach.

‘From a fertiliser perspective, the key decision facing many will be whether to put on nitrogen to promote quick growth, or phosphate, potassium and sulphur (PKS) to maintain soil fertility. The choice will partly depend on cash reserves and partly on the overall fertility status of the farm.

‘Soil tests will show the fertility status of your farm. Note that during a drought, sulphur and potassium soil test results tend to be elevated, because there is little nutrient uptake by the plants and no loss through leaching. Soil tests taken well after the drought has broken will give a more accurate picture of true soil fertility,’ says Mr Catto.

If soil test results show that fertility is below desirable levels, then for the long-term benefit of the farm it will be helpful to apply a PKS fertiliser to raise the levels of any deficient nutrients.

If soil test results show sufficient nutrient levels to meet production goals, then it will be reasonably safe to defer PKS application until next year, and concentrate instead on using nitrogen to boost growth.

After a severe drought it is preferable that nitrogen applications are delayed for two weeks after it has rained as the soil has good reserves of mineralised nitrogen and pastures take time to recover.

‘Immediately following a drought there is a strong desire to boost pasture growth to feed stock. However, it’s important to remember that nitrogen (N) enhances growth; it doesn’t start it. For nitrogen to be of any use there must be some plant growth occurring when it is applied,’ explains Mr Catto.

‘Don’t apply N fertiliser until paddocks have some pasture cover (1000 kg DM/ha). Once you have applied N, spell the paddock for four to six weeks. This will give the N time to have an effect and will also help to minimise the risk of nitrate poisoning.’

ENDS

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