The closed period for spreading chemical fertiliser is from 15 September to January or February, depending on location.

Slurry and farmyard manure can be applied into October and November.

Farmers often complain about farming by calendar, but there is evidence that the highest risk period for nitrate contamination of groundwater and rivers is in early winter, when heavy rains flush nitrogen from the land to watercourses.

Thus, reducing the amount of nitrogen in the soil is a way of controlling the amount of nitrogen that ends up in waterways.

Leaching

The ban on spreading after 14 September is not because there’s a higher chance of it raining then, the ban is in place because there’s a greater chance of the nitrogen spread after that date of getting leached at some point in the future.

At this stage, farmers should be looking at getting nitrogen blanket-spread, rather than following the cows with it.

I say this because rotation lengths are going to increase and some paddocks may not be grazed for a while, meaning they will miss out on nitrogen.

Response

Response to nitrogen is still good and with good growing conditions expected this week, it’s a good opportunity to get fertiliser out.

However, caution should be taken and fertiliser shouldn’t be spread before very heavy rain.

As for rates, I would be inclined to spread 30 units/acre now and another 30 to 40 units/acre of nitrogen before the closed period.

How much to spread all depends on the average farm cover and how much grass you need to grow this autumn, which is dependent on the stocking rate.

Don’t forget phosphorus and potassium.

Potash can be spread any day of the year, but is better spread on grasslands in autumn.

Target low-index fields (index one and two) with 50 units/acre of muriate of potash.

Phosphorus should be drip-fed throughout the growing season.

Farmers with low P and K soils are spreading compounds such as 18:6:12 across the year.

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