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Saturday 10 December 2016

Know your new Nitrates rules

Published 15/02/2011 | 05:00

The revised Nitrates Action Plan includes several changes that will affect tillage growers and their fertiliser choices this year.

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Speaking at the National Tillage Conference recently, Teagasc Oak Park's Dr Richie Hackett outlined the main changes, which include higher phosphorus (P) rates for cereals, higher nitrogen (N) rates for winter barley and spring barley, additional nitrogen for malting barley and changes to the rules on successive organic manure applications.

Until now, where organic manure was applied to an arable field for two years in a row, the field was deemed to move from index 1 to index 2 in the third season. This meant that less nitrogen could be applied in year three, a nitrogen penalty that most growers considered too severe. Their reaction was to restrict their use of organic manures to every second year.

Under the revised Nitrates Action Plan, organic manures can now be applied to the same field for two or more years in succession without having any effect on the soil N index.

While farmers will still have to reduce the amount of fertiliser N applied to crops to take account of the N in the organic manure, spreading manure in one season will not affect the chemical N allowances in the next season.

Simply put, tillage growers can now spread organic manure on a field every year, without moving up into the higher soil index.

Under the old Nitrates rules, the limits for P applications were 45kg/ha at soil index 1, 35kg/ha at soil index 2, 25kg/ha at soil index 3 and 0kg/ha at soil index 4. These rates were the same for all cereal crops, regardless of yield expectations.

However, research has shown that because most P is contained in the grain, higher-yielding crops can accumulate and remove more P than the farmer is allowed to apply. Over time, this would result in a reduction in soil P reserves.

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Excess

Under the revised Nitrates Action Plan, the base P inputs for cereals remain at 45, 35, 25 and 0kg/ha on soil indices 1, 2, 3 and 4 respectively.

However, where a farmer achieves yields in excess of 6.5t/ha of wheat, barley or oats (winter or spring), the farmer can apply an extra 3.8kg P/ha for each additional tonne per hectare above 6.5t/ha. This new rule only applies to soil P indices 1, 2 and 3 and does not apply to index 4.

For example, a farmer who grows 10t/ha of a cereal crop at soil P index 3 can apply the basic rate of 25kg/t, plus as additional 13.3kg/ha.

"Whether or not a grower decides to use this extra allowance will be largely determined by fertiliser prices, grain prices and previous experience of the field in question," said Dr Hackett.

Low proteins in spring malting barley have been reported over the past few seasons, leading to rejection of barley for malting purposes. While the reasons for these low proteins were unclear, it could relate to insufficient fertiliser N inputs, claimed Dr Hackett.

Low

Growers also believe that N inputs allowed under the old Nitrates Action Programme were too low to produce high yields of spring barley, both feed and malting, he added.

Under the old Nitrates Action Programme, the allowed available N for spring barley was 135, 100, 75 and 40kg/ha for soil N indices 1, 2, 3 and 4. Where a yield higher than 7.5t/ha could be proven, an extra 20kg N/ha could be applied for each additional tonne of yield.

However, the national average yield has been less than 7.5t/ha so many growers could not avail of the additional fertiliser N.

Under the new rules, the base yield has been reduced from 7.5t/ha to 6.5t/ha, so now growers who achieved average yields above 6.5t/ha in any of the last three seasons can apply an extra 20kg N/ha for each additional tonne per hectare above 6.5t/ha.

Malting barley growers have been given a further concession in that where malting barley is grown on contract, they can apply a further 20kg N/ha, if their tillage adviser can prove that extra nitrogen is needed to address low protein content in the grain.

However, Dr Hackett warned tillage growers that lodging was a danger in crops that received too much nitrogen.

"Just because you're allowed to do something does not mean you should do it," he cautioned.

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