Before tillage farmers start applying organic manures to stubble ground or crops, two questions must be addressed. <\/p>\n\n\n\n
Firstly, is there sufficient allowance, specifically where phosphate (P) is concerned, to apply the organic manure?<\/p>\n\n\n\n
Secondly, how to get the most from the organic manure that is to be applied?<\/p>\n\n\n\n
These raw materials include: slurries<\/a>; farmyard manure; poultry litter; spent mushroom compost; and sludge.<\/p>\n\n\n\n Head of the Crops Knowledge Transfer Department at Teagasc, Michael Hennessy, said:<\/p>\n\n\n\n \u201cThe days of applying an organic manure and largely ignoring the nutrient content have come to an end, with the introduction of the Department of Agricultural National Fertiliser Database. <\/p>\n\n\n\n \u201cThis is because the Department of Agriculture, Food and the Marine (DAFM) will have a clear view of all chemical fert<\/a>i<\/a>lisers <\/a>purchased by every farmer each year.\u201d<\/p>\n<\/blockquote>\n\n\n\n According to Hennessy, every tonne or 1,000gal of organic manure applied to a farm means the allowance for chemical fertilisers must be reduced.<\/p>\n\n\n\n \u201cP will generally be the limiting nutrient for most tillage farms,” he said. <\/p>\n\n\n\n The following example is relevant. It centres on a 40ha (100ac) block on a farm, with up to date soil samples, all showing a P index of three, and the area is planted to spring barley. <\/p>\n\n\n\n This farm will have a standard allowance of 25kg P\/ha or 1,000kg P for the block. <\/p>\n\n\n\n Where the farmer chooses to use 13:6:20 compound (which contains 60kg of P in every 1,000kg of product), the total tonnes which can be bought is 16.6t (416kg\/ha or 3.36 x 50kg bags\/ac) based on P as the limiting element.<\/p>\n\n\n\n If the farmer imported 22m3<\/sup>\/ha (2,000 gal\/ac) of cattle slurry to half (20ha) the block (a total of 440m\u00b3 of slurry), this would apply a total of 220kg of P (1m3<\/sup>\u00a0of cattle slurry contains 0.5kg P).\u00a0<\/p>\n\n\n\n The farmer would also incorporate the slurry within two hours of application to stubbles to ensure that nitrogen (N) losses are minimised.<\/p>\n\n\n\n Before the farmer can buy chemical fertiliser, the P in slurry (220kg P) must be deducted from the total allowance (1,000kg P), leaving 780kg P remaining to be applied to the block.<\/p>\n\n\n\n If the farmer was to stick to purchasing 13:6:20, now the farmer can only purchase 13t. <\/p>\n\n\n\n However, as 1m3 <\/sup>of slurry also contains 3.5kg of K (potash), therefore the slurry will apply almost all of the crop’s K requirements. <\/p>\n\n\n\n The farmer can now switch to applying straight P (4.8t of super phosphate) and balance the N with straight calcium ammonium nitrate (CAN) or urea. <\/p>\n\n\nOrganic manures <\/h2>\n\n\n\n
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Case example<\/h2>\n\n\n\n