In terms of the benefits of spreading slurry on crops, it has been noted by specialists that 1,000 gallons of pig slurry could be worth up to €50.
Tillage specialist Michael McCarthy joined Mallow cereal grower Tom Barry on the most recent edition of the Tillage Edge podcast to discuss this subject.
According to McCarthy, pig slurry is a very valuable source of nitrogen (N), phosphate (P) and potash (K).
“This is especially so, given the current state of the fertiliser market. The latest estimates from Teagasc would indicate that each 1,000 gallons of pig slurry is worth up to €50 in this regard.
“The slurry that Tom Barry is using on his crops at the present time has a dry matter of around 3%. This means that for every 1,000 gallons spread, he is getting 14 units of N; five units of P and 15 units of K.
“These are readily available nutrients to the crop.”
Slurry spreading
McCarthy also pointed out that slurry should be spread on ground when there is crop there to use it.
“There is no point putting slurry out on to a stubble in the autumn,” he stressed.
“It is a very valuable source of manure. So why would you put it on stubble when there is nothing there to take it up?
“Adding slurry in the autumn represents a huge loss of N to the system. This is not good for the environment and it creates a significant loss in the pocket for the farmer.
“It is a far better approach to put slurry out on to a crop that is ready to take it and is ready to go,” he added.
In Tom Barry’s case, slurry is spread on to cereals as close to Growth Stage (GS) 30 as possible.
“This makes perfect sense,” said the Teagasc tillage specialist.
“This means that the organic nitrogen is being put out when the crops needs it most.”
Fertiliser
McCarthy explained that fertiliser recovery values of up to 100% can be obtained, in terms of available N, P and K, if slurry is put out in good, warm temperatures.
Tom Barry urged caution on the part of tillage farmers seeking to use slurry as a means of providing all the P and K their crops will need.
“This is especially so in cases where organic manures have not been traditionally used for crop production purposes,” he explained.
“Most tillage soils are between Index 1 and Index 2 for both P and K.
“One also has to take account of the significant quantities of P and K removed from soils, courtesy of the harvested grain and straw.
“Straw chopping will help return a proportion of the K taken up by the crop,” he added.
“But as a general rule, I would not advise tillage farmers to cut back significantly on the amounts of chemical P and K they apply, particularly if they are using slurry on crops for the first time.