Pig slurry can save you money and improve your crops

by 5m Editor
9 February 2006, at 12:00am

UK - A simple system has allowed Driffield based JSR Farms to consistently make major financial savings and still grow high yielding crops. As Phillip Huxtable, director of the company explains, “savings are there for the taking, farmers really should not ignore the nutrient value of pig slurry.“

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A new ADAS run initiative, Environment Sensitive Farming, was launched this spring to get messages like this across. “For too long the spreading of slurries and manures has been seen as a waste disposal operation. In fact they are a useful resource,“ suggests ADAS manure expert Dr Ken Smith. “With nitrogen fertilisers costing up to 160 pounds a tonne the targeted use of pig slurry in cereal crops can bring savings of up to 100 pounds/ha.“

Statistics from the annual, British Survey of Fertiliser Practice show that farmers generally fail to allow adequately for the nutrient value of manures. Taking winter wheat in 2002 for example, the average rate of nitrogen applied after manure was used was 187kg/ha, whilst those fields with no manure applied received 193kg/ha – a difference of only a few kg/ha. The pattern is similar for phosphate and potash.

Such over-application has the potential to add to agriculture’s diffuse pollution problem and with cross compliance conditions now including nutrient management they could also put the single payment at risk. In addition, early lodging in cereal crops, which can be the result of excessive nitrogen supply from fertilisers or, more often manures, can cut yields by 75%. Lodging means slower harvesting and increased drying costs too. “So by ignoring the nutrient value of manures not only are farmers missing out on savings they could also be paying for the privilege“, he warns.

So what’s stopping farmers from changing their practices? A number of reasons contribute to this, Dr Smith explains, “In particular, not knowing the nutrient losses following application. Even more basic is the uncertainty about how much has been applied to a field. Research has provided answers to these uncertainties, but still we find it difficult to convince farmers of the benefits. That’s why it is good to come to Yorkshire and find a farm business, such as JSR Farms, that puts a positive emphasis on manures and slurries“.

At JSR Farms, straw-based Farm Yard manure (FYM) is stored until autumn and then ploughed into stubbles, usually before a second wheat. Load cells on the contractor’s spreading equipment record the weight and records are kept of the number of loads spread, and when. Fibre removed from the slurry is mixed with the FYM, which helps the composting effect during the storage period. Slurry separation is also an effective way of removing ‘coarse solids’ which could cause problems with pumping of the slurry through the irrigation mains and umbilical supply to the field application equipment. Slurry is stored in lagoons or aboveground tanks until early spring.

“The aim is to apply as much slurry as possible to winter wheat or spring barley crops GS 24-31 (tillering to early stem extension) during the period February to late April,“ advises Phillip Huxtable. “Application rate is carefully controlled, according to slurry nitrogen content and regular samples are checked by a ‘Quantofix’ slurry N meter. An in-line flow meter records the rates delivered to the low trajectory boom-mounted, splashplate or trailing hose applicator. The MANNER manure N software gives us as an accurate assessment of the N supply from the application, taking account of the slurry analysis, date of application and soil type.“

Pig slurry can be quite variable in its nutrient content and Phillip Huxtable stresses the importance of regular analysis. Ken Smith confirms that this is very much the ADAS experience too, with recent research showing that slurry analysis can change substantially, and quite suddenly, in successive tanker loads, as the sludge layer towards the lower part of the store is reached during emptying.

Used in this way, it is quite common to anticipate a slurry nitrogen contribution of up to 90kg/ha N, which represents about half of the crop requirements and at recent fertiliser prices (c. 3160/tonne for 34.5%N), a saving of 340/ha for N alone. Depending on soil analysis, there will also be further savings for the slurry P, K and S Contribution. “At this rate, over 160 ha of cereals, we are likely to save up to 14.5 tonnes of N equivalent (42 tonnes of 34.5% N product) – about 36,500 p.a. on N fertiliser alone.“ Confirms Phillip Huxtable. “The MANNER software takes all the guesswork out of the calculations and we can have confidence in the nutrient value of the slurry we apply. So, reducing the risk of diffuse pollution in this way is a matter of common sense to us and it is also quite profitable,“ he concludes.

Source: Farming in Yorkshire Magazine and JSR Genetics - 18th January 2006

5m Editor