Benefits of METS Slurry Equipment

Slurry from housed livestock in N. Ireland contains valuable sources of plant nutrients in the form of Nitrogen, Potash and Phosphate. At current fertilizer prices, the total nutrient value of 4.5 m³ (1000 gallons) is worth approximately £30.

The method and timing of slurry application are two main factors that determine the utilization efficiency of these nutrients by the growing crop, whether grass or arable. Spreading slurry during the growing season, using systems such as the Trailing Shoe, Shallow Injection or Trailing Hose can improve the utilization of slurry nitrogen compared to the traditional splash-plate. This is particularly important given the high cost of inorganic fertilizer and on heavily stocked farms where fertilizer application levels are limited under the Nitrates Directive regulations.

Recent research at AFBI, Hillsborough has demonstrated that spreading slurry using a Trailing Shoe slurry tanker increases the utilization of slurry nitrogen by up to 26 percent compared to conventional splash plate application systems. The resultant saving in nitrogen fertilizer costs is worth up to £25 per hectare (£10/acrea) for each crop of grass silage, depending on the slurry application rate.

In addition to the fertilizer nitrogen savings, other benefits of the technology include:

Recent research work at AFBI Hillsborough has demonstrated a 29 percent reduction in phosphorus runoff from slurry applied by Trailing Shoe compared to the splash-plate. In addition, waiting 10 to 20 days after silage harvesting before applying slurry can reduce phosphorus runoff by 50 percent. Such delays are only possible with the wider application window presented by Trailing Shoe or Shallow Injection technologies.

Research trials at AFBI, Hillsborough indicate yield benefits from trailing shoe slurry application up to three weeks after the silage harvest, without any detrimental impacts on the quality of silage made from subsequently ensiled grass re-growths. This wider window of opportunity also applies prior to first cut silage in March or early April, when farmers would traditionally have been reluctant to apply late slurry applications to silage swards.

Most trial work has been carried out at relatively high application rates, typically 50 m³/ha (4500 gal/acre). With conventional splash plate application, most dairy farmers would restrict application rates to less than 50 percent of these levels between silage cuts. The trailing shoe application system therefore presents heavily stocked farms with the opportunity to apply greater quantities of slurry during the growing season resulting in improved nutrient utilization and savings in fertilizer costs.

Large quantities of potash (K) are removed from the soil by heavy crops of grass harvested for silage. Many silage fields are deficient in potash as a result. Dairy cow slurry has more potash than nitrogen. The typical N : P : K analysis is 3.0 : 1.2 : 3.5 per m³ of slurry. Cattle return manure to the field while grazing. Most grazed swards thus have no additional requirement for potash. It is therefore good financial and nutrient management practice to apply the majority of slurry to fields destined for silage harvesting to replace the potash removed by the crop and to only spread any surplus slurry on grazing swards.

Trailing shoe slurry spreading equipment deposits slurry on the soil surface in narrow bands of approximately 50mm in width. By comparison, with conventional splash plate spreading the slurry is spread across the complete sward surface. Trailing shoe spreading reduces the exposure of slurry to the air, reducing ammonia volatilization and resulting in the improved slurry nitrogen utilization. This reduction in ammonia volatilization also means a reduction in the level of smell associated with slurry spreading. Combined with the slurry deposition on the soil surface, the reduced visibility and smell from slurry spreading operations can help improve relations between farmers and other rural dwellers!

The alternative slurry spreading equipment grant aided by METS has a range of management and financial benefits. The METS funding makes this equipment more affordable for both individual farmers and groups of cooperating farmers. If you would like to learn more about the METS funding, CAFRE has organized a series of Information Workshops for applicants across N. Ireland on the dates and times listed below.

If you plan to attend one of the above CAFRE Information Workshops, please contact Janine Small on: 028 9442 6770 or email: janine.small@dardni.gov.uk

Slurry being spread by Trailing Shoe at Greenmount Campus, CAFRE