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Grow More Now With Super Duper Dairy Poo

Dairy effluent is an unattractive shade of green and sticks like superglue, yet put to good use it can be of great benefit to summer crops and pastures on the farm.

By Department of Primary Industries - 26th November 2007 - Back to News

Project Manager, Barrie Bradshaw, from DPI Gippsland’s Nutrient Extension team said that about 8 – 10 per cent of this waste matter can be deposited in cow yards each day, and the figure rises if cows are stressed or milking takes longer than usual.

"Dung and urine along with washdown water, detergents, sand, cow hair, paper, and other unmentionables generally wind up in an effluent pond or effluent swamp in a paddock," Mr Bradshaw said.

"Fortunately, this mixture can be recycled and used as a good source of major plant nutrients including nitrogen, phosphorus, and potassium."

"The nutrient content in the effluent depends on the amount of time cows spend in yards, type of effluent storage system, length of storage period, number of cows milked and amount of water used.

"Accounting for these factors, the stored effluent that you irrigate to your crops or pastures could be worth in fertiliser equivalent on average about $1400/megalitre, but ranging from $273 to $3500."

The Environment Protection Authority stipulates that no dairy shed effluent may leave a farm or contaminate surface or ground water.

Phosphorus escaping into waterways, along with other factors, can lead to toxic blue-green algal blooms that can cause animal and human health problems, as well as severely affect tourism and the marine livelihoods of other farmers downstream.

Mr Bradshaw suggests under current weather conditions that if pastures are actively growing then now is a good time to consider applying dairy effluent before it’s too late.

"It’s worth noting, that most storage ponds are only designed to hold effluent from one winter season, so they probably need to be emptied now, or at the latest before the autumn break," Mr Bradshaw said.

Recent analysis of effluent from Gippsland ponds has measured that in one megalitre (ML), the average nutrient content was 500 kg Nitrogen (N), 182 kg Phosphorus (P) and 550 kg Potassium (K).

Farmers need to be aware that these ranged from 58 - 1200 kg N, 16 - 450 kg P and 41 – 1133 kg K over the various effluent storage systems.

These figures do not reflect the effluent flowing into the ponds every day, but are the result of varying storage times and concentration in ponds.

Mr Bradshaw said it may also explain why the grass grows like fury (high N and P), why docks suddenly appear around effluent disposal areas (they love potash), why cows may be twitchy at milking time (potentially due to sub-clinical to clinical grass tetany), and why grass is often not eaten (low palatability).

One megalitre is equivalent to 100 mm of water over one hectare. If the above average effluent is spread over one hectare then the actual application is the equivalent of about 1100 kg/ha urea, 2100 kg/ha single superphosphate, and 1100 kg/ha muriate of potash.

Both N, and particularly K levels are far too high from both environmental and animal health issues. In this case, if the effluent was spread over 10 hectares, we are now applying the equivalent of about 110 kg/ha urea (51kg/ha N), 210kg/ha single superphosphate (18kg/ha P), and 110kg/ha muriate of potash (55kg/ha K).

Ideally potassium rates should not be in excess of about 60 kg/ha K or 120 kg/ha muriate of potash to avoid possible grass tetany problems.

Some other factors to consider are:

  • The nutrient levels of the ponds.
  • Frequency that the spray or hose is moved.
  • How much area does the effluent end up on?
  • Whether the effluent will be spread over different areas each.

Due to the high variation in nutrient concentrations, farmers should consider testing their own effluent storages for nutrients.

As a point of caution, dairy shed effluent can include a multitude of bacteria (for example Johne’s Disease, Salmonella, Leptospirosis, mastitis) worm eggs, coccidial eggs, clostridial organisms and tetanus spores if they exist in the herd.

However, the period of storage, dilution rate and time of application (usually in hot and dry weather) when applied to land greatly reduces the risk of disease.

To further reduce the risk:

· Apply it straight after grazing to allow a full rotation length before re-grazing.

· Keep young stock (under 12 months of age) off any land where effluent was spread, irrigated or allowed to run.

The best time to irrigate effluent from ponds in rain-fed areas is while the pastures and crops are actively growing or to fodder crops. This is towards the end of spring/early summer and prior to the wet winter period.

On irrigated pastures, effluent can be applied anytime throughout the irrigation season, but particularly ensuring that there is no runoff when the effluent is shandied with the irrigation water.

If you would like more information or a free dairy effluent management plan, please contact the Gippsland Nutrient Extension Team at DPI Ellinbank on 5624 2222 or DPI Maffra on 5147 0800.


Source: http://gippsland.com/

Published by: news@gippsland.com



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