Digest It and slurry management for the winter

14th September 2018

Now that we are in the middle of September, we are starting to think about slurry management for the winter ahead.

Introduction

Now that we are in the middle of September, we are starting to think about slurry management for the winter ahead. Slurry is a growing concern on many farms due to increasing herd size, longer winters and environmental issues. Volume and composition of the slurry produced varies greatly according to the individual herd, diet and season. The general trend is now for storing slurry longer in bigger tanks or lagoons. The upshot of this that slurries are going anaerobic and crusting over in the tank or lagoon. From a health and safety perspective, this can lead to an increase in hydrogen sulphide gas.

Slurry lagoon illustration

What is it?

Digest It® is a blend of fermented microbial culture contains a rich source of vitamins, minerals, proteins, enzymes, amino acids, carbohydrates, dormant organisms and growth promoters. In effect, it provides a rich food source for microbes as well as dormant aerobic bacteria species that are able to feed on and break down the organic matter in the slurry and use the ammonia gas as a source of nitrogen to grow, thus turning it into microbial nitrogen.

The benefits

When Digest It® is used in a tank the benefits in the tank are:

  • Stimulates aerobic microbial activity
  • Converts solids into plant-available liquid nutrients
  • Eliminates surface crusting
  • Reduces fertiliser costs
  • Increases the liquid to solid ratio
  • Reduces energy required to stir and pump slurry

The benefits in the field are:

  • Digested slurry improves soil fertility
  • Reduces odour when spreading.

In a trial by Kingshay in the UK, a study was conducted on the difference between treated slurries and untreated slurries.

Table 1: Replicated trail data from Kingshay on the nutritional and microbial composition of slurry

Control Digest It Difference %
Total Nitrogen % 0.217 0.237 +9.2 (p<0.05)
NH4 Nitrogen % 0.132 0.144 +9.1 (p<0.05)
Organic Nitrogen % 0.085 0.093 +9.4 (NS)
TVC Aerobic Bacteria (5 days 22 (5 days 22°C) cfu/gx10 10.33 13.07 +26.5 (NS)
TVC Aerobic Bacteria (5 days 22 (5 days 22°C) cfu/gx10 8.2 11 +34.1 ( p< 0.05)
Slurry Crust Depth (cm) 11.83 10.33 –12.7 (NS)
Slurry Crust Shear (K Pa) 2.48 2.12 -14.5 (NS)
Slurry Crust Weight (kg) 16.61 14.58 –12.2 (NS)

The results in table1 Digest It® has demonstrated its capability of improving Nitrogen supply from slurry, turning the nitrogen from ammonia gas to its solid form of ammonium. Based on a significant increase in aerobic bacterial activity, which was also apparent in a marked reduction in crusting after 12 weeks of treatment.

The benefits of having more available nutrients when using Digest It® are clear to be seen, at our research farm at Dowth, we have been consistently achieving an average of 16% better yield on 1st cut silage trials over 3 years from 2016 to 2018 as can be seen in table 2.

Table 2: First cut silage yields from treated and untreated slurry

First cut silage yields from treated and untreated slurry

How much Digest It® do I need?

Digest It® is applied at a dose rate of 1 litre per 5000 gallons of slurry in a tank. A 20 litre drum will treat 100,000 gallons.

To get the best application, Devenish recommends diluting Digest It® with 2 or 3 times the amount of water and spread pour evenly over your slats or at the entry point to your lagoon.

For more information on Digest It® or help to size your tanks, please get in touch with us to talk to one of our agronomists on how to get the best out of your slurry this coming winter.

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