Guide to Dry Matter Testing of Silage

Frank Mickan is the Pasture and Fodder Conservation Specialist with the Department Environment and Primary Industries (DEPI) at Elinbank in Victoria. 

“Silage should be made at the correct dry matter, if possible, to ensure a desirable lactic acid fermentation in the absence of air soon after harvesting and sealing,” says Frank Mickan, Fodder and Pasture Specialist, Natural Resources and Environment, Ellinbank. Undesirable and/or mouldy silages will be the result of silage made too dry or too wet. These silages will be less palatable, lower quality and not so pleasant to smell or handle.

 The following dry matter contents are suggested for the various silage crops and type of harvesting.

 

Crop Type                                                          Pit/ Stack                                             Bale

                                                                            (DM %)                                              (DM %)

Pasture                                                               

Long Chopped                                       28-35                                                     40-55

Precision chopped                                 35-50                                    

Leguminous crops

                Long chopped                                    33-45                                                     40-55

                Precision chopped                             35-50    

Whole crop cereal

                Wilted & Fermented (Leafy)            28-35                                                     40-50

                Direct Harvested (Soft Dough)        35-45                                                     35-45

Maize

                Precision chopped                             32-35

Summer Forages

                Long chopped                                    28-35                                                     35-45

                Precision chopped                             35-50                                                   

There are two methods for measuring the dry matter of pastures to determine their readiness for ensiling. These are the hand and microwave methods. The current hay moisture meters are not suitable for silage! Initially the microwave method could be used to calibrate your own hand method or some other technique that you could develop for quick paddock use.

Hand Method

  1. Take a representative sample of pasture ready for ensiling.
  2. Cut into 1 - 2 cm lengths.
  3. Tightlysqueeze a handful for 20 - 30 seconds.
  4. Quickly open your hands.
  5. Discern approximate dry matter content from table below.

Dry Matter Content                                        Condition of the Sample

Below 25%                                          Ball holds its shape.  Lots of free juice.  Hand is wet or moist.

25% - 30%                                          Ball just holds it shape.  Hand barely moist.  Ideal for wilted chopped                                                                   stack or pit silage at drier end of range.

30% - 40%                                         Ball falls apart slowly.  No free juices.  Makes excellent silage, but                                                                        because of its springiness, requires fine chopping or extra care to exclude                                                              air at drier end of range.

Over 40%                                           Ball springs apart quickly.  Suitable for round/square bale silage and                                                                      precision chopping but total air exclusion is essential.        

Microwave Method

  1. Collect representative samples from the crop and thoroughly mix together - sub sample to get a test sample.
  2. Weigh out approx.100 g sample of the chopped forage excluding the weight of the container. Weigh to the nearest gram. This is the initial wet weight.
  3. Spread the weighed forage sample on a paper tray and put it in the microwave oven.
  4. Place a 250-ml glass three-quarters full of water in the oven to prevent igniting the sample after some initial drying.  Maintain water level during oven use.
  5.  Heat at 80 to 90% of maximum power for 4 minutes if sample is estimated to be 30 - 50% dry matter.
  6. Remove the sample, mix and weigh.
  7. Continue to re-heat for 1 - 2 minute intervals, re-weighing each time.  To prevent burning use lower heat and 30 second time intervals as the sample approaches being dry.  If the weight of the sample does not change after two or three drying intervals, it is 100 per cent dry within 1 – 2% units. This is near enough!  This is the final dry weight.  If the sample burns use the last recorded weight.
  8. Calculate dry matter content as follows  :-

                Final Dry Weight (gms)                                                 100

                Initial Wet Weight (gms)             X         1          = ……….. % Dry Matter

 

                                                Eg. 1   33 gms                X   100    =    33  % Dry Matter

                                                            100 gms         1

e.g. 2.  48 gms           X   100   =   42.8  % Dry Matter

                                                            112 gms                 1