Friday, 13 June 2014

Steps to Silage Making - Part 2

The second part of Steps to Silage Making concentrates on how to harvest and save your grass in order to produce the highest quality silage.  The first job is to monitor the growth of your grass and aim to cut it just as seed heads begin to appear.  Remember that yield increases with time, while your DMD (dry matter digestibility) decreases. 

Silage is basically pickled grass.  In order to produce the acid to pickle the grass we need sugars. Ideally we want a high level of sugars in the grass (>3%) in order to get high preservation.  Alternatively we can concentrate sugar levels in the grass through wilting to reduce the water content. Tedding (spreading) the grass can substantially increase the drying process. Not cutting in the morning (i.e. when dew is on the grass) will also reduce water content.  Sugars are highest on bright sunny days with cool nights. 

Once filling the pit has begun it should be completed as rapidly as possible.  During this stage of the harvest the most important thing is to expel as much air as possible from the silage.  The grass should be rolled after every load is added to the pit.  It should then be covered with two layers of plastic to ensure all air is excluded.  Once the silage has settled it may be necessary to adjust the plastic to maintain a tight seal. The pit should also be inspected regularly and any damaged areas should be patched.
 
If harvesting conditions are poor it is even more important to follow the steps above.  You may need to adjust cutting heights to reduce soil contamination. Soil compaction is a big issue and this may also need to be addressed through using lighter machinery, reducing tyre pressures and only half-filling trailers.  As effluent production can be much greater, proper drainage and collection facilities are vital.
 
For second cut silage apply up to 100kgs/Ha (80 units/acre) of Nitrogen and Potassium and 16kgs/Ha of Phosphorus (13 units/acre).  If you have soil samples ensure that recommendations are adhered to.  Applying slurry on the bare stubble immediately after cutting will provide much needed nutrients at a low cost.