There is little doubt that silage harvesting is later than previous years and recent discussions with the farmers in my area have highlighted the challenges that this brings. I decided to put this guide together for farmers on the key points involved with making quality silage.
Dry Matter Value
My advice for making quality silage is based on sugar content, nitrates and dry matter value (DM) and that farmers make silage at its best nutritive value so that it can be efficiently converted to meat or milk.
Highly digestible, free from mould, palatable and waste free are the key attributes of quality silage however, I appreciate there are many factors that impact significantly on achieving this not least the cutting date. The cutting date is determined 42 days following the latest Nitrogen (N) application of 90 units per acre – I encourage Nitrate testing to check for this together with sugar content and DM value to ensure the quality of silage.
Dry Matter Digestibility
While weather is not something I can control for our farmers, harvest date is a crucial element to achieving quality silage. When cutting date is delayed it reduces dry matter digestibility (DMD) by 3units/week. This year is a concern; slow growth caused by the cold weather means many of the farmers in my area were challenged with this and faced a later than usual cutting date, which may compromise DMD value. For those still to cut, target to cut at noon when sugar content is at its highest.
Wilting of silage is also a key consideration as this will increase the sugar content value. I encourage farmers to allow wilting over a 24hr period while I recognise this is not always possible. Target DM of wilted grass is 30%.
The key parameters for optimal silage quality that are within our control are to achieve the following;
- Soil fertility index 3
- pH 6.5
- High proportion of perennial ryegrass
- Correct chop length
- Correct N application (high N level leads to high buffering capacity which resists acidification; reducing sugar content of grass and making it more difficult to preserve).
When it comes around to covering the pit, in my experience farmers need to be more aware of the impact a delay on covering the pit can have. It is vital that the crop is quickly compacted and limit the amount of air in the clamp – covering should take place ideally within three to four hours to allow the initiation of fermentation to begin and create the optimum anaerobic environment to convert sugars. There is a direct impact on preservation at this stage and I believe silage inoculants have a role to play to establish a higher population of bacteria to increase aerobic stability where sugar content is particularly low.
When covering the pit my recommendation is a 0.125mm polythene cover, ideally two covers to achieve appropriate anaerobic conditions. Four layers of plastic for wrap silage.
For farmers reseeding silage ground at this time, my advice would be to select a high proportion of perennial ryegrasses in the mixture. Perennial ryegrasses are more digestible, have a high content of sugars and are easier to preserve. Mid-summer reseeding is now popular and working very well for a lot of my farmers, often grazing after 42 days in comparison to conventional Autumn/September reseeding programmes. Better germination, better overall cover, less chance of germination failure often caused by weather challenges are some of the benefits of reseeding at this time of year.
Making quality silage is vital for the profitability on all farm enterprises and I encourage farmers to pay attention to the detail. If you are looking for advice on silage harvesting or agri-nutrition, feel free to leave us a question.
- dry grass
- dry matter