Managing your grass after first cut silage
For many livestock farmers their听silage crop is the most important crop they harvest.听It鈥檚听therefore critical to manage the grass sward accordingly to听ensure efficient听and听cost-effective听production is maximised, while ensuring that silage quality and quantity is optimised听听听
As the first cut of silage comes off fields, farmers are faced with the crucial question of听what鈥檚听next? The actions you take after first cut silage have a significant impact on the quality of the next cut as well as the productivity and longevity of the sward.听听
Cutting听date听
Firstly,听the cutting date needs to be considered, as听second cut听yields or听regrowth听can be limited if the听first听cut is delayed and the grass becomes too stemmy.听Delayed cutting also reduces the energy and protein content of the silage, which can result in more concentrate feeds being听required听in winter听to听maintain liveweight gains.听
Timing of听fertiliser/slurry听applications听
Fertilising the aftermath with slurry or bagged fertiliser听immediately听after the first cut is听critical听as yields can be reduced by up to 6% if application is delayed by up to听eight听days.听Delayed application of organic manure can also lead to higher levels of bacterial infection in the听second听cut which can affect the听quality of the fermentation.听
Slurry听application method听
The use of trailing shoes or dribble bars when applying slurry can also improve the efficiency of nitrogen use听increasing grass yields by up to 25% through the听minimisation of听volatilisation and contamination of the sward, compared to splash plate application.听
Fertiliser听recommendations for听second and third听cuts听
Silage removes significant quantities of nutrients, so it is important to replenish these losses to avoid poor regrowth.听
Nitrogen Fertiliser听
Application rates will vary depending on the quantity of silage听required听in听subsequent听crops but听can typically be 90kg/ha of N for听second听cut and听70kg/ha for听third听cut.听Clover dominant swards however can manage with significantly lower levels of nitrogen fertiliser.听
Phosphate and Potash听
Applications of phosphate in established grass/clover swards are听generally aimed听at听maintaining听soil phosphate levels at a moderate status听(typically 12-20kg/ha of P2O5 for听second听cut and 10-15kg/ha for听third听cut).听Higher applications can听benefit听clover-based听swards if soil reserves are in a low or lower moderate status.听
Potash is the second most important nutrient in silage crops, as offtakes can be considerable, resulting in the rapid depletion of soil reserves (especially on lighter soils) if not replaced with muck/slurry or a high potash fertiliser. It is therefore vital to ensure soil reserves are maintained at a moderate level. Typically, the level of potash required is approximately two thirds of the level of Nitrogen fertiliser, with any surplus applications applied at the end of the season to avoid luxury uptake and subsequent removal by the silage crop. Typical levels for second and third crop silage should be 50鈥�60kg/ha and 40-50kg/ha. 听
Sulphur levels听
As industrial deposition of听sulphur decreases there is an increasing requirement to apply sulphur as a fertiliser and grass can be the second most responsive crop after brassicas.听The most reliable prediction of the likely response to sulphur is to听consider听a听herbage test听ten听days before your anticipated silage cut to determine if the Nitrogen to Sulphur ratio is greater than 13:1.听Profitable responses to applications of听sulphur can be obtained in听second听and听third听cuts of silage.听Typical applications of 40kg/ha听of SO3听are recommended.听
Applications of organic manure however can enable significant savings in fertiliser as shown in the table below:听
1听鈥� Readily available N content is before losses of N due to leaching or gaseous emission.听
Further information can be found at
Long term aspects听
Grass growth is influenced by temperature, moisture, soil pH, soil drainage, soil structure, and available听nitrogen;听therefore,听it is also important to address the issues within your control,听including听drainage, soil pH and soil structure听through appropriate听long term听investment in the field鈥檚听productivity.听
Grass is still the cheapest feed source for ruminants, and investment in boosting growth and productivity are good investments, even with higher nitrogen fertiliser prices 鈥撎齟.g.听1 kg N at 拢1.45/kg (拢500/t for 34.5%N) can provide approx. 15kg听DM听of grass (拢0.09/kg DM or 拢90/tDM) compared to concentrate feed at 拢250/t.听
Weed听control听听
Cutting silage often leaves the ground bare in places, creating the perfect opportunity for weeds to germinate. Weeds to look out for and control include docks and thistles. It is important to tackle weeds early to avoid a reduction in grass yield. More information on controlling weeds in grass can be found at .听
Reseeding听
If you are faced with a tight turnaround time for reseeding silage fields and seek to control perennial weeds听(e.g.听docks,听thistles听and nettles)听an application of glyphosate onto silage crops听pre-cutting听can also be done听(at least听five听days prior to cutting).听This method is听perhaps less听conventional but听could be useful in island or hill locations where establishment times are critical due to the speed that autumn weather and colder growing conditions听begin听to听limit grass growth, or where an autumn听fodder crop听seeks听to be听established.听
Post-silage grassland management is a balancing act between short-term productivity and long-term sward health. Contact your local SAC consultant if you would like to discuss options whether you are planning to reseed, resting the grass, grazing after taking a cut or making a second cut of silage.听听
Ewan Johnston,听Principal Consultant,听Ewan.Johnston@sac.co.uk
Posted by SAC Consulting on 16/06/2026
