Farmers who are aiming for a first cut of silage in late May, need to be getting fertiliser out on silage ground this week, if it is not out already.
Generally speaking, a first cut of silage is allocated anywhere from 70 – 100 units of nitrogen (N)/ac and, with ideal growing conditions, will utilise approximately two units of N/day.
Reseeded fields and fields that tend to grow more grass every year will use more N than older, less productive swards.
The fertiliser applied can be composed of organic fertiliser (slurry) and chemical fertiliser, or chemical fertiliser only.
Farmers aiming for a cut of silage in late-May will ideally have slurry out on silage ground one week or longer, to allow sufficient time between the organic and chemical fertiliser applications.
Where using slurry to make up part of the N, phosphorus (P) and potassium (K) requirements, slurry should ideally be tested to identify its nutrient value.
Teagasc nutrient value guidelines:
- As a guideline, 1,000 gallons of cattle slurry with a Dry Matter (DM) of 7% would have the same nutrient value as a 50kg bag of 9:5:32;
- 1,000 gallons of pig slurry (4% DM) has the same nutrient value as a 50Kg bag of 19:7:20.
3,000 gallons/ac of the cattle slurry mentioned above will provide maintenance P and K levels to grow a crop of grass silage – where soil is Index 3 for P and K.
Silage ground with a P and K soil index of 4 needs no P or K application for two or three years. Soil should then be retested after this time.
The table below outlines the N, P and K requirements for first-cut grass silage (5t/ha DM) and suggested fertiliser programmes:
Where ground conditions are too tricky in the spring for a slurry application with a tank, farmers should consider hiring a contractor with an umbilical system.
Also, with fertiliser in short supply and at a record price, getting every grain of it spread where it is needed has never been more important.
To avoid overlapping and unnecessary wastage, many farmers are calling in a contractor with a GPS spreader to apply their fertiliser.
More and more contractors are now offering this service and where a reasonable amount of acreage has to be spread, the price works out at a relatively nominal rate/ac – compared to this year’s fertiliser prices.
Remember, seven weeks from today is June 1, so getting fertiliser out on silage ground, if it is not out already, should be a priority job on beef farms this week.