The last article in our four-part series looks at the cost of grassland rejuvenation and the options available for implementing the works and why replacing tired swards with modern varieties can increase the return from existing land.
Farmers wanting to improve grassland but considering the financial outlay of inputs such as seed, fertiliser, and machinery, should factor in the yield and quality improvements of a new sward compared to existing leys to maximise the return on investment.
Low yielding or underperforming swards sown with old grass varieties will have reduced their productivity over time and, with no maintenance, the same area of grassland will become less productive year on year and contribute to an increased exposure to bought-in feed to supplement the lack of nutritional grass quality.
Mhairi Dawson, regional manager covering Scotland for global leading seed breeder Barenbrug, explains that upfront costs of inputs should not only be factored in against year one, as the improvements in yield and quality will be seen in subsequent seasons, too.
“A well-established sward of perennial ryegrass can be more or as productive as the crop it has replaced for five or more years, therefore spreading the outlay of initial works across a greater period. Breeding advances (in grass) over the past 50 years have shown an average yield increase of 0.5% per year under silage management, and 0.35% under simulated grazing management, alongside other benefits such as greater disease resistance and drought tolerance, so annual reseeding allows farmers to take advantage of different traits,” says Ms Dawson.
Choosing the equipment and cultivation techniques that suits your land type is key, and the technique used will depend on the field history and previous crop, but don’t be afraid to trial something new on a small area. Although the figures (see table) indicate what equipment is required for an intensive tillage-based reseed, there is a growing focus on establishing new leys by moving less soil through direct drilling to save money and increase soil health.
“In some cases, although ploughing will have been employed in the past, it may be a practice that isn’t required in the same way as it was before, therefore the cost of establishment can be reduced,” says Ms Dawson.
By closely monitoring sward health, farmers could arrest the decline of a ley by overseeding rather than needing a full reseed to restore production levels. With less machinery in operation, it is a cost-effective way to prolong grass production over an extended period.
Jill Hewitt, CEO at the National Association of Agricultural Contractors, says farmers must consider if kit used infrequently is worth the high cost of purchase.
“Depreciation, breakdowns, maintenance, and insurance are all considerations, and machines such as grass seeders are used for a matter of weeks each year and it can be beneficial to bring in a contractor for these specialist operations. Grassland maintenance and management can be carried out with timeliness and without interfering with livestock day-to-day activities, such as milking. This can mean less hassle for the farmer not having to move implements around on tractors.”
What does the return on investment look like?
To assess what the returns could look like from a reseed, we compared Grass Index (GI) 5 field at peak productivity – autumn sown intermediate and late perennial ryegrass mix with two cuts and graze – to a GI 3 field, where only 50% of the sown species are left, it has been in use for several years, and there are significant gaps and weeds in the sward.
Ms Dawson sets out how renewing an old sward could payback on increased yield: “On average, an old field, will typically yield around 7t DM/ha. Compare this with a new sward sown with productive modern varieties which could produce up to 15t DM/ha. You could increase your grass yield threefold.”
In production terms, achieving yields of 15t DM/ha on the GI 5 sward could translate into 35,362 litres of milk. With prices at 40ppl, the return on the full crop is £14,144. In comparison, the older GI 3 sward, which only returns 7t DM/ha, would return a milk yield of 19,060 litres, which translates into £7,624 at 40ppl.
“The difference in financial terms between the two scenarios is over £6,500 in extra milk yield, and this isn’t factoring in the increased nutritional benefits of the new varieties and potential to sow extra species.”
Establishment considerations
Practical decisions such as the length of ley and plans for routine maintenance will be contributing factors when deciding on the mixture to sow. Using the correct drill, such as a specific grassland drill, rather than a cereal model, will guarantee a consistent establishment and encourage even emergence.
For the best results, the right depth is critical, and this can vary between species and seed size, as Ms Dawson explains. “White clover is a tiny seed and should be placed no more than 1cm below the surface to ensure it has the energy reserves to break through. A depth of 1-1.5cm for all grassland works should be sufficient.”
Depending on the mixture, a reseed rate of 14kg/ac, or 10kg/ac for an overseed should achieve the desired results. Consolidation is critical after drilling to ensure the seed to soil contact and break up any large clods to prevent uneven emergence.
Once the crop is established, making sure the nutrition is correct, and prevent it being outcompeted by weeds, will promote strong early growth and grazing will improve tillering, too. “Between 8-10 weeks should be fine for grazing depending on conditions and species sown – grazing too soon will cause damage to the new plant. To check, pull some plants to mimic grazing – if roots come out, then it is too early to graze.”
Balanced nutrition is key in the early growth stages and Tom Oates, nutrition agronomist at Origin Fertilisers, says it is worth remembering that crops with high nitrogen requirements, such as ryegrasses, will also have high sulphur needs to allow the nitrogen to be made available.
“Sulphur is a key nutrient linked to protein formation and crop quality and the crop’s need for S is closely linked to its N requirements. It is highly mobile in the soil, so should be considered as an essential application to young swards to help with nitrogen availability and uptake,” says Mr Oates.
When planning a reseed it is essential that expert advice is taken on the correct mixture for the type of soil. Getting this right will allow a return on investment that far outweighs the reseed cost and increases your farm’s resilience by making the most of your home-grown forage.
Table 1
Cost of grassland reseeding (ha)
| Soil sample | £25 |
| Lime (2.5t/ha) | £95 |
| 5l/ha Glyphosate | £52.50 |
| Spraying costs x2 | £33 |
| Ploughing | £75 |
| Rotovating | £88 |
| Rolling x4 | £104 |
| Fertiliser 250kg/ha 8.20.30 | £189 |
| Fertiliser application | £15 |
| Grass drilling (with harrow) | £48 |
| Grass Seed (perennial + clover) | £160 |
| Post emergence spray | £35 |
| Total Cost | £919.50 |
Costs are based on the National Association of Agricultural Contractors 2022/23 rates
Part 4 of the 4 part British Dairying Grassland series. We partnered with British Dairying to create this Grassland Special series which ran from October to December 2022. Read the FULL FOUR PART British Dairying series here
