Pastures can lose quality as they get older. Although the fields are still covered with grass it is not certain that farmers are still getting maximum output from their pastures. In many modern dairy systems it is crucial to maintain maximum output from the grassland. If not, the fields will produce less dry matter and also the forage quality will become insufficient, resulting in higher (additional) feeding costs per cow. It therefore is important to renovate pastures as soon as they start to lose quality.
When to renovate?
- If one or more of the following problems appear during the growing season:
- water remains on top surface during growing season
- the grass shows slow regrowth
- the grass is heading continuously
- the botanical composition consists of less than 75% good grasses
- cows have difficulties to maintain their milk production level
If one or more of the following conclusions can be drawn from the silage analysis:
- the total dry matter yield is too low
- the crude ash content is too high
- the digestibility of the organic substance is lower than 70%
- disappointing feeding value despite good ensiling technique
What are the costs and benefits of pasture renovation?
For the renovation of one hectare grassland we can use the cost indication below.
|Spraying old sward (including product)||25|
|Rotary cultivating (5cm)||100|
|Ploughing (with land packer)||113|
|Seedbed preparation & sowing||90|
|Total costs per hectare||438 Euro|
|(Costs are based on a Dutch situation)|
After renovation, the improved field offers a better botanical composition of the sward, better sward density and increased dry matter yield and feeding value. What this will mean in economic terms for the farm is presented in the next table.
|Old sward/ha||kg DM/kg dm||VEM*)/ha||kVEM|
|60% good grass||12.000||980||7.056|
|20% weed grass||8.000||790||1.264|
|10% bare soil||0||0||0|
|Yield per hectare||9.200||8.620|
|New sward/ha||kg DM/kg dm||VEM/ha||kVEM|
|90% good grass||12.000||980||10.584|
|4% weed grass||8.000||790||253|
|2% bare soil||0||0||0|
|Yield per hectare||11.280||10.957|
*) VEM= energy value per kg dry matter feed product Fresh grass (normal cut) has an avarage feeding value of 930
*) VEM= energy value per kg dry matter feed product Fresh grass (normal cut) has an average feeding value of 930 VEM/ kg dry matter. Converted into foreign energy systems this will be:
930 VEM = 6.7 MjNel
930 VEM = 0.85 NFE
930 VEM = 10.9 ME
What is the effect of grassland renovation?
- Increased dry matter yield per hectare resulting in lower costs for purchasing concentrates or forage products.
- Better forage quality (VEM) per kg dry matter (palatability + digestibility)
- In this example: + 2337 kVEM per ha
- An added value of (2337 kVEM x 0.15 ct/ kVEM) = 350 Euro/ha
- Better dry matter intake by the animals
If the condition of an old sward is even worse than in this example the return of investment will be much faster.