Is a grassland reseed needed?

A grassland reseed could improve paddock and animal performance. Use our flow chart to help you decide whether a grassland reseed is needed.

When is a reseed needed?

Reseeding should be considered if two or more of the following criteria have been met:

Sward productivity has fallen significantly
Proportion of sown species has fallen below 60%
High levels of native grasses and weeds are present
Significant evidence of soil compaction, especially at depth

Paddock performance

Some farmers may opt to reseed a set proportion of the farm each year, e.g. 10 or 15%, in a rotational pattern to ensure grass swards are regularly renewed.

There can be large variation in the performance of paddocks across the farm, so the best way to identify swards eligible for reseeding is to measure grass growth regularly to identify the poorest-performing fields. Using regular grass growth data can highlight fields that need attention and may require a full reseed.

Using a plate meter, nine Irish dairy farms measured grass throughout the grazing season in 2014. The results show wide variation in the performance of individual paddocks, varying by 280%.

Variation in paddock performance on nine Irish dairy farms

Farm number	Mean growth (t DM/ha)	Highest paddock (t DM/ha)	Lowest paddock (t DM/ha)
1	11.7	14.1	8.7
2	14.3	16.8	11.0
3	12.3	20.3	7.2
4	14.4	17.8	8.8
5	12.4	15.8	9.0
6	11.0	14.3	8.9
7	9.9	14.8	7.5
8	10.8	12.2	6.0
9	10.1	14.2	5.4

Influence on livestock performance

The progress of a grass reseed

PRG content (%)	Production (t DM/ha)	Herbage ME (MJ/kg DM)	Lost ME grown (MJ/ha)	Milk equivalent of lost ME (litres/ha)	*Meat equivalent of lost ME (kg LW/ha)**	Concentrate cost to replace lost ME^ (£/ha)
95	13.5	12.0
90	12.6	11.8	13,320	1,885	133	197
80	11.2	11.5	33,200	4,698	332	491
70	9.8	11.3	51,260	7,254	513	759
60	8.4	11.0	69,600	9,849	696	1,030
50	7.0	10.8	86,400	12,226	864	1,279