Pasture Profit Index

The Pasture Profit Index or PPI is an index of grass seed varieties that are ranked on their economic performance.

The PPI puts a monetary value on important traits that a variety displays. These traits are spring, summer and autumn growth, quality, silage yield and persistency. Each value is then summed, which gives the variety a total PPI value.

The grazing utilisation trait sits outside of the PPI and uses a star system to denote the value. A variety with five stars means that cows graze that variety out very well – it’s another important indicator of quality. The PPI is developed by Teagasc.

Recommended Lists

These are produced each year by the Department of Agriculture based on their five trial sites across the country. Varieties are compared for yield and quality parameters plus ground score. Data from the recommended lists is fed into the PPI.

The Department of Agriculture is changing the timing of when it publishes the recommended lists, with a new list being published in the last quarter of 2023. This is to allow the seed trade to have more time to plan seed mixtures for the next season.


Ploidy refers to whether a variety is diploid or tetraploid. The difference between the two refers to the way they were bred, with diploid varieties having two chromosomes per cell, while tetraploids have four.

Physically, diploids tend to be shorter growing and denser, with higher ground cover than tetraploids. However, tetraploids tend to have higher growth and quality characteristics.

Most seed mixtures contain a mix of tetraploid and diploid varieties. In recent years, tetraploids have outperformed diploids on the PPI.

Heading date

This refers to the average date in which the variety goes to seed.

Quality deteriorates after a plant heads, so later heading varieties are preferable to early heading varieties, particularly in grazing situations.

Earlier heading varieties are more likely to head out at multiple times during the year also, making it harder to maintain quality.

It’s important that varieties in a seed mix have a similar range of heading dates. Choosing varieties with a high PPI overrides the importance of heading date.

Sowing rate

Most grass seed mixtures are sold in 12kg bags, which are often referred to as acre-packs. However, there is general agreement that sowing rates should be much higher, at up to 15kg/acre of seed. White clover should be included at a rate of 2kg/acre, so a 14kg/acre pack should contain 12kg of grass seed and 2kg of clover seed.

Clover safe

Clover safe is a term which refers to the post-emergence spray used on reseeds. Most post emergence sprays are not clover safe and will kill clover seedlings, so only clover safe sprays should be used where clover is sown.


A monoculture is where just one variety of grass seed is sown in a sward. Monocultures gained popularity over the last decade, as farmers sowed monocultures as part of Teagasc on-farm variety evaluation.

It has become popular to sow a very high performing variety on its own, but the majority of grass seed in Ireland is sown as part of a seed mixture containing three or four varieties.


A multispecies sward is a sward that contains multiple species of grass, legumes and herbs. They typically contain two or three types of grass, such as perennial ryegrass, timothy and cocksfoot; two types of clover, such as red and white clover; and herbs, such as plantain and chicory.

The advantages of multispecies are that they require less inputs as plants have different rooting depths, so are drawing nutrients from different parts of the soil profile. The downside is lack of persistency, with the herbs lasting only two or three seasons.