Cotswold Seeds Ltd - Organic Overseeding. A low cost method of improving grass leys. Ryegrass and White Clover

At the start of organic conversion many organic farmers introduce white clover into leys or permanent pasture. Organic feed commands a high price and is the key variable cost of livestock production. There is therefore a need to reduce the cost of milk and meat production by reducing the amount of purchased feed. Organic dairy, beef and sheep farmers naturally aim to become more self sufficient by growing more clover in grazing and silage swards with considerably lower costs. Clover in grass swards is an essential pre-requisite for a self sufficient system. Grass leys with no or low levels of clover are candidates for over-seeding.

Over-Seeding Clover
The introduction of white clover into a grass sward, with its high protein content, is of great benefit to the grazing animal. White clover has the additional advantages of fixing free nitrogen, improving summer feed value and providing ground cover during dry seasons. Seed can be successfully sown into an existing ley or pasture, but it is essential to ensure the sward is grazed tightly before sowing and that the regrowth of grass doesn’t smother the clover seedlings by grazing about five weeks after sowing. Avoid sowing when grass growth is expected to be vigorous.

White Clover Mixtures
Clovers are classified by leaf size. There are three categories: very small, medium and large leaved. The very small, low yielding but extremely persistent type is known as wild white. These little clovers fill the base of the sward and can be grazed hard with sheep. Original varieties such as S184 have been used for over fifty years and are still popular today. Medium leaved varieties such as Aberhearld and Crusader are higher yielding and grow early in the spring. They are suitable for grazing and cutting. The large leafed varieties such as Barblanca and Alice are the highest yielding but are not suitable for hard grazing.

Introduction of Grass Seed
A very good way to improve old or damaged leys without re-seeding is to over-seed with ryegrass. The main advantages are that there is not much interruption to the use of the field and yields can be increased at minimal expense. The seed can be broadcast or drilled, but beware of sowing too deep. If broadcast, the seed should be rolled in or stock turned onto the area for a short time.

Timing is important
It is best to avoid sowing when the existing grass is growing vigorously during May and June, so either sow March-April or July-September ideally after grazing or close cutting. In many open swards it is possible to broadcast seeds after chain harrowing. The sward should then be consolidated using a ring roller or by treading in with sheep. Comb harrows are also very good and with wider availability are now becoming popular. Alternatively, a grass drill such as the ‘Moores’ or ‘Aitchison’ may be used. Heavy direct drills with discs designed for cereals do not produce such good results. Grazing may be resumed 5 weeks after sowing, but be careful not to over graze especially with sheep. The following year treat the field as usual.

Tetraploid Ryegrass Varieties do Best
It is usual to use ryegrass for over-seeding as it is low cost, competitive as a seedling and establishes rapidly. Tetraploid varieties are particularly recommended as they have a larger seed and are capable of strong, competitive growth. They are also considered to be more resistant to drought than diploid grasses. This is most important for successful results. For the successful establishment of new plants it is wise to check the soil pH, together with phosphate and potash. If necessary apply lime to bring the pH to 6 and ensure phosphate and potash levels are above a soil index of 2. (Don’t forget that this practice is a means of improving the content of ryegrass and/or clover. If the existing sward contains no productive grass or is densely matted with creeping grasses such as Couch, then a full re-seed should be considered.)

Organic Overseeding

A low cost method of improving existing grass leys