20 July 2010

4 minute read

Table 1 shows that grazed grass, even with high clover quantities costs substantially less than other feedstuff.

With this in mind it is in all grass farmers benefits to improve soil and subsequently grass quality as much as possible.

Speaking at an event in Yorkshire, UK, Liz Genever from the English beef levy board looks at what can be done to improve soil and grass quality.

1. Check soil conditions and fertility regularly

Without testing your soil, it is impossible to know how much fertiliser to apply. You may be over applying, which is not only a waste of resources but also potentially damaging to the environment. However an undersupply will mean a shortage of vital nutrients.

A soil test, which is minimal in cost, will help decide which nutrients are required allowing a more targeted approach to fertiliser use, saving time and money.

EBLEX, the English beef levy board recommend soil sampling every five years, in the same season and at least two months after the last application of manure, fertiliser or lime.

Soil tests are particularly useful, says Liz Genever a Livestock Scientist from EBLEX, if you feel your fields are under-performing or if you are planning on improving pastures.

"Improving soil fertility will also improve early and late season growth, increase perennial ryegrass and white clover content, decrease weed competition and increase nutrient uptake," she said.

2. Ensure swards contain a high proportion of perennial ryegrass and clovers

The actual cost of grass depends on overheads and productivity. Reseeding typically costs £240/ ha but a 20 per cent yield reduction increases grass cost from 6.5p/ kg dry matter (DM) up to 8,2p/ kg DM.

Grazing or grazing/silage leys should be considered for reseeding at eight to ten years depending on:

• The proportion and distribution of good grasses, particularly perennial ryegrass and white clover.
• Soil condition<
• Assessment of performance, e.g. spring growth, silage yield.

White clover leys should contain varieties selected for cutting and/or grazing.

Ms Genever recommends avoiding repeated and prolonged periods of very heavy grazing and use short four to five week mid/ late summer rest periods, ideally for a light silage cut to encourage clover recovery.

Managing white clover

White clover is a perennial legume. The key to its survival and production is its multibranded creeping stem called a stolon, which provides sites for new leaves, roots and flowers.

White clover fixes nitrogen into the ground - converting it to nitrates.

Livestock are likely to consumer 20 -30 per cent more white clover than grass assuming equal access - which leads to increased liveweight gains.

With higher digestibility and nutrient contents it has a higher feed value.

White clover will increase the crude protein content of first cut silage by one per cent for every 10 per cent increase in the amount of clover in the sward.

The root system of white clover can also help tackle soil compaction, allowing freer movement of nutrients and water.

The optimum amount of clover in a field is 30 per cent of DM. At this level, clover can fix 150kg N/ ha per year.

To reach 30 per cent clover growing, the sward needs to look more like there is 50-60 per cent clover at its peak growth in August.

Ideally grass/clover leys should follow cereals, roots or brassicas, as these will have reduced nitrogen levels in the soil which in turn encourages clover establishment.

In mixed swards, seed rates should be 2-4 kg per ha (150 clover seedlings per metre squared), with broadcasting being a more reliable method than drilling.

Undersowing a cereal crop is an alternative. Clover should be sown into warm soil between April and August.

3. Monitor Grass Availability

Stock numbers/ grazing area should be regularly adjusted to maintain a leafy pasture and high intake.

Between May and June, sward grazing height should be six to eight centimeters. In June to July, seven to nine centimeters, and in August to September, eight to ten centimeters high.

Ms Genever says that grazed pasture must be continuously maintained at these levels. On rotationally grazed fields, she says to graze to the lower sward height before moving to a new field.