Some of the questions worrying those of you who are just starting out and often a mystery to all of us, are related to the measurements used in agriculture:

How big is an acre and is it larger or smaller than a hectare?

How many livestock will an acre support?

How much hay will an acre yield and how big a building will be required to store it?

How much hay will my livestock use in a winter?

We will attempt to answer some of these questions in this article.

The NewLandOwner team, being of a certain age, tend like most farmers to think in Imperial, with a smattering of Metric thrown in from time to time, just to confuse the issue. This will become evident as you read on.

Land Measurement:

Acres, the old Imperial units for land measurement are how we refer to field sizes, but all official documents must use Hectares. We expect most students and many younger people use only Hectares.

We will attempt to throw some light on the relationship between Metric and Imperial and how these relate to the requirements of livestock.

So, how big IS an acre?

One acre is 4840 square yards. Easy isn't it!

A Cricket pitch is 22 yards between the wickets, so an acre is two pitches wide by five long.

One Hectare is equivalent to 2.47 acres.

With experience it is of course possible to look at a field and with reasonable accuracy, estimate its' area. This becomes much more difficult in an irregular shaped field, particularly one with undulations.

Alternatively, to arrive at a reasonably accurate assessment, stride out the average width and length, then multiply the two to get the square yards. Then of course divide by 4840 to arrive at acres.

Should you have particularly long legs, you may stride in meters, which are three inches (10%) longer than yards, and 10,000 square meters will be one Hectare!

Many maps used in agriculture have field sizes marked upon them in both acres and hectares. The new Digital Maps however, now required for any DEFRA related activities, have only the hectares marked.

How much Hay do I need?

We have talked, in previous issues, about the total land area required per Livestock Unit (One cow and calf).

Now let's look at the requirements for hay production.

Grass growth habits:

It is of course necessary to understand that only the first half of the summer is used for hay (if cut in July). The land is then available for grazing for the rest of the year, although growth is only half that of the April to July period.

Grass, like all crops responds to soil temperature and moisture content. It starts to grow in April as the soil warms up, produces maximum growth in May and June when the combination of moisture and temperature are at their best.

Growth slows in July and August as the soil dries out and falls to nearly nothing in October, when soil temperature drops again.

Add to this, the fact that plants slow down once they have produced a seed head in June or July and you will see that production peaks in May and June and tails off through late summer.

The feed value of the grass is also reduced in late summer too, so each mouthful is less nutritious.

Translate this into grazing animals and it works like this:

From April to haymaking in July, two thirds of the grass area can be shut up for hay or silage. The remainder will provide grazing for your livestock.

During July, to the end of September, those same livestock will require the whole area to graze.

From October to April, very little growth or nutrition is available and this is when you feed the hay conserved in July.

The area required for Hay:

In theory, stocked at about 1.5 acres per Livestock Unit, there should be sufficient hay to keep those same animals through the winter.

Too many animals and you will run out of grazing in July and hay in the winter.

Hay production, from an average lowland pasture, utilising little or no artificial fertiliser, should produce about 2 tonnes per acre.

In small bales this amounts to 80 bales (40 bales per tonne @ 25Kg each). Big round bales of five-foot diameter will weigh about 200 to 250 Kg (four or five to the tonne)

The amount of hay required to feed one Livestock Unit (One cow and calf, or eight medium sized sheep) for a 180-day winter, will be about two tonnes, (80 to 90 bales or one acre).

The hay must be carefully stored under cover, in a building of some sort. A sheet will not do the job and hay will be spoiled!

The space required for hay is about 9 cubic yards (7 cubic meters) per tonne.

A 20 foot wide barn, will therefore hold, in each fifteen foot bay, about 18 tonnes when stacked 15 feet high.

This quantity will be enough to feed 9 cows and calves, or 72 medium sized sheep for a winter.

All these figures are approximations and will vary considerably with the quality of hay, the size of the livestock and the length of the winter.

A summary of our deliberations is:

1 Ha = 10,000 sq meters = 2.47 acres

1 acre = 4840 sq. yds = 4047 sq meters

1 acre yields about two tonnes of hay

1 Ha. will yield about five tonnes

1 LU = 1 cow & calf, or 8 sheep

1 LU requires 2 tonnes of hay

1 hay-barn bay holds about 18 tonnes

1 tonne of hay will be 40-45 small bales or 4 to 5 round bales.

Old wives (or NewLandOwner) tales: Interestingly, the measurement of an acre is said to be the area, which could be ploughed by one man with horses, in a day.

The Hectare is just a boring 100 meters square.

To contact "The Experts" at NewLandOwner for free telephone advice and help with your land: Tel. 01283 585 410

Email: r.jeffery@btconnect.com

www.newlandowner.co.uk

Write to; NewLandOwner, Aston House Farm, Sudbury, Ashbourne DE6 5AG