This has been a very late spring and grass in our hills and uplands is only now beginning to grow again. On lower-lying farms there is some grass, but many fields on heavier land are still too wet to safely graze with cattle without the risk of trampling or poaching the pasture.

It's been an exceptionally long winter for many livestock farmers, and most are anxious to get their cattle back out to grass as they have almost run out of silage and straw.

Last year's wet summer forced many to bring their cattle indoors much earlier than usual to prevent them poaching the fields. At the same time as cattle were prematurely munching their way through scarce winter supplies of silage, many farmer's were struggling to finish silage making in the atrocious weather, and some crops of grass were left uncut.

Many eke out scarce stocks of silage by feeding straw to cattle, but it was scarce last autumn. One of the reasons is that modern cereal varieties have shorter straw so they can carry heavy yields of grain without going flat in windy, wet weather. In addition, the volume of straw grown last year was down by about 30 per cent in some areas as a result of poorer growing conditions.

Then there was the wet weather at harvest. As crops become weathered the straw shrinks in volume, rather like a woollen garment can do after washing. Even after combining it continues to shrink in the rows, or swathes as we call them, in a wet spell, particularly if it is worked-up in a good day to speed up the drying process ready for baling. There were few opportunities for that last autumn, and countless fields were left with wet straw lying that was never baled - although I saw a field being baled this February after a cold, dry spell.

One of the problems with straw is that many arable farmers regard it as a by-product at best and a nuisance at worst because valuable dry days are needed to get it baled before the fields can be cleared to allow the next crop to be sown. That uses men and machinery at a busy time when harvesting is still underway and next year's crops have somehow to be sown.

Modern combines can have straw-choppers fitted that chop up the straw as it leaves the combine and spreads it on the land. It is then incorporated into the soil as part of preparation for sowing the next crop, as well as returning valuable crop nutrients to the land.

Typically the UK produces between 11 and 12 million tonnes of straw annually of which about 5.5m tonnes are incorporated into the soil.

Latest complication for the dynamics of the straw market is the increasing popularity of burning straw - mostly wheat straw - to generate electricity. That currently uses about 0.8m tonnes annually.

Most livestock farmers in the west of Scotland only use straw as bedding for pregnant cows about to calve, young calves that are still being reared, and ewes in lambing sheds. Other cattle like cows are kept in cubicles where dung passages are automatically scraped at regular intervals, while a fair number of young cattle are kept on slatted floors where dung and urine falls through slots between the concrete slats into storage vaults below. Straw has become too expensive to use as bedding, and matters were made worse recently by Irish merchants importing straw from England.

Spot market straw prices in Scotland have risen around £50/tonne since harvest 2017 due to scarcity. Prices recently rose to around £130/t delivered in the Central Belt with more remote areas in the west and north paying another £15-£20/t, and the islands more again.

To give an idea of the scale of the problem, economists estimate that an example 110 cow upland beef herd may have incurred additional costs this winter of around £8,000 due to higher straw use as a result of the extended housing period and the higher straw prices, leading to a potential reduction of 19 per cent in beef enterprise gross margin. Little wonder that farmers are so anxious to turn their cattle out to grass.

Dairy farmers, who haven't already done so, will start turning their cows out to grass after the morning milking, but most will keep them indoors overnight after the afternoon milking, until it becomes warmer. That system also allows milking cows to adjust to their new diet of lush spring grass, by continuing to eat their winter rations at night in the sheds.