Soil Compaction

Many meadows and pastures suffer soil compaction due to the regular passing of heavy machinery and high stocking rates. This can increase run-off during rainfall events and result in the delivery of fine sediments and nutrients to watercourses that can have significant impacts on river ecology. Soil compaction also has impacts on farm yields. If compaction impedes the root stock from penetrating into the soil layers then plant growth, and nutrient uptake, is reduced. This can result in poor crops of silage and hay which are required for feeding stock through the winter months; which is especially important in upland locations where growing seasons are short and winters long.

There are methods to improve conditions where soil compaction has occured. Sub-soil ploughs can penetrate below the compacted layer and break the soil allowing root penetration. This is not always possible in upland regions where soils can be thin with bedrock and boulders close to the surface. Steep slopes can also hinder the use of sub-soil ploughs. Aerators are often a better solution in such locations. These simple rotary blades penetrate into the soil and through the compacted layer allowing greater yields due to oxygen replensihment of the soil and root growth beyond the compacted layer.

If this is carried out in conjunction with newer methods of slurry spreading then yields can be massively improved. Two methods that appear to improve nutrient uptake are dribble bars and slurry injectors. These reduce the liklihood of run-off and allow improved use of a nutrient resource. If carried out alongside aerators and soil testing, for nutrient levels and pH, then savings in time and money can be passed onto the farm enterprise. Often pH levels can be lower then optimal and testing can identify where lime is required. This raises the pH and improves plant nutrient uptake. Soil testing can also idnetify which fields have high levels of phosphates and so allows the farmer to reduce inputs saving them money on fertiliser purchase.

These kind of options, if built into the farm plan, can be beneficial to the farmer and help improve the ecological condition of rivers. Cost of the machinery can be prohibitive but presently there are grants that can help with purchasing the kit. For example Yorkshire Forward's Farm Resource Efficiency Programme grants (FREP: www.yorkshire-forward.com/helping-businesses/rural-businesses/funding/frep) will pay up to 60% of costs. It will even pay up to 50% of costs for the pruchase of one piece of kit for contractors. These grants can make such options feasible for the farmer, either to purchase the kit directly or through their contractors.

Hay time



Soil profiles can help identify if compaction has occurred



Slurry injector





Dribble bar on umbilical

PINPOINT

Just leaving Cornwall after a week learning how to identify and tackle diffuse pollution of rivers using the PINPOINT method. Its the end of October and the weather has been impresive, hitting 18 to 20 degrees most days. Three of my fellow students spent their mornings swimming off the North coast. It wasn't for me, as much for the 5am starts as anything.

The course was run by the West Country Rivers Trust and the Association of Rivers Trusts. We were given a great insight into the work the West Country Rivers Trust have carried out down in Cornwall and Devon on finding win-win situations with landowners and farmers to reduce inputs of sediments and nutrients to rivers. This improves in-stream habitats and increases Salmon and Trout numbers. It also creates a deeper understanding between farming and conservation creating less polarised views.

It was good to see a variety of farms from high intensity dairy operations to low input extensive organic smallholdings. The contrast between the two was fascinating. We saw how dairy operations can concentrate nutrients over a small area of land whilst more extensive systems gave us a view into a nearly lost pastoral English landscape that provides a true habitat mosaic. What was even more intriguing was the mix of options between the two systems that helped tackle diffuse pollution. Simple measures such as fencing river banks, putting hard coverings around supplementary feeders, sub-soiling to reduce soil compaction and coppicing multi-stem river bank trees to reduce shading and increase ground cover all enhance riparian habitats and break the links between erosion sources and watercourses.

Its now the turn of myself and my fellow students and rivers trusts colleagues to roll out similar schemes around the country. Its only by working with agricultural communities that we will find ways to reduce diffuse pollution without impacting on farm incomes. Many of the options available will even save time and money.

The intricacies of the dales

The little intricate waterfalls of the dales are the hidden gems of this land. Everyone knows the big famous ones like Aysgarth and Hardraw (both of which have had visits by Kevin Costner) but tucked away on some of the small high altitude streams are jewels of waterfalls that are rarely visited. Some of these are virtually dry but surge into life once the clouds burst. These ephemeral places contain ecology trained by evolution to cope with constant change.

Walks over the hills brings a natural closeness with the land. You can become lost in the scales here. One moment watching pipits swarm across coarse grass swards to pick at tiny beetles the next taking in wide vistas or your vision being tunnelled down a far winding dale. Hills like Ingleborough and Pen-y-ghent always seem to break into the skyline. Their obvious stepped tops revealing millions of years of strata, borne from scales we can barely grasp.

Heading over the top from Ballowfields the sound of water rushing beneath scree piles highlights that you are walking over limestone. The rock is taken into solution by acidic rain and streams drop underground forming caves and caverns from the tiniest of sink holes that swallow water with a giants thirst.

The water here doesnt behave as expected. Below the summit of Addleborough, a brooding hill that decieves its low altitude, is a waterfall dry for most of the year. Water is swallowed from the stream above and as you walk over the land you can hear it bubbling and gurgling beneath the surface like a hungry stomach. And at the lower reaches of the redundant waterfall it re-emerges from two places before combining back into one of the best trout spawning streams of Wensleydale.

And if you walk the other way, towards Addleborough top, calcareous flushes clear and potable emerge from the ground. Just metres from their source they mix with dark peaty streams and then for a short distance two different waters flow side by side till they become mixed, their pH and chemistry settling somewhere between the two.

In many ways water has shaped this land. Over 300 million years ago coral reefs grew in tropical waters and their remnants now form the majority of rock in the dales. Then huge columns of frozen water scraped the land forming u-shaped valleys that are the prominent feature of the landscape. After this liquid water ran over the surface of these scraped clean valleys cutting narrow V's in the land and dissolving the rock to form the caves and caverns that form underground mosaics like fungal hyphae. This isn't a perfect timeline of the processes but the idea of how these places were formed is there.


In the last few thousand years people cultivated the land and our signals can be seen all over the floodplains and down to the Humber estuary. A soil core of these plains shows that the rate of sediment movement increased massively after we cleared the original vegetation. It shows that we can have bigger impacts on the land then we suppose. But it is this patchwork of fields delineated by dry stone walls created by farming that is one of the biggest draws to the dales, and rightly so.

Modelling at the catchment scale

Understanding how water moves across the land and what chemicals and sediments it delivers to rivers is vital to the understanding of river ecology. The rivers trust movement has played a key role in recent years by helping to decipher how catchment processes control river morphology and how morphology and water quality affect ecology.

Excessive fine sediment in upland rivers degrades river habitats by clogging up the spaces between the gravel. This reduces egg survival of Salmon and Trout and changes the macroinvertebrate communities by favouring organisms such as Chironimidae worms over Stonefly and Mayfly.

A number of rivers trusts including the Yorkshire Dales Rivers Trust have been using a modelling tool developed by Durham and Lancaster universities called SCIMAP (Sensitive Catchment Integrated Modelling and Analysis Platform). This provides detail on where fine sediment is likely to be delivered to a watercourse based on slope, landcover and its associated erosion risk and rainfall.

SCIMAP outputs show the average risk for in-stream fine sediment in any catchment being modelled with a number of risk classes either side of the average ranging from high risk (red) to low risk (green). Underneath this output is a second output in grey that highlights the land parcels of a catchment most likely to be the source of the sediment. From this it is easy to locate the red 'streams' and then look up stream for the most likely locations that are delivering the sediment. Some ground truthing is then necessary but once the risk has been established it is possible to enter negotiations for changing land management to methods that can reduce these inputs. Simple measures such as buffer strips or contour planting of trees slows surface run off allowing sediment to settle out before the water reaches a watercourse.

This has the benefit of reducing the degradation of rivers and streams and allows species composition to restore itself back to the natural community of the river type. It is these simple habitat measures, developed through catchment scale thinking, that will restore habitats to something like their potential. This kind of large scale thinking is constantly developing which makes working as part of a rivers trust an exciting and rewarding vocation.