BD2304 Scoping study to assess soil compaction affecting upland and lowland in England and Wales

APPENDICES TO SID5

The appendices give more detail about each part of the project and include all relevant references at the end of each section.

APPENDIX 1 Mapping the extent of soil compaction (Work Package 1)

APPENDIX 2 The causes of soil compaction (Work Package 2a)

APPENDIX 3 The impacts of soil compaction (Work Package 2b)

APPENDIX 4 Conflicts and synergies within existing and potential ES options, between objectives relating to soil compaction and its remediation and other scheme objectives (Work Package 3)

APPENDIX 5 Responses received at the Stakeholder workshop (Work Package 5)

APPENDIX 6 Glossary of terms

Appendix to SID5 1 Soil compaction in England and Wales January 2008 APPENDIX3:Impacts of soil compaction

3.4 Impact of soil compaction on grassland systems on water resources and risk

3.4.1 Background Livestock numbers have generally risen over the past century. Between 1866 and 1980, the number of cattle increased threefold to 13,426,000, but this number declined to 10,345,000 in 2002. In 1922, 75% of UK cattle were in England & Wales, 15% in Scotland and 10% in N. Ireland. Little change took place in the 1930s and World War II. Cattle have become relatively less important in England & Wales since the mid 1950s (as land was more suitable for profitable crop production) while in Scotland and Northern Ireland the opposite has occurred.

Sheep and lamb numbers rose rapidly in the 1980s (a 60% increase above 1960 levels). Typically there were 25-30 m during the 1930s and World War II but this then fell to 17m in 1947. From 1956, profitability began to improve and the numbers rose to 30 m. Following CAP for sheep meat, numbers rose further in the 1980s to just under 40 m. The increases in recent years have also been due to a relative decline in profitability of suckler calf production in uplands and milk and beef production in other regions, resulting in a switch to sheep meat production. In some parts of the country, particularly Yorkshire and Cumbria, this increase was halted by the foot and mouth disease epidemic of 2001, but restocking of many farms took place soon after the outbreak was declared over.

Pig numbers increased from 4,500,000 in 1937 to 5,588,000 in 2002, down from a peak of 8,100,000 in 1970. There has been a movement to outdoor pig production, a trend which may increase as a consequence of legislation banning sow stalls (an indoor farming practice) in 1999 and other animal welfare issues.

3.4.2 Impacts of livestock

Introduction The following are extracts from Trimble and Mendel’s (1995) review paper on the cow as a geomorphic agent:

“Cows are important agents of geomorphological change. On the uplands, heavy grazing compacts the soil, reduces infiltration, increases runoff, and increases erosion and sediment yield. However, light and moderate grazing have effects that are much less significant. In riparian zones, grazing decreases erosional resistance by reducing vegetation and exposing more vulnerable substrate. Trampling directly erodes banks, thus increasing turbulence and consequent erosion.

Most landscapes are composed of mostly upland slopes and it is here that cattle have perhaps collectively their greatest effects. They directly reshape the earth, compact the soil and cause increased runoff, sometimes transforming the runoff regime from variable source area to unsaturated (Hortonian) overland flow. They further weaken biological resistance and trample and loosen soil, changing its susceptibility to both water and wind erosion.

The direct force of cattle hoofs reshapes the land. That force is often conceptually underestimated because it is conceived as static, i.e. the mass of the cow (typically 400-500 kg) divided by a few cm2 of basal hoof area. But in the movement of a cow, that mass is often transferred to one or two hooves and there is acceleration in the movement. Using a mechanical simulator, Scholefield and Hall (1986) calculated that a 530 kg cow would exert 250 kPa of vertical stress while walking on level ground. However, the process is best seen and most effective when a cow is climbing a steep slope. Then, the mass is often concentrated on the downslope rear leg which propels the animal some distance upslope. The most common

Appendix to SID5 70 Soil compaction in England and Wales September 2007 manifestation of direct force is the path or trail. Because the trails are less permeable (from compaction and crusting: Rostagno, 1989) and because they conduct water, they may erode to larger proportions (Hole, 1981) even under “light” grazing (Naeth et al., 1990). Cooke and Reeves (1976) speculate that concentration of runoff along such trails could help initiate downslope gully development and the work of Rostagno (1989) would appear to support such a suggestion.

Removal of phytomass by grazing and lessened phytomass production can reduce fertility and organic matter content of the soil. Soil aggregate stability is decreased and the surface sometimes becomes crusted. Proportion of bare soil appears to correlate well with surface runoff (and sediment yield) (Copeland, 1965; Lusby, 1970; Branson et al., 1981; Thurow et al., 1986; Warren et al., 1986; Takar et al., 1990; Bari et al., 1993).

Although the literature is very sketchy, it appears that fauna ranging from earthworms to moles have more difficulty surviving in the impacted soil condition resulting from heavy grazing (Hole, 1981; Abbott et al., 1979). Lusby (1970), working in western Colorado, found that runoff from a grazed watershed was 30% greater than that from an ungrazed watershed. Rauzi and Smith (1973) report that infiltration rates varied with grazing intensity on pastures in northeastern Colorado. Under “light” to “moderate” grazing, infiltration rates were 5.6 and 5.9 cm hr-1, respectively, of which about 30% of the total water infiltrated within the first 15 minutes. Under “heavy” grazing, the infiltration rate was 4.8 cm hr-1. Usman (1994) also found that infiltration rates decreased substantially under “moderate” and “heavy” grazing and he attributed these reductions to changes in soil structure. It will be observed that there is a general decrease of infiltration capacity with grazing intensity, but there is also large variance about all of the means.

Branson et al. (1981) cite several studies which investigate the recovery of soil infiltration rates with the cessation of grazing. Hydrologic recovery was evident within 3 years on pastures in southwestern Wisconsin, within 4 years on sandy loam soil in Utah, within 6 years on ponderosa pine-grassland and within 13 years on grassland locations in Colorado.

Overgrazing alters streambank morphology by creating false, setback banks (Kauffman and Krueger, 1984). A hoof can actually shear off slices of bank material ≤ 10 cm thick, pushing them toward the stream. The net results of grazing riparian areas, can be both (1) direct modification of stream channels and banks and (2) reduction of resistance to erosion by higher flows which promotes channel erosion. Grazing on riverine and upland areas usually go hand-in-hand so that riverine erosion is increased by the enhanced runoff regime from grazed upland areas.”

Soil compaction and infiltration

Livestock exert a significant pressure on soil. Godwin and Dresser (2003) noted that it is no coincidence that sheep were used to compact soils in canal beds and are used in compacting soils for earth dams and roadways. It is estimated that for a sheep with a body mass of 40 kg and area per foot of 0.0006 m2, the pressure under the sheep’s foot, when static, is approximately 160 kPa, but this could easily rise to 320 kPa when walking and to 480 kPa under dynamic conditions (Godwin and Dresser, 2003). Figure 16 shows the relationship between water table levels and the surface strength of a grassland soil, indicating that, under the shallow watertables common in many upland or poorly drained soils under grassland, compaction by livestock is likely.

Appendix to SID5 71 Soil compaction in England and Wales September 2007 Figure 16 The relationship between water table levels and the surface strength of a grassland (redrawn from Massey et al., 1974)

The problem is compounded by the fact that many of our grass growing regions are in areas of high rainfall. There is considerable economic pressure on livestock farmers to extend the grazing season so as to increase the proportion of grazed grass in animal diets and to increase grass utilisation by heavier grazing - grazed grass is much cheaper as a feed than the use of concentrates and less costly than using silage or hay. Headage payments have historically encouraged high stocking rates, but the replacement of these by area payments may help the situation.

These trends for increases in grazing pressure and extending the length of the grazing season result in more treading of the soil surface which leads to greater sealing of the soil (Figure 17). Overgrazing also leads to the appearance of more bare patches which tend to shed rainwater quickly rather than allowing it to infiltrate (Harris et al., 2004).

Figure 17 Topsoil compaction caused by poaching due to high stock density in cattle holding area (from Holman et al., 2001)

Dense, compacted surface layer with lack of soil structure

Improving structure with depth

Fieldwork in the Yorkshire Ouse, Severn, Uck and Bourne catchments in the winter of 2000/01, following the severe flooding of that autumn, showed significant proportions of grassland soils having soil structural degradation (Table 13) (Holman et al., 2003). In many case, this was

Appendix to SID5 72 Soil compaction in England and Wales September 2007 manifest in extensively poached soil surfaces and topsoil compaction leading to extensive areas of standing water and marked vertical wetness gradients (topsoil water content being significantly greater than in the subsoil). However, in some ley grassland sites, soil degradation was sufficient to cause extensive rill erosion.

Table 13 Observations of grassland soil conditions in 2000/01 (from Holman et al., 2003)

Soil degradation class

Low Medium High Severe

Few signs of Slight poaching Extensively Extensive rill enhanced (locally severe) poached erosion + runoff + localised surface + characteristics mechanisms. areas of extensive areas of Class H Localised standing water of standing poaching and water + topsoil standing water compaction + Catchment if whole profile vertical wetness maintains good gradient soil structure Yorkshire Ouse 14 12 13 0 Severn 12 11 10 0 Uck 4 11 14 2 Bourne 10 4 4 0

Early work by Holtan and Kirkpatrick (1950) clearly showed the effect of land cover and management on soil infiltration rates (Figure 18). In general, grassland and in particular long established permanent pasture has a higher infiltration rate than arable crops - especially during periods of the year when the latter are bare or crusted (Holtan and Kirkpatrick, 1950). The high infiltration rates shown for old pasture in Figure 18 and Table 14 can be attributed to the increase in voids and air spaces caused by soil fauna and earthworms, which give continuity of pores through the soil profile to depth (Godwin and Dresser, 2003).

Appendix to SID5 73 Soil compaction in England and Wales September 2007 Figure 18 Typical mass infiltration curve (from Holtan and Kirkpatrick, 1950)

Table 14 Final infiltration rates (from Holtan and Kirkpatrick, 1950)

Soil cover Final infiltration rate (mm hr-1)

Old permanent pasture 60 4-8 year old pasture 36 3-4 year old pasture, lightly grazed 30 Permanent pasture, moderately grazed 24 Hay 17 Permanent pasture, heavily grazed 15 Strip cropped, mixed cover 11 Arable 10 Bare soil, cultivated 9 Bare soil, crusted 5

However, grazing pressure also has a major impact on infiltration and runoff (Table 14) (Holtan and Kirkpatrick, 1950). Experimentation by Heathwaite et al. (1990) with a rainfall simulator and runoff plot monitoring in the Slapton Catchment in South Devon showed that heavy grazing of permanent grassland resulted in an 80 percent reduction in the infiltration capacity. Clark (1997) showed significant differences between the saturated hydraulic conductivity of topsoils under grassland and woodland in the Upper Brue catchment, Somerset (Figure 19). Similar results are reported in Clark (1987) and Clark (2005).

Meyles et al. (2001) worked on a small Dartmoor catchment in Devon and found that soils associated with areas of intense sheep grazing had a significantly lower porosity, causing a reduction in hydraulic conductivity. Soil water contents in the topsoil at the standard matric pressures were also reduced with increasing grazing pressure (Meyles et al., 2006)

Appendix to SID5 74 Soil compaction in England and Wales September 2007 Figure 19 Saturated hydraulic conductivity of grassland and woodland soils in the Upper Brue catchment (from Clark, 1997)

Runoff generation According to Harris et al. (2004), the emerging consensus view is that changes in grassland husbandry techniques, especially in the last 20 years has led to greatly increased levels of surface runoff. Increased stocking rates have led to a trampling effect, where the soil surface is sealed and infiltration greatly reduced (Godwin and Dresser 2003). Such differences in infiltration rate or hydraulic conductivity might be expected to produce differences in runoff generation. Poaching by livestock promotes the occurrence of overland flow in some circumstances in the view of Leinweber et al. (2002).

Measurements by Heathwaite et al. (1989) showed that surface runoff from heavily grazed permanent pasture in Devon was 53% of total rainfall compared to 7% from ungrazed land. Poaching or severe trampling of grassland around feeding troughs and in gateways are point sources of surface runoff. Heathwaite et al. (1990), using a rainfall simulator and runoff plot monitoring in the Slapton catchment in South Devon, showed that surface runoff from overgrazed permanent grassland was double that from lightly grazed areas, and at least twelve times that from ungrazed areas.

Samson (1996) points to the "well documented" evidence that sheep damage the uplands by overgrazing leading to loss of heather, poaching of the soil surface, degradation of river banks, and accelerated erosion. She suggests that "sheep may be causing enough loss of vegetative

Appendix to SID5 75 Soil compaction in England and Wales September 2007 cover and serious poaching of the soil surface to lead to increased runoff rates and thus to an increase in the likelihood of serious " (p2). She notes that at Mickley Weir on the River Ure, the highest recorded floods (since 1982) have increased in [almost] chronological order and cites qualitative evidence that the time scale of spates in the Dales rivers has become much shorter. She gives more weight to the effects of sheep rather than of drainage because "the main period of drainage was earlier during the 1960s and 1970s" (p2), and calls for more investigations into whether there is a link between sheep and floods. According to O’Connell et al. (2004), the analysis presented by Samson (1996) makes a reasonable case for stocking densities of sheep to have an effect on flood runoff production but is not backed up by a quantitative analysis.

There are ongoing studies of upper Wharfedale at Leeds University which also suggest a significant impact of sheep on runoff production. According to O’Connell et al. (2004), research at Leeds University (Prof S. Lane) was reported in the Daily Telegraph (2/4/03, page 14) with the headline “Flooding is blamed on sheep and cows”. Prof S. Lane was quoted as saying that large increases in sheep and cattle stocking densities have trampled upland pasture to such an extent that the ground now absorbs less water. However, no controlled experimental studies of the effects of stocking densities on runoff production in the UK were found by O’Connell et al. (2004).

Mutter and Burnham (1990) concluded that runoff on plots at Wye College in Kent was very much lower in undisturbed grass than on bare soil (akin to the effects of sheep grazing). Fullen (1992) found consistently low runoff rates on grassland plots in Shropshire compared to bare soil where runoff was high.

Appendix to SID5 76 Soil compaction in England and Wales September 2007 3.4.3 Methods for quantifying the effect of land management on flood generation and water resources

Two main methods have been previously used to provide preliminary quantification of the hydrological effects of agricultural land management in the UK. The Curve Number method has been used by Godwin and Dresser (2003) and Holman et al. (2003), and the Hydrology of Soil Types (HOST) by Packman et al. (2004).

Curve Number

The USDA developed the Soil Conservation Service (SCS) method for the estimation of direct runoff from storm rainfall in agricultural catchments. This is an easy to understand and use (Ponce and Hawkins, 1996) event-based lumped model, which has been extended to allow it’s incorporation into widely-used continuous hydrological models, including EPIC (Williams, 1995) and SWAT (Arnold et al., 1998).

The SCS method has its origins in empirical analyses of rainfall-runoff data from a number of hillslope plots and small catchments in the US (Mockus, 1949, cited by O’Donnell et al., 2004). It is usually interpreted as an infiltration excess equation, but the method incorporates some empirical knowledge of fast runoff generation (see Beven, 2001b for discussion of background and other interpretations of the SCS equation). The equation for runoff from an event is:

where Q is runoff, P is rainfall, S is potential maximum storage retention and Ia is the initial abstraction (all in inches). The initial abstraction is the amount of water required for runoff to start, which, in a physical interpretation, should be dependent on interception storage, infiltration and surface storage. The SCS recommends that the initial abstraction Ia should be set to 0.2S, which leaves the maximum storage potential, S, defined as:

where the dimensionless curve number CN has a value between 0, representing a catchment with unlimited storage (Q=0), and 100, representing an impervious surface (Q=P- Ia).

Tables are available for relating CN to: (1) hydrologic soil group, defined in terms of infiltration rate; (2) land use/treatment class, defined for various types of vegetations, crops and urban environments; and (3) surface condition, which indicates the effect of cover condition on infiltration, usually estimated from plant density and residue cover.

Although a single value of CN may not be applicable to similar conditions over the entire US (Pilgrim and Cordery, 1993), which implies that US-derived CN values should not be used under UK conditions, the Curve Number-based SWAT model is widely used across Europe (including the UK) and performed well in the EC EUROHARP project. The effects of soil compaction can be incorporated either through changing the Curve Number to that for poor soil conditions (Holman et al., 2003) or by changing the Soil Hydrological Group to reflect lower infiltration rates(Godwin and Dresser, 2003).

HOST class

Appendix to SID5 77 Soil compaction in England and Wales September 2007 The FEH rainfall-runoff model, as detailed in volume 4 of the Flood Estimation Handbook (Institute of Hydrology, 1999) uses Standard Percentage Runoff (SPR) which separates flow into slow and fast response components. SPR is the percentage runoff derived from event data, adjusted to standard rainfall and catchment moisture conditions (Boorman et al., 1995). In Packman et al. (2004), a procedure was developed for adjusting SPR, based on an intuitive approach that accounts for the effects of soil degradation through a reclassification of HOST classes.

The HOST system (Boorman et al, 1995) provides values of Baseflow Index (BFI) and SPR values for each of the 29 HOST class. To assess the likely effect of soil compaction due to future land use/management practices, revised SPR values have been proposed for each HOST class by Packman et al. (2004) by assigning an appropriate analogue HOST class to represent the degraded soil. The rationale for the proposed changes is that soil structural degradation, in the form of topsoil and upper subsoil compaction or seasonal ‘capping’ and sealing of soil surfaces, causes a reduction in the effective soil storage, which in turn results in increased surface runoff. Increased surface runoff on a specific HOST class will give an increased SPR value, assuming that there is no change in the proportion of the surface runoff that is transferred from the fields to the surface water network i.e. that the effects of landscape connectivity remain unchanged. Thus the general principle is that soil structural degradation affects the soil storage / wetness component of the HOST classification but does not alter the hydrogeological component.

In addition, alternate SPR values were derived from the analogue HOST class using the relationship between BFI and SPR presented in the FEH (v4, p28): SPR = 72 - 65.5 BFI (1)

Packman et al. (2004) suggests that the two degraded SPR values are applied as two ‘worst- case’ or ‘fully degraded’ scenarios to all of a catchment’s area under cereal or lowland grass cover.

Table 15 HOST class, analogue, SPRHOST, revised and alternate degraded SPR (from Packman et al., 2004) HOST Class 1 2 3 4 5 6 7 8 9 10 Analogue 3 3 7* 6* 7* 8 7* 8 9 10 Original SPR 2 2 15 2 15 34 44 44 25 25 Revised SPR1 14 14 27 15 27 44 44 44 25 25 Alternate SPR2 9 9 22 11 22 39 48 44 25 25 HOST Class 11 12 13 14 15 16 17 18 19 20 Analogue 11 12 3* 24 15 18* 18 20 22 20 Original SPR 2 60 3 25 48 29 29 47 60 60 Revised SPR 2 60 15 40 48 47 47 59 60 60 Alternate SPR 2 60 9 30 48 41 35 55 60 60 HOST Class 21 22 23 24 25 26 27 28 29 Analogue 23 27 25 25 25* 26 27 28 29 Original SPR 47 60 60 40 50 59 60 60 60 Revised SPR 60 60 60 49 60 59 60 60 60 Alternate SPR 55 60 60 47 60 59 60 60 60 ‘*’ represents a greater degree of uncertainty in its appropriateness. 1 Based on the SPR (from Boorman et al., 1995) of the analogue HOST class 2 Based on SPR calculated from equation 1 using the BFI (from Boorman et al., 1995) of the analogue HOST class

Indicative assessment of hydrological Impact of grassland soil compaction

Methodology

Appendix to SID5 78 Soil compaction in England and Wales September 2007 An indicative assessment of the potential hydrological impact of grassland soil compaction has been carried out using a modification of the FD2114 method proposed as a short-term improvement to the FEH rainfall-runoff model (Packman et al., 2004). Packman et al. (2004) suggests that the degraded SPR values are applied to all of a catchment’s area under cereal and lowland grass cover. This provides a‘worst-case’ or ‘fully degraded’ scenario which is unlikely to be representative of conditions in the catchment.

The assessment of the effect of grassland soil compaction on flood risk in this current study have been based on the following method and assumptions:  The dominant HOST class in each 1 x 1 km grid square in England and Wales has been derived from the 1:250,000 scale National Soil Map of England and Wales  Data on the area of managed grassland in each 1 x 1 km grid square have been provided from the June agricultural census data  Each 1 x 1 km grid square therefore has a single HOST class, Poaching Risk class and proportion of grassland.  The area of each grid square that is not grassland soils has been allocated a ‘normal’ SPR as given in Boorman et al. (1995), according to the HOST Class.  The area of each grid square that is grassland in grid squares of Poaching Risk class 1 has been allocated the ‘normal’ SPR for the HOST class (as given in Boorman et al., 1995) owing to the low risk to compaction due to one or both of low livestock numbers and non-vulnerable soils;  The area of each grid square that is grassland in grid squares of Poaching Risk class 3 have been allocated a ‘degraded’ SPR from their analogue HOST class as given in Table 3 from Packman et al. (2004) owing to their high risk to compaction due to high livestock numbers and vulnerable soils  The area of each grid square that is grassland in grid squares of Poaching Risk class 2 have been allocated a SPR which is midway between those given in Boorman et al. (1995) and Packman et al. (2004).  A catchment-average SPR has been calculated based on an area-weighting of the relevant SPR values for the non-grassland soils and grassland soils in Poaching Risk classes 1-3.  The catchment-average change in SPR has been calculated as the difference from that calculated using the original SPR values from Boorman et al. (1995)

A similar indicative assessment has been made on the potential impacts on water resources through using the Base Flow Index (BFI) of the analogue HOST class.

Results

The results of the assessment, which are expressed as an absolute increase in SPR (or absolute decrease in Base Flow Index) are given in Figures 20 and 22.

Figure 20- shows that the indicative absolute increase in SPR is less than 6 %, with the area of generally greatest increases being in the south west. Figure 21 shows that the largest increases in SPR are generally found in the catchments with SPR’s according to Boorman et al. (1995) of 25 – 45%. Catchments with low SPR’s (i.e. less than 25%) are generally found in chalk, sandstone and limestone landscapes, where the well drained soils, relatively dry climate and arable dominated farming systems limit the potential for compaction of grassland soils. The catchments with the highest SPR’s in Fig. 21 which show little impact from grassland soil compaction represent upland catchments with little managed grassland due to wet soil conditions.

The small absolute increases in SPR represent relative increases of less than 13 % in most catchments, although a number (mostly in the south west) show indicative increases of 13 - 41 % (Figure 20). However, the relative increases in SPR are much lower than those reported in plot

Appendix to SID5 79 Soil compaction in England and Wales September 2007 studies (e.g. Heathewaite et al., 1989, 1990) representing the moderating effects of landscape connectivity.

Appendix to SID5 80 Soil compaction in England and Wales September 2007 Figure 20 Indicative increases in Standard Percentage Runoff (SPR) due to grassland soil compaction – (left) absolute increase and (b) relative increase

Appendix to SID5 81 Soil compaction in England and Wales September 2007 ) 60 % (

f f 50 o n u R

40 e g a

t Degraded SPR

n 30

e Original SPR c r e

P 20

d r a

d 10 n a t

S 0 1 86 171 256 341 426 511 596 681 766 851 Catchments

Figure 21 Indicative catchment SPR incorporating the effects of grassland soil compaction, ordered by catchment SPR using Boorman et al. (1995)

As would be expected, the spatial patterns in the change in Base Flow Index (Figure 22) is similar to that for SPR, as increased runoff to surface water is reflected in reduced infiltration and recharge. Indicative changes in catchment BFI are less than 8 %, which represents a small reduction in groundwater resources and summer surface flows but which may be significant in catchments with limited water availability.

Figure 22 Indicative absolute decreases in Baseflow Index (BFI) due to grassland soil compaction

Appendix to SID5 82 Soil compaction in England and Wales September 2007 References

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Appendix to SID5 83 Soil compaction in England and Wales September 2007 Meyles, E. W., Williams, A. G., Ternan, J. L. and Anderson, J. M. (2001). Effects of grazing on soil properties and hydrology of a small Dartmoor catchment, southwest England. In Regional Management of Water Resources. Proceedings of a Symposium held during the Sixth IAHS Scientific Assembly. Edited by A. H. Schuman, M. C. Acreman, R. Davis, M. A. Marino, D. Rosbjerg and J. Xia, IAHS Press, Wallingford, UK, Maastricht, Netherlands, 18-27 July 2001, pp. 279-286. Meyles, EW, Williams AG, Ternan JL, Anderson JM and Dowd JF (2006). The influence of grazing on vegetation, soil properties and stream discharge in an small Dartmoor catchment, southwest England, UK. Earth Surface Processes and Landforms, 31, 622-631. Mockus, V., 1949. Estimation of total (and peak rates of) surface runoff for individual storms. Exhibit A of Appendix B, Interim Survey Report, Grand (Neosho) River Watershed, USDA. Mutter, G. M. and Burnham, C. P. (1990). Plot studies comparing water erosion on chalky and non-calcareous soils. In Soil Erosion on Agricultural Land. Proceedings of a Workshop Sponsored by the British Geomorphological Research Group. John Wiley & Sons Ltd, Chichester, UK, Coventry, UK, January 1989. pp. 15-23. Naeth, M. A., Pluth, D. J., Chanasyk, D. S., Bailey, A. W., and Fedkenheuer, A. W. (1990). Soil compacting impacts of grazing in mixed prairie and fescue grassland ecosystems of Alberta. Canadian Journal of Soil Science 70, 157-167. O’Donnell G. M., O’Connell P. E. and Quinn P. F. (2004). Review of impacts of rural land use and management on flood generation: Impact study report Appendix B: data analysis and modelling at the catchment scale. Defra R&D Technical Report FD2114/TR Packman J.C., Quinn P.F., Hollis J. and O’Connell P.E. (2004). Review of impacts of rural land use and management on flood generation- Short-term improvement to the FEH rainfall- runoff model: Technical background Defra R&D Project Record FD2114/PR3 Pilgrim, D.H. and Cordery, I., 1993. Flood runoff. In: D.R. Maidment (Editor), Handbook of Hydrology. McGraw-Hill, New York, Chapter 9. Ponce, V.M. and Hawkins, R.H., 1996. Runoff curve number: Has it reached maturity? Journal of Hydrologic Engineering, 1(1): 11-19. Rauzi, F., and Smith, F. M. (1973). Infiltration rates: three soils with three grazing levels in northeastern Colorado. Journal of Range Management 26, 126-129. Rostagno, C. M. (1989). Infiltration and sediment production as affected by soil surface conditions in a shrubland of Patagonia, . Journal of Range Management 42, 382- 385. Samson, A., 1996. Floods and sheep - is there a link? Circulation, 49: 1-4. Scholefield, D. and Hall, D. M. (1986). A recording penetrometer to measure the strength of soil in relation to the stress exerted by a walking cow. Journal of Soil Science 37, 165-176. Thurrow, T. L., Blackburn, W. H. and Taylor, C. A. (1986). Hydrologic characteristics of vegetation types as affected by livestock grazing systems, Edwards Plateau, Texas. Journal of Range Management 39, 505-509. Takar, A. A., Dobrowolski, J. P. and Thurrow, T. L. (1990). Influence of grazing, vegetation, life-form and soil type on infiltration rates and interrill erosion on a Somalian rangeland. Journal of Range Management 43, 486-490. Trimble, S. W. and Mendel, A. C. (1995). The cow as a geomorphic agent – a critical review. Geomorphology 13, 233-253. Usman, H. (1994). Cattle trampling and soil compaction effects on soil properties of a northeastern Nigerian sandy loam. Arid Soil Resource Rehabilitation 8, 69-75. Warren, S. D., Blackburn, W. H., and Taylor, C. A. (1986). Soil hydrologic response to number of pastures and stocking density under intensive rotation grazing. Journal of Range Management 39, 500-504. Williams, J.R., 1995. The EPIC model. In: V.P. Singh (Editor), Computer Models of Watershed Hydrology. Water Resource Publications, Ranch, Colorado, pp. 909- 1000.

Appendix to SID5 84 Soil compaction in England and Wales September 2007