Ingrebourne Valley Ltd Agricultural Land Classification ...

May 2018

Ingrebourne Valley Ltd

Agricultural Land Classification and Soil Resources

Proposed Elton Quarry Extension, Land North of A605, Warmington

Beechwood Court,

Long Toll, Woodcote,

RG8 0RR

01491 684 233

readingagricultural.co.uk

7941 1

1 Introduction

1.1 Reading Agricultural Consultants Ltd (RAC) is instructed by Ingrebourne Valley Ltd to investigate

the Agricultural Land Classification (ALC) and soil resources of land at Warmington, by means of

a detailed survey of soil and site characteristics.

1.2 Guidance for assessing the quality of agricultural land in England and Wales is set out in the

Ministry of Agriculture, Fisheries and Food (MAFF) revised guidelines and criteria for grading the

quality of agricultural land (1988)1 , and summarised in Natural England's Technical Information

Note 0492.

1.3 Agricultural land in England and Wales is graded between 1 and 5, depending on the extent to

which physical or chemical characteristics impose long-term limitations on agricultural use. The

principal physical factors influencing grading are climate, site and soil which, together with

interactions between them, form the basis for classifying land into one of the five grades.

1.4 Grade 1 land is excellent quality agricultural land with very minor or no limitations to agricultural

use, and Grade 5 is very poor quality land, with severe limitations due to adverse soil, relief,

climate or a combination of these. Grade 3 land is subdivided into Subgrade 3a (good quality

land) and Subgrade 3b (moderate quality land). Land which is classified as Grades 1, 2 and 3a in

the ALC system is defined as best and most versatile agricultural land.

1.5 As explained in Natural England's TIN049, the whole of England and Wales was mapped from

reconnaissance field surveys in the late 1960s and early 1970s, to provide general strategic

guidance on agricultural land quality for planners. This Provisional Series of maps was published

on an Ordnance Survey base at a scale of One Inch to One Mile (1:63,360). The Provisional ALC

map shows the site as undifferentiated Grade 3 land. However, TIN049 explains that:

"These maps are not sufficiently accurate for use in assessment of individual fields or development

sites, and should not be used other than as general guidance. They show only five grades: their

preparation preceded the subdivision of Grade 3 and the refinement of criteria, which occurred

after 1976. They have not been updated and are out of print. A 1:250 000 scale map series based

1 MAFF (1988). Agricultural Land Classification of England and Wales. Revised guidelines and criteria for grading the quality of agricultural land. MAFF Publications.

2 Natural England (2012). Technical Information Note 049 - Agricultural Land Classification: protecting the best and most versatile agricultural land, Second Edition.

7941 2

on the same information is available. These are more appropriate for the strategic use originally

intended …"

1.6 TIN049 goes on to explain that a definitive ALC grading should be obtained by undertaking a

detailed survey according to the published guidelines, at an observation density of one boring

per hectare. This survey follows the detailed methodology set out in the MAFF guidelines.

2 Site and climatic conditions

General features, land form and drainage

2.1 The site extends to approximately 20ha of agricultural grassland and is surrounded on all sides

by the River Nene and to the south-east by the A605.

2.2 Topography is predominantly flat across the area at an elevation of 18m above Ordnance Datum

(AOD).

Agro-climatic conditions

2.3 Agro-climatic data for the site have been interpolated from the Meteorological Office’s standard

5km grid point data set at a representative altitude of 18m AOD, and are given in Table 1. The

site is moderately warm and dry with large crop moisture deficits. The number of Field Capacity

Days (FCD) is lower than is typical for lowland England and is very favourable for providing

opportunities for agricultural field work. There is no climatic limitation to the ALC Grade.

Table 1: Local agro-climatic conditions

Parameter Value

Average Annual Rainfall 583 mm

Accumulated Temperatures >0°C 1,442 day°

Field Capacity Days 111 days

Average Moisture Deficit, wheat 118 mm

Average Moisture Deficit, potatoes 113 mm

7941 3

Soil parent material and soil type

2.4 The principal bedrock geology mapped by the British Geological Survey3 across the site is the is

the Grantham Formation comprising sandstone, siltstone and mudstone. A smaller band of the

Rutland Formation underlays the eastern side of the site made up of mudstone and siltstone

with subordinate beds of sandstone and limestone.

2.5 Alluvial superficial deposits overlie the bedrock and comprise clay, silt, sand and gravel.

2.6 The Soil Survey of England and Wales soil association mapping4 (1:250,000 scale) shows the

Fladbury 1 association across the site. These soils are deep clayey alluvial soils commonly found

on the flanks of rivers. Profiles are usually slowly permeable, although the main source of

waterlogging comes from raising ground water level associated with changes in river level. Soils

in this profile are commonly assessed as Wetness Class (WC) V or IV5.

3 Agricultural land quality

Soil survey methods

3.1 In total, 19 soil profiles were examined using an Edelman (Dutch) auger at an observation

density of one per hectare in accordance with the established recommendations for ALC

surveys2. Two observation pits were also excavated to examine subsoil structures. The locations

of observations are indicated on Figure RAC8063-1. At each observation point the following

characteristics were assessed for each soil horizon up to a maximum of 120cm or any

impenetrable layer:

• soil texture;

• significant stoniness;

• colour (including localised mottling);

• consistency;

• structural condition;

• free carbonate; and

3 British Geological Survey (2018). Geology of Britain viewer, http://mapapps.bgs.ac.uk/geologyofbritain/home.html

4 Soil Survey of England and Wales (1984). Soils of Eastern England. (1:250,000), Sheet 4

5 Hodge et al (1984). Soils and their Use in Eastern England. Soil Survey of England and Wales Bulletin No 13

7941 4

• depth.

3.2 One topsoil sample was submitted for laboratory determination of particle size distribution, pH,

organic matter content and nutrient contents (P, K, Mg). Results are presented in Appendix 1.

3.3 Soil Wetness Class (WC) was inferred from the matrix colour, presence or absence of, and depth

to, greyish and ochreous gley mottling, and slowly permeable subsoil layers at least 15 cm thick,

in relation to the number of Field Capacity Days at the location.

3.4 Soil droughtiness was investigated by the calculation of moisture balance equations (given in

Appendix 2). Crop-adjusted Available Profile Water (AP) is estimated from texture, stoniness and

depth, and then compared to a calculated moisture deficit (MD) for the standard crops wheat

and potatoes. The MD is a function of potential evapotranspiration and rainfall. Grading of the

land can be affected if the AP is insufficient to balance the MD and droughtiness occurs.

Agricultural land classification and site limitations

3.5 Assessment of land quality has been carried out according to the MAFF revised ALC guidelines

(1988)1. Soil profiles have been described according to Hodgson (1997)6 which is the recognised

source for describing soil profiles and characteristics according to the revised ALC guidelines.

3.6 The main limitations to agricultural land quality at this site is flood risk and soil wetness, which

restrict the site to Subgrade 3b and Grade 4.

3.7 Flood risk has been determined using mapped data from the Environment Agency. This data

shows three zones of flood risk. Flood Zone 1 has a low probability of flooding, Flood Zone 2 has

a medium probability, Flood Zone 3a has a high probability and Flood Zone 3b comprises land in

the functional floodplain7.

3.8 There is one topsoil type across the site. Topsoil is of dark greyish brown, dark olive brown

(2.5Y4/2, 3/3 in the Munsell soil colour charts8) silty clay to heavy silty clay loam of 20cm

average depth. The topsoil is stoneless across the site with a well-developed granular structure.

There is one exception to this topsoil pattern, at observation number 1 where topsoil is of olive

brown (2.5Y4/3) clay.

3.9 Where heavy silty clay loam topsoil is recorded a transitional layer between topsoil and subsoil

can be seen by the presence of light olive brown (2.5Y5/3, 5/4) silty clay between depths of

6 Hodgson, J. M. (Ed.) (1997). Soil survey field handbook. Soil Survey Technical Monograph No. 5, Silsoe. 7 Environment Agency (2018). Flood map for planning. Available: https://flood-map-for-planning.service.gov.uk/. Last accessed 15/03/3018. 8 Munsell Color (2009). Munsell Soil Color Book, Grand Rapids, MI, USA

7941 5

around 20-30cm. This layer shows a change in soil type and an increase in clay content.

Recordings of this layer have common distinctive mottles in the majority of the site. However

profiles along the north and west of the site, which are more calcareous and better drained, lack

these mottles.

3.10 There are two broad subsoil types across the site.

Subsoil type 1 (Grade 4)

3.11 This upper subsoil predominantly occupies the central and south-eastern parts of the site. The

upper subsoil is of olive brown (2.5Y5/3, 5/4) slowly permeable clay. Profiles containing this

subsoil are waterlogged showing visible drainage impedance by way of surface water. Upper

subsoil is non-calcareous with a poor medium/coarse, angular, blocky structure with common,

distinct to prominent mottles.

3.12 Profiles with this subsoil type are limited to Grade 4. Primary limitations are flood risk and the

related drainage issues of flood waters. Further drainage is unlikely to improve the problem.

3.13 The lower subsoil is of light grey, grey (10YR7/1, 6/1) clay. This lower subsoil is slowly permeable

and has a coarse to moderate, subangular blocky structure with no stone and roots disappearing

at around 40cm.

Subsoil type 2 (Subgrade 3b)

3.14 This subsoil predominantly occupies the northern and eastern boundaries of the site. The upper

subsoil is of olive brown (2.5Y5/3, 5/4) permeable clay. Upper subsoil is calcareous with a fine to

medium, subangular blocky structure. Due to the lack of a slowly permeable layer profiles under

this type are better drained with distinctively less standing water at surface level. Some fine,

faint mottling can be seen within this layer.

3.15 The lower subsoil is of light grey, grey (10YR7/1, 6/1) clay. This lower subsoil is slowly permeable

and has a coarse to moderate angular blocky structure.

3.16 The areas of each ALC grade of land on the site are given in Table 2 and are shown in Figure

RAC8063-2.

Table 2: Agricultural land classification

Grade Description Area (ha) % of agri land

3b Moderate quality 9.5 48

4 Poor quality 10.5 52

Total 20.0 100

7941 6

Appendix 1: Laboratory Data

Determinand Pit 1 Pit 2 Units

Sand 2.00-0.063 mm 7 15 % w/w

Silt 0.063-0.002 mm 26 24 % w/w

Clay <0.002 mm 67 61 % w/w

Organic Matter 12.7 8.4 % w/w

Texture Organic Clay Clay

Determinand Pit 1 Pit 2 Units

Soil pH 7.7 7.6

Phosphorus (P) 18.6 16.4 Mg/l (av)

Potassium (K) 172 168 Mg/l (av)

Magnesium (Mg) 144 130 Mg/l (av)

Determinand Pit 1 Profile 32 Units

Phosphorus (P) 2 2 ADAS Index

Potassium (K) 2- 2- ADAS Index

Magnesium (Mg) 3 3 ADAS Index

7941 7

Soil Texture by Particle Size Distribution

Organic Matter Content

7941 8

Appendix 2: Soil Profile Summaries and Droughtiness Calculations

Wetness / workability limitations are determined according to the methodology given in Appendix 3 of the ALC guidelines, MAFF 1988

Droughtiness calculations are made according to the methodology given in Appendix 4 of the ALC guidelines, MAFF 1988.

Grades are shown for drought, wetness and any other soil or site factors which are relevant. The overall Grade is set by the most limiting factor and shown on the right.

Stone types

Climate Data

Wetness Class Guidelines II III IV

V

%

TAv Eav

MDwheat 118

SPL within 80cm, gleying within 40cm >57cm <57 cm

hard 1 0.5

MDpotato 113

SPL within 80cm, gleying at 40-70cm >36cm <36cm

FCD 111

No SPL but gleying within 40cm coarse subsoil I other cases II

hard flint & pebble

AAR

583

Maximum depth of auger penetration is underlined

Log. Site Depth Texture CaCO3 Colour Mottle abund- stone% stone% Struct- APwheat AP potato Gley SPL WC Wetness Final Limiting

No. cm colour ance hard ure mm mm grade WE Grade Factor(s)

S6 1 T 0 15 C 2.5Y 4/3 0 26 26 n n III 3b 3b WE FL

15 34 C

2.5Y 5/3 Fe few 0

30 30 n n

34 60 C

2.5Y 6/3 Fe com 0

poor 28 34 y y

60 120 C

10Y 7/1 FeMn many 0

poor 42 13 y y

Total 126 103

FL.Winter flood zone 2 3b

MD 8 -10

Droughtiness grade (DR) 2 3a

clearing in wood, better drained

S5 2 T 0 18 oZC 2.5Y 3/3 0 41 41 n n III 3b 4 FL-WE

18 33 C

2.5Y 5/3 Fe com 0

24 24 y n

33 70 C

2.5Y 6/3 FeMn many 0

poor 36 48 y y

70 120 C slight 10Y 7/1 Fe many 0

poor 35 0 y y

Total 136 114


MD 18 1

Droughtiness grade (DR) 2 2

many waterlogged patches, pond to north

7941 9

S7 3 T 0 18 oZC 2.5Y 4/2 wet 0 41 41 n n III 3b 4 FL-WE

18 32 C

2.5Y 5/3 Fe many 0

22 22 y n

32 85 C


poor 48 49 y y

85 120 C

10Y 7/1 Fe many 0

poor 25 0 y y

Total 136 113


MD 18 0


many waterlogged patches

S4 4 T 0 10 oZC 2.5Y 2/2 0 23 23 n n II 3a 4 FL-WE

T 10 22 ZC

com 0

20 20 n n

22 42 C

2.5Y 5/3 OMFe few 0

32 32 n n

42 80 C


poor 31 36 y y

80 120 C slight 10Y 7/1 Fe many 5

poor 27 0 y y

Total 134 112


MD 16 -1


river 20m to east

S3 5 T 0 20 ZC slight 2.5Y 3/3 0 34 34 n n III 3a 4 FL-WE

20 42 C slight 2.5Y 5/3 Fe com 0

35 35 y n

42 85 C


poor 35 36 y y

85 120 C

10Y 7/1 Fe many 0

poor 25 0 y y

Total 129 106


MD 11 -7


many waterlogged patches

S2 6 T 0 18 ohZCL 2.5Y 3/2 0 50 50 n n III 3b 4 FL-WE

18 32 C

2.5Y 5/3 Fe com 0

22 22 y n

32 80 C


poor 44 49 y y

80 120 C

10Y 7/1 Fe many 0

poor 28 0 y y

Total 145 122


7941 10

MD 27 9


underwater to east

S1 7 T 0 18 ohZCL 2.5Y 3/2 0 50 50 n n III 3b 4 FL-WE

18 35 ZC

2.5Y 5/3 Fe com 0

26 26 y n

35 70 C

2.5Y 6/4 Fe com 0

poor 34 46 y y

70 120 C

10Y 7/1 FeMn many 0

poor 35 0 y y

Total 144 121


MD 26 8


wet in slight depressions

A1 8 T 0 20 hZCL 2.5Y 3/3 0 0 38 38 n n III 3b 4 FL-WE

20 30 ZC

2.5Y 4/3 Fe com 0 0

15 15 n n

30 75 C

2.5Y 5/3 Fe many 0 0 poor 44 52 y y

75 120 C

10Y 7/1 Fe many 0 0 poor 32 0 y y

Total 128 105


MD 10 -8


A2 9 T 0 25 hZCL 2.5Y3/3 0 0 48 48 n n III 3b 4 FL-WE

25 35 ZC

2.5Y4/3 Fe few 0

15 15 n n

35 80 C

2.5Y 5/3 Fe many 0

poor 41 46 y y

80 120 C

2.5Y6/2 Fe many 0

poor 28 0 y y

Total 131 108


MD 13 -5


wet in slight depressions

A3 10 T 0 25 hZCL slight 2.5Y3/3 0 2 47 47 n n II 2 3b FL

25 40 C/ZC mod 2.5Y5/3 Fe com 0 5

22 22 y n

40 60 C mod 2.5Y 5/3 Fe com 0 1

24 32 y n

60 120 C mod 2.5Y6/1 Fe com 0 0 poor 42 13 y y

7941 11

Total 134 113


MD 16 0


A4 11 T 0 20 hZCL 2.5Y3/3 0 0 38 38 n n II 3a 3b FL

20 40 ZC v.sli 2.5Y5/3 Fe few 0 0

30 30 n n

40 60 C v.sli 2.5Y 5/3 Fe com 0 0

24 32 y n

60 120 C slight 2.5Y6/1 Fe com 0 0 poor 42 13 y y

Total 134 113


MD 16 0


S8 12 T 0 10 ohZCL 2.5Y 2/2 0 28 28 n n II 3a 3b FL

T 10 22 hZCL

2.5Y 4/3

0

23 23 n n

22 55 C slight 2.5Y 5/4 OMFe com 0

49 53 n n

55 85 C

2.5Y 6/4 Fe com 0

poor 21 20 y y

85 120 C

10Y 7/1 FeMn many 0

poor 25 0 y y

Total 145 123


MD 27 10


waterfilled depression to north


20 35 ZC v.sli 2.5Y4/3 Fe

0 0

23 23 n n

35 50 C slight 2.5Y 4/3 Fe com 0 0

24 24 n n


Total 134 111


MD 16 -3


S9 14 T 0 20 hZCL slight 2.5Y 4/3 0 28 28 n n II 2 3b FL

20 35 ZC mod. 2.5Y 5/4

0

49 53 n n

7941 12

35 55 C slight 2.5Y 6/4 FeOM com 0

21 20 n n

55 85 C

2.5Y 6/2 Mn com 0

poor 21 20 y y

85 120 C

10Y 7/1 FeMn wet 0

poor 23 0 y y

Total 144 123


MD 26 10



20 60 ZC v.sli 2.5Y5/4 Fe

0 0

53 60 n n

60 100 C slight 2.5Y 6/3 FeMn com 0 0 poor 28 13 y y


Total 133 111


MD 15 -2



20 35 ZC

2.5Y5/4 Fe

0 0

23 23 y n

35 75 C slight 2.5Y 6/3 Fe com 0 0 poor 37 46 y y

75 120 C

10YR7/1 Fe many 0 0 poor 32 0 y y

Total 129 106


MD 11 -7


Surface water nearby


15 30 ZC

2.5Y5/3 Fe

0 0

23 23 n n

30 90 C

2.5Y6/3 FeMn com 0 0 poor 54 52 y y

90 120 C

10YR6/1 Fe com 0 0 poor 21 0 y y

Total 126 103


MD 8 -10


7941 13

S10 18 T 0 20 oZC slight 2.5Y 4/2 wet 0 46 46 n n III 3b 4 FL-WE

20 30 C

2.5Y 5/2 Fe many 0

16 16 y n

30 70 C

2.5Y 6/2 Fe com 0

poor 40 52 y y

70 120 C

10Y 7/1 FeMn wet 0

40 0 y

Total 142 114


MD 24 1


wet in depressions

A9 19 T 0 18 ZC 2.5Y3/3 0 0 31 31 n n III 3b 4 FL-WE

18 35 C

2.5Y5/3 Fe com 0 0

27 27 y n

35 100 C

2.5Y6/3 FeMn many 0 0 poor 55 46 y y

100 120 C

10YR6/1 Fe com 0 0 poor 14 0 y y

Total 126 103


MD 8 -10


7941 14

Appendix 3: Pit descriptions and photographs

Pit

1

Description permanent grass

Ah 0-18

cm

Dark olive brown (2.5Y3/3) organic heavy silty clay loam. Excellent medium granular

structure. Many roots, a few worms. Medium macropores.

Eb 18-26

cm

Olive Brown (2.5Y 4/3) silty clay. Medium angular blocky structure. A few roots and worm

channels.

Btg 26-45

cm

Light yellowish brown (2.5Y6/3) clay with common distinct medium mottles. Moderate

subangular blocky structure with some root. At about 40cm changes to firm coarse angular

blocky structure with no roots.

Comment: Topsoil very moist. Water seeped into the pit at 30cm. Impeded drainage and Wetness Class III.

.

Pit 1 Pit 1 Structures

Red mark is 30cm

7941 15

Pit 2 Description under permanent grass

Ah 0-10 cm Dark olive brown (2.5Y3/3) organic heavy silty clay loam. Good medium granular

structure. Many roots and worms. Non-calcareous.

A2 10-30 cm Heavy silty clay loam. Fine subangular blocky and granular.

Bw 30-55 cm Light olive brown (2.5Y5/3) silty clay with a few fine faint mottles. Fine subangular

blocky structure. Many worms. Slightly calcareous.

Bg 55 cm + Light yellowish brown (2.5Y6/4) clay with common, fine, distinct mottles.

Medium/coarse angular blocky structure. Slowly permeable (water entering pit at

55cm).

Comment: Better drained than pit 2 (Wetness Class II)

Pit 2 Pit 2 Structures

Red mark is 30cm

7941 16

Boundary of grass and plantation (waterlogged)

Plantation: many wet patches

7941 17

Pit 1 surface water in channels, elsewhere topsoil is moist

View north of pit 2 - shallow lagoon. The surrounding soil drains adequately

View south of pit 2: soil is wetter in middle and distance

View of central drain; the water level is about 0.5m less than the land either side.

RAC 8063-1

AGM

1:2500@A3

AIF

May.2018

+Pit 1

+Pit 2

Figure 8063-1 Observations

IV Ltd

1:2500 scale print at A3, Centre:507141 E, 291935 N

©Crown Copyright and databaserights 2018 OS 100019980

1:2500 scale print at A3, Centre:507141 E, 291935 N

©Crown Copyright and databaserights 2018 OS 100019980

Figure 8063-2 Agricultural Land Classification

IV Ltd

RAC 8063-2

AGM AIF

1:2500@A3 May. 2018

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