5.2. SOIL SECTION
For the full soil results see table 5.5.
5.2.1. pH, PARTICLE SIZE AND CARBON
Mean pH on set-aside is lower than that of arable fields. The lowest pH was recorded on Chaplefield and on Springfield at pH 5.7. Thirteen of the set-aside fields were slightly acid (i.e. pH 5.6 – 6.5) and seven fields were neutral (i.e. pH 6.6 – 7.5). The highest set-aside pH recordings were at White House Farm. Of the arable soils, on White House 1 the soil was slightly acid (pH 6.0), whereas all other arable soils were neutral.
Particle Size Analysis
The fields of White House have the highest clay and fine silt percentage. Saunders Lakeside has the highest sand content (47.3%). All soils are generally silty clay soils or silty loams.
Carbon – loss on ignition
The carbon, in the form of organic matter, of the soils varied considerably from 5.73% at Reeds North Field, to 13.93% at Birkett Hall, Front Meadow. The mean levels for set-aside is 8.99% and for the arable fields is 7.60%. The organic matter for the arable field at Reeds does not differ greatly from the set-aside levels (5.66% on the wheat field).
5.2.2. WATER EXTRACTS
Chloride levels are higher on the set-aside (mean 38.5 mg kg-1) than on the arable fields (mean 26.7 mg kg-1). Chlorides are highest on the fields at Birkett Hall
(50 mg kg-1 Cowbridge SE and Bell Meadow)
Phosphate levels are higher on the set-aside, mean 3.35 mg kg-1 compared to
1.82 mg kg-1 on arable. Highest occurred on Front Meadow (8.20 mg kg-1) at Birkett Hall. Reeds Farm has the highest arable phosphate levels (3.10 mg kg-1).
Ammonium is higher on set-aside soils (mean 2.48 mg kg-1) than on the arable soils (mean 0.96 mg kg-1). Highest levels on set-aside are on Bell Meadow and Springfield ‘bottom-end’ at Birkett Hall. Ammonium is generally quite low on all arable fields.
Mean nitrate levels are much higher on arable soils than on set-aside soils. Highest set-aside levels occur on Bell Meadow (11.42 mg kg-1) and Front Meadow
(13.19 mg kg-1) at Birkett Hall. However the arable soils are quite variable, at White House nitrate levels are at only 10.04 mg kg-1 and 10.01 mg kg-1, whereas at Woodham Lodge nitrates are at 44.81 mg kg-1, the highest recorded, over three times higher than Front Meadow.
Nitrite levels are generally very low. Set-aside mean 0.56 mg kg-1, arable mean
0.29 mg kg-1. Highest levels occur at Bell Meadow (2.38 mg kg-1) and Front Meadow
(1.81 mg kg-1) and lowest for the North Field at Reeds (0.05 mg kg-1).
Higher on set-aside with a mean of 6 mg kg-1. Highest levels recorded on Front Field (11 mg kg-1) and Middle Field (13.5 mg kg-1) at White House, and on Cowbridge SE at Birkett Hall (11 mg kg-1). The arable fields have very consistent levels.
There was little variation between set-aside and arable fields. Set-aside was slightly lower (mean 208 mg kg-1). Highest levels occurred on Cowbridge SE and Springfield ‘grazed field’ at Birkett Hall, and the arable field at Woodham Lodge. Lowest levels were on Springfield ‘bottom end’, and on South Field at Reeds Farm.
Calcium levels are quite low on set-aside (mean 11.65 mg kg-1). Many of the fields at Birkett Hall had no extractable calcium present, although the highest calcium levels were found on Saunders by the lake on the sandier soils. The highest levels recorded were on the second arable field at White House (143 mg kg-1).
Magnesium is higher on the arable fields (mean 12.4 mg kg-1) than on the set-aside (mean 5.1 mg kg-1). The lowest levels under set-aside occur at Birkett Hall. The highest levels occur on South Field at Reeds Farm, and Front Field and Middle Field at White House Farm.
Mean sodium levels are slightly higher on the arable soils, but overall there is little variation.
Mean potassium is slightly higher on set-aside soils. On Front Meadow and Cowbridge SE at Birkett Hall concentration reached 68 mg kg-1 and 64 mg kg-1 respectively, but also fell as low as 17 mg kg-1 and 18 mg kg-1 on Saunders Roadside and Chaplefield.
5.2.3. TOTAL DIGESTS
The mean total calcium present in the soil is higher on the arable fields. The soils of Birkett Hall and Brazils Farm have the highest levels generally (Table 5.5).
Mean magnesium is higher on set-aside. Highest levels occur at White House on Front Field (6188 mg kg-1). The amount of magnesium appears to be determined by the clay content of the soil.
Mean sodium in the soil is similar on both set-aside and arable fields.
Mean potassium is lower on arable fields. Set-aside mean is 7475 mg kg-1 and arable mean is 6493 mg kg-1.
Table 5.5 cont.
5.2.4. SIGNIFICANCE OF NUTRIENT CHANGE UNDER SET-ASIDE
The results of the students T-test are in the Appendix.
Table 5.6: Soil nutrient changes on set-aside
|INCREASE||DECREASE||NO SIGNIFICANT CHANGE|
* Total digest sample
Table 5.7: Level of significance for soil nutrient changes
* Total digest sample