14.5 Distinguishing Between Recent Soils
and Related Soil Orders
In the New Zealand Soil Classification key to soil orders,
Recent Soils are almost at the end of the key (being followed
only by Raw Soils). The key acts as a logic filter and Recent
Soils are identified by lacking the features that distinguish
other soil orders that have priority earlier in the key.
The Recent Soils are frequently associated with landscapes where active, or recently active, erosion and sedimentation processes are prevalent. Common landscape
associates are Raw Soils that differ by having no B horizon,
no topsoil, or a topsoil less than 5 cm thick. Gley Soils occur
where high ground water tables are prolonged and Organic
Soils occur where water tables are permanently high and
there has been an accumulation of humified plant material.
14.6 Correlation with Other Classification
Systems
The Recent Soils mainly correlate with the Entisols of Soil
Taxonomy and with a variety of soil orders in the World
Reference Base (Table 14.3). They were formerly classified
as Recent soils in New Zealand.
14.7 Use and Management of Recent Soils
Recent Soils on flat or gently sloping land are some of the
most versatile and productive dairying, grazing, and cropping land in New Zealand. However, there are a number of
potential hazards that must be considered, particularly the
risk of flooding, hillslope mass movement and deposition,
Fig. 14.8 Median and upper and
lower quartiles of soil pH, organic
carbon, and P retention for Recent
Soils in the New Zealand Soil
Data Repository
Table 14.2 Typical example of
chemical properties for a
Weathered Fluvial Recent Soil
(Waimakariri series, SB10105)
Horizon Depth
pH
(in H 2 O)
Carbon
(%)
Nitrogen
(%)
CEC
a
(cmol
(+)
/kg)
Sum bases
(cmol
(+) kg)
P retention
(%)
Ap1
0–18
5.5
2.7
0.23
11.9
8.50
15
Ap2
18–27
5.4
2
0.17
10
6.76
16
BA
27–38
5.4
1.2
0.11
7.4
5.69
15
Bw
38–46
5.5
0.63
0.06
6.4
4.00
12
Cu1
46–54
5.5
0.37
0.04
4.3
3.18
10
Cu2
54–80
5.9
0.2
0.03
3.2
2.58
6
Cu2
80–113 6.1
0.16
0.03
3.3
2.93
5
Cu3
113–124 6.4
0.11
0.02
2.8
2.60
4
2bBw1 124–134 6.7
0.25
0.04
9.1
9.02
13
2bBw2 134–160 6.7
0.28
0.04
8
7.92
12
a CEC = cation exchange capacity
226
14 Recent Soils
and Related Soil Orders
In the New Zealand Soil Classification key to soil orders,
Recent Soils are almost at the end of the key (being followed
only by Raw Soils). The key acts as a logic filter and Recent
Soils are identified by lacking the features that distinguish
other soil orders that have priority earlier in the key.
The Recent Soils are frequently associated with landscapes where active, or recently active, erosion and sedimentation processes are prevalent. Common landscape
associates are Raw Soils that differ by having no B horizon,
no topsoil, or a topsoil less than 5 cm thick. Gley Soils occur
where high ground water tables are prolonged and Organic
Soils occur where water tables are permanently high and
there has been an accumulation of humified plant material.
14.6 Correlation with Other Classification
Systems
The Recent Soils mainly correlate with the Entisols of Soil
Taxonomy and with a variety of soil orders in the World
Reference Base (Table 14.3). They were formerly classified
as Recent soils in New Zealand.
14.7 Use and Management of Recent Soils
Recent Soils on flat or gently sloping land are some of the
most versatile and productive dairying, grazing, and cropping land in New Zealand. However, there are a number of
potential hazards that must be considered, particularly the
risk of flooding, hillslope mass movement and deposition,
Fig. 14.8 Median and upper and
lower quartiles of soil pH, organic
carbon, and P retention for Recent
Soils in the New Zealand Soil
Data Repository
Table 14.2 Typical example of
chemical properties for a
Weathered Fluvial Recent Soil
(Waimakariri series, SB10105)
Horizon Depth
pH
(in H 2 O)
Carbon
(%)
Nitrogen
(%)
CEC
a
(cmol
(+)
/kg)
Sum bases
(cmol
(+) kg)
P retention
(%)
Ap1
0–18
5.5
2.7
0.23
11.9
8.50
15
Ap2
18–27
5.4
2
0.17
10
6.76
16
BA
27–38
5.4
1.2
0.11
7.4
5.69
15
Bw
38–46
5.5
0.63
0.06
6.4
4.00
12
Cu1
46–54
5.5
0.37
0.04
4.3
3.18
10
Cu2
54–80
5.9
0.2
0.03
3.2
2.58
6
Cu2
80–113 6.1
0.16
0.03
3.3
2.93
5
Cu3
113–124 6.4
0.11
0.02
2.8
2.60
4
2bBw1 124–134 6.7
0.25
0.04
9.1
9.02
13
2bBw2 134–160 6.7
0.28
0.04
8
7.92
12
a CEC = cation exchange capacity
226
14 Recent Soils