Agriculture Reference
In-Depth Information
Table 3.4.1.
Calculation of N returns in arable crop residues in England and Wales, based on
Sylvester-Bradley (1993). Calculations exclude 210,000 ha of 'miscellaneous' crops and
126,000 ha of vegetable crops.
Yield of
produce
a
(t ha
−
1
)
N content
of produce
(kg t
−
1
)
Maximum
N uptake
(kg ha
−
1
)
N content
of residue
(kg ha
−
1
)
Total
residue N
(kt)
Area
a
000 ha Residue
N
index
b
Crop
Wheat
2036
Straw
0
.5
7.43
17
.5
193
67
136.4
Barley
1358
Straw
0
.5
5.78
17
.5
150
52
70.6
Oats
100
Straw
0
.5
5.41
17
.5
141
49
4.9
Rye
12
Straw
0
.5
5.41
18
.5
141
43
0.5
Triticale
8
Straw
0
.5
5.41
18
.5
141
43
0.3
Linseed
73 Straw
0
.5
1.49
38
.5
75
18
1.3
Sugarbeet
196
Leaf/crown
0
.5
45
. 5
1.7
200
124
24.3
Peas
78
Haulm/straw
0.5
3.79
130
.5
265
135
10.5
Beans
99
Haulm/straw
0.5
3.8
155
.5
285
130
12.9
Oilseed rape
446
Haulm/straw
1
.5
3.23
30
.5
240
143
63.8
Potatoes
c
16
Haulm
1
.5
23.8
3.5
167
83
1.3
Potatoes
d
150
Haulm
1
.5
45.3
2.5
227
113
17.0
Total
4572
Total
343.8
a
Based on the statistics for 1997 (Anon, 1998);
b
from MAFF (1994);
c
early crop;
d
maincrop.
KCl extraction from soil cores taken in 30-cm increments (MAFF, 1986).
Crop yields were measured following harvesting by hand or determined
using a plot combine harvester. Sub-samples were taken to determine
moisture and N content, with the latter measured by near infrared
spectrophotometry.
The effect of time and method of residue incorporation
This was investigated in an experiment on a free-draining loamy sand soil
(Bridgenorth series, Badger Farm, Salop). A crop residue (cereal foliage cut
and air-dried for storage: average composition 87% dry matter and 2.0%
N) was spread on to the bare soil surface at a rate of 10 t ha
−1
fresh weight
to separate, replicated plots on 7 June, 2 August, 2 September, 5 October,
7 November 1994 and 11 January 1995. Each time, the residue was incor-
porated immediately by ploughing to a maximum depth of 25-27 cm, and
throughout the experiment period (until March 1996) the entire site was
kept free of plants. The effect of incorporation method (plough, disc or left
on the surface) was also investigated for a limited range of dates (August,
September and October) in the same experiment.
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