Directory UMM :Data Elmu:jurnal:S:Soil & Tillage Research:Vol53.Issue3-4.Feb2000:
Soil & Tillage Research 53 (2000) 185±200
Assessment of tillage strategies to decrease nitrate leaching in the
Brimstone Farm Experiment, Oxfordshire, UK
J.A. Catta,*, K.R. Howsea, D.G. Christianb, P.W. Lanec, G.L. Harrisd, M.J. Gosse
a
Soil Science Department, IACR, Rothamsted, Harpenden, Herts AL5 2JQ, UK
Crop and Disease Management Department, IACR, Rothamsted, Harpenden, Herts AL5 2JQ, UK
c
Statistics Department, IACR, Rothamsted, Harpenden, Herts AL5 2JQ, UK
d
ADAS Gleadthorpe, Meden Vale, Mans®eld, Notts NG20 9P, UK
e
Centre for Land and Water Stewardship, Richards Building, University of Guelph, Guelph, Ont., Canada N1G 2W1
b
Accepted 13 August 1999
Abstract
Tillage may in¯uence nitrate losses from agricultural soils. Losses of nitrate were measured in drain¯ow at 60 cm depth and
in combined surface runoff and inter¯ow in the A horizon (surface layer ¯ow) on hydrologically sealed plots with a two-year
comparison (1988±1990) of shallow-tine cultivation vs. mouldboard ploughing. Ploughing increased concentrations and
loadings of nitrate in drain¯ow and surface layer ¯ow, especially in the ®rst year. After these two years the shallow-tined plots
were ploughed to plant winter beans (Vicia faba L.), and nitrate in drain¯ow then increased over the next three winters, slightly
exceeding that from the plots which had been ploughed throughout for winter cereals. The composition of the surface layer
¯ow did not show this effect, however. Calculations of net winter mineralisation of soil organic nitrogen showed that shallowtine cultivation may have decreased mineralisation slightly compared with ploughing in the ®rst two years. These calculations
did not indicate any increase in mineralisation for two winters after the minimally cultivated plots were ploughed in autumn
1990, probably because the soil was then very dry. This increase was apparently delayed until the ®fth winter (1992/1993),
which was much wetter than any since autumn 1990. In the previous eight years (1980±1988) half of the plots had been
ploughed and half had been direct drilled. Averaged over the ®ve winters 1988/1989±1992/1993, the ®ve measures of nitrate
loss in drain¯ow from plots previously direct drilled were 6±57% more than from plots previously ploughed, and winter
mineralisation was 20% more, with no evidence of any decline in either with time. The nitrate produced by mineralisation of
organic matter conserved by the eight years of direct drilling was mainly lost by leaching or denitri®cation; it was of little or
no bene®t to the crops. The results suggest that in the long term more nitrate is leached from land subject to periods of
minimal or zero tillage and ploughing than from land ploughed every year. # 2000 Elsevier Science B.V. All rights reserved.
Keywords: Drain¯ow; Surface layer ¯ow; Nitrate loss; Mineralisation; Leaching; Shallow tillage; Direct drilling
1. Introduction
*
Corresponding author. Tel.: 44-1582-763133; fax: 44-1582760981.
E-mail address: john.catt@bbsrc.ac.uk (J.A. Catt).
The Brimstone Farm Experiment, situated near
Faringdon, Oxfordshire, UK (National Grid Reference
0167-1987/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 1 6 7 - 1 9 8 7 ( 9 9 ) 0 0 1 0 5 - 1
186
J.A. Catt et al. / Soil & Tillage Research 53 (2000) 185±200
SU 248946), has twenty 0.2 ha hydrologically isolated
plots (Cannell et al., 1984; Harris et al., 1984), which
have been used since 1978 to study the effects of various
soil and crop management techniques on nitrate leaching. Brimstone is oneof the few experimental sites where
nitrate loss can be measured directly in plots large
enough for use of standard farm machinery.
Results from Phase I of the experiment (1978±
1988) indicated the importance of mineralisation of
crop residues and other soil organic matter in producing nitrate that is leached during the autumn and
winter. For example, on land sown to winter cereals
after mouldboard ploughing with no seedbed (autumn)
fertiliser N, a mean of 21.8 kg N haÿ1 (SE 6.0) was
leached as nitrate over the following winter periods
(Goss et al., 1993). Although some of this leached N
could have come from atmospheric deposition or
®xation by free-living soil micro-organisms, such as
blue-green algae, a tentative N balance showed that
most of it must have been derived from mineralisation
of soil organic matter. Mineralisation also contributes
a large proportion of the nitrate leached from arable
land at Rothamsted (Addiscott, 1988; Jenkinson and
Parry, 1989). Consequently, in Phase II of the Brimstone
Experiment (1988±1993) several possible strategies
for limiting mineralisation of soil organic matter were
tested. This paper gives results for the technique of
minimal (shallow-tine) cultivation, which was compared with mouldboard ploughing, and also examines
the effect on nitrate leaching of ploughing plots that
had previously been direct drilled for eight years.
2. Site characteristics and experimental
procedures
2.1. The Brimstone Farm Experiment
Brimstone Farm is on a cracking clay soil (pelostagnogley soil of Avery, 1980, Verti-eutric Gleysol of
FAO-Unesco, 1988) of the Denchworth series (Jarvis,
1973) developed on Upper Jurassic Oxford Clay. The
Ap horizon contains 540 g kgÿ1 clay (
Assessment of tillage strategies to decrease nitrate leaching in the
Brimstone Farm Experiment, Oxfordshire, UK
J.A. Catta,*, K.R. Howsea, D.G. Christianb, P.W. Lanec, G.L. Harrisd, M.J. Gosse
a
Soil Science Department, IACR, Rothamsted, Harpenden, Herts AL5 2JQ, UK
Crop and Disease Management Department, IACR, Rothamsted, Harpenden, Herts AL5 2JQ, UK
c
Statistics Department, IACR, Rothamsted, Harpenden, Herts AL5 2JQ, UK
d
ADAS Gleadthorpe, Meden Vale, Mans®eld, Notts NG20 9P, UK
e
Centre for Land and Water Stewardship, Richards Building, University of Guelph, Guelph, Ont., Canada N1G 2W1
b
Accepted 13 August 1999
Abstract
Tillage may in¯uence nitrate losses from agricultural soils. Losses of nitrate were measured in drain¯ow at 60 cm depth and
in combined surface runoff and inter¯ow in the A horizon (surface layer ¯ow) on hydrologically sealed plots with a two-year
comparison (1988±1990) of shallow-tine cultivation vs. mouldboard ploughing. Ploughing increased concentrations and
loadings of nitrate in drain¯ow and surface layer ¯ow, especially in the ®rst year. After these two years the shallow-tined plots
were ploughed to plant winter beans (Vicia faba L.), and nitrate in drain¯ow then increased over the next three winters, slightly
exceeding that from the plots which had been ploughed throughout for winter cereals. The composition of the surface layer
¯ow did not show this effect, however. Calculations of net winter mineralisation of soil organic nitrogen showed that shallowtine cultivation may have decreased mineralisation slightly compared with ploughing in the ®rst two years. These calculations
did not indicate any increase in mineralisation for two winters after the minimally cultivated plots were ploughed in autumn
1990, probably because the soil was then very dry. This increase was apparently delayed until the ®fth winter (1992/1993),
which was much wetter than any since autumn 1990. In the previous eight years (1980±1988) half of the plots had been
ploughed and half had been direct drilled. Averaged over the ®ve winters 1988/1989±1992/1993, the ®ve measures of nitrate
loss in drain¯ow from plots previously direct drilled were 6±57% more than from plots previously ploughed, and winter
mineralisation was 20% more, with no evidence of any decline in either with time. The nitrate produced by mineralisation of
organic matter conserved by the eight years of direct drilling was mainly lost by leaching or denitri®cation; it was of little or
no bene®t to the crops. The results suggest that in the long term more nitrate is leached from land subject to periods of
minimal or zero tillage and ploughing than from land ploughed every year. # 2000 Elsevier Science B.V. All rights reserved.
Keywords: Drain¯ow; Surface layer ¯ow; Nitrate loss; Mineralisation; Leaching; Shallow tillage; Direct drilling
1. Introduction
*
Corresponding author. Tel.: 44-1582-763133; fax: 44-1582760981.
E-mail address: john.catt@bbsrc.ac.uk (J.A. Catt).
The Brimstone Farm Experiment, situated near
Faringdon, Oxfordshire, UK (National Grid Reference
0167-1987/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 1 6 7 - 1 9 8 7 ( 9 9 ) 0 0 1 0 5 - 1
186
J.A. Catt et al. / Soil & Tillage Research 53 (2000) 185±200
SU 248946), has twenty 0.2 ha hydrologically isolated
plots (Cannell et al., 1984; Harris et al., 1984), which
have been used since 1978 to study the effects of various
soil and crop management techniques on nitrate leaching. Brimstone is oneof the few experimental sites where
nitrate loss can be measured directly in plots large
enough for use of standard farm machinery.
Results from Phase I of the experiment (1978±
1988) indicated the importance of mineralisation of
crop residues and other soil organic matter in producing nitrate that is leached during the autumn and
winter. For example, on land sown to winter cereals
after mouldboard ploughing with no seedbed (autumn)
fertiliser N, a mean of 21.8 kg N haÿ1 (SE 6.0) was
leached as nitrate over the following winter periods
(Goss et al., 1993). Although some of this leached N
could have come from atmospheric deposition or
®xation by free-living soil micro-organisms, such as
blue-green algae, a tentative N balance showed that
most of it must have been derived from mineralisation
of soil organic matter. Mineralisation also contributes
a large proportion of the nitrate leached from arable
land at Rothamsted (Addiscott, 1988; Jenkinson and
Parry, 1989). Consequently, in Phase II of the Brimstone
Experiment (1988±1993) several possible strategies
for limiting mineralisation of soil organic matter were
tested. This paper gives results for the technique of
minimal (shallow-tine) cultivation, which was compared with mouldboard ploughing, and also examines
the effect on nitrate leaching of ploughing plots that
had previously been direct drilled for eight years.
2. Site characteristics and experimental
procedures
2.1. The Brimstone Farm Experiment
Brimstone Farm is on a cracking clay soil (pelostagnogley soil of Avery, 1980, Verti-eutric Gleysol of
FAO-Unesco, 1988) of the Denchworth series (Jarvis,
1973) developed on Upper Jurassic Oxford Clay. The
Ap horizon contains 540 g kgÿ1 clay (