survive winter conditions. Mineralization of plant nutrients during decay should synchronize with
the uptake of nutrients by the following crop.
4
.
2
.
2
. Perennial cereals In some parts of the world the risk of erosion is
so high that a permanent vegetative cover is es- sential. Perennial cereals enable the production of
grains in areas that are otherwise not possible. Development of such species seems to be a mean-
ingful task Pimm, 1997.
4
.
3
. Acti6e management of soil biological processes
4
.
3
.
1
. Decomposition and synchronization Decomposition processes in soil are comprised
of the humification of fresh litter and the break- down of humus. Measures that enable a more
efficient carbon stabilization of fresh litter can enable an increase in carbon sequestration in soil.
Speeding up the breakdown of mineralizable N during crop growth will result in better synchro-
nization between release and uptake. Slowing down the breakdown of mineralizable N during
autumn
and winter
may help
to conserve
nutrients.
4
.
3
.
2
. Climatic trace gas emissions Soil biological processes are linked to the trace
gas composition of the atmosphere. Reduced CO
2
emission from soil and the use of the land as a sink for excess CO
2
can help to counteract an increase in the atmosphere. It is most likely that
emissions of nitrous oxides from soils as well as methane oxidation can also be controlled. An
understanding of regulating factors and knowl- edge of the effect of different cultivation tech-
niques may enable us to actively manage soil biological processes.
4
.
4
. Maximum circulation of plant nutrients
4
.
4
.
1
. Animal wastes A balanced distribution of animal manure on
farm areas is the most important step to establish effective circulation of plant nutrients. Further-
more, the development of new methods to handle and store solid animal manures on farms that
enable nutrient conservation are desirable.
4
.
4
.
2
. Food and urban wastes Development of new or supplemental industrial
systems for utilization of plant nutrients in munic- ipal wastes is needed in order to enable recycling
without contamination by environmental pollu- tants. Waste products need to be transported over
longer distances to avoid too high nutrient levels in arable soils in the circumference of cities and
towns. Methods that enable long-distance circula- tion are desirable.
5. Outlook
5
.
1
. Intensi6e agricultural production — en6ironmental pollution
?
The production of food has to increase as the global human population will increase by about
two billion during the next 25 years Greenland et al., 1997. Thus, intensive production seems abso-
lutely necessary to guarantee that production will be able to keep pace with population growth. The
critical question is whether it will be possible to increase production without an increase or even a
lowering of emissions.
In general, emissions from arable land increase with more intensive fertilization. Nitrate leaching,
for example, increased slightly with higher fertil- ization intensity and first at an excessive supply of
N fertilizer, leaching reached very high and unsat- isfactory levels Bergstro¨m and Brink, 1986. A
slight increase in emissions at higher intensity has to be distinguished from the very high emissions
due to excessive use.
In low- or medium-intensive cropping systems, emissions from arable land, expressed on an areal
basis or as a concentration in flows, are normally lower than from high intensive systems Feige and
Ro¨thlingsho¨fer, 1990; Eltun and Fugleberg, 1996; Goldstein et al., 1998. If, however, emissions are
related to yields, leaching or gaseous emissions are lower at high intensive cropping per unit of
biomass production, presupposing good agricul- tural practices. Bertilsson 1992 showed that
leaching of N in organic farming, for example, amounted to 5.5 kg N per ton of cereals but to 4.2
kg N per ton for cereals conventionally farmed in the south of Sweden. This result, that emissions
per unit of yield are not lower in low- or medium- intensive cropping systems, needs to be taken into
consideration when evaluating the environmental impact from cropping systems. Addiscott 1995
pointed out that low-intensive crop production is least sustainable, whereas high-intensive use of
arable land is most sustainable, in accordance with the theory of thermodynamics.
Furthermore, with high yields per area, more food can be produced and more land can be saved
for other uses. This is most important in countries with limited land resources and a high population
density. Still, a high degree of knowledge is essen- tial for intensive agriculture to be able to utilize
the means of production in a highly efficient way and avoid misuse of resources, overfertilization
and any negative effects on the environment.
5
.
2
. Nutrient imbalances Regional specialisation of farms has resulted in
production that is most often much greater than the need of the immediate market. Agricultural
products are transported long distances, both crops used for human consumption and fodder
concentrates for animal husbandry, which means a net removal and no return of harvested nutri-
ents. On the other hand, a large import of feeding stuff to farms contributes to an excessive supply
at a local or even regional level. This more or less open plant nutrient cycle causes nutrient imbal-
ances. Examples of long distance transport across countries are also common. For example, concen-
trates may be produced on land in developing countries where rain forests were cut and soils
may
degrade through
erosion and
nutrient depletion.
We need tools to prevent and overcome the negative impacts of this development. Specialisa-
tion of single farms need not necessarily have a negative impact on the environment — for exam-
ple, an excess of manure can be distributed within acceptable areas to adjacent farms — but special-
isation of farms in a whole region carrying out the same production will have a negative impact.
Thus, we need to question the development of one-sided, regional agricultural production.
Farm specialisation of regions has been highly influenced by the climate, soil properties and eco-
nomic conditions and it may be difficult to reintroduce mixed farming, i.e. a combination of
animal and crop husbandry. Although mixed farming is a straight-forward solution to avoid
imbalances, this form of farming may put the farm’s economy at risk. Economic implementa-
tions to favour mixed farming may be one possi- bility. Another measure to prevent a further
increase in animal density is to limit the number of farm animals kept in relation to the arable land
available regionally.
One probable way to affect farming in the future is through analysis and classification of
agricultural production and environmental stew- ardship on individual farms. This analysis, to-
gether with an assessment system see below, may stimulate favourable farming development. If
properly designed and well founded, a quality assessment system for agriculture can be a driving
instrument to be used for legislative implementa- tion of guidelines.
5
.
3
. A quality assessment system for agriculture A range of quality assessment systems such as
for forest landscape, groundwater, lakes and wa- tercourses, coasts and seas, contaminated sites
and agricultural landscape have been published by the Swedish Environmental Protection Agency
Naturva˚rdsverket, 1999. The assessment systems were designed as a tool to evaluate the situation.
Each assessment system contains a selection of variables which were chosen because of their vital
importance for the functioning of each ecosystem. The classification of variables, expressed on a
scale of 1-5, involved two aspects: i an appraisal of whether the recorded state may have an ad-
verse effect on the environment or human health, and ii an appraisal of the extent to which the
recorded state deviates from a ‘comparative value’.
As to a quality assessment of agriculture, both the influence of agricultural practices on the envi-
ronment, the status of selected properties and the efficiency of production must be taken into ac-
count. The quality components outlined in this paper can be useful for a structural outline. A
comprehensive
quality assessment
system, combining different aspects of production and
environmental stewardship, can be a very power- ful tool to direct development towards environ-
mentally sound and sustainable cropping systems.
The use of such an assessment system may favour agricultural production in certain areas
and question it in others. Within a country, this assessment may lead to setting aside agricultural
land. However, as food production is a funda- mental need for humans, most nations are inter-
ested in producing their own food to some extent. The result could be that agricultural land used in
one country could be set aside in another. Where to actually carry out agriculture is therefore also a
political decision.
6. Conclusions
