Loomis, R.S.

Rabbinge, R.

English

Wageningen Yield 

Apple production in the Netherlands where integrated pest control is increasingly widespread (Photo ANWB) 
There is another way 
Agriculture may be defined as a human 
activity that uses the sun's energy to con-
vert plants and animals into useful or-
ganic materials. Few resources are 
necessary: a suitable crop, a piece of 
land, some sun and rain and human 
labour. Man tries to manage the crops and 
soils so as to achieve a reasonable return 
on his input of capital, labour and energy. 
During the past fifty years, agriculture has 
been strongly influenced by industrialisa-
tion and by advances in biological and 
environmental science. For example, new 
iri its use of land. Within the agricultural 
landscape there must still be space for 
other human activities, and agricultural 
operations should not be to the total detri-
ment of nature and landscape conserva-
tion. The agricultural work-force should 
be maintained at optimal level and its in-
come should be comparable with that of 
skilled industrial workers. 
Present-day, modern agriculture 
information about plant nutrition and Modern high-technology agriculture is a 
plant breeding has led to marked im- heavy consumer of energy and chemicals 
Rudy Rabbinge and R. S. Loomis 
The fossil energy used per kg of wheat 
produced has stayed the same since 1950, 
but labour has been halved. These data 
characterise the increased efficiency in 
production. If this· trend continues one 
must wonder what its effects will be on 
nature conservation, ecology and en-
vironmental pollution. The answer to 
these questions must be sought within the 
relationship between increased produc-
tion and input of labour and fossil energy. 
The law of diminishing returns 
provements in crop yields. The vagaries of derived from fossil sources. Fossil energy When other production factors are kept 
human nature, climate, and individual is used to power labour-replacing constant, an increased application of 
skill and knowledge have meant that machinery and fossil chemicals are the nitrogen results in an increase in yield~ 
farming systems seldom operate at an op- source of fertilisers which may increase each additional amount of nitrogen, how-
timum in economic, social or, for that production levels. At present, the use of ever, gives a smaner additional yield. This 
matter, biological terms. Increasingly, fossil energy in Dutch agriculture is an illustration of the law of diminishing 
however, knowledge of production amounts to 420 g. Joule per agricultural returns. However, no. farmer will apply 
methods and plant biology means that, labourer per year, which compares with only nitrogen; rather he will adapt the 
theoretically, maximum yield is no longer manufacturing industry and, incidentally, input of different production factors so 
governed by human whim and fallibility. equals the energy use of fifteen average that more nitrogen is applied only when 
The last ten years have seen an increasing Dutch families. Agriculture is thus among the amount of phosphorus is correct and 
interest in nature conservation, the de- the more energy-intensive human ac- the water availability etc. is sufficient. A 
r1and for landscaping on amenity tivities. The very large increase in agricul- good farmer takes care that his husbandry 
grotmd~h~~~~ngd~-t~u~r~a~l ~p~ro~d~u~c~t~io~n~d~u~ri~nAq~r~e~ce~n~t~~~e~c~a~d~e~s~i~s~~~~~h~fa~orsruecon-
has been required for urbanisation and mainly due to the growth of technological sidered and controlled as effectively as 
recreation. Compromises therefore have knowledge and the input of additional possible. One may ask if the law of dim in-
had to be reached. This article describes fossil energy. ishing returns is also valid when a combi-
some policies for land use and empha- The following figures illustrate these nation of growth factors and agricultural 
sises one direction for selective develop- changes: in 1950 the average yield of engineering is considered. Then the con-
ment. So far as agriculture itself is con- wheat amounted to 3 500 kg/ha; in 1970 trary is true. Without external inputs, fac-
cerned, its principal aim should be re- that average had increased to 5 000 kg/ tors such as low natural nitrogen and dis-
garded as the production of food and ha; in 1978 the average yield was ease limit yield to a low level. Small inputs 
other organic products in such a way that 6 700 kg/ha, and yields of 7 000 to 8 000 of fossil energy (such as fertilisers) can 
their prices are reasonably low and the kg/ha were no exception. Similar trends greatly increase that efficieqcy. If we then 
use of energy and other resources is opti- can be observed for sugar-beet, potatoes consider the total responsE\ curve on an 
mal.. Agriculture must be economical also and grass. energy basis we can have an increasing 
32 
output per unit of input. This unexpected 
response is due to the nature of the pro-
duction process. A soil with a pH of 6 is 
necessary for normal production levels, 
say 5 000 kg/ha of wheat, but may also 
yield at a much higher level (1 0 000 kg/ 
ha). An increase of the production factor 
lime is then riot needed. Very important 
prerequisites for high yield, however, are 
protection against pests and diseases and 
the availability of water. However, protec-
tion against pests and diseases does not 
require so much energy· but rather the 
skill and experience to apply appropriate 
chemical and biological controls. Pest 
and disease control. must be carried out at 
the right time; so too must the various 
stages of crop husbandry, especially har-
vesting, since poor timing sometimes 
causes serious reductions in yields. With 
grass production, it has become increas-
ingly clear that a potential yield of 20 tons 
dry matter per ha can be reached in 
North-West Europe. However, mowing 
and grazing losses are very high, so that 
in practice the yields are not very much 
more than 7 to 8 tons dry matter/ha. Bad 
timing and lack of attention to the crop 
are the principal causes for these big dif-
ferences between potential and actual 
yield. The techniques to limit these con-
siderable losses are known, but lack of 
labour at the right time affects efficiency. 
In fact, the input of fossil energy to in-
crease yields is only fully effective when 
backed by the knowledge, skill and exper-
tise of the farmer. As a result of our ex-
panding knowledge of water use and 
water management, of soil structure and 
texture, and as a result of the increased 
use of nutrients and the considerably in-
creased knowledge of pests and diseases, 
these factors, which are all subject to the 
farmer's control, are no longer so limiting 
for agricultural production. Solar radia-
tion, temperature ·and the physiological 
characteristics of the crop are now fre-
quently found to be the principal limiting 
factors. 
This conclusion is in accordance with the 
historical development of agricultural 
oroduction. Increasing yields may en-
hance labour prodvctivity and may pro-
mote a more efficient use of fossil energy, 
but one should realise that the keystone 
for these benefits is the management skill 
it takes to apply. productivity-increasing 
measures at the right time and in the right 
manner. 
In the Champagne district, vines are 
also treated with natural products: 
spraying with a growth substance 
containing plant extracts 
(Photo R. Zimmermann- Nature at 
Progres) 
Aspects of nature conservation 
At first glance a description of the devel-
opments in high-technology agriculture 
may seem strange in a journal about 
nature conservation, and about conserva-
tion of wildlife and its habitat. However, 
high-technology agriculture is with ·us, 
and it is essential to ensure adequate food 
supplies in heavily populated countries. 
Policies for nature conservation must take 
into account this need for a viable agricul-
ture. 
Productivity per ha may increase con-
siderably when fossil energy is introduced 
as nutrients or soil additives and when the 
availability of skilled labour is guaranteed. 
This rise in productivity per ha may actu-
ally release surplus land for alternative 
uses such as forestry, urbanisation, rec-
reation and nature reserves, and also for 
less intensive agriculture. This last possi-
bility is of particular importance in West-
ern Europe, where much of the landscape 
has been shaped by the agriculture of the 
past. Because less arable land is needed 
per capita for food supply in high-tech-
nology agriculture, the opportunities to 
put such a concept into practice will arise. 
Nature conservation, extensive agricul-
ture and intensive agriculture may be inte-
grated in the majority of our farming 
areas. The systems that provide both a 
good economic return from an agriculture 
of low intensity and improved values for 
wildlife are still to come. Within the next 
few decades a clearer idea of the options 
will emerge. 
To see how such a technology might work 
one could look more closely at pastures 
used for beef rearing. 
These extensive agricultural systems 
must be retained, not so much for their 
products, but more to retain rural employ-
ment opportunities and to maintain 
historical landscapes. 
In these low-yielding agricultural areas 
the number of farm workers per ha should 
be low and the input of fossil energy need 
not rise too much. In this way pastures 
rich in number of species of herbs and 
plants may stand a better chance of 
survival. Because this system is primarily 
aimed at landscape/amenity preservation, 
stock levels are lower than they would be 
for maximum productivity. A high propor- . 
tion of land could therefore be reforested 
or used for nature conservation. 
Thus three different management systems 
emerge: labour and fossil energy inten-
sive production on a limited land area; a 
less intensive agriculture that aims at 
landscaping goals a.1d wildlife conserva-
tion and, finally, an area that is used solely 
for forestry, .nature conservation and so 
on. 
Selective development 
The suggested alternative agricultural 
system may cause complications in terms 
of current agricultural policy. 
One must be· careful not to imply that high 
yielding and labour and fossil energy in-
tensive agriculture is totally incompatible 
with wildlife. The cropped areas may be 
barren of wildlife; this need not apply, 
·however, to boundaries, field divisions 
and uncropped corners. We can also 
make improvements, especially in ad-
vanced pest and disease control mea-
sures. In many cases production of 6 tons 
wheat/ha requires no m0re fossn energy 
input than a-production of8to 10 tons/ha. 
Use of pesticides might be reduced if we 
could improve biological control mea-
sures. An example of this is apple produc-
tion in the Netherlands, where integrated 
· pest an disease control is beco~ing an 
accepted practice. This requires much 
skill and experience but has sharply re-
duced the amounts of pesticides required 
for crop protection. 
There is 
another way 
Starting in the mid-1960s, the normal 
practice was to spray apples some twenty-
five times a season against disease and 
pests. Most of these sprayings were pre-
ventatively applied according to a set 
schedule. The problems caused by this 
system were manifold. Resistance against 
pesticides developed so that the number 
of sprayings had to be increased and the 
range of compounds had to be adapted. 
To break this vicious circle, and to dimin-
ish the negative effects of pest control,-
integrated control was developed. 
Integrated control in this example now 
involves both the classical methods of 
biological control, including host plant re-
sistance, and the more advanced new 
techniques of pest control involving culti-
vation methods, genetic manipulation of 
pests and selective use of pheromones 
and insect hormones, as well as the usual 
selective pesticides. Considerable pro-
gress has been made through research in 
this field. In apples, the number of spray-
ings has decreased considerably and the 
use of the more selective compounds is 
becoming more and more normal. Bio-
logical control is used against many of the 
secondary species, which became pests 
after spraying and treatment against pri-
mary pests because those sprays also 
eliminated the secondary species' natural 
enemies. For example, fruit-tree red 
spider mite and apple leaf roller, the most 
severe animal pests on apples, can be 
kept under control by their natural en-
emies. Fruit-tree red spider mite is con-
trolled by predatory mites, and apple leaf 
roller by a combination of parasites and 
bacteria. Against these secondary pests, 
sophisticated techniques are being devel-
oped vvf1ich should result in a satisfactory 
control system. 
It has not been easy or inexpensive, since 
a well-equipped research team was re-
quired. working in combination with a 
skilled management team. 
We have attempted to present a concept 
of agriculture which is compatible with 
the aims formulated in the introduction 
and does not exclude nature conserva-
tion, but even paves the way for it. The 
development of this concept requires 
fundamental changes in existing practice, 
since the safeguarding of historic small-
scale iandscapes requires a low-intensity 
agriculture running in parallel with an 
34 
agriculture dependent on high tech-
nology. 
An alternative could be the division of the 
land between ·nature conservation and 
high-technology agriculture, but this 
seems incompatible with the objective of 
landscape conservation and the mainten-
ance of an agricultural work-force. Much 
historical agricultural land would then be 
taken out of production and used for 
probably poor, natural forests. A third di-
rection for future agricultural develop-
ment is promoted by those who maintain 
that agriculture should use less fossil 
energy and more "biologically" sound 
methods. 
These alternative technologists also wish 
to remove artificial fertilisers and biocides 
from the production system. Farms 
should become more labour-intensive 
and the number of tractors and other 
energy-consuming machines should be 
decreased. Clearly that approach is based 
on an ideology which ignores the pres-
ence of the real world as it now exists. 
While we might decrease fossil energy 
input somewhat, the input of labour 
would be increased considerably. 
Moreover, all land would then be required 
for agricultural production, since produc-
tivity would be much lower (2 000 to 3 000 
kg wheat/ha instead of 7 000 to 8 000 kg/ 
ha in high-technology agriculture). At 
some point dietary adequacy could be 
placed in jeopardy. The high number of 
people in the production process would 
have either to live at a very low wage or 
prices would have to increase consider-
ably. The prospect for society would not 
be very hopeful, nor would that for nature 
conservation,·since too much land would 
be required for agricultural production. 
Se~ective development is necessary with a 
high-technology agriculture centred on 
the best lands. This means an agriculture 
that is labour- as well as capital- intensive 
and needing highly skilled and well-
equipped farm-workers with sufficient 
time to apply their knowledge. To limit the 
use of biocides, more attention should be 
paid to the development of integrated 
pest control and early warning systems. 
More research should be directed into the 
development of new management tech-
niques for those extensive areas of low-
intensity agriculture. These management 
systems can still apply much modern 
technology, but in such a way that labour 
and unit of land are both 
very important 
in these areas and revenue from them 
should be sufficient to cover the farmer's 
expenses. 
In this system of selective development a 
considerable part of all land is available 
for other activities, such as forestry, · 
nature conservation and urbanisation. 
Hopefully, policy makers will start dis~ 
cussion on these options in the near fu-
ture. R.R. and R.S.L. 


There is another way

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