Biophysical possibilities of European agriculture: an explorative investigation

sion on product quality and production process shows a lot of ideology and a considerable interest in agricultural techniques that are dominated by a particular view on life and man, such as in or- ganic farming. The ban on artificial fertilisers and synthetic biocides is justified on basis of a philoso- phy that originates from a time before the enlight- enment in agriculture started. In spite of what was just stated, in the near future such discussions on agricultural methods and their consequences for the environment, as well as various accepted values, will continue. Finally there is a growing awareness that too narrow crop rotation and in generic terms too intensive cropping and farming systems are sub- optimal in biotechnical and in environmental terms. In fact, a crop should be grown at nearly maximum production levels potential levels, es- pecially on the better soils, to realise the highest productivity and efficiency for each of the individ- ual production factors. In general, it is therefore necessary to extensify too intensive generic sys- tems and, counter intuitively, to intensify individ- ual crops when grown to reach optimality in biotechnical and environmental terms. That movement is present at various places and most clearly in those areas of Europe where too inten- sive systems in generic terms were developed dur- ing the last few decades.

4. Biophysical possibilities of European agriculture: an explorative investigation

The rise in productivity of various crops under different conditions may be illustrated in various ways. In a detailed study for the European Union Rabbinge et al., 1994 it is shown very clearly that the majority of agricultural area is still sub- optimally used. That will be illustrated with a simulation study on potential attainable and ac- tual yield of wheat in Europe. 4 . 1 . Production potential for winter wheat in Europe The biophysical production potential and its regional distribution can be estimated using data generated by the MARS project monitoring agri- culture with remote sensing. The MARS project was carried out by the Joint Research Center JRC of the European Commission to modernise the collection of regional agricultural statistics by combining GIS, remote sensing and crop mod- elling techniques. The MARS system includes the crop growth monitoring system CGMS Vossen and Rijks, 1995; van Diepen et al., 1998 which makes year-specific estimates of the regional crop yields on the basis of the agrometeorological crop model WOFOST Supit et al., 1994. The MARS database covers Europe west of the Ural, and in addition Turkey and the Maghreb down to a latitude of 33°N. The CGMS informa- tion products include simulated potential and wa- ter-limited yields for eleven field crops and grass. The long-term average simulated water-limited yield of winter wheat can serve as indicator for regional production potential. The geographical land unit to which the WOFOST model is applied is a unique combina- tion of soil, crop and climate. The grid cell 50 × 50 km dictates the climate unit that is used in the study. That may lead to errors but they seem to be acceptable. All suitable soils within a cell are clustered in groups of similar physical profile. The model is applied to each group with a crop variety that matches the regional crop calendar. The crop data have been derived from field experiments in Western Europe up to 1985. The environmental data needed by the model are daily weather data, including solar radiation, minimum and maximum temperature, rainfall, air humidity and wind, and soil profile data including the available moisture holding capacity and maxi- mum rootable depth. These data are used to calculate the growth and yield formation, the crop phenology, the crop water use and the soil water balance. The model assumption is that the soil is freely draining, that there is no influence of shal- low groundwater and that there is no redistribu- tion of water by run off mechanisms. The growth driving process is photosynthesis, of which the maximum is determined by light interception and temperature. If the soil becomes too dry, the growth is limited, and the resulting drought-af- fected yield is called the water-limited yield. The meteo data were available for some 600 stations for periods of 15 – 30 years and have been ob- tained partly from the various national meteoro- logical services, and partly from US National Climatic Data Center NOAA-NCDC. The daily station weather data have been transformed to a uniform format and interpolated from the stations to the grid. The soil data have been derived from the soil map of Europe at scale 1:1 million for West and Central Europe Le Bas, 1996; Monta- narella, 1998, and from the FAOUnesco, soil map of the world at scale 1:5 million for Northern and Eastern Europe FAO, 1981, Turkey and the Maghreb. The coarser scale of the latter map suggests much less variation in soils than in Cen- tral and Western Europe. The soil data have been used as input to the crop model, and for the evaluation of the land resources for their suitabil- ity for cereal cropping. The maximum crop production per grid can be roughly estimated by multiplying the average sim- ulated water-limited yield with suitable area. The mean simulated winter wheat yields and suitable areas were compared with FAO data on national agricultural statistics for 1995 FAO, 1996 on yield, arable area and production volume of cere- als and wheat. A logical reference would be the average of the national yields over a number of recent years. This proved quite complicated be- cause of changes in political boundaries in East- ern Europe. In addition, the accuracy of the national figures is a problem. For the EU coun- tries the errors in the national figures are esti- mated at 9 5 for Northern Europe and higher for Mediterranean countries Vossen and Rijks, 1995. Also, it is not yet known how the long term technology trend in national yields has been influ- enced by changes in the Common Agricultural Policy and politico economic developments in Central and Eastern Europe over the last decade. For the countries of EU12, Russell and Wilson 1994 did not observe a trend in national wheat yield over the period 1985 – 91 and they found that the inter-annual fluctuations in yield coeffi- cient of variation were close to 6 for most countries. When it exceeded 10 it could be re- lated to a year with an exceptional low yield, so it is only in years with extreme weather conditions that large yield fluctuations occur. In 1995 the weather over the whole of Europe was rather favourable except for Spain and Portugal, which experienced a severe water shortage period in late spring. Also in Southeastern Russia there was a relatively strong summer drought in 1995 MARS, 1995. In these countries the reported 1995 yield may be somewhat below average. The range in statistical yields over countries is larger than the within-country range in yields over the years. The differences in statistical yield level be- tween countries show a fairly consistent pattern over the years, except for extreme years. There- fore we may use the statistical yield data for the single not-extreme year 1995 as an approximation for the geographical pattern of average national yields. The figures are indicative only. The present study deals with Europe only, excluding Turkey and Maghreb. It demonstrates clear differences in regional cereal yield potentials, taking into ac- count that these data are used as an explorative first step in a further analysis on the options for agriculture and land use in Europe. 4 . 2 . Land resources and regional distribution of suitable soil areas The assessment of soil suitability for mecha- nised cereal cropping consisted of assigning a label ‘suited’ or ‘unsuited’ to each soil map unit on the basis of given or derived properties: un- suited may be due to steep slope, shallow soil depth, salinity, alkalinity, stoniness. The climatic suitability was not evaluated a priori, but will be discussed on the basis of the simulation results. The largest contiguous area of predominantly suitable soils is found in the plains of the Ukraine, Belarus and Russia and is formed by the soil zones of Chernozem and Podzoluvisols. It is pos- sible that part of the latter soils are in reality too wet for cereal cropping, but in principle this can be remedied by improving drainage conditions, so that they can be considered as potentially arable. Although, in the current situation this may nei- ther be economically feasible nor ecologically de- sirable. The southern and southeastern boundary of this area is formed by the transition of the Chernozem to the Kastanozem zone, classified as Table 1 Land resources and their use per country in Europe a MARS Data source FAO MARS FAO Total excluding north Suited area Current arable area Current cereal area Total area 314 148 UK+Ireland 73 314 35 547 421 France 183 547 83 68 54 68 16 Benelux 5 356 235 118 66 Germany 356 84 24 14 84 8 Austria 43 40 Denmark 23 43 15 193 93 450 28 Sweden 11 130 88 25 Finland 10 337 597 245 Spain+Portugal 175 597 73 301 102 Italy 81 301 42 132 29 24 132 13 Greece 80 16 10 3 Norway 324 41 8 4 41 2 Switzerland 534 320 Poland+Cz+Slovk+Hung 236 534 138 349 199 349 133 Rumania+Bulgaria 85 285 285 131 Former 72 39 Yugoslavia+Albania 175 Baltic states 114 175 58 17 207 Belarus 135 207 61 26 603 392 603 333 Ukraine 129 2885 1875 European part Russia 751 4215 299 7924 4669 All Europe 2418 9962 1099 a Total area extents 1000 km 2 of land surface, of land suited for the cultivation of cereals, of land currently 1995 used as arable land, and of cereal land for the various groups of countries in Europe. MARS: MARS-CGMS data base Vossen and Rijks, 1995. FAO: FAO, 1996. Production yearbook 1995. Climatically unsuited area in northern Europe is excluded. largely unsuited because of alkaline soils. To the north, the suitability of the land for cereal grow- ing is determined largely by the temperature regime. The second largest patch of suitable soils is the western half of France, third comes the succession of plains along the Danube River in Central Europe. The lowest concentration of suit- able soils, with less than 50 suitable soils, is shown for Norway, Sweden, the United Kingdom and Ireland, and large parts of the Mediterranean countries, such as Italy, Greece, and the former Yugoslavia. Statistics on land use resources and their use and use potential are given by country in Tables 1 – 4. The countries are grouped by political and climatic blocks for which subtotals are given in Tables 5 – 10. The political blocks are the Eu- ropean Union, two non-EU countries Switzerland and Norway, Central Europe and the countries in the European part of the former USSR. The data on the Russian Federation refer to its European area only. The 15 EU-countries are grouped by climatic zone. EU-South includes Portugal, Spain, Italy and Greece. EU-North is Denmark, Sweden and Finland, and the other eight countries are labelled as EU Middle. The northern territories have been excluded from the land suitability as- sessment, because in these regions the climate is not suitable for cropping, and this overrules soil suitability. The dividing line runs roughly east west and attains 61° latitude North in Finland. Tables 1 and 2 give the total extent of land resources per country, and the shares of suitable land, arable land and land under cereals. The aggregate figures for climatic zones within EU15 are in Tables 5 and 6, and for political groups of countries are in Tables 8 and 9. The area used as arable land in the European Union is about half the area classified as suitable. When the possibil- ity of classification and mapping errors is ig- nored, the other half must be occupied by other land use including forest, permanent crops, pas- ture and grazing land, and build up area. A lower proportion of arable land indicates a pref- erence for other land use than arable farming, e.g. grassland in the Netherlands and forest in Sweden. A higher proportion arable land may indicate the occurrence of few other kinds of land use, or a high pressure on the land, where arable farming is practised on unsuited soils. In Italy and Greece the area extent of arable land is about 80 of the suitable land, in Central Eu- rope about 70. In Eastern Europe, the use in- tensity of suitable land is highest in the Ukraine, about 85. About half of the arable area is used for cereal cropping. The other half is under root crops, oil seeds, pulses and green fodder crops. The per- centage of arable land under cereals is highest in Central Europe, about 60. Table 2 The importance of cereal cultivation in the countries of Europe a Cereal area Arable area Arable area Suited area fraction of suited area fraction of total area fraction of total area fraction of arable area excluding north excluding north UK+Ireland 0.47 0.49 0.23 0.48 0.33 0.45 France 0.43 0.77 Benelux 0.79 0.30 0.24 0.31 0.66 Germany 0.56 0.50 0.33 Austria 0.57 0.17 0.57 0.29 Denmark 0.93 0.58 0.53 0.65 0.48 0.30 Sweden 0.06 0.39 Finland 0.68 0.28 0.07 0.40 0.42 0.29 0.71 Spain+Portugal 0.41 0.34 0.79 Italy 0.27 0.52 Greece 0.18 0.22 0.83 0.54 0.30 0.20 0.63 0.03 Norway 0.20 0.49 0.10 0.50 Switzerland 0.58 0.60 Poland+Cz 0.74 0.44 + Slovk+Hung 0.64 0.57 Rumania 0.67 0.38 + Bulgaria 0.55 0.46 Former 0.54 0.25 Yugoslavia+Albania 0.65 0.51 Baltic states 0.33 0.29 0.43 0.29 0.45 Belarus 0.65 0.65 0.85 Ukraine 0.55 0.39 0.65 0.40 0.18 0.40 European part Russia 0.45 0.59 0.52 0.24 All Europe a The relative availability of suitable land and the relative importance of cereal cropping: cereal area as fraction of arable area, and arable area as fraction of both suited area and total area. Climatically unsuited area in northern Europe is excluded. Table 3 Current yield levels of wheat and cereals compared to the simulated water limited yield of winter wheat a FAO Data source FAO Current yield MARS wheat fraction of wlim yield Mean sim. current yield current yield cereals wheat water-lim yield DMDM tonha tonha wheat tonDMha 7.8 6.9 UK+Ireland 0.77 8.5 6.5 6.5 7.0 0.78 France Benelux 8.0 7.5 8.0 0.79 6.9 6.1 6.5 0.89 Germany 5.2 6.3 Austria 0.62 7.0 7.3 Denmark 6.0 6.0 1.02 6 4.5 Sweden 1.12 4.5 3.7 3.0 6.0 0.52 Finland 1.7 Spain+Portugal 1.8 3.0 0.48 3.2 4.8 5.0 0.54 Italy 2.5 Greece 2.5 3.1 0.84 5 Norway 3.3 5.0 0.84 6.2 5.0 Switzerland 0.74 7.0 6.5 3.5 Poland+Cz 2.6 0.45 + Slovk+Hung 3 Rumania +Bulgaria 3.1 4.5 0.56 4.5 3.2 2.6 0.60 Former Yugoslavia+Albania 2.2 Baltic states 1.8 7.0 0.26 2.5 1.9 8.0 0.26 Belarus 6.0 Ukraine 3 2.5 0.42 2 1.5 6.0 0.28 European part Russia – 3.1 – All Europe – a MARS: MARS-CGMS data base Vossen and Rijks, 1995. FAO: FAO, 1996. Production yearbook 1995. See text in chapter 4 for explanation of fraction of wlim yield above 1.0. DM, dry matter. 4 . 3 . The water-limited yield le6el and their regional distribution The regional distribution of water-limited yields is shown in Fig. 2, and the national mean simulated water-limited yields are given in Table 3. The simulated yield is expressed as tonha dry matter grain. If we assume a standard moisture content of 16 in grain, the equivalent of 1 ton dry matter is 10084 = 1. 19 ton of the real product. The highest yields above 8 tonsha dry matter grain with regional maxima just exceeding 9.5 tonsha are found where the weather is cool, sunny and with sufficient rain during the growing season, allowing a long period of grain filling. These conditions are found along the Atlantic, e.g. Ire- land, Scotland and the north coast of Spain, in some areas at higher elevations, e.g. Bavaria Ger- many and Galicia Poland, and a very large area in Belarus and Russia, roughly delimited by the triangle Bialystok at the Polish border, Petersburg and Moscow. Table 4 Theoretical maximum production volume winter wheat on all suited lands compared to current 1995 production volume, and production per inhabitant a Data source FAO 1995 MARS Wlim prod all FAO MARS Wlim prod all Cereals population suited land per capita prod cereals suited land Mton Million Mton kgperson Mton DM 24 62 149 387 UK+Ireland 125 351 295 54 58 931 France 51 43 4 25 160 Benelux 40 82 182 488 Germany 153 5 Austria 8 17 625 20 9 5 24 1800 Denmark 29 Sweden 50 5 9 556 42 63 53 3 5 600 Finland 13 49 73 265 87 Spain+Portugal Italy 61 20 57 351 51 4 10 400 9 7 Greece 1 4 Norway 250 8 10 1 7 7 143 Switzerland 6 248 36 64 208 563 Poland+Cz + Slovk+Hung Rumania +Bulgaria 107 26 31 839 90 59 Former 70 10 28 357 Yugoslavia+Albania 3 Baltic states 8 80 375 95 5 10 500 Belarus 108 128 32 52 280 615 Ukraine 235 1339 1125 44 94 468 European part Russia All Europe 339 2802 668 507 3334 a For the comparison the simulated dry matter yield is converted to grain yield having a moisture content of 16. MARS: MARS-CGMS data base Vossen and Rijks, 1995. FAO: FAO, 1996. Production yearbook 1995. North of this area the yield decreases, and at only a few hundred kilometers distance the north- ern limits of cereal cultivation is found. The short temperature determined growing season is the ma- jor limitation. Yet in Southern Finland a water- limited yield of nearly 6 tonha is found. Table 5 Land resources and their use per climatic region of the European Union a Current arable area Suite area Total area excluding north Total area Current cereal area 000 sqkm 000 sqkm 000 sqkm 000 sqkm 000 sqkm 882 EU — middle 404 1369 197 1369 830 366 221 76 36 EU — nordic 376 EU — south 280 1030 128 1030 3229 2765 361 760 Total EU15 1479 a Countries are grouped as shown in Tables 1–4. Total area extents 1000 sq km of land surface, of land suited for the cultivation of cereals, of land currently 1995 used was arable land, and of cereal land. Table 6 The importance of cereal cropping per climatic region of the European Union a Suited area fraction of Arable area fraction of Arable area fraction of Cereal area fraction suitable area total excluding north total area excluding north of arable area 0.64 EU — middle 0.46 0.30 0.49 0.60 EU — nordic 0.34 0.09 0.47 0.74 0.27 0.37 0.46 EU — south 0.51 0.24 0.48 Total EU15 0.53 a The relative availability of suitable land and the relative importance of cereal cropping: cereal area as fraction of arable area, and arable area as fraction of both suited area and total area. Table 7 Theoretical maximum production volume winter wheat on all suited lands compared to current 1995 production volume, and production of cereals per hectare and per inhabitant, per climatic region of the European Union Wlim prod all Wlim prod all 1995 prod cereals Population Cereals per Cereals per ha capita suited land suited land Mton Mton Million Mton DM kgperson tonha 753 127 EU — middle 235 633 540 6.4 EU — nordic 119 141 17 19 895 4.7 157 37 116 319 2.9 EU — south 132 1051 181 370 489 884 5.0 Total EU15 Table 8 Land resources and their use per political group of countries in Europe a Total area excluding north Suite area Current arable area Total area Current cereal area 000 km 2 000 km 2 000 km 2 000 km 2 000 km 2 2765 1479 EU15 760 3229 361 121 24 NorwaySwitzerland 14 365 5 1168 650 1168 441 Central Europe 262 Former European 5200 3870 2516 1203 471 USSR 7924 4669 All Europe 2418 9962 1099 World 6910 a Total area extents 1000 sq km of land surface, of land suited for the cultivation of cereals, of land currently 1995 used as arable land, and extent of cereal land. In reality, some of the areas with the highest simulated yields may not be the most favourable for the production of winter wheat, because some production and growth factors have not been included in the model. In the Atlantic top- yield regions Ireland such a factor is the high humidity, which is sub-optimum for maturing and harvesting, causing yield losses and grain quality problems. In the high elevation zones the simulated growing season may be too long, so that the maturing period extends too far in the late summer or autumn. A choice for a short-season, lower yielding variety would be real- istic. In the northeastern zone several yield lowering factors may play a role. The model does not take into account the effect of frost damage to the standing crop. In the northernmost regions roughly above the line Stockholm-Moscow winter wheat has a great risk of crop failure due to winter frost. Next, the simulated growing season starts too early because in the model, the crop reacts to air temperature only, ignoring the fact that in spring the soil temperature remains too Table 9 The importance of cereal cropping per political group of countries in Europe a Cereal area fraction Suited area fraction of Arable area fraction of Arable area fraction of total area including north of arable area suitable area total excluding north 0.53 EU15 0.48 0.51 0.24 NorwaySwitzerla 0.04 0.36 0.58 0.20 nd Central Europe 0.68 0.38 0.59 0.56 0.39 0.65 Former European 0.48 0.23 USSR 0.45 0.24 0.52 0.59 All Europe a The relative availability of suitable land and the relative importance cereal cropping: cereal area as fraction of arable area, and arable area as fraction of both suited area and total area. Fig. 2. Regional distribution of water limited yields in Europe, simulated values. low long after the winter frost. In addition the soil is then too wet because of the frozen under- ground. In the late summer also high humidity may cause problems in these regions, which pleads for early maturing varieties. All these fac- tors indicate that the water-limited wheat yield gives a too optimistic impression for Northeastern Europe. At the country level this applies espe- cially to Finland. The water-limited yield may be estimated 2 or 3 tonsha too high; the exact yield effects can be quantified by experiments and im- proved models. Another factor that could contribute to the relatively high simulated yield level in Russia is that the radiation data are derived from tempera- ture data, and not from cloud cover data as in the rest of Europe. In Eastern Europe going from the high water- limited yield zone to the south, the simulated yield decreases by the shortening of the grain filling period and the effects of summer drought. Near the Black Sea it falls below 50 of the highest yield level. In the Balkan roughly south of 45° latitude Beograd, the water-limited yield varies between 3 and 5 tonsha. In the rest of Europe north of Alps and Pyrenees the yield level varies mostly between 4.7 and 8 tonha, forming a com- plex pattern related to elevation rainfall and tem- perature, distance to the sea, latitude, soil depth and soil water holding capacity. Areas with re- markably lower yields down to 3.2 tonsha are: 1 around Berlin because of rather low rainfall and high proportion of sandy soils; 2 parts of South Sweden, because of shallow sandy soils; and 3 the Mediterranean part of France Languedoc-Rousillon, because of shallow soils and low summer rainfall. In Italy there is a north-south gradient in yield from above 6 to below 3 tonsha. The west coast is more humid than the east coast, the driest parts are the heel of the boot and Southern Sicily. The mild winter on the west facing coasts of Italy and also Portugal advances the growth cycle so that the grain filling takes place before the early spring and summer drought can hit the crop. In fact, water shortage is most severe in May and that may affect the attainable yield considerable. The lowest yield levels are found for the largest part of Spain, where the yield level varies from 1.6 to 3.2 tonsha, which is related to a short grain filling duration and severe water shortage. In areas where the occurrence of drought results in low water-limited yield levels it may be possible to obtain higher yields by applying supplementary irrigation or, even without irrigation, from soils with a more favourable water regime than as- sumed in the model, e.g. in river plains and on foot slopes. Where the simulated water-limited yield is very low, e.g. in Spain, the competition for water between plants can be reduced by applying a lower plant density than simulated in the crop model. 4 . 4 . Comparison water-limited yield le6el with obser6ed 1995 yield In the major cereal producing countries of the EU, France, Germany and the UK, the actual yield level is about 75 – 80 of the water-limited yield Table 3. Actual yield levels of more than 100 are obtained in Sweden and Denmark. This high yield level can probably be attributed to irrigation Denmark or the use of better soils than the average of the suitable soils Sweden. In Finland the actual yield is 50 of the calculated water-limited yield, but, as explained in the pre- ceding section, the water-limited yield is probably too high, it therefore may be better to reverse the calculation. The current yield level in Finland is 3.5 tonha and assuming that this corresponds to 80 of the water-limited yield, the water-limited yield should be 4.4 tonha. In Italy the actual yield is only 55 of the water-limited yield. This can be explained by the use of relatively low yielding durum wheat varieties by the farmers, and because wheat is not grown on the best soils, which are used for higher value crops. The low relative yield in Spain 50 can be attributed partly to the year effect, because 1995 was a relatively dry year. In the humid year 1996, the national yield was nearly twice as high as in the preceding year. In Central Europe the actual yields vary between 45 and 60 of the waterlim- ited yields. It should be possible to raise these yields with 30 – 50 by intensifying farming prac- tices, and reach the West European yield level of 75 – 80 of the water-limited yield. In Northeast- ern Europe Baltic countries and east and north- east of them the actual yields are about 25 of the calculated water-limited yields. Even if there is some doubt on the simulated yield level due to model and data deficiencies, there is evidence that the yields could be at least as high as in Finland. This means that the yields can be nearly doubled in these countries by improving land and water management and intensifying crop management. Doubling the yield level seems also possible in the long run for the Ukraine, where the actual yield level is at about 40 of the water-limited poten- tial. The aggregate production figures for climatic zones within EU15 are in Table 7, and for politi- cal groups of countries in Table 10. 4 . 5 . Current and potential production 6olume The total yearly cereal production of the EU amounts to 180 Mton, of which 54 Mton are produced by France and 40 Mton by Germany Table 4. The average amount per capita is about 500 kg cereals, which is largely used to feed animals. The total production volume of Central Europe is about 72 Mton of which 26 Mton by Poland and 20 Mton by Rumania. This corre- sponds with nearly 600 kg per capita, largely sufficient to feed the population and a large num- ber of animals. A 40 yield increase will bring the production volume of Central Europe at 100 Mton. The current cereal production volume in Eastern Europe is 84 Mton, of which 32 Mton by the Ukraine and 44 Mton by European Russia. The per capita production is about 500 kg. It is not realistic to assume that the whole area classified as suitable for cereal production will be used for growing cereals. The land use pressure is too varied over the countries and regions to draw general conclusions on possible expansion or con- traction of the cultivated area. Whether intensifi- cation will take place depends on economic conditions, but it is definitely possible to realise higher yields. The results of the analysis of regional produc- tion potential in Europe shown above suggest that large increases in rainfed crop production are feasible in Central and Eastern Europe, while these countries produce currently largely enough to feed their population, leaving a big surplus for their livestock. Although the analysis was done for winter wheat, this conclusion holds for cereals in general and also for other rainfed field crops or grass, under the assumed condition that soil drainage, nutrient supply and crop protection are adequate. A constraint for this study was the use of a very heterogeneous database, combining many data from different sources and of varying accuracy. The explored regional yield potential was at the level of water-limited yield, but a number other limitations was not considered such as effects of frost and excess moisture. The effects of nutrient limitations were not considered. In reality, a num- ber of yield reducing factors will also play a role, e.g. weeds and diseases, suboptimal timing of farm Table 10 Theoretical maximum production volume winter wheat on all suited lands compared to current 1995 production volume, and production of cereals per hectare and per inhabitant, per political group of countries in Europe Cereals Population Cereals per ha Wlim prod all Wlim prod all 1995 prod cereals suited land Mton suited land Million tonha per capita kgperson Mton Mton DM 181 370 489 5.0 EU15 884 1051 4.0 182 11 Norway 16 2 14 Switzerland 2.7 585 123 Central Europe 72 357 425 164 512 Former European 1.8 1548 1842 84 USSR 507 3.1 All Europe 2802 3334 339 668 1902 5700 334 World 2.8 operations. These factors become important for the planning of measures to improve the efficiency of agricultural production. More detailed analysis will be needed to assess the specific situation of each country, taking into account soil and climatic resources, the possibili- ties for expansion of the arable area and intensify- ing farming practices, in the context of socio-economic and political developments. This analysis demonstrates evidently that there is still ample room for expansion of the agricul- tural production. It also shows that considerable innovations in agricultural production techniques and changes in land use are possible and needed. The availability of water and other limiting factors such as nutrients should be guaranteed and the effect of growth and yield reducing factors such as pests, diseases and weeds should be controlled and with biological means as is nowadays already widely demonstrated in practice. Best technical means lead to biotechnical and environmental technical improvements.

5. Multiple goals of agriculture and land use