sou · GVB360d10 · 2008-01-01 00:00:00 — The main reason for this is that insects will presumably be favoured by a warmer climate during the and will therefore be more numerous in the spring. The effects of insects on crops are direct since they feed on crops, but indirect damage through the ability of insects to spread various virus diseases is also of great importance. region in will probably experience increased problems with damage caused by insects and virus diseases, but the increase will be greatest in and in drier areas. Insects will be considerably earlier in the spring than at the present time since the growing period will be extended, which will probably cause increased attacks on spring-sown crops. At present, spring tillage coincides rather well with the start of the growing period, but by ~2085 spring tillage will probably be delayed by up to a month compared with the growing period. The greater numbers of insects at spring sowing and the fact that spring crops will be exposed to virus diseases at an earlier stage of development will increase the need for pesticides unless there is an increase in other methods such as the use of resistant varieties. The assessment is that this effect will be of equal magnitude in and , but less in . Insects are also favoured by high temperatures in the summer and pesticide requirements can be predicted to increase here too for most crops. Insect and virus attacks in autumn in crops are currently limited by the fact that the number of insects is relatively low in the autumn and that there is no between infected springsown crops and vulnerable newly-sown crops. In a future warmer climate, there will probably be more insects in the autumn, while newly introduced spring-sown crops such as maize that grow long into the autumn could act as a for viruses from spring to autumn-sown crops and thus virus attacks in crops could increase. New species of insects will become established in , e.g. depending on the types of crops grown, but it is difficult to predict the species involved and a monitoring system is needed to follow developments in this area. Fungal diseases are favoured by both temperature and moisture. The moisture situation will be altered more irregularly in different SOU 2007:60 Bilaga B 24 33 parts of than the temperature. This means that we can expect large differences between regions. In addition, there are fungal diseases that are favoured by high temperature but not specifically by high air humidity. cereals will be particularly vulnerable since they will have a long infection period in the autumn. For spring crops, the effect can be less than at present in areas with a predicted relatively dry early summer period, such as southern areas of the country. In northern , however, these fungi will probably be of increased importance due to the generally wetter and warmer climate. In potatoes, leaf blight will probably increase somewhat. In a future changed climate, seed crops, perhaps particularly seed potatoes, will run a greater risk of being subjected to insect and virus attack than at present. The need may then arise to establish some form of seed reservation area in which ordinary commercial crops with a high proportion of virus-infected plants are restricted. This need may arise for the whole of . An increased incidence of pests after climate change can be counteracted with an increased use of pesticides, but this is not desirable from a number of perspectives. Improved cropping technology, increased use of resistant varieties and a good crop rotation to decrease the spread of diseases will therefore be of increasing importance. Weeds In general, the need for weed control can be expected to increase with climate change. A strong reason for this conclusion is that in countries with a warmer climate than , the use of herbicides is considerably greater than in . There are a number of natural explanations for this. A warmer climate will probably give rise to a more species-rich weed flora, e.g. because more species will have time for their reproductive phase in the extended growing period. In addition, crops with poorly competitive stands (e.g. maize with its wide row spacing) will probably increase in scope. An increased proportion of autumn-sown crops, at the expense of spring-sown crops, will risk leading to propagation of annual weeds, which will in turn increase the herbicide requirement. monotonous crop rotations and thus greater weed control intensity with increased use of herbicides will increase the Bilaga B 24 SOU 2007:60 34 risk of herbicide resistance, a problem that is predicted to increase with climate change. Strategies for adaptation to climate change mainly involve the development of methods of weed control and planning of cropping systems. There is of course a conflict relationship between weed control and the to decrease the use of herbicides, but also the to decrease nutrient leaching. Ploughless tillage limits this leaching but at the same time the grower loses an opportunity to control weeds by non-chemical methods. Quality The intention in crop production is to produce a product of a certain quality, where each product is defined by a number of different quality parameters. This leads to many conceivable effects of climate change and thus it is very difficult to present a general picture. The problems in presenting this picture are exacerbated by that fact that, with few exceptions, there is a lack of methods to predict the effects of given changes in climate. Greater problems can generally be expected with the hygiene quality, since pest attack is generally expected to increase. These difficulties will probably be greater in spring-sown crops than in autumn-sown, and greater in than in northern, since the risk of pest attack is predicted to be greatest in the former. Other factors that can cause changes in quality include changes in overwintering and snow cover conditions, but it is unclear whether this will lead to worse or better quality. The nutritional quality of crops consists of elements taken up from the soil and air and synthesised in the plant. The protein content in the plant is proportional to the nitrogen content, which is determined by carbon uptake from the atmosphere (growth) and nitrogen uptake from the soil. In a cereal crop, the main amount of nitrogen is taken up during early summer up to the beginning of and the main proportion of carbon is taken up thereafter. Our few calculations for fertilised grassland indicate that plant nitrogen requirements will increase considerably and that the increase in mineralisation will only be able to meet this requirement until the end of , while there will be a large deficit in April and . If fertilisation rates are not increased, this will mean lower protein concentrations. The decreasing soil water content in could SOU 2007:60 Bilaga B 24 35 limit carbon uptake and give an increase in protein concentration, but the crop will probably be so near maturation at this time that the effect might be small. In the example of malting , where the protein content must not be too low or too high, this will exacerbate existing growing problems. Too large a nitrogen dose in the spring can give rise to excessively high protein content in the event of a dry summer. However, a high nitrogen dose is desirable if summer growth is to proceed at a high rate. This type of problem applies to many crops and must also be understood in various cropping systems with different pre-crops and co-crops, which will require comprehensive analysis and synthesis work. In addition, high temperatures during grain filling can affect protein storage and protein composition, and these problems can generally be expected to increase. With climate change, protein storage in crops will also display a tendency to favour autumn-sown crops over spring-sown. Other quality parameters will also be affected by the climate but in most cases there is a lack of methods to evaluate whether the net effect will be positive or negative. However, higher temperatures during grain filling will generally cause increased problems in achieving planned quality standards. The possibilities for adjustment will probably consist of breeding new crop varieties, both traditional and genetically modified, for local growing conditions but also the more quickly available option of changes in cropping methods and systems (when these are known). For example, harvest times for silage cutting can be brought forward and cuts can be made more frequently to obtain forage with the correct quality. The need for nitrogen fertilisers will probably increase to produce the same protein concentrations as in the present climate. Bilaga B 24 SOU 2007:60 36 Table S1: Rough estimates of the effects of climate change on areas of Swedish crop production Land use: Reduced requirement for arable land for food and feed production Uncertainty in calculations, e.g. due to uncertainty in evaluating the effects of technological developments on yields per hectare Competitive ability of Swedish crop production in Europe is favoured by climate change but hampered by societal development sowing favoured at the expense of spring sowing General increase in yields per hectare Growing period: Growing period extended mainly in spring but also in autumn Spring tillage brought forward less than start of growing period Harvest brought forward sowing delayed Changes greater in south than north Water availability: Spring growth favoured by temperature increase Growth in - possibly restricted by increasing water deficit Increased irrigation requirement for horticultural crops and potatoes in particular Water deficit greater locally than regionally, and greater in and than in Autumn-sown crops favoured compared with spring-sown Crop pests: Insect attack generally increased, particularly in southern and eastern Spring-sown crops more vulnerable than autumn-sown New insect species, crops and crop sequences causing new and possibly greater attacks Fungal infection increased/decreased depending on regional differences in precipitation Pesticide requirements increased Weeds: weed species establishing in Weed incidence generally increased Increased incidence of annual weeds Herbicide requirements increased Quality: Growth, nutrient requirements and nutrient uptake increased, especially in spring Protein composition of cereal negatively affected by high temperature Forage cuts brought forward to maintain good quality Generally more difficult to control quality parameters in crops Increased fertiliser requirement Nutrient leaching: - Risk of nutrient leaching generally increased, mainly due to increased precipitation/runoff and nitrogen mineralisation - Increased leaching risks possibly dampened by increased plant uptake and removal with crops - Phosphorus losses expected to generally increase due to increased runoff and higher frequency of intensive rainfall, but can decrease in certain areas due to decreased surface runoff at snowmelt - Altered land use as a result of climate change can increase the risks of nutrient leaching SOU 2007:60 Bilaga B 24 37 Nutrient leaching The expected changes in climate will very probably bring about an increase in the leaching of both nitrogen and phosphorus from agricultural land. Quantifications of nitrogen leaching in a future climate have only been carried out for a few individual sites/areas in , but indicate an increase in leaching of (depending on site and climate scenario). This tendency should be compared with the National Environmental Objective of decreasing nitrogen leaching from agricultural land to neighbouring water courses by by the year 2015. The potential to decrease leaching in the current climate situation (19802000) with current cropping methods has been estimated to be a maximum of . Current food and feed production on agricultural land is thus causing a leaching of nitrogen that is at or above the limit for the relevant Environmental Objective. This problem will probably be accentuated by climate change. To achieve the above-mentioned Environmental Objective in the future, there will most probably need to be a change in both cropping methods and land use. Several land use scenarios (see above) indicate a decreased requirement for agricultural land for food and feed production. The Environmental Objective could thus to a certain extent be achieved through alternative land uses that are aimed at decreasing leaching. Adaptation A large proportion of the adaptation to climate change within agriculture will occur through farmers adjusting the timing of sowing and cultivation measures to the start of the growing period and soil drying and adjusting the time of harvest to earlier crop ripening. It can be more difficult to predict when autumn sowing should occur, since farmers will not know what the weather will be like in the following autumn and . Experiences from previous years will then be central. Since the climate varies widely between years, there is a high risk that what worked in the previous year will perhaps not work in the coming year, especially when farmers attempt to adapt their cropping to a progressively warmer climate through introducing new crops, varieties and cultivation methods. Here, research should be able to assist farmers with strategic crop planning by developing models concerning the effects of Bilaga B 24 SOU 2007:60 38 climate on crop production and methods for calculating the statistical probability of yield levels of different crops based on climate change scenarios and climate statistics. This would provide farmers with support in evaluating the risks associated with new crops and the potential for introducing these in such a way that risk-taking is adjusted to the finances of the entire farm. In addition, the increased requirement for crop protection chemicals and irrigation and the increasing variability in the weather will probably create an increasing need for requirement-based cropping measures. Research should be able to help farmers by developing applicable models that can simulate e.g. the developments in crops, crop pests and weeds based on weather forecasts. Alternative uses of arable land (alternatives to annual crops) may be necessary to decrease nitrogen leaching from arable land to a level that meets the specified Environmental Objectives. The most extreme and probably most effective method would be to plant a part of that area with . Most land use scenarios predict a considerable proportion of excess land, which could be used for purposes other than agricultural production, except in a strongly growth-orientated society with a high degree of global trade, where Swedish arable land would probably be more competitive for food and feed production than it is at present. However, we must bear in mind that the land use scenarios showed great uncertainty in the assumptions of both societal development and climate, not least the assumption of productivity increases per hectare caused by technological developments. If technological developments do not prove to be as strong as predicted, it is unclear whether Swedish food and feed production in the event of future climate change would not only be more competitive but also essential for food supply. Therefore in the perspective of these uncertainties, an alternative use of arable land to reduce nitrogen leaching should also consider the possible need for returning this land for use in supplying food. This means that alternative land uses for decreasing nutrient leaching should concentrate on crops that have a high capacity to take up nitrogen throughout the year, that do not have a negative effect on soil fertility and that are relatively simple to remove and replace with food and feed crops. In this perspective, is less suitable. Alternatively, or as a complement to altered land use, wetlands and barrier zones could be established to limit phosphorus and nitrogen leaching from agricultural soil. The need for such measures will increase in a climate change situation. SOU 2007:60 Bilaga B 24 39 Technical advances with the aim of improving crop nitrogen use efficiency through both plant breeding and cropping techniques can also contribute to decreased nitrogen leaching in the future. Improved cropping techniques, increased use of resistant varieties and improved crop sequences will be required to limit the expected increased use of crop pesticides. This will require research and development of e.g. methods of crop protection tailored to need, development of new varieties, alternative pest control methods and development of new systems that limit the spread of diseases. Adaptation to limit the expected increased use of herbicides to control weeds will principally involve the same components. A frequently recurring problem in crop production is that a measure to achieve one Environmental Objective often counteracts another Environmental Objective. For example, reduced tillage of the soil to reduce nutrient leaching provides less scope for nonchemical control of weeds. Increased difficulties in simultaneously achieving the Environmental Objectives and production objectives should be counteracted with increased knowledge of how crop production systems can be optimised. Use of existing systems analysis knowledge and technology to optimise planning of crop production systems against certain predetermined objectives will be an essential process that will also provide tools for evaluating the potential benefits of the new potential adaptation measures. The first adaptation to the expected decrease in water availability during the summer is to accept a moderate level of crop production increases in agriculture and perhaps increased variability between years. To utilise the production potential of climate change to the full, irrigation will probably be required. For horticultural crops and potatoes, the decrease in water availability must be covered by a corresponding increase in irrigation. The magnitude of this requirement could be approximately the same as the decrease in precipitation due to climate change. However, this figure is very rough and derives from individual cases. Model simulations must be performed to provide a measure of the magnitude of the water deficit for individual sites and years and its average value over years and regions. Such simulations will require organised indata for the various growing sites. These tools are available for individual locations and are used within research, but have not been applied in practical crop production in . Before irrigation measures are planned, the requirement must be mapped and the first adaptation measure must be to calculate the Bilaga B 24 SOU 2007:60 40 water deficit caused by climate change scenarios for different crops on different soil types in different parts of . The predicted increase in crop nitrogen requirements to achieve the desired protein concentrations can be met by increased fertilisation and by including more nitrogen-fixing crops in the crop sequence. These adaptation measures will lead to increasing difficulties in fulfilling the Environmental Objective of decreasing nitrogen leaching from arable land, and alternative uses of areas of arable land may be a necessary consequence. Quantification of the additional fertiliser requirement will require extensive calculations of the same type as those required to calculate the decrease in water availability. In general, the nitrogen calculations can be regarded as more complicated. In environmental protection work within agriculture, this type of calculation tool has been used on a relatively large scale in to assess leaching risks, but has not been linked to modelling of crop dynamics in relation to climate. Corresponding calculations for crop growth dynamics and nitrogen requirement are lacking, but modelling tools for such calculations are available within research. These calculations are strongly linked to the calculations of water requirements. Increasing problems will probably arise with the hygiene quality of crops. These will probably be counteracted by using alternative cropping systems, new varieties and increased inputs of crop protection chemicals. However, as regards a number of other quality parameters there is a lack of methods to evaluate the effects of climate change, even within research, and it is not possible to determine the net positive/negative effect. The first adaptation measure within research must therefore be to find methods (i.e. weather-driven models) for evaluating the effects of climate on quality parameters. measures can then be proposed. In practical cropping, farmers experience and knowledge will have to be used to evaluate any patterns in how quality determination appears to react to weather, which will probably depend to a high degree on the specific growing conditions on the farm. SOU 2007:60 Bilaga B 24 41 Table S2: Adaptation requirements within areas of Swedish crop production due to climate change Measure Aim Weather-controlled, precision fertilisation Efficient fertilisation, control of protein content and minimisation of leaching Weather-controlled, precision crop protection Decreased use of crop protection chemicals Climate-controlled design of irrigation systems Assured irrigation requirements for horticultural crops and potatoes in particular Climate-driven quality model Calculation of the effects of climate change on crop quality Climate-controlled crop production planning Basis for evaluating the risks and potential of growing new crops in a changing climate assessment New varieties Decreased crop chemical requirements, adaptation of sowing and harvest times, improved quality and yields per hectare, improved resource utilisation, decreased nutrient leaching Alternative crop protection methods Decreased use of crop protection chemicals Alternative soil tillage Decreased nutrient leaching, decreased use of crop protection chemicals Alternative cropping systems Decreased use of crop protection chemicals, improved resource utilisation, improved quality and yields per hectare, decreased nutrient leaching Optimised crop production planning Combined environmental and production objectives Alternative land use Decreased nutrient leaching Research requirements Perhaps the most obvious adaptation measure is to establish and enhance expertise in evaluating the effects of climate change on crop production within agriculture and to propose adaptation strategies and implement these. This report deals primarily with the former, but also provides some suggestions for adaptation measures and reveals great deficiencies in methods for evaluating the effects of climate change. For example, the evaluations in this report cannot be regarded as strictly scientific since we did not have the time for qualified calculations and since appropriate analytical methods are still lacking in a number of sub-areas. Within certain areas, research has made great progress in Bilaga B 24 SOU 2007:60 42 developing analytical methods and there is mainly a lack of systems for application and calibration to Swedish conditions (e.g. water), while in other areas there is still a lack of conceptual models (e.g. quality). Proposals for practical and strategic adaptation measures for crop production within Swedish agriculture thus currently rest on a weak scientific foundation. To strengthen research within this area, there is a need for increased concentration on the development and application of weather-driven and climate-driven models for crop production systems. A central precondition for the applicability of these models for future studies is that they can explain observed variations. Therefore model development must have strong links to observable data. The models can be of very different character depending on the issue.