National Activities - UK UK Review of MAFF Supported Biomass R and D Activities - Part 2

Contacts
Summary Information



To find similar Items, click on a keyword below:
Biological Conversion : Crops for Liquid Biofuels and Biogas : Crops for Solid Biofuels : Integrated Crop Protection & Biological Control : Liquid Biofuels and Biogas : National Activities - UK : Solid Biofuels : Thermochemical Conversion : Wood (Lignocellulose)



Continued from Summary Information

---

Crop breeding

Theoretical vs. realistic target yields

SRC Willow Under UK growing conditions it was stated that the theoretical yield of SRC Willow was around 22 tonnes per hectare per annum (t/ha/a) dry matter but that realistically yields of 15 t/ha/a dry matter were achievable within a 5 year time scale with perhaps 18 t/ha/a dry matter by years 10-12. The underlying reasons for higher yields from some breeding lines were not understood. In view of this, it was considered that there was a requirement for underpinning research on the physiology of the crop, including factors such as leaf area index, water use efficiency and radiation use efficiency, in order to determine the reasons for higher yields and thus assist in genetic improvement.

SRC Poplar Two new poplar clones, on unfertilised, un-irrigated sites, have produced yields of 18 t/ha/a dry matter at 15,000 cuttings/ha. It was stated that in 5 years the aim would be to achieve the current yield potential (20 - 22 t/ha/a dry matter), but increase resistance to disease. It was, however, stated that there was currently no UK breeding programme for SRC poplar. For both willow and poplar there are many clones which show good yield potential but many of these are sterile/non-breeding. A greater understanding of the genetics of reproduction could facilitate the manipulation of breeding characteristics to allow greater use of promising material in breeding programmes.

Miscanthus A realistic yield for Miscanthus was estimated to be 24 t/ha/a dry matter but, as for poplar, there is currently no UK breeding programme. A target for any potential breeding programme would be to improve cold tolerance.

Crop breeding aims

SRC Willow

• broaden the genetic base and ensure a flow of diverse genetic material
• increase yield
• incorporate/achieve pest and disease resistance

Herbicide tolerance was viewed as being of low priority with transgenic techniques considered to be inappropriate for a crop with 'green' credentials. It was agreed, however, that molecular techniques could provide useful research tools to underpin physiological studies and perhaps be used in areas such as sterility and disease resistance.

SRC Poplar

• ensure a flow of diverse genetic material and broaden the genetic material base by out-sourcing to new crosses from America, for example.
• increasing yield was not considered to be a difficult target due to a relatively low starting point
• collaboration should be increased, particularly with the USA
• research and modelling was considered to be important to ascertain whether the priority should be single stemmed or coppicing varieties.

Miscanthus No commercial breeding of Miscanthus is currently taking place in the UK. It was noted that the crop does, however, appear to have a wide geographic and ecological range which should provide a greater range of genetic diversity than is seen in the currently available material. A breeding programme was seen as the next stage, possibly within the next 2-3 years, if molecular techniques are extended to the new wild source material collected under the MAFF funded project. The genetic base was reported as currently being screened and selected, in particular for early season leaf development.

Biomass Genetic Material Collections

It was said that the UK National Willow Collection was essential and should be strengthened. The Forestry Commission's poplar collection was considered to be useful, although not essential, and the collection of Miscanthus genetic material at Kew and ADAS important, particularly if there is potential for a breeding programme in the future.

Crop agronomy

Agronomic issues for short rotation coppice (SRC) and Miscanthus were assumed to be broadly the same. Yield was identified as the most important factor in determining the cost of energy because, unlike establishment costs, it is a recurring factor. It was suggested that yield should therefore be optimised with respect to costs rather than simply maximised.

Physiology

Mechanistic, process-based modelling was seen as necessary to integrate physiological, site and environmental factors so that yield can be modelled under a wide range of conditions. Such a model could also be used to calculate carbon/energy balances and production margins. Further empirical, ecophysiological data would be needed to underpin the modelling. In addition it was felt that greater collaboration and access to data from the Forestry Commission trials, which seek to establish such models, would be desirable.

Nutrition

Some experiments were reported where, for willow and poplar, the nutrient export to the harvested wood, etc, was similar to atmospheric inputs and therefore neutral overall. It was noted that the situation may be different on light sandy soils, where nutrients may be more limited. Better yields had been observed on ex-ley sites compared to ex-arable sites because of the flush of available nitrogen released from the ley.

It was thought that nutrition may become limiting in the long-term, for example after 3 rotations, with the result that the stools would become less vigorous. On arable land, soil fertility is maintained by the annual mixing of the soil at ploughing. It was noted that this would not take place under SRC and could lead to nutrient gradients developing. Important issues identified for further investigation were:

• Long-term nutrition: The value of ash recycling and sewage sludge in maintaining nutrient supply. (There has been some Swedish research on this topic, while the Northern Ireland study on sewage sludge application should provide some useful information on N, H20, pathogens and heavy metals concentration in soils and crops). Further work was identified as being needed.
• Summer harvesting: a short-term ETSU study has shown that this can be undertaken once with no ill-effects. However, the longer- term effects of repeated summer harvests on stool vigour would need further investigation.
• Partitioning - Root growth: it is still unclear how far roots extend and at what point they stop growing. (It was noted that some data may be available from Sweden.)

Husbandry

Soil R&D on ways of avoiding compaction needs to continue so as to provide practical recommendations for farmers/producers.

Weeds It was suggested that the use of organic mulches for weed control should be investigated. The stance of no herbicides on farm forestry was commonly quoted, but not felt to be justified. It was noted that arable crops are sprayed with herbicides at least annually, but that trees required infrequent treatment. It was proposed that weed control should be investigated in established stands after 2 or 3 harvests.

Hydrology

Development of SRC could be restricted to wetter Western areas where the impact of SRC on hydrology would be proportionately less. It was thought that the impact in drier Eastern areas would be largely a matter of scale of SRC plantations and could be acceptable if, for instance, the proportion of land within individual catchments was low. However, this may be inhibited by practical considerations, such as the need for biomass to be grown within fairly limited distances of processing/power generating plants.

It was noted that SRC does have a considerably greater water requirement than cereal crops, such as winter wheat, so impacts on groundwater recharge would be important, particularly in those areas which are already suffering from over- abstraction. Research by the Institute of Hydrology was quoted which has demonstrated that water use by SRC is greater than that of any arable crop, including potatoes, and is only exceeded by demand from coniferous forest. Further water requirements research was felt to be needed on the particular soil types likely to be planted in Eastern England.

There are very limited data on water use by Miscanthus. It was agreed that a better understanding of how it will perform in both the wet and dry areas of the UK in relation to water use, etc. was required. The application of sewage wastes to biomass crops was thought to be more likely for the nutritional benefit they confer, rather than for irrigation purposes. Tertiary treatment of wastes might need to be carried out prior to spreading so as to meet the more rigorous environmental standards. There could be a large potential to use SRC for disposal of farm animal wastes - however the suitability of SRC for regular applications of slurry etc. would need to be established and any potential problems identified before this took place.

It was suggested that willow cultivars could be screened for water use efficiency, a factor which has not been used for screening to date. There was felt to be a need to examine water use in biomass crops both at a strategic level and on smaller scales. It was noted that these needs should also be seen against a background of climate change which could significantly alter the current growing pattern of biomass crops in the UK. Due to the uncertainties in this area, the selection of cultivars would need to be sufficiently wide to accommodate the potential range of conditions that might be experienced in the future. It was noted that if SRC were to be classified as a forestry crop (which is not currently the case) it would be necessary to carry out an Environmental Impact Assessment (EIA) of SRC production. The EIA, due to SRC's predicted impact on hydrology, might then prove to be a further limiting factor on coppice distribution.

Potential pollution issues

It was noted that whether biomass crops have on balance a positive or negative impact will depend largely on the type of crop that they are replacing. Large fluxes of nitrogen are likely to be released if grassland is ploughed up for biomass crop planting but impacts are more likely to be positive in the same area where planting takes place on arable land. Where the effective rainfall (total minus evapotranspiration) is low, as in most of East Anglia, nitrate leaching levels are likely to exceed the EC Directive limit of 50mg/1. It was agreed that surface run-off, which may cause soil erosion and remove phosphorus from the soil, can be greatly reduced where planting is across the direction of slope. The general consensus was that nutrient applications are most likely to be necessary for SRC planting on agriculturally marginal and restored land. Timing of fertiliser application to achieve the maximum benefit and least negative impacts is not known and requires further research.

The long term effects of biomass crops on soils are not known. If slurry and sludge are applied in accordance with existing good practice guidelines accumulation of heavy metals in soil should not be a problem, but accumulation in the crop will occur (willow is known to accumulate particularly cadmium and zinc, and Miscanthus is believed to accumulate heavy metals in its rhizomes). It was questioned whether large amounts of heavy metals would be released to the soil from decaying root clumps. Research will be needed to ascertain whether there would be problems in returning land used for biomass crops to arable use. It was felt that burning biomass crops to produce energy should not present new pollution problems. Technology is known to exist already to clean emissions from burning stations and safely dispose of waste ash. Distribution of pathogens may be a concern if biomass crops routinely receive applications of sewage and other wastes. However it was concluded that risks would be less than for applications of the same wastes to land used for growing food crops, which already occurs.

Wildlife and Visual Impact

The conference view was that there are few circumstances under which an assessment of visual impact would be required. However, it is desirable to have up-to-date guidelines on good practice to pre- empt possible objections in this area. Research into growing of shade tolerant wild plants below biomass crops for wildlife benefit was not thought to be a priority. However, this could be given a higher priority if they were thought to confer soil and nutrient conservation benefits. Headland management is an important consideration as the headlands may confer the greatest potential wildlife benefits, as well as being a highly visible area.

Integrated pest and disease control

Background New biomass crops are seen as potentially low input crops. It was agreed that any excessive 'whole life-cycle' energy use in production would be uneconomic and hence unsustainable. It was also felt that the potential environmental benefits from new perennial crops are likely to be jeopardised by reliance on pesticides. The practical difficulties of treating large areas of tall, plantation-style crops were acknowledged as was the likelihood that few registered pesticides would be available for a low value crop without any quality premium. It was agreed that prevention of diseases and pests should be achieved by good agronomic, sustainable practice, with plantations designed with resistant cultivars and cultivar mixtures to curtail outbreaks of disease and pests. However, it was stressed that pesticides should be kept in reserve for 'fire brigade' use, i.e. only for those times when the crop is seriously under threat. It was noted that developing Integrated Crop Management (ICM), as opposed to prophylactic pesticide use, requires a good supporting knowledge of pest and pathogen biology, natural enemies and intrinsic biochemical defences in host plants. In addition, crops may be a source of beneficial insects enhancing farm habitat and biodiversity

With the crop area likely to increase substantially as SRC is taken up, it was acknowledged that diseases and pests are also likely to increase in numbers and diversity. There is therefore a need to know, in advance, what potential diseases and pests are likely. It is also important to establish economic damage thresholds and suitable monitoring methods for the main pest and disease problems. On this basis, the current priority should be on diseases and pests already known to kill willows or prevent full yearly growth. Poplars have similar diseases to willow while Miscanthus pests are not currently a problem. However, there is a need for a watching brief for emerging problems as all biomass crops become more widely grown.

Rusts: Non-chemical approaches, based on cultivar mixtures and biological control, were currently considered adequate and thought to be potentially durable as crop expands. It was, however, agreed that further R&D and monitoring of pathotypes/populations is needed to confirm this. There was some uncertainty that all diseases could be satisfactorily controlled in same way. 'Self sustaining' biological methods were felt to be preferable to fungicides as new chemical products potentially active against rusts can be expensive to buy and use. It was questioned whether fungicides should be used as a supplement at establishment or be held in reserve for severe attacks.

Chrysomelid beetles Non-chemical approaches were felt to be currently insufficiently developed to prevent damaging outbreaks of beetle attack on willow. It was noted that the differing risks from the range of pest species complicate attempts to use resistant cultivars or mixtures as the sole control method. Barrier (crop edge) pesticide spraying is an option which is currently under investigation as a means of reducing beetle spread into the plantation. It was also suggested that 'trap' crops could be worthy of consideration. Overall work on pest dispersal, population dynamics and forecasting, and the role of biological control/natural enemies need further investigation.

Palatability Fencing to exclude vertebrate pests is expensive so alternative protection strategies are seen as being desirable. Cultivar screening (in agroforestry poplars) suggests that it could be feasible to select lines with reduced palatability to animals and possibly with an associated reduction in insect feeding too.

As SRC is a non-food crop, biotechnology (genetic modification) could offer an alternative route to improved pest and disease resistance. However low crop value coupled with the environmental concern that hybridisation with wild willow species could well occur, as well as potential adverse effects on the diverse non-target species within plantations, would be likely to act against direct exploitation. Improvement in breeding lines through marker-assisted selection was felt to be rather less controversial.

Rabbits A need to disseminate R&D results from DTI-funded work in this area was identified. With the high costs of rabbit fencing, a cheap way of protecting plantings in early years is required, for example, electrified wire on top of straw bales.

R&D It was noted that there is currently a very successful programme of research into pest and disease control in operation. This involves several funders and has good between-contractor collaboration. It was agreed that it would be valuable to continue and extend this approach. A wealth of knowledge and experience could now be collated from the various groups to form a provisional growers' manual. However there is a continuing need for practical R&D and Technology Transfer to guide growers on managing (increasing) pest and disease problems without immediate recourse to pesticides.

Other yield issues

Most of the factors already mentioned have a direct impact on yield. Yield was assessed as being of paramount importance and the need to increase yields was acknowledged. In addition, it was suggested that primary work should be aimed at establishing the true farmgate cost of production of harvested material (as bundles or chips). Training farmers to follow 'good practice' when growing biomass crops was felt to help ensure reasonable yields.

Alternative markets for biomass crops

A wide range of potential markets and end uses were identified, although due to time constraints the discussion largely concentrated on more general issues and pyrolysis. In order to maximise financial return it was generally agreed that as much of the biomass crop should be used as is possible. An example given was pyrolysis, by which a variety of chemicals/fuels are produced for a number of markets.

Alternative energy markets It was suggested that the energy sector should not focus only on national grid electricity generation but should also consider niche market generation. There was felt to be scope, for example, for farmers to act in collectives for the production of CHP plants to replace grid electricity. However the economics will clearly be a key factor in the viability of these types of schemes.

Fibres It was felt unlikely that the UK would ever become a cheap cellulose producer although the scope to manufacture UK-fibre based composites and building materials was acknowledged. Primary scientific information is now available on the production of building materials (chipboard, etc) from coppice and Miscanthus, and future development in this area is likely to require 'pump priming'. Further R&D is needed, particularly with respect to the storage of biomass, the potential health effects from handling the material, and the development of marketing strategies and general commercialisation.

Briquettes There is a need to demonstrate pre-market economics and to establish a 'green' market for the product. Further work on the carbonised and non-carbonised briquette markets is required.

Peat substitute compost Further work is needed to identify suitable combinations for product development.

Animal bedding This could prove to be a high value use for Miscanthus and could help to encourage the uptake and production of Miscanthus by growers in advance of power plants coming on stream.

Speciality chemicals and Secondary metabolites It was reported that there is ongoing activity on speciality chemicals but a structured programme, which could exploit the known products and search for new compounds, is required. This was seen as being a potentially high value area.

Summary on alternative markets:

Alternative markets are already available for biomass crops, with many more currently under development. The presence of these markets could help to encourage the initial establishment of biomass crops in many areas of the UK. This should also be of help to the developing renewable energy industry, with farmers becoming used to growing the crops and other areas of crop production, such as large-scale harvesting and storage, becoming established.