James Morison

An assessment of the total external costs of UK agriculture

This trans-disciplinary study assesses total external environmental and health costs of modern agriculture in the UK. A wide range of datasets have been analysed to assess cost distribution across sectors. We calculate the annual total external costs of UK agriculture in 1996 to be £2343 m (range for 1990‐1996: £1149‐3907 m), equivalent to £208/ha of arable and permanent pasture. Significant costs arise from contamination of drinking water with pesticides (£120 m/year), nitrate (£16 m), Cryptosporidium (£23 m) and phosphate and soil (£55 m), from damage to wildlife, habitats, hedgerows and drystone walls (£125 m), from emissions of gases (£1113 m), from soil erosion and organic carbon losses (£106 m), from food poisoning (£169 m), and from bovine spongiform encephalopathy (BSE) (£607 m). This study has only estimated those externalities that give rise to financial costs, and so is likely to underestimate the total negative impacts of modern agriculture. These data help to identify policy priorities, particularly over the most eAcient way to internalise these external costs into prices. This would imply a redirection of public subsidies towards encouraging those positive externalities under-provided in the market place, combined with a mix of advisory and institutional mechanisms, regulatory and legal measures, and economic instruments to correct negative

Reducing food poverty by increasing agricultural sustainability in developing countries

Abstract We examined the extent to which farmers have improved food production in recent years with low cost, locally available and environmentally sensitive practices and technologies. We analysed by survey during 1999–2000 208 projects in 52 developing countries, in which 8.98 million farmers have adopted these practices and technologies on 28.92 million hectares, representing 3.0% of the 960 million hectares of arable and permanent crops in Africa, Asia and Latin America. We found improvements in food production occurring through one or more of four mechanisms: (i) intensification of a single component of farm system; (ii) addition of a new productive element to a farm system; (iii) better use of water and land, so increasing cropping intensity; (iv) improvements in per hectare yields of staples through introduction of new regenerative elements into farm systems and new locally appropriate crop varieties and animal breeds. The 89 projects with reliable yield data show an average per project increase in per hectare food production of 93%. The weighted average increases across these projects were 37% per farm and 48% per hectare. In the 80 projects with small (

Improving water use in crop production.

Globally, agriculture accounts for 80–90% of all freshwater used by humans, and most of that is in crop production. In many areas, this water use is unsustainable; water supplies are also under pressure from other users and are being affected by climate change. Much effort is being made to reduce water use by crops and produce ‘more crop per drop’. This paper examines water use by crops, taking particularly a physiological viewpoint, examining the underlying relationships between carbon uptake, growth and water loss. Key examples of recent progress in both assessing and improving crop water productivity are described. It is clear that improvements in both agronomic and physiological understanding have led to recent increases in water productivity in some crops. We believe that there is substantial potential for further improvements owing to the progress in understanding the physiological responses of plants to water supply, and there is considerable promise within the latest molecular genetic approaches, if linked to the appropriate environmental physiology. We conclude that the interactions between plant and environment require a team approach looking across the disciplines from genes to plants to crops in their particular environments to deliver improved water productivity and contribute to sustainability.

Plant Growth and Climate Change

Evidence grows daily of the changing climate and its impact on plants and animals. Plant function is inextricably linked to climate and atmospheric carbon dioxide concentration. On the shortest and smallest scales, the climate affects the plant’s immediate environment and so directly influences physiological processes. At larger scales, the climate influences species distribution and community composition, as well as the viability of different crops in managed ecosystems. Plant growth also influences the local, regional and global climate, through the exchanges of energy and gases between the plants and the air around them. Plant Growth and Climate Change examines the major aspects of how anthropogenic climate change affects plants, focusing on several key determinants of plant growth: atmospheric CO2, temperature, water availability and the interactions between these factors. The book demonstrates the variety of techniques used across plant science: detailed physiology in controlled environments; observational studies based on long-term data sets; field manipulation experiments and modelling. It is directed at advanced-level university students, researchers and professionals across the range of plant science disciplines, including plant physiology, plant ecology and crop science. It will also be of interest to earth system scientists.

Lateral Diffusion of CO2 in Leaves Is Not Sufficient to Support Photosynthesis

Lateral diffusion of CO2 was investigated in photosynthesizing leaves with different anatomy by gas exchange and chlorophyll a fluorescence imaging using grease to block stomata. When one-half of the leaf surface of the heterobaric species Helianthus annuus was covered by 4-mm-diameter patches of grease, the response of net CO2 assimilation rate (A) to intercellular CO2 concentration (Ci) indicated that higher ambient CO2 concentrations (Ca) caused only limited lateral diffusion into the greased areas. When single 4-mm patches were applied to leaves of heterobaric Phaseolus vulgaris and homobaric Commelina communis, chlorophyll a fluorescence images showed dramatic declines in the quantum efficiency of photosystem II electron transport (measured as Fq′/Fm′) across the patch, demonstrating that lateral CO2 diffusion could not support A. The Fq′/Fm′ values were used to compute images of Ci across patches, and their dependence on Ca was assessed. At high Ca, the patch effect was less in C. communis than P. vulgaris. A finite-volume porous-medium model for assimilation rate and lateral CO2 diffusion was developed to analyze the patch images. The model estimated that the effective lateral CO2 diffusion coefficients inside C. communis and P. vulgaris leaves were 22% and 12% of that for free air, respectively. We conclude that, in the light, lateral CO2 diffusion cannot support appreciable photosynthesis over distances of more than approximately 0.3 mm in normal leaves, irrespective of the presence or absence of bundle sheath extensions, because of the CO2 assimilation by cells along the diffusion pathway.

Reductions in mesophyll and guard cell photosynthesis impact on the control of stomatal responses to light and CO2

Transgenic antisense tobacco plants with a range of reductions in sedoheptulose-1,7-bisphosphatase (SBPase) activity were used to investigate the role of photosynthesis in stomatal opening responses. High resolution chlorophyll a fluorescence imaging showed that the quantum efficiency of photosystem II electron transport (Fq′/Fm′) was decreased similarly in both guard and mesophyll cells of the SBPase antisense plants compared to the wild-type plants. This demonstrated for the first time that photosynthetic operating efficiency in the guard cells responds to changes in the regeneration capacity of the Calvin cycle. The rate of stomatal opening in response to a 30 min, 10-fold step increase in red photon flux density in the leaves from the SBPase antisense plants was significantly greater than wild-type plants. Final stomatal conductance under red and mixed blue/red irradiance was greater in the antisense plants than in the wild-type control plants despite lower CO2 assimilation rates and higher internal CO2 concentrations. Increasing CO2 concentration resulted in a similar stomatal closing response in wild-type and antisense plants when measured in red light. However, in the antisense plants with small reductions in SBPase activity greater stomatal conductances were observed at all Ci levels. Together, these data suggest that the primary light-induced opening or CO2-dependent closing response of stomata is not dependent upon guard or mesophyll cell photosynthetic capacity, but that photosynthetic electron transport, or its end-products, regulate the control of stomatal responses to light and CO2.

Arabidopsis HEAT SHOCK TRANSCRIPTION FACTORA1b overexpression enhances water productivity, resistance to drought, and infection

Heat-stressed crops suffer dehydration, depressed growth, and a consequent decline in water productivity, which is the yield of harvestable product as a function of lifetime water consumption and is a trait associated with plant growth and development. Heat shock transcription factor (HSF) genes have been implicated not only in thermotolerance but also in plant growth and development, and therefore could influence water productivity. Here it is demonstrated that Arabidopsis thaliana plants with increased HSFA1b expression showed increased water productivity and harvest index under water-replete and water-limiting conditions. In non-stressed HSFA1b-overexpressing (HSFA1bOx) plants, 509 genes showed altered expression, and these genes were not over-represented for development-associated genes but were for response to biotic stress. This confirmed an additional role for HSFA1b in maintaining basal disease resistance, which was stress hormone independent but involved H2O2 signalling. Fifty-five of the 509 genes harbour a variant of the heat shock element (HSE) in their promoters, here named HSE1b. Chromatin immunoprecipitation-PCR confirmed binding of HSFA1b to HSE1b in vivo, including in seven transcription factor genes. One of these is MULTIPROTEIN BRIDGING FACTOR1c (MBF1c). Plants overexpressing MBF1c showed enhanced basal resistance but not water productivity, thus partially phenocopying HSFA1bOx plants. A comparison of genes responsive to HSFA1b and MBF1c overexpression revealed a common group, none of which harbours a HSE1b motif. From this example, it is suggested that HSFA1b directly regulates 55 HSE1b-containing genes, which control the remaining 454 genes, collectively accounting for the stress defence and developmental phenotypes of HSFA1bOx.

Development and evaluation of ForestGrowth-SRC a process-based model for short rotation coppice yield and spatial supply reveals poplar uses water more efficiently than willow

Woody biomass produced from short rotation coppice (SRC) poplar (Populus spp.) and willow (Salix spp.) is a bioenergy feedstock that can be grown widely across temperate landscapes and its use is likely to increase in future. Process‐based models are therefore required to predict current and future yield potential that are spatially resolved and can consider new genotypes and climates that will influence future yield. The development of a process‐based model for SRC poplar and willow, ForestGrowth‐SRC, is described and the ability of the model to predict SRC yield and water use efficiency (WUE) was evaluated. ForestGrowth‐SRC was parameterized from a process‐based model, ForestGrowth for high forest. The new model predicted annual above ground yield well for poplar (r2 = 0.91, RMSE = 1.46 ODT ha−1 yr−1) and willow (r2 = 0.85, RMSE = 1.53 ODT ha−1 yr−1), when compared with measured data from seven sites in contrasting climatic zones across the United Kingdom. Average modelled yields for poplar and willow were 10.3 and 9.0 ODT ha−1 yr−1, respectively, and interestingly, the model predicted a higher WUE for poplar than for willow: 9.5 and 5.5 g kg−1 respectively. Using regional mapped climate and soil inputs, modelled and measured yields for willow compared well (r2 = 0.58, RMSE = 1.27 ODT ha−1 yr−1), providing the first UK map of SRC yield, from a process‐based model. We suggest that the model can be used for predicting current and future SRC yields at a regional scale, highlighting important species and genotype choices with respect to water use efficiency and yield potential.

Survey and Analysis of Labour on Organic Farms in the UK and Republic of Ireland

A survey of 1144 organic farms in the UK and Republic of Ireland (IE) was used to assess whether organic agriculture provides more labour than conventional (nonorganic) farming. The sampled farms comprised 23% of all organic farms. The jobs per farm and per area varied greatly with enterprise type and farm size, and between regions. Comparison of the survey with national statistics showed that organic farms employ 135% more FTE (full time equivalent jobs) per farm than conventional farms. The mean jobs per area was markedly lower for organic farms (1.35 compared to 2.43 FTE per 100 ha), because they are larger (216 ha compared to 51 ha). Even when corrected for the different size distribution, organic farms had more jobs per farm than the national averages (2.52 and 1.49 FTE for the UK and IE, compared to 1.28 and 1.16 FTE). The farm size weighted FTE per area for organic farms in the UK (4.33 FTE per 100 ha) was almost twice that for conventional farms. We predict there would be 19% and 6% more farming jobs in the UK and IE if 20% of the farms of both countries were to become organic (compared to the present 1–2%).

Climatic conditions during seed growth significantly influence oil content and quality in winter and spring evening primrose crops (Oenothera spp.)

Evening primrose (Oenothera spp) seed is an important source of g-linolenic acid, a relatively rare fatty acid with value as a pharmaceutical and nutritional supplement. The influence on oil content and quality of climatic conditions during seed growth was investigated in three years of field trials comparing crops sown in the late summer and overwintered with crops spring-sown the following year. At the onset of oil accumulation, palmitic acid, linoleic acid and a-linolenic acid were the predominant fatty acids in the seeds and g-linolenic acid was hardly present. At maturity, linoleic acid constituted 70‐75% of the oil, g-linolenic acid content ranged from 8.0 to 9.9% and a-linolenic acid was almost undetectable. In all years, seeds from the overwintered plants of cv. Merlin contained more oil than did seeds from the equivalent spring-sown plants, but the g-linolenic acid content of the oil was lower. The rate of increase in seed oil content was faster in the overwintered crops but the duration of oil accumulation was shorter. Oil content at seed maturity in cv. Merlin was positively correlated with both mean daily temperature (r 2 , 0.59) and mean daily incident solar radiation (r 2 , 0.71) during the main period of seed filling. Strong negative correlations existed between the final g-linolenic acid content of the oil and both climatic variables during the final phase of oil accumulation (r 2 , 0.78 and 0.83, respectively). Temperature was probably the primary determinant of the final g-linolenic acid content but it was unclear which variable most influenced final seed oil content. Differences in oil content and seed size also existed between seeds harvested from different parts of the same plant.