The majority of cotton produced in Australia is exported. The Australian cotton industry must maintain product quality in order to remain globally competitive. In addition, carbon-conscious consumers need reassurance that the system used to grow the product is environmentally sustainable. The aim of the present study was to estimate greenhouse gas (GHG) emissions due to various farm inputs in three common types of cotton farming systems on the Darling Downs region, southern Queensland. Analysis revealed that GHG emissions for dryland solid-plant and dryland double-skip cotton farming systems are similar, but emissions are much higher for irrigated solid-plant cotton farming (1367, 1274 and 4841 kg CO2e/ha, respectively). However, if comparisons of GHG emissions are based on yield (per tonne), the positions of dryland double-skip farming and dryland solid-plant farming are reversed, but the position of irrigated cotton farming still remains as the highest GHG emitter. If the cotton industry comes under the Australian Government Carbon Pollution Reduction Scheme (CPRS) without any subsidies and preconditions, and with a carbon price of A$25/t CO2e, the costs borne by each system would be A$66.8/t for the irrigated cotton industry, A$39.7/t for the dryland solid-plant cotton industry and A$43.6/t for the dryland double-skip cotton industry. This suggests that irrigated cotton would be more profitable in financial terms but with heavy environmental sustainability costs.

Biofuels can reduce greenhouse gas (GHG) emissions by replacing fossil fuels. However, the energy yield from agronomic crops varies due to local climate, weather and soil variability. A variation in the yield of raw material used (feedstock) could also cause variability in GHG reductions if biofuels are used. The goal of the present study was to determine the net reduction of GHG emissions if ethanol from wheat produced in different regions of the south-eastern USA is used as an alternative to gasoline from fossil fuel sources. Two scenarios were investigated; the first included ethanol produced from grain only, and the second included ethanol produced from both grain and wheat straw. Winter wheat yield was simulated with the Cropping System Model (CSM)-CERES-Wheat model for climate, soil and crop management representing six counties in the following USA states: Alabama, Florida and Georgia. Ethanol production was determined from the simulated grain and straw yields together with fixed grain and straw yield ethanol ratios. Subsequently, net reductions in GHG emissions were determined by accounting for the emissions from the replaced gasoline, and by animal feed and electricity that were replaced by ethanol processing co-products. Greenhouse gases that were emitted in the ethanol production chain were also taken into account. Across all locations, the reduction in GHG emissions was 187 g CO2-equivalents/km in the grain-only scenario and 208 g CO2-equivalents/km in the grain and straw scenario. The reductions in GHG emissions varied significantly between locations and growing seasons within the two scenarios. Similar approaches could be applied to assess the environmental impact of GHG emissions from other biofuels.

The goal of the present study was to assess the impact of selected soil protection measures on soil erosion and retention of rainwater in a 1·14 km2 watershed used for agriculture in the north-east of Austria. Watershed conditions under conventional tillage (CT), no-till (NT) and under grassland use were simulated using the Water Erosion Prediction Project (WEPP) soil erosion model. The period 1961–90 was used as a reference and results were compared to future Intergovernmental Panel on Climate Change (IPCC) scenarios A1B and A2 (2040–60).

The simulations for the NT and grassland options suggested runoff would decrease by 38 and 75%, respectively, under the current climatic conditions. The simulation results suggest that, under future climate scenarios, the effectiveness of the selected soil conservation measures with respect to runoff will be similar, or decreased by 16–53%.

The actual average net soil losses in the watershed varied from 2·57 t/ha/yr for conventional soil management systems to 0.01 t/ha/yr for grassland. This corresponds to a maximum average annual loss of about 0·2 mm, which is considered to be the average annual soil formation rate and therefore an acceptable soil loss. The current soil/land use does not exceed this limit, with most of the erosion occurring during spring time. Under future climate scenarios, the simulations suggested that CT would either decrease soil erosion by up to 55% or increase it by up to 56%. Under these conditions, the acceptable limits will partly be exceeded. The simulations of NT suggested this would reduce annual soil loss rates (compared to CT) to 0·2 and 1·4 t/ha, i.e. about the same or slightly higher than for NT under actual conditions. The simulation of conversion to grassland suggested soil erosion was almost completely prevented.

The selected soil conservation methods maintain their protective effect on soil resources, independent of the climate scenario. Therefore, with small adaptations, they can also be recommended as sustainable soil/land management systems under future climatic conditions.

However, based on the available climate scenarios, climate-induced changes in the frequency and intensity of heavy rainstorms were only considered in a limited way in the present work. As the general future trend indicates a strong increase of rainstorms with high intensity during summer months, the results of the present study may be too optimistic.

There is a very significant, cost effective greenhouse gas (GHG) mitigation potential in agriculture. The annual mitigation potential in agriculture is estimated to be 4200, 2600 and 1600 Mt CO2 equiv/yr at C prices of 100, 50 and 20 US$/t CO2 equiv, respectively. The value of GHG mitigated each year is equivalent to 420 000, 130 000 and 32 000 million US$/yr for C prices of 100, 50 and 20 US$/t CO2 equiv, respectively. From both the mitigation and economic perspectives, we cannot afford to miss out on this mitigation potential.

The challenge of agriculture within the climate change context is two-fold, both to reduce emissions and to adapt to a changing and more variable climate. The primary aim of the mitigation options is to reduce emissions of methane or nitrous oxide or to increase soil carbon storage. All the mitigation options, therefore, affect the carbon and/or nitrogen cycle of the agroecosystem in some way. This often not only affects the GHG emissions but also the soil properties and nutrient cycling. Adaptation to increased variability of temperature and rainfall involves increasing the resilience of the production systems. This may be done by improving soil water holding capacities through adding crop residues and manure to arable soils or by adding diversity to the crop rotations.

Though some mitigation measures may have negative impacts on the adaptive capacity of farming systems, most categories of adaptation options for climate change have positive impacts on mitigation. These include: (1) measures that reduce soil erosion, (2) measures that reduce leaching of nitrogen and phosphorus, (3) measures for conserving soil moisture, (4) increasing the diversity of crop rotations by choices of species or varieties, (5) modification of microclimate to reduce temperature extremes and provide shelter, (6) land use change involving abandonment or extensification of existing agricultural land, or avoidance of the cultivation of new land. These adaptation measures will in general, if properly applied, reduce GHG emissions, by improving nitrogen use efficiencies and improving soil carbon storage.

There appears to be a large potential for synergies between mitigation and adaptation within agriculture. This needs to be incorporated into economic analyses of the mitigation costs. The inter-linkages between mitigation and adaptation are, however, not very well explored and further studies are warranted to better quantify short- and long-term effects on suitability for mitigation and adaptation to climate change. In order to realize the full potential for agriculture in a climate change context, new agricultural production systems need to be developed that integrate bioenergy and food and feed production systems. This may possibly be obtained with perennial crops having low-environmental impacts, and deliver feedstocks for biorefineries for the production of biofuels, biomaterials and feed for livestock.

It is predicted that climate change will increase not only seasonal air and soil temperatures in northern Europe but also the variability of rainfall patterns. This may influence temporal soil moisture regimes and the growth and yield of winter wheat. A lysimeter experiment was carried out in 2008/09 with three factors: rainfall amount, rainfall frequency and soil warming (two levels in each factor), on sandy loam soil in Denmark. The soil warming treatment included non-heated as the control and an increase in soil temperature by 5°C at 100 mm depth as heated. The rainfall treatment included the site mean for 1961–90 as the control and the projected monthly mean change for 2071–2100 under the International Panel on Climate Change (IPCC) A2 scenario for the climate change treatment. Projected monthly mean changes in rainfall compared to the reference period 1961–90 show, on average, 31% increase during winter (November–March) and 24% decrease during summer (July–September) with no changes during spring (April–June). The rainfall frequency treatment included mean monthly rainy days for 1961–90 as the control and a reduced frequency treatment with only half the number of rainy days of the control treatment, without altering the monthly mean rainfall amount. Mobile rain-out shelters, automated irrigation system and insulated heating cables were used to impose the treatments.

Soil warming hastened crop development during early stages (until stem elongation) and shortened the total crop growing season by 12 days without reducing the period taken for later development stages. Soil warming increased green leaf area index (GLAI) and above-ground biomass during early growth, which was accompanied by an increased amount of nitrogen (N) in plants. However, the plant N concentration and its dilution pattern during later developmental stages followed the same pattern in both heated and control plots. Increased soil moisture deficit was observed only during the period when crop growth was significantly enhanced by soil warming. However, soil warming reduced N concentration in above-ground biomass during the entire growing period, except at harvest, by advancing crop development. Soil warming had no effect on the number of tillers, but reduced ear number and increased 1000 grain weight. This did not affect grain yield and total above-ground biomass compared with control. This suggests that genotypes with a longer vegetative period would probably be better adapted to future warmer conditions. The rainfall pattern treatments imposed in the present study did not influence either soil moisture regimes or performance of winter wheat, though the crop receiving future rainfall amount tended to retain more green leaf area. There was no significant interaction between the soil warming and rainfall treatments on crop growth.

Starch is a major component of wheat grain and, to a great extent, determines the grain weight. Starch accumulation in wheat (Triticum aestivum L.) is closely associated with sink strength. Four winter wheat cultivars, Lumai 21 and Jimai 20 (compact-spike cultivars) and Shannong 1391 and Shannong 12 (loose-spike cultivars) were grown to evaluate the amylose and amylopectin accumulation in both superior and inferior grains (higher and lower individual grain weight, respectively) and the relationship between starch accumulation and sink strength. In general, superior grains showed a higher starch accumulation rate, endosperm cell number and activity of enzymes including sucrose synthase (SS), uridine diphosphorate glucose pyrophosphorylase (UGPP), adenosine diphosphorate glucose pyrophosphorylase (AGPP), soluble starch synthase (SSS) and granule-bound starch synthase (GBSS), and subsequently produced higher starch accumulation and grain weight than inferior grains. Greater differences in starch accumulation and grain weight were found between the two classes of grains for compact-spike cultivars than between those for loose-spike cultivars. These results suggest that the grain sink strength, determined by endosperm cell number and the activity of synthesis-related enzymes, is closely associated with starch accumulation in superior and inferior grains on a wheat spike.

Root system senescence and nitrogen (N) release from red clover (Trifolium pratense L.) plants, grown under semi-sterile conditions and a controlled environment, were studied for 28 days following temporary or prolonged abiotic stress. Plants stressed temporarily, to simulate grazing, recovered with no additional N lost in leachate. In contrast, plants subjected to prolonged stress that simulated overwintering conditions and inhibited shoot re-growth survived stress lasting 7 days, but plant viability was reduced to 50% by 14 days and 0% at 21 days. There were no significant differences in root protein, catalase activity, root death index or total N loss in leachate over 21 days, but by 28 days total N loss in leachate increased to 214% above control levels, with a 433% increase in total oxidized N. This increase in N loss between 21 and 28 days indicated the start of cellular breakdown of the root system, coinciding with the failure of plants to recover.

Key enzyme activities and protein concentrations in nodules decreased rapidly over 10 days' prolonged stress. cDNA–amplified fragment length polymorphism (AFLP) analysis identified contaminating bacterial and fungal genes, along with plant gene sequences with consistent or altered expression profiles. Four plant sequences, glyceraldehyde-3-phosphate dehydrogenase (Tp-gapdh1), nodule senescence reduced (Tp-nsr1), nodule senescence enhanced (Tp-nse1) and a cysteine protease gene (Tp-cp8) were differentially expressed throughout the plant: Tp-nsr1 and Tp-nse1 have potential as molecular markers for nodule senescence.

Root and nodule death in agricultural legumes, such as red clover, are implicated in N release into watercourses and the wider environment. Differences in the ability of these plants to survive prolonged stress lasting 14 days, and the delayed release of root N into leachate until 28 days after the stress, highlight the potential for the development of new red clover varieties with different rates of root system senescence.

The effects of deficit irrigation (DI) and partial rootzone drying (PRD) on the growth and mineral nutrition of citrus rootstock seedlings in the glasshouse were determined, as well as the potential of DI and PRD to trigger root-to-shoot signalling of abscisic acid (ABA) to increase the growth per amount of water used (water use efficiency (WUE)). In the DI study, 3-month-old seedlings of the important citrus rootstock Swingle citrumelo with intact roots received three irrigation treatments: control (1·00 evapotranspiration (ET)), 0·75 ET and 0·50 ET. DI clearly decreased growth, the net assimilation of CO2 (ACO2), WUE and the total content of N and K in leaves, even though concentrations of leaf N and K were increased in the drought-stressed smaller plants. Root K was not affected by DI treatments. Leaf ABA concentration increased linearly with DI. For the PRD study, root systems of 6-month-old Swingle citrumelo were split into half and allowed to become established in adjacent pots. There were three irrigation treatments: control (1·00 of the total crop ET, 0·50 in each pot), PRD 50-0 (0·50 ET by weight applied to only one-half of root zone) and DI 25-25 (0·50 ET in total, with 0·25 ET applied to each root half). Although the total root length was decreased by the DI 25-25 treatment, PRD 50-0 did not affect any growth characteristics compared to control plants. The dry root zone of the PRD 50-0 treatment had a higher specific root length, longer roots per dry weight, than the wet root zone. Leaf ACO2 and WUE of the DI 25-25 treatment were significantly lower than control plants after 11 weeks. Although the total contents of N and K in leaves were not affected by either PRD treatment, the concentrations of N and K in leaves were increased by DI 25-25. Root K was decreased by PRD treatments. Leaf ABA concentration was increased by PRD 50-0 but not by DI 25-25. Although all drought stress treatments increased the levels of ABA in leaves, DI and PRD treatments did not affect the whole plant WUE. Compared to well-irrigated control plants, DI reduced growth, whereas PRD 50-0 did not.

A possible outcome of policies designed to reduce obesity in the human population and to mitigate greenhouse gas (GHG) emissions may be a decrease in human consumption of livestock products. However, livestock products currently make substantial contributions to intakes of specific micro-nutrients. Therefore, the present review examines the potential for increasing micro-nutrient concentrations of milk, muscle meats and eggs by nutritional and genetic means. Of the trace elements, copper (Cu), iron (Fe) and zinc (Zn) concentrations were largely resistant to manipulation by dietary means, but iodine (I) and selenium (Se) could be readily manipulated. Similarly, while α-tocopherol concentrations were readily manipulated, responses to dietary supplementation with retinol, folate and cobalamin were lower and riboflavin was resistant to dietary manipulation. There were differences between products in the ease with which composition could be manipulated: egg concentrations were most responsive followed by milk and muscle meats. However, livestock products with increased micro-nutrients concentrations can supply a substantial proportion of the daily reference nutrient intake.

Relationships between sward height and short-term ingestive behaviour of cattle were examined for two tropical stoloniferous grasses with contrasting growth forms: centipede grass (Eremochloa ophiuroides (Munro) Hack.; (CG); strongly prostrate) and bahia grass (Paspalum notatum Flügge; (BG); more erect). Turves (500×500 mm) were extracted from field monoculture swards of each grass after the varying duration of re-growth, and presented to animals for a short period (10 bites) to measure bite dimensions (area, depth and volume), bite mass, time per bite and intake rate. In the same re-growth period, CG was always shorter and denser than BG. Bite dimensions, the bite mass and the intake rate of animals increased at a declining rate as the sward height increased for both grasses, showing a tendency for a steeper initial increase, an earlier plateau and a lower maximum in CG than in BG. Due to the difference in the shape of the intake rate response, animals on BG were estimated to require a longer grazing time than those on CG to attain the same daily herbage intake, when the sward is shorter than about 200 mm. The sward height below which the daily intake of animals may be restricted was lower for CG (61–70 mm) than for BG (71–92 mm). The results indicate an advantage of strongly prostrated, highly dense grasses (e.g. CG) over more erect, less dense grasses (e.g. BG) when grazed at a relatively low height (<200 mm). In relation to increasing bite mass, the time per bite pooled over CG and BG was constant until the bite mass reached a critical value (0·55 g dry matter (DM)) and thereafter increased linearly with the bite mass, confirming that cattle are able to perform compound jaw movements that gather herbage into the mouth (manipulative jaw movement) and chew herbage already in the mouth (chewing jaw movement) within one cycle of opening and closing of the jaws.