Keith Chaney

Influence of beetle banks on cereal aphid predation in winter wheat

An experiment was conducted to investigate whether polyphagous predators dispersing from a within field overwintering refuge (‘beetle bank’) could reduce cereal aphid numbers in an adjacent crop of winter wheat. To assess the impact of predators emigrating from the beetle bank on populations of Sitobion avenae in the crop, polyphagous predator densities were manipulated using exclusion barriers placed at set distances away from the beetle bank. Results from the pitfall trap data indicated that the exclusion barriers were effective in significantly reducing the number of ‘boundary’ Carabidae, ‘open-field’ Carabidae, Staphylinidae, Linyphiidae and Lycosidae in the enclosed areas compared to the control areas by 56, 31, 46, 24 and 57%, respectively. Aphid numbers were significantly greater in the enclosures, where they were 34% higher compared to the control areas during the aphid peak. The impact of polyphagous predation decreased with increasing distance away from the beetle bank and the distribution of polyphagous predators in relation to the beetle bank varied over time. The results are discussed in terms of the peak activity periods of the different predatory groups and the consequences for integrated crop management (ICM).

Alkaline pre-treatment of oilseed rape straw for bioethanol production: Evaluation of glucose yield and pre-treatment energy consumption

The objective of the research was to investigate the effect of biomass loading, alkali (NaOH) concentration and pre-treatment time on the yield of glucose obtained following alkaline pre-treatment and enzymatic hydrolysis of oilseed rape (OSR) straw. A maximum glucose yield of (440.6 ± 14.9)g glucose kg(-1) biomass was obtained when OSR straw was pre-treated at a biomass loading of 50 g kg(-1) and an alkali concentration of 0.63 mol dm(-3) NaOH for 30 min. The energy efficiency of glucose extraction (0.39 kg glucose MJ(-1) consumed) was highest when OSR straw was pre-treated at a biomass loading of 50 g kg(-1) and an alkali concentration of 0.63 or 0.75 mol dm(-3) for 30 min. The study demonstrated alkaline pre-treatment of OSR straw is superior to acid pre-treatment in terms of glucose yield and energy efficiency.

Factors affecting nest survival of Northern Lapwings Vanellus vanellus in arable farmland: an agri-environment scheme prescription can enhance nest survival

Capsule A spring/summer fallow agri-environment prescription improved Lapwing nest survival. Aims To identify the key determinants of nest survival in arable landscapes, and assess the effectiveness of an agri-environment prescription designed to provide nesting habitat for breeding Lapwings. Methods Lapwing nest success was monitored on a number of farms in Shropshire and Staffordshire, UK, during 1999 and 2000. All nests were mapped and a number of habitat variables recorded. Results Compared with previous studies, nest survival was generally quite high, although there were significant differences between crop types. Nests on fields managed under the agri-environment prescription Option 1B had a greater chance of survival than nests on conventionally managed fields. Overall, the main causes of nest loss were predation and agricultural operations, but causes of nest loss were not consistent between crop types. Crop type, nest status and distances to field boundary and predator perches had a significant effect on nest survival. Nests that were more than 50 m from the nearest field boundary had a higher daily survival rate than nests that were closer. Conclusion Lapwing nest survival on arable farmland can be enhanced through the promotion of an agri-environment prescription that promotes spring/summer fallow and consideration of the timing of agricultural operations. To maximize benefits of conservation measures, fields should be managed to have areas within them that are sufficiently distant from field boundaries to reduce predation.

Continuous bioethanol production from oilseed rape straw hydrosylate using immobilised Saccharomyces cerevisiae cells

The aim of the study was to evaluate continuous bioethanol production from oilseed rape (OSR) straw hydrolysate using Saccharomyces cerevisiae cells immobilised in Lentikat® discs. The study evaluated the effect of dilution rate (0.25, 0.50, 0.75 and 1.00 h(-1)), substrate concentration (15, 22, 40 and 60 g L(-1)) and cell loading (0.03, 0.16 and 0.24 g d.c.w.mL(-1) Lentikat®) on bioethanol production. Volumetric productivity was found to increase with increasing substrate concentration from 15 g L(-1) to 60 g L(-1). A maximum volumetric productivity of 12.88 g L(-1)h(-1) was achieved at a substrate concentration of 60 g L(-1) and at a dilution rate of 0.5h(-1). An overall mass balance for bioethanol production was created to determine the energy recovery from bioethanol and concluded that a biorefinery approach might be the most appropriate option for maximising the energy recovery from OSR straw.

Factors affecting the yield of winter cereals in crop margins.

Yields of arable crops are commonly lower on the crop margins or headlands, but the nature of the relationship between yield and distance from the crop edge has not been clearly defined, nor have the reasons for lower marginal yields. Surveys of 40 winter wheat headlands were carried out in 2 years to determine how yield changed with distance, and what factors might influence this relationship. Two field experiments were also conducted over 3 years in winter cereal headlands, in which the effect of distance was measured under conservation headland and conventional (fully sprayed) management. Yields in the headland surveys varied from 0.8 to 10.2 t/ha. An inverse polynomial regression model was fitted to yield and weed data. Best fits were obtained by using separate parameters for each site. Adjusting yields to take account of weed dry matter improved the non-linear fit between yield and distance from crop edge. Field experiments provided similar results but the non-linear relationship was not as apparent. There was a negative relationship between soil compaction, as measured by a cone penetrometer, and yield in one field experiment, where soil density values were relatively constant. No relationship was found between pattern of nitrogen fertilizer application and yield. Conservation headland management resulted in lower yield at one experimental site, especially in the third year, but not at the other site. Where yields were affected, weed dry matter was higher in conservation headland plots than in fully sprayed plots. Although greater weed competition appears to account for at least part of the observed yield reductions on headlands, the role of other factors, particularly soil compaction, needs further study. Increased weed infestation may be an indirect result of reduced crop competition caused by other adverse conditions.

Effect of non-inversion tillage on field usage by UK farmland birds in winter

Capsule Several guilds of wintering farmland birds showed preferences for cereal fields established by non-inversion tillage, rather than ploughing. Aims To compare the effects of cereal crop establishment methods using non-inversion tillage and ploughing on field use by wintering farmland birds. Methods Cereal fields on commercial farms, established by non-inversion tillage or conventional ploughing, were censused for birds over the winter months of 2000 to 2003, using standard whole-field count methodologies. Multivariate logistic regression methods were used to assess the difference in bird use between fields with the two crop establishment methods, whilst controlling for the effects of a variety of other variables. Results In late winter, Skylarks Alauda arvensis, granivorous passerines and gamebirds occupied a greater proportion of fields established by non-inversion tillage than conventional tillage. Conclusions As well as documented benefits for resource protection, such as soil and water conservation, non-inversion tillage methods appear to enhance suitability of winter cereal fields for foraging birds. Future studies could usefully identify the mechanisms, in terms of food abundance and sward structure, which drive these preferences.

The Impact of Cultivation Techniques on Earthworm Populations

Earthworms are a vital constituent of the soil ecosystem and influence many soil properties and processes including structure, aeration and drainage. Intensive cultivations have been shown to affect earthworms directly through injury and fatalities and indirectly by changing their habitat, altering soil temperature, soil moisture and the availability of food. The encouragement of sustainable agriculture has resulted in increased interest and research into conservation tillage, a practise that allows earthworm populations to increase gradually in under-populated soils. Conservation tillage techniques when compared with conventional tillage utilising the mouldboard plough have been shown to have a positive impact on earthworm populations.

Bioethanol Production From Canola Straw Using a Continuous Flow Immobilized Cell System

Global cultivation of canola increased by approximately 22% between 2000 and 2009, due to increased demand for canola oil for biodiesel production and as an edible oil. In 2009 over 290,000 km2 of canola was cultivated globally. In contrast to oilseed, the commercial market for canola straw is minimal and it is generally ploughed back into the field. The high carbohydrate content (greater than 50 % by dry weight) of canola straw suggests it would be a good feedstock for second-generation bioethanol production. There are four major steps involved in bioethanol production from lignocellulosic materials: (i) pretreatment, (ii) hydrolysis, (iii) fermentation, and (iv) further purification to fuel grade bioethanol through distillation and dehydration. Previous research demonstrated a glucose yield of (440.6 ± 14.9) g kg−1 when canola straw was treated using alkaline pretreatment followed by enzymatic hydrolysis. Whilst bioethanol can be produced using cells free in solution, cell immobilization provides the opportunity to reduce bioethanol production costs by minimizing the extent to which down-stream processing is required, and increasing cellular stability against shear forces. Furthermore, the immobilization process can reduce substrate and product inhibition, which enhances the yield and volumetric productivity of bioethanol production during fermentation, improves operational stability and increases cell viability ensuring cells can be used for several cycles of operation. Previous research used cells of Saccharomyces cerevisiae immobilized in Lentikat® discs to convert glucose extracted from canola straw to bioethanol. In batch mode a yield of (165.1 ± 0.1) g bioethanol kg−1 canola straw was achieved.Continuous fermentation is advantageous in comparison to batch fermentation. The amount of unproductive time (e.g. due to filling, emptying and cleaning) is reduced leading to increased volumetric productivity. The higher volumetric productivity of continuous fermentation means that smaller reactor vessels can be used to produce the same amount of product. This reduces the capital costs associated with a fermentation plant. Research demonstrated a higher bioethanol yield was attained (224.7 g bioethanol kg−1 canola straw) when glucose was converted to bioethanol using immobilized cells in packed-bed continuous flow columns. On an energy generation basis, conversion of 1 kg of canola straw to bioethanol resulted in an energy generation of 6 MJ, representing approximately 35% energy recovery from canola straw. The amount of energy recovered from canola straw could be improved by increasing the amount of energy recovered as bioethanol and by utilising the process by-products in a biorefinery concept.Copyright

Preliminary work on the compression behaviour of canola straw to high density products

In the United Kingdom (UK), the total area of canola harvested increased between 2000 and 2008 from 332,000 ha to 598,000 ha, respectively. Currently there is not a significant market for canola straw in the UK, and consequently development of a market for canola straw would add value to the gross margin of the crop at farm level. As a biomass waste product, canola straw could be used as a fuel to generate heat through combustion. However, straw exhibits a low bulk density which makes its transport more expensive than the transfer of natural gas or petroleum. Reducing the cost of collection, transport and storage of biomass through densification is thus critical to developing a sustainable infrastructure capable of working with significant quantities of raw material.

Effect of Pre- and Post-pelletisation Storageof Canola (Oilseed Rape) Straw on the Quality and Properties of Pellets

With the growing demand for biomass for alternative energy supplies, it would be prudent to investigate a range of alternative sources of energy. The current research study, of which this is part, will investigate the effect of pre and post pelletisation storage on the quality and combustion properties of canola (oilseed rape) straw and short rotation coppice willow, which, unlike wood pellets, have had little or no detailed research upon the variation of the physical, chemical, biological and combustion properties over the period of storage. This paper focuses on the effect of storage period on canola straw and canola straw pellets in terms of pellet quality. The quality of canola pellets was assessed in terms of their chemical, biological and physical characteristics. The chemical and biological properties of both straw and pellets, included the determination of moisture content, gross calorific value, ash content, volatile content, biomass temperature development, ambient temperature and bacterial and fungal growth. The physical characteristics of canola straw pellets included their durability, compression resistance, particle and bulk density, particle size and mean pellet length and diameter. The chemical and biological properties of both straw and pellets are presented.