Richard M. Weightman

Opportunities for avoidance of land‐use change through substitution of soya bean meal and cereals in European livestock diets with bioethanol coproducts

An analysis is presented which quantifies the potential for distillers dried grains with solubles (DDGS, a coproduct of wheat bioethanol production) to replace soya bean meal (SBM) and cereals in livestock rations. A major proportion of the SBM imported into Europe as a protein‐rich feedstuff for livestock comes from South America, where land‐use change (LUC) is associated with high carbon emissions. Production of DDGS can therefore reduce LUC in South America by substitution of SBM in animal feed. The analysis indicates that a single bioethanol distillery processing 1 million tonnes of wheat, and producing ca. 330 000 tonnes of DDGS per annum, would substitute at least 136 493 tonnes of whole soya beans grown on 47 725 ha of land, and save greenhouse gas emissions equivalent to 0.63 million tonnes CO2 per annum. By growing sugar beet and wheat in an average ratio of 0.06 : 0.94 on 1 ha of land in Europe, the net area of agricultural land required to produce feed ingredients equivalent to 6.08 t of sugar beet pulp (SBP) and 1.72 t of DDGS associated with 2363 L of bioethanol, is reduced to 0.40 ha. This accounts for 0.42 ha of soya that is not required when DDGS displaces SBM, and 0.18 ha of wheat that is not required when DDGS and SBP displace wheat in livestock rations.

Modelling a two-dimensional spatial distribution of mycotoxin concentration in bulk commodities to design effective and efficient sample selection strategies

Mycotoxins in agricultural commodities are a hazard to human and animal health. Their heterogeneous spatial distribution in bulk storage or transport makes it particularly difficult to design effective and efficient sampling plans. There has been considerable emphasis on identifying the different sources of uncertainty associated with mycotoxin concentration estimations, but much less on identifying the effect of the spatial location of the sampling points. This study used a two-dimensional statistical modelling approach to produce detailed information on appropriate sampling strategies for surveillance of mycotoxins in raw food commodities. The emphasis was on deoxynivalenol (DON) and ochratoxin A (OTA) in large lots of grain in storage or bulk transport. The aim was to simulate a range of plausible distributions of mycotoxins in grain from a set of parameters characterising the distributions. For this purpose, a model was developed to generate data sets which were repeatedly sampled to investigate the effect that sampling strategy and the number of incremental samples has on determining the statistical properties of mycotoxin concentration. Results showed that, for most sample sizes, a regular grid proved to be more consistent and accurate in the estimation of the mean concentration of DON, which suggests that regular sampling strategies should be preferred to random sampling, where possible. For both strategies, the accuracy of the estimation of the mean concentration increased significantly up to sample sizes of 40–60 (depending on the simulation). The effect of sample size was small when it exceeded 60 points, which suggests that the maximum sample size required is of this order. Similar conclusions about the sample size apply to OTA, although the difference between regular and random sampling was small and probably negligible for most sample sizes.

Effects of light level, time of harvest and position within field on the variability of tissue nitrate concentration in commercial crops of lettuce (Lactuca sativa) and endive (Cichorium endiva).

Seven commercial crops of lettuce and one crop of endive were sampled in order to study the variability in plant tissue nitrate concentration (TNC). Assuming that an appropriate sampling pattern was employed, ten plants were sufficient to give an acceptable estimate of the mean TNC. Short-term shading (24–48 h) had no significant effects on mean TNC, unlike the increase in TNC known to occur following dull periods 10–14 days before harvest. The effect on TNC of time of day harvested was significant, but there was no obvious pattern of diurnal variation. Averaged over all experiments, the coefficient of variation for TNC was in the order of 35%. Increasing the sample size from ten to 40 plants would only be expected to decrease the standard error of measurement of TNC from 16 to 12% of the mean because of the underlying analytical error, which would remain constant.

Geostatistical analysis of the spatial distribution of mycotoxin concentration in bulk cereals.

Deoxynivalenol (DON) and ochratoxin A (OTA) in agricultural commodities present hazards to human and animal health. Bulk lots are routinely sampled for their presence, but it is widely acknowledged that designing sampling plans is particularly problematical because of the heterogeneous distribution of the mycotoxins. Previous studies have not explicitly looked at the interactions between the spatial distribution of the mycotoxin and the strategy used to take samples from bulk. Sampling plans are therefore designed on the assumption of random distributions. The objective of this study was to analyse the spatial distribution of DON and OTA in bulk commodities with geostatistics. This study was the first application of geostatistical analysis to data on mycotoxins contamination of bulk commodities. Data sets for DON and OTA in bulk storage were collected from the literature and personal communications, of which only one contained data suitable for geostatistical analysis. This data set represented a 26-tonne truck of wheat with a total of 100 sampled points. The mean concentrations of DON and OTA were 1342 and 0.59 µg kg–1, respectively. The results showed that DON presented spatial structure, whilst OTA was randomly distributed in space. This difference between DON and OTA probably reflected the fact that DON is produced in the field, whereas OTA is produced in storage. The presence of spatial structure for DON implies that sampling plans need to consider the location of sample points in addition to the number of points sampled in order to obtain reliable estimates of quantities such as the mean contamination.

Safety assessment of genetically modified plants with deliberately altered composition

The development and marketing of ‘novel’ genetically modified (GM) crops in which composition has been deliberately altered poses a challenge to the European Union (EU)s risk assessment processes, which are based on the concept of substantial equivalence with a non-GM comparator. This article gives some examples of these novel GM crops and summarizes the conclusions of a report that was commissioned by the European Food Safety Authority on how the EUs risk assessment processes could be adapted to enable their safety to be assessed.

Factors influencing tissue nitrate concentration in field-grown wild rocket (Diplotaxis tenuifolia) in southern England.

Wild rocket (Diplotaxis tenuifolia) is a leafy vegetable known for its high tissue nitrate concentration (TNC) which can exceed the limits set in the relevant European legislation designed to protect human health. The aim of this work was to understand the factors influencing TNC and to develop best practice guidelines to growers. Commercial crops of field-grown wild rocket were studied over two seasons. In 2010, ten separate crops were sampled representing a range of soil types and time periods during the summer. Two fields sampled using a ‘W’- or ‘X’-shaped sampling pattern demonstrated that 10 incremental samples bulked to make 1 kg of fresh material could be used to provide an adequate sample for determination of TNC in the wild rocket crop, as is the case for other leafy vegetables. Of eight commercial crops sampled in 2010 with an average nitrogen (N) fertiliser application of 104 kg N ha−1, two exceeded the limit of 6000 mg  kg−1 set in the legislation. In 2011, six N response experiments were carried out, and only two sites showed a significant yield response to N fertiliser. The reason for the lack of response at the other sites was principally due to high levels of soil mineral N prior to drilling, meaning the crops’ requirement for N was satisfied without additional fertiliser N. In the experimental situation at an N fertiliser application rate of 120 kg N ha−1, 50% of crops would have exceeded the 6000 mg  kg−1 limit. In both seasons, low radiation levels in the 5 days prior to harvest were shown to increase TNC, although the relationship was also influenced by N supply. Strategies for optimising N nutrition of field-grown wild rocket are discussed.

A short geostatistical study of the three-dimensional spatial structure of fumonisins in stored maize

The heterogeneous three-dimensional spatial distribution of mycotoxins has proven to be one of the main limitations for the design of effective sampling protocols. Current sample collection protocols for mycotoxins have been designed to estimate the mean concentration and fail to characterise the spatial distribution of the mycotoxin concentration due to the aggregation of the incremental samples. Geostatistical techniques have been successfully applied to overcome similar problems in many research areas. However, little work has been developed on the use of geostatistics for the design of sampling protocols for mycotoxins. This paper focuses on the analysis of the two and three-dimensional spatial structure of fumonisins B1 (FB1) and B2 (FB2) in maize in a bulk store using a geostatistical approach and on how results help determine the number and location of incremental samples to be collected. The spatial correlation between FB1 and FB2, as well as between the number of kernels infected and the level of...

Physiological traits influencing hardness and vitreosity in wheat grain

ABSTRACT Of the 2 million ha of wheat grown annually in the UK, about 700,000 ha are grown on drought-prone soils. With predicted climate change, the frequency of summer droughts is likely to increase. By mapping genes controlling improved end-use quality under stress, the objective is to provide UK plant breeders with information on genes, and selection methods for traits conferring more stable end-use quality under drought-stress conditions. A mapping population of 48 doubled haploid lines and their parents (Beaver & Soissons), has been investigated over two seasons (2002 and 2003 harvest years), on a drought-prone, loamy sand at ADAS Gleadthorpe. The different lines were grown both with, and without irrigation, in fully replicated field experiments, to examine the differential response of the lines to drought. Physiological assessments were made throughout the season, and yield determined at grain maturity. Hand harvested grain was assessed for mealiness (=100-vitreosity), hardness, grain size, grain weight, grain protein content and measurements made of gel protein quality. The initial observations suggest that the effect of drought was to reduce grain size, increase grain crude protein concentration, and to increase vitreosity of the grain. At the same time, grain protein quality was improved, and grain hardness increased under drought conditions. New QTL have been identified and further work is ongoing to understand the interactions between genotype and environment on grain quality in these lines.

Heavy Metal and Microbial Contamination of Valerian (Valeriana officinalis L.) Roots Grown in Soil Treated with Sewage Sludge

ABSTRACT Contamination with heavy metals and microbes of roots of Valerian (Valeriana officinalis L.) grown in either unamended soil (US) or sewage sludge-amended soil (SSAS) were studied in two seasons in the UK. The concentrations of heavy metals found in the washed roots from SSAS were greater than the concentrations found in roots from the US plots by 480, 2800, 215, 1900, and 82% (in 2002) and 234, 446, 187, 426, and 450% (in 2004) for cadmium, chromium, copper, lead, and zinc, respectively. Drying reduced the levels of coliforms, and washing treatments also tended to reduce the levels of microorganisms (Clostridia, molds, Bacillus sp.) detected on dried roots.