Paths to last in mixed crop–livestock farming: lessons from an assessment of farm trajectories of change

Mixed crop–livestock systems, combining livestock and cash crops at farm level, are considered to be suitable for sustainable intensification of agriculture. Ensuring the survival of mixed crop–livestock systems is a challenge for European agriculture: the number of European mixed crop–livestock farms has been decreasing since 1970. Analysis of farming system dynamics may elucidate past changes and the forces driving this decline. The objectives of this study were (i) to identify the diversity of paths that allowed the survival of mixed crop–livestock farming and (ii) to elucidate the driving forces behind such survival. We analysed the variety of farm trajectories from 1950 to 2005. We studied the entire farm population of a case study site, located in the ‘Coteaux de Gascogne’ region. In this less favoured area of south-western France, farmers have limited specialisation. Currently, half of the farms use mixed crop–livestock systems. The data set of 20 variables for 50 farms on the basis of six 10-year time steps was collected through retrospective surveys. We used a two-step analysis including (i) a visual assessment of the whole population of individual farm trajectories and (ii) a computer-based typology of farm trajectories on the basis of a series of multivariate analyses followed by automatic clustering. The European Common Agricultural Policy, market globalisation and decreasing workforce availability were identified as drivers of change that favoured the specialisation process. Nevertheless, farmers’ choices and values have opposed against these driving forces, ensuring the survival of some mixed crop–livestock farming systems. The trajectories were clustered into five types, four of which were compatible with mixed crop–livestock systems. The first type was the maximisation of autonomy by combining crops and livestock. The second type was diversification of production to exploit economies of scope and protect the farm against market fluctuations. The other two types involved enlargement and progressive adaptation of the farm to the familial workforce. The survival of mixed crop–livestock systems in these two types is largely dependent on workforce availability. Only one type of trajectory, on the basis of enlargement and economies of scale, did not lead to mixed crop–livestock systems. In view of the current evolution of the driving forces, maximising autonomy and diversification appear to be suitable paths to deal with current challenges and maintain mixed crop–livestock systems in Europe.     

Mixed crop–livestock farming systems: a sustainable way to produce beef? Commercial farms results,questions and perspectives

Mixed crop–livestock (MC–L) farming has gained broad consensus as an economically and environmentally sustainable farming system. Working on a Charolais-area suckler cattle farms network, we subdivided the 66 farms of a constant sample, for 2 years (2010 and 2011), into four groups: (i) ‘specialized conventional livestock farms’ (100% grassland-based farms (GF), n=7); (ii) ‘integrated conventional crop–livestock farms’ (specialized farms that only market animal products but that grow cereal crops on-farm for animal feed, n=31); (iii) ‘mixed conventional crop–livestock farms’ (farms that sell beef and cereal crops to market, n=21); and (iv) organic farms (n=7). We analyse the differences in structure and in drivers of technical, economic and environmental performances. The figures for all the farms over 2 years (2010 and 2011) were pooled into a single sample for each group. The farms that sell crops alongside beef miss out on potential economies of scale. These farms are bigger than specialized beef farms (with or without on-farm feed crops) and all types of farms show comparable economic performances. The big MC–L farms make heavier and consequently less efficient use of inputs. This use of less efficient inputs also weakens their environmental performances. This subpopulation of suckler cattle farms appears unable to translate a MC–L strategy into economies of scope. Organic farms most efficiently exploit the diversity of herd feed resources, thus positioning organic agriculture as a prototype MC–L system meeting the core principles of agroecology.     

Influence of co-inoculation of bacteria-cyanobacteria on crop yield and C–N sequestration in soil under rice crop

The performance of three selected bacterial strains—PR3, PR7 and PR10 (Providencia sp., Brevundimonas sp., Ochrobacterium sp.) and three cyanobacterial strains CR1, CR2 and CR3 (Anabaena sp., Calothrix sp., Anabaena sp.), and their combinations was evaluated in a pot experiment with rice variety Pusa-1460, comprising 51 treatments along with recommended fertilizer controls. Highest yield enhancement of 19.02% was recorded in T12 (CR2), over control, while significant enhancement in nitrogen fixing potential was recorded in treatments involving combination of bacterial-cyanobacterial strains—T37 (PR3 + CR1 + CR3) and T21 (PR7 + CR1). Organic carbon was significantly increased in all microbe-inoculated treatments, which could be correlated with microbial biomass carbon values and activities of all the enzymes tested in our study. Also, panicle weight and plant biomass were highly correlated with soil microbial carbon. Comparative evaluation revealed the superior performance of strains CR2, CR1 (both Anabaena sp.) and PR10 (Ochrobacterium sp.) in increasing the growth and grain yield of rice and improving soil health, besides N (nitrogen) savings of 40–80 kg ha⁻¹. The study for the first time illustrated the positive effects of co-inoculation of bacterial and cyanobacterial strains for integrated nutrient management of rice crop.     

Transgene escape: what potential for crop–wild hybridization?

To date, regional surveys assessing the risk of transgene escape from GM crops have focused on records of spontaneous hybridization to infer the likelihood of crop transgene escape. However, reliable observations of spontaneous hybridization are lacking for most floras, particularly outside Europe. Here, we argue that evidence of interspecific reproductive compatibility derived from experimental crosses is an important component of risk assessment, and a useful first step especially where data from field observations are unavailable. We used this approach to assess the potential for transgene escape via hybridization for 123 widely grown temperate crops and their indigenous and naturalized relatives present in the New Zealand flora. We found that 66 crops (54%) are reproductively compatible with at least one other indigenous or naturalized species in the flora. Limited reproductive compatibility with wild relatives was evident for a further 12 crops (10%). Twenty-five crops (20%) were found to be reproductively isolated from all their wild relatives in New Zealand. For the remaining 20 crops (16%), insufficient information was available to determine levels of reproductive compatibility with wild relatives. Our approach may be useful in other regions where spontaneous crop-wild hybridization has yet to be well documented.     

High-rate nitrogen removal from livestock manure digester liquor by combined partial nitritation–anammox process

In this study, combination of a partial nitritation reactor, using immobilized polyethylene glycol (PEG) gel carriers, and a continuous stirred granular anammox reactor was investigated for nitrogen removal from livestock manure digester liquor. Successful nitrite accumulation in the partial nitritation reactor was observed as the nitrite production rate reached 2.1 kg-N/m³/day under aerobic nitrogen loading rate of 3.8 kg-N/m³/day. Simultaneously, relatively high free ammonia concentrations (average 50 mg-NH₃/l) depressed the activity of nitrite oxidizing bacteria with nitrate concentration never exceeding 3% of TN concentration in the effluent of the partial nitritation reactor (maximum 35.2 mg/l). High nitrogen removal rates were achieved in the granular anammox reactor with the highest removal rate being 3.12 kg-N/m³/day under anaerobic nitrogen loading rate of 4.1 kg-N/m³/day. Recalcitrant organic compounds in the digester liquor did not impair anammox reaction and the SS accumulation in the granular anammox reactor was minimal. The results of this study demonstrated that partial nitritation–anammox combination has the potential to successfully remove nitrogen from livestock manure digester liquor.     

Habitat type plays a greater role than livestock grazing in structuring shrubsteppe plant–pollinator communities

Livestock grazing is a widespread grassland disturbance and can negatively impact biodiversity. Pollinators constitute a vital component of grassland ecosystems, but the impact of grazing on pollinator diversity has seldom been evaluated in North America. We assessed vegetation structure, and pollinator and flowering plant abundance, richness, diversity, and community composition in four pairs of spring-grazed/ungrazed sites in south-central British Columbia, Canada. We also investigated whether pollinator or floral communities differed between the two threatened shrubsteppe habitat types we sampled—antelope-brush and big sagebrush shrubsteppe. Pan-trapping surveys captured 5907 bees, flies, beetles, wasps and butterflies constituting 253 species. We found that the percent cover of shrubs and bare soil increased with grazing, while the height of grasses and forbs decreased. In contrast, pollinator and flowering plant abundance, richness, diversity, and community composition were not significantly affected by grazing. Flowering plant and pollinator community composition did differ significantly between shrubsteppe habitats. Our results indicate that grasslands in North America, when managed responsibly, can maintain pollinator and flowering plant diversity under grazing pressure. The continued effort of land managers to balance ecological integrity and economic viability will be important for the conservation of grassland pollination systems.     

Effect of livestock grazing in the partitions of a semiarid plant–plant spatial signed network

In recent times, network theory has become a useful tool to study the structure of the interactions in ecological communities. However, typically, these approaches focus on a particular kind of interaction while neglecting other possible interactions present in the ecosystem. Here, we present an ecological network for plant communities that consider simultaneously positive and negative interactions, which were derived from the spatial association and segregation between plant species. We employed this network to study the structure and the association strategies in a semiarid plant community of Cabo de Gata-Níjar Natural Park, SE Spain, and how they changed in 4 sites that differed in stocking rate. Association strategies were obtained from the partitions of the network, built based on a relaxed structural balance criterion. We found that grazing simplified the structure of the plant community. With increasing stocking rate species with no significant associations became dominant and the number of partitions decreased in the plant community. Independently of stocking rate, many species presented an associative strategy in the plant community because they benefit from the association to certain ‘nurse’ plants. These ‘nurses’ together with species that developed a segregating strategy, intervened in most of the interactions in the community. Ecological networks that combine links with different signs provide a new insight to analyze the structure of natural communities and identify the species which play a central role in them.     

The requirement of zinc for improvement of crop yield and mineral nutrition in the maize–mungbean–rice system

A study was made over 3 years to find out an optimum rate of Zn application for the maize–mungbean–rice cropping system in a calcareous soil of Bangladesh. Zinc application was made at 0, 2 and 4 kg ha⁻¹ for maize (cv. Pacific 984, Thai hybrid) and at 0, 1 and 2 kg ha⁻¹ for rice (cv. BRRI dhan33), with no Zn application for mungbean (cv. BARI mung5). Effect of Zn was evaluated in terms of yield and mineral nutrients contents (N, P, S and Zn). All the three crops responded significantly to Zn application. The optimum rate of Zn for the maize–mungbean–rice cropping system was found to be 4–0–2 kg ha⁻¹ for the first year and 2–0–2 kg ha⁻¹ for subsequent years particularly when mungbean residue was removed, and such rates for mungbean residue incorporation being 4–0–1 and 2–0–1 kg ha⁻¹, respectively. For all crops, the Zn and N concentrations of grain were significantly increased with Zn application. For the case of grain-S, the concentration was significantly increased for maize and mungbean, but it remained unchanged for rice. The grain-P concentration on the other hand tended to decrease with Zn application. For maize, the grain-Zn concentration increased to 27.0 μg g⁻¹ due to 2 kg Zn ha⁻¹ treatment from 16.5 μg g⁻¹ for Zn control and at higher Zn rate (4 kg Zn ha⁻¹) the increment was very minimum. Another field experiment was performed over 3 years on the same soil to screen out maize varieties for Zn efficiency. Of the eight varieties tested, the BARI maize 6 and BARI hybrid maize 3 were found Zn in-responsive (Zn efficient) and the others Zn responsive (Zn-inefficient).     

Removal of livestock alters native plant and invasive mammal communities in a dry grassland–shrubland ecosystem

The impacts of domesticated herbivores on ecosystems that did not evolve with mammalian grazing can profoundly influence community composition and trophic interactions. Also, such impacts can occur over long time frames by altering successional vegetation trajectories. Removal of domesticated herbivores to protect native biota can therefore lead to unexpected consequences at multiple trophic levels for native and non-native species. In the eastern South Island of New Zealand large areas of seral grassland–shrubland have had livestock (sheep and cattle) removed following changes in land tenure. The long-term (>10 years) outcomes for these communities are complex and difficult to predict: land may return to a native-dominated woody plant community or be invaded by exotic plants and mammals. We quantified direct and indirect effects of livestock removal on this ecosystem by comparing plant and invasive mammal communities at sites where grazing by livestock ceased c.10–35 years ago (conservation sites) with paired sites where pastoralism has continued to the present (pastoral sites). There was higher total native plant richness and reduced richness of exotic plants on conservation sites compared with pastoral sites. Further, there were differences in the use of conservation and pastoral sites by invasive mammals: rabbits and hedgehogs favoured sites grazed by livestock whereas house mice, brushtail possums and hares favoured conservation sites. Changes in the relative abundance of invasive mammal species after removal of domesticated livestock may compromise positive outcomes for conservation in successional plant communities with no evolutionary history of mammalian grazing.     

Review: From human–animal relation practice research to the development of the livestock farmer's activity: an ergonomics–applied ethology interaction

Animal husbandry and working conditions for livestock farmers have changed significantly in recent years as agriculture has been exposed to economic as well as health, environmental and ethical challenges. The idea of interdependent welfare between humans and animals is more relevant now than ever. Here, we innovatively bridge two disciplines—ergonomics and applied ethology—to achieve an in-depth observational understanding of real husbandry practice (by farmers, inseminators, vets) at work. Ergonomics aims to gain a detailed understanding of human activity in its physical, sensitive and cognitive dimensions in relation to a task. It also aims to transform work situations through a systemic approach drawing on multiple levers for change. Here, we examine how this analysis holds up to the inclusion of animals as an integral component of the livestock farmer’s work situation. Applied ethology studies behaviours in animals managed by humans. It aims to understand how these animals perceive their environment, including how they construct their relationship with the livestock farmer. This paper proposes an original conception of the human–animal relationship in animal husbandry that employs core structural concepts from both disciplines. From an ergonomic point of view, we address the human–animal relations by examining the relationship between ‘prescribed’ and real work practices, between work and personal life situation, between professional task and human activity. On the applied ethology side of the equation, the human–animal relationship is a process built through communication and regular interactions between two ‘partners’ who know each other. The goal is to understand how each partner perceives the other according to their multimodal sensory world and their cognitive and emotional capacities, and to predict the outcome of future interactions. We cross-analyse these scientific views to show, based on examples, how and in what way they can intersect to bring better analysis of these human–animal relationships. We reflect on common working hypotheses and situated observational approaches based on indicators (behaviour and animal and human welfare/health). This analysis prompts us to clarify what human–animal relational practice means in animal husbandry work, i.e. a strategy employed by the livestock farmer to work safely and efficiently in a healthy environment, where the animal is treated as a partner in the relationship. In this perspective, the challenge is for the livestock farmer’s activity to co-build a positive relationship and avoid being subject to this one.     

Multi-residue extraction–purification procedure for corticosteroids in biological samples for efficient control of their misuse in livestock production

A fast and efficient multi-residue extraction–purification procedure was developed for 12 corticosteroids in biological matrices (hair, urine and meat), in order to control their illegal use as growth promoters in cattle. Detection and identification of the analytes were achieved using a previously described LC–MS–MS method based on negative electrospray ionisation and a triple quadrupole analyser. The presented procedures included acid (hair) or enzymatic (urine and meat) hydrolysis, C₁₈ reversed-phase SPE, Na₂CO₃ liquid–liquid clean-up and SiOH normal-phase SPE. The detection limits of the developed methods were between 2.9 and 9.3 pg/mg (ppb) for hair samples and in the 40 – 70 pg/g (ppt) range for the urine or meat samples. The acid hydrolysis used for corticosteroid extraction in hair was optimised using an experimental design and response surface methodology. Achieved performances were linked to a physico–chemical approach based on the corticosteroids specific C₁₇ side-chain. This original multi-residue and multi-matrices analytical methodology will be used for further metabolism studies.     

Characteristics of white-tailed deer visits to cattle farms: implications for disease transmission at the wildlife–livestock interface

Bovine tuberculosis (bTB) is endemic in free-ranging white-tailed deer (Odocoileus virginianus) in MI, USA. Currently, the rates of farm visitation by deer and co-use of forage resources by cattle and deer are poorly understood. To evaluate the extent deer and livestock may share forage resources, we investigated farm, yard, and cattle-use area visitation by white-tailed deer and compared visitation with common livestock management practices. We fitted 25 female white-tailed deer near the bTB-infected zone in Michigan’s Lower Peninsula with global positioning system collars. Livestock management practices associated with farm visitation included presence of confined feeding pastures, number of cattle water sources, and the number of cattle pastures. Fewer farm visits occurred at night than during the day. A higher proportion of nighttime visits occurred between midnight and sunrise. Visitation to yards and cattle-use areas were similar: a higher proportion of visits occurred at night, and a higher proportion of nighttime visits occurred between midnight and sunrise. Multiple visits during the same day were common. Visitation increased through spring and peaked during the fawning season. Results suggest that mitigation and control efforts to guard against potential transmission of bTB should include the season and time of day during which deer visitation occurs. Furthermore, specific livestock management practices may contribute to farm visitation by deer. Deer visiting multiple farms may contribute to local area spread of bTB. Focusing risk mitigation efforts on individual deer that are most likely to visit farms may reduce potential bTB transmission.     

Genetically engineered livestock: closer than we think?

The potential of biotechnology to benefit production agriculture has long been speculated. Whereas many transgenic crops have been produced and commercialized, there has yet to be any implementation of genetically engineered livestock. A recent publication by Wall et al. represents one of the first reports to bring the potential of genetic engineering closer to realization by improving disease resistance in dairy cattle: a practical advantage to both the producer and animal.     

Can improvement in photosynthesis increase crop yields?

The yield potential (Y_p) of a grain crop is the seed mass per unit ground area obtained under optimum growing conditions without weeds, pests and diseases. It is determined by the product of the available light energy and by the genetically determined properties: efficiency of light capture (?_i), the efficiency of conversion of the intercepted light into biomass (?_c) and the proportion of biomass partitioned into grain (η). Plant breeding brings η and ?_i close to their theoretical maxima, leaving ?_c, primarily determined by photosynthesis, as the only remaining major prospect for improving Y_p. Leaf photosynthetic rate, however, is poorly correlated with yield when different genotypes of a crop species are compared. This led to the viewpoint that improvement of leaf photosynthesis has little value for improving Y_p. By contrast, the many recent experiments that compare the growth of a genotype in current and future projected elevated [CO₂] environments show that increase in leaf photosynthesis is closely associated with similar increases in yield. Are there opportunities to achieve similar increases by genetic manipulation? Six potential routes of increasing ?_c by improving photosynthetic efficiency were explored, ranging from altered canopy architecture to improved regeneration of the acceptor molecule for CO₂. Collectively, these changes could improve ?_c and, therefore, Y_p by c. 50%. Because some changes could be achieved by transgenic technology, the time of the development of commercial cultivars could be considerably less than by conventional breeding and potentially, within 10–15 years.     

Plant genome sequencing — applications for crop improvement

1. Download : Download high-res image (182KB)
2. Download : Download full-size image

     

Are we ready for back-to-nature crop breeding?

Download : Download video (12MB)     

The energy balance in farm scale anaerobic digestion of crop residues at 11–37 °C

Crop residues can be used for biogas production in farm scale reactors. Use of a process temperature below mesophilic conditions reduces the need for heating as well as investment and operating costs, although it may also reduce the methane yield. In the present study the effect of temperature on net energy output was studied using sugar beet tops and straw as substrates for two pilot-scale reactors. Digestion was found to be stable down to 11 °C and optimal methane yield was obtained at 30 °C. The methane yield and process performance was studied at 15 °C and 30 °C as organic loading rates were increased. It was found that the highest net energy production would be achieved at 30 °C with a loading rate of 3.3 kg VS m⁻³ day⁻¹. Running a low-cost process at ambient temperatures would give a net energy output of 60% of that obtained at 30 °C.