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The effect of crop residues, cover crops, manures and nitrogen fertilization on soil organic carbon changes in agroecosystems: a synthesis of reviews
Get PDFInternational initiatives are emphasizing the capture of atmospheric CO2 in soil organic C (SOC) to reduce the climatic footprint from agroecosystems. One approach to quantify the contribution of management practices towards that goal is through analysis of long-term experiments (LTEs). Our objectives were to analyze knowledge gained in literature reviews on SOC changes in LTEs, to evaluate the results regarding interactions with pedo-climatological factors, and to discuss disparities among reviews in data selection criteria. We summarized mean response ratios (RRs) and stock change rate (SCR) effect size indices from twenty reviews using paired comparisons (N). The highest RRs were found with manure applications (30%, N = 418), followed by aboveground crop residue retention and the use of cover crops (9–10%, N = 995 and 129), while the effect of nitrogen fertilization was lowest (6%, N = 846). SCR for nitrogen fertilization exceeded that for aboveground crop residue retention (233 versus 117 kg C ha−1 year−1, N = 183 and 279) and was highest for manure applications and cover crops (409 and 331 kg C ha−1 year−1, N = 217 and 176). When data allows, we recommend calculating both RR and SCR because it improves the interpretation. Our synthesis shows that results are not always consistent among reviews and that interaction with texture and climate remain inconclusive. Selection criteria for study durations are highly variable, resulting in irregular conclusions for the effect of time on changes in SOC. We also discuss the relationships of SOC changes with yield and cropping systems, as well as conceptual problems when scaling-up results obtained from field studies to regional levels
Effect of immobilizing reagents on soil Cd and Pb lability under freeze-thaw cycles: Implications for sustainable agricultural management in seasonally frozen land
Get PDFAgricultural soil contamination in seasonally frozen land threatens food security. It is necessary to investigate the effects of freeze-thaw cycles on heavy metal bioavailability so as to select suitable immobilization agents. In this study, the soil was collected from a mid-latitude agricultural site in Liaoning Province, China, which was spiked with cadmium (Cd2+) and lead (Pb2+). Four immobilization treatments were set up, including (i) corn stover biochar, (ii) organic fertilizer, (iii) combined biochar and organic fertilizer, and (iv) the control group. The immobilized soils were subjected to 16 freeze-thaw cycles to temperatures of −10 °C, −20 °C, and −30 °C. It was found that freeze-thaw cycling increased the labile cadmium (Cd) and lead (Pb) content in the soil (i.e., exchangeable). The organic fertilizer treatment performed best in short-term immobilization, which was demonstrated by the amount of diethylenetriaminepentaacetic acid (DTPA) extractable lead (Pb) being 17.3–53.3% lower than that of the other treatments, and 7.2–31.5% lower for cadmium (Cd). Biochar, on the other hand, displayed better long-term performance under freeze-thaw cycling. This is probably because the biochar’s organic carbon content is relatively stable, and therefore, releases relatively little dissolved organic carbon (DOC) which could re-mobilize heavy metals. Furthermore, additional sorption sites are formed and the abundance of oxygen-containing functional groups increased when biochar breaks down during freeze-thaw cycles. Overall, the joint application of biochar and organic fertilizer had the greatest immobilization effect, which inhibited the cracking of soil aggregates, reduced the labile metal content, and displayed both short- and long-term immobilization effectiveness. It is suggested that combined biochar and organic fertilizer may offer an effective strategy for the sustainable agricultural management of cadmium (Cd) and lead (Pb) contaminated in seasonally frozen land
Politics of smell: Constructing animal waste governmentality and good farming subjectivities in colonial Hong Kong
Get PDFThis paper examines the governmentality of colonial Hong Kong throughout the 1980s and 1990s, focusing on the implementation of the Livestock Waste Control Scheme (1987–1997), the production of normative waste treatment knowledge, the spatial control of farming practices and the resulting subjectivity in the construction of the ‘environmentally friendly farmer’ identity. These themes are examined by analysing archival materials and conducting in-depth interviews with two Pig Farmers Association representatives and 19 pig farmers. This paper argues that the colonial government of Hong Kong relied on environmental ordinances and zoning regulations, livestock waste demonstration projects and socially constructed perceptions of olfactory acceptability as major technologies of governance in the creation of ‘environmentally friendly’ pig farmers. Through being exposed to these technologies, pig farmers learned and internalised a particular concept of what constitutes appropriate animal waste management and treatment. This paper shows how the concept of being ‘environmentally friendly’ contributes to the creation and use of ‘good farming’ subjectivities when modernising pig farmers’ waste management practices
On-farm biosecurity in livestock production: farmer behaviour, cultural identities and practices of care
Get PDFDefinitions of biosecurity typically include generalised statements about how biosecurity risks on farms should be managed and contained. However, in reality, on-farm biosecurity practices are uneven and transfer differently between social groups, geographical scales and agricultural commodity chains. This paper reviews social science studies that examine on-farm biosecurity for animal health. We first review behavioural and psychosocial models of individual farmer behaviour/decisions. Behavioural approaches are prominent in biosecurity policy but have limitations because of a focus on individual farmer behaviour and intentions. We then review geographical and rural sociological work that emphasises social and cultural structures, contexts and norms that guide disease behaviour. Socio-cultural approaches have the capacity to extend the more commonly applied behavioural approaches and contribute to the better formulation of biosecurity policy and on-farm practice. This includes strengthening our understanding of ‘good farming' identity, tacit knowledge, farmer influence networks, and reformulating biosecurity as localised practices of care. Recognising on-farm biosecurity as practices of biosecure farming care offers a new way of engaging, motivating and encouraging farmers to manage and contain diseases on farm. This is critical given government intentions to devolve biosecurity governance to the farming industry
The effectiveness of flower strips and hedgerows on pest control, pollination services and crop yield: a quantitative synthesis
No full textFloral plantings are promoted to foster ecological intensification of agriculture through provisioning of ecosystem services. However, a comprehensive assessment of the effectiveness of different floral plantings, their characteristics and consequences for crop yield is lacking. Here we quantified the impacts of flower strips and hedgerows on pest control (18 studies) and pollination services (17 studies) in adjacent crops in North America, Europe and New Zealand. Flower strips, but not hedgerows, enhanced pest control services in adjacent fields by 16% on average. However, effects on crop pollination and yield were more variable. Our synthesis identifies several important drivers of variability in effectiveness of plantings: pollination services declined exponentially with distance from plantings, and perennial and older flower strips with higher flowering plant diversity enhanced pollination more effectively. These findings provide promising pathways to optimise floral plantings to more effectively contribute to ecosystem service delivery and ecological intensification of agriculture in the future
Moving from a compliance-based to an integrity based organizational climate in the food supply chain
Get PDFCompliance is the act or status of complying with an imperative regulatory or normative requirement i.e. compliance means working within boundaries defined by contractual, social or cultural standards. The aim of this narrative review is to use the food supply chain as a lens of enquiry to distinguish between compliance based and integrity based organizational climates and frame and rationalize why deviant behavior arises and how it can be identified. Contemporary theory is explored and critiqued using case studies to contextualize the challenge of organizations promoting supply chain compliance and at the same time recognizing the need for deviant behavior to occur in order to drive innovation and continuous improvement within food supply chains. Deviant behavior can be perceived as either positive in terms of driving continuous improvement or destructive where this behavior has a negative impact on the organization. Whilst multiple cultural maturity models seek to characterize positive food safety culture and climate, there is minimal research that focuses on the characterization of deviant negative behavior or the development of early warning systems designed to pinpoint signals, traits or characteristics of this behavior such as low staff morale, theft, property destruction or absenteeism. The use of cultural maturity models and assessment tools is of value in assisting organizations to translate from a rule, instrumental or compliance-based organizational climate to an ethically strong organizational climate that focuses on integrity, building trust and values and a new model is proposed and explored
Mapping the bacterial ecology on the phyllosphere of dry and post soaked grass hay for horses
Get PDFSoaking hay fodder to reduce dust and soluble carbohydrate (WSC) contents prior to feeding is common practice among horse owners. Soaking can increase bacteria load in hay but
no information exists on how this process alters the bacteria profile, which could pose a
health risk or digestive challenge, to horses by introducing foreign bacteria into the gastrointestinal tract and so altering the normal profile. The current objectives were to map the bacterial profile of 3 different hays and determine how soaking alters this with the aim of
improving best practice when feeding stabled horses. A Perennial Rye grass hay and two
meadow s hays were soaked for 0, 1.5, 9 or 16 hours. Pre and post treatment, hays were
analysed for WSC and total aerobic bacteria (CFU/g), and differences in bacteria family profiles were determined using ANOVA with significance set at P<0.05. Bacteria were identified
via genomic DNA extraction and 16S library preparation (V3 and V4 variable region of 16S
rRNA) according to the Illumina protocol. Differences in family operational taxonomic units
(OTUs) between individual dry hays and different soaking times were identified via paired ttests on the DESeq2 normalised data and false discovery rates accounted for using Padj
(P<0.05). Mean % WSC losses and actual g/kg lost on DM basis (+/- SE) increased with
soaking time being 18% = 30 (10.7), 38% = 72 (43.7), and 42% = 80 (38.8) for 1.5, 9 and 16
hours soak respectively. No relationship existed between WSC leaching and bacteria
growth or profile. Grass type influenced bacterial profiles and their responses to soaking,
but no differences were seen in richness or Shannon diversity indices. PCA analyses
showed clustering of bacteria between meadow hays which differed from the perennial rye
grass hay and this difference increased post soaking. Soaking hay pre-feeding causes
inconsistent WSC leaching, bacteria growth and alterations in bacterial profiles which are
unpredictable but may decrease the hygienic quality of the fodder
The energy requirements of performance horses in training
Get PDFThe aim of this study was to estimate the energy requirements of performance horses in active, variable training in the field. Sixty horses in England and Switzerland were measured over two-week periods, and for fifteen of these the measurement period was extended, ranging from 21 to 42 weeks. Energy intake was estimated by measuring daily feed consumption. Energy output was measured using heart rate monitors during 608 training sessions, relating heart rate (HR) to VO₂ and converting VO₂ to energy. Field maintenance requirements were calculated by deducting the marginal energy cost of training from energy input. The mean field maintenance expenditure for performance horses with a normal temperament was found to be 0.118 MJ of metabolisable energy (ME) / kg of bodyweight (BW) / day (SD = 0.008, CI = 0.005, n = 60 horses). This result is between 1.9% (P = 0.086) and 20.9% (P < 0.001) greater than the official guidance found in the US, France, Germany and Holland. Heart rate monitoring of training revealed a mean energy expenditure / ridden session of 0.023 MJ ME (SD = 0.001, CI = 0.001, n = 175 training sessions). The mean daily energy expenditure for exercise based on a full week’s training was 0.018 MJ ME / kg BW / day (SD = 0.005, CI = 0.001, n = 60 horses) representing a multiple of maintenance of 15.3%. This implies that the official guidance in the US and France may overstate expenditure for exercise by 111% and 15%, respectively (P < .01). Daily energy expenditure between countries and within disciplines was consistent, allowing for the creation of user-friendly tables which can be used in budgeting the energy component of diets