Search

Pulp and paper mill sludge (PPMS) is applied on agricultural soils as an organic fertilizer. Although it is well accepted that land application of PPMS has benefits for soils and crops, information on PPMS-induced soil N 2 O emissions is still limited. We assessed the effect of substituting mineral N fertilizer for PPMS on soil N 2 O emissions after a single application at planting on a clay loam cropped to wheat ( Triticum aestivum L.) over two snow-free seasons in eastern Canada. Fertilization treatments consisted of 0, 25, 50, 75, and 100% of crop N requirements derived from N supplied by PPMS, the remaining N being supplied as urea-N. Soil CO 2 and CH 4 emissions were also measured and not affected by the fertilizer addition; a slight CH 4 oxidation occurred. Area-based N 2 O emissions from PPMS fertilization (4.4 to 12.1 kg N 2 O-N ha −1 ) were similar or higher than from urea alone (3.4 and 6.2 kg N 2 O-N ha −1 ). Although crop yields were not affected by the type of fertilizer, yield-based N 2 O emissions, N uptake efficiency and N surplus (applied N minus aboveground N uptake in crop biomass) indicated that N availability from the mineral fertilizer was higher than from PPMS for the wheat crop. However, treatments with PPMS had fertilizer-induced N 2 O emission factors (FIEF, applied N lost as N 2 O-N; 0.8 to 3.1%) similar to urea alone (−0.3 and 4.5%). Although substituting urea-N with PPMS in agricultural fields might reduce N 2 O emissions under moderate soil moisture conditions, PPMS land application produced greater N 2 O emissions under high soil moisture conditions. Further research on a variety of agricultural practices is needed before concluding that including PPMS in the fertilization plan could result in a global GHG abatement as compared to mineral fertilizers under the cool climate of eastern Canada. [ABSTRACT FROM AUTHOR]

Incorporation of crop residues and other organic material to agricultural soils may increase nitrous oxide (N2O) emissions, depending on the quantity and quality of the incorporated material. The effects of combining materials of contrasting quality on these emissions have still to be investigated. In this paper, the effects of applying paper mill sludge (PMS), incorporating plant residues, and cultivation on emissions of N2O are reported. Two field experiments were undertaken on Cambisol soils (FAO classification), previously cropped to iceberg lettuce (Lactuca sativa var. saladin) and calabrese (Brassica oleracea italica var. cymosa) in Fife, eastern Scotland. Emissions were measured using both automated and manual closed chambers and comparisons were made between these techniques. Nitrous oxide emissions were high after incorporation of PMS; with up to 4.9 kg N2O&z.sbnd;N ha−1 emitted over the first 3 weeks. These increased emissions were probably due to the high input of organic C for denitrification. Emissions from deep ploughed PMS treatments were higher (P<0.05) than from rotary tilled and conventional ploughed treatments. Application of PMS resulted in an increase in microbial biomass C, but not biomass N. Measurements using autochambers recorded higher N2O emissions than those obtained by less frequent manual measurements, partly due to diurnal variations in N2O with soil temperature. High Q10s (up to 4.0) for this temperature response were recorded in one period in July. It is recommended that diurnal temperature variations be recorded when sampling from manual closed flux chambers so that corrections can be made for diurnal variation in N2O. [Copyright &y& Elsevier]

Abstract: Stable isotopic measurements (δ 15N and δ 18O), combined with hydrochemical assessment, were used to elucidate the chemical quality of groundwater and the sources of nitrate (NO3 −) in the groundwater in an agricultural region at Huzhou City, China. Paddy rice (Zhejing 41) and vegetables (Chinese cabbage) are the typical crops grown in the study area. The chemical properties of groundwater in the study area were controlled using natural geochemical processes and anthropogenic activities. The results show that SO4 2− and NH4 + were the major contaminants. Surficial conditions influenced the shallow groundwater. However, no relationship between the ion concentration in groundwater and well depth was found. The combined use of isotopes was useful for identifying NO3 − sources. The isotopic values for δ 15N and δ 18O ranged from −0.8‰ to 20.8‰ and from −2.0‰ to 18.8‰, respectively. The isotopic data were definitive and revealed that N-fertilizer, soil organic matter, and manure dominated the sources of NO3 − in the study area. The δ 15N and δ 18O data for NO3 − indicated a significant degree of nitrification and a lesser extent of denitrification in the agricultural area. Spatial variations in δ 15N for NO3 − showed that NO3 − concentration and δ 15N values in the upper groundwater (<200cm) were higher than the values in the lower groundwater (>200cm). [Copyright &y& Elsevier]

In recognition of the impacts of climate change and air pollution, a special issue was prepared to address the response and adaptation of agricultural ecosystems to global changes. A total of thirteen papers were published, delving into the mechanisms underlying the effects on crops and agroecosystems and adding important insights into the modeling and adaptation of agroecosystems to global change through optimized management practices. This collection of papers has a broad relevance to numerous areas in agriculture, ecology, and environmental and earth sciences. • A special issue dedicated to 'agricultural ecosystems response and adaptation to global changes'. • A total of thirteen papers were published. • Studies concerned ozone, precipitation, warming, management, and modelling. • This Editorial discusses the content of the publications included in the special issue. [ABSTRACT FROM AUTHOR]

Soil nitrogen (N) is one of the most limiting factors affecting crop production in sub-Saharan Africa (SSA). Here we conducted a meta-analysis on the effect of climate smart agricultural (CSA) practices (conservation agriculture (CA) and/or biochar (BC)) application on: (1) soil nitrate-N (NO 3 -N), nitrous oxide (N 2 O) emission, biological N 2 -fixation, percent of nitrogen derived from the atmosphere (%Ndfa), grain yield and nitrogen use efficiency (NUE), (2) the role of soil properties and regions on grain yield and N cycling under CA and/or BC biochar application; and (3) the relationship between inorganic N fertilizer and NO 3 -N, N 2 O emissions, NUE and grain yield. We synthesized 87 unique papers, from 15 countries in SSA with 1643 paired observations. On average across all studies, CA and/or BC significantly increased grain yield and NUE, compared to conventional practices. Residue retention resulted in a significant increase in soil NO 3 -N and N 2 O emission, compared to conventional practices. Our analysis further indicates that BC application significantly increased biological N 2 -fixation, grain yield and NUE. Auxiliary soil parameters also affected grain yield and N cycling. Grain yield was significantly influenced by total organic carbon classes (TOC), whereby highest grain yield was recorded under CSA in soils with 0.5–1 % TOC, compared to soils with < 0.5 % TOC and > 1 % TOC. In addition, total nitrogen (TN) significantly affected the response ratio of CSA and conventional agriculture on N 2 O emission and biological N 2 -fixation. N 2 O emission increased significantly in soils with < 0.05 % TN, while biological N 2 -fixation increased significantly in soils with > 0.2 % TN. Increasing N fertilizer use significantly increased the response ratio of CSA and conventional agriculture on N 2 O and NO 3 -N while significantly reducing the response ratio of yield and NUE. The gap in yield and NUE between CSA and conventional agriculture practises was more pronounced at lower N rates of 0 kg ha−1 and narrowed as N input increased to 120 kg ha−1; this implies that, CSA offers more benefits compared to conventional agricultural practices under low N rates. • Conservation agriculture significantly increased grain yield and NUE, compared to conventional practices. • Residue retention significantly increased soil NO 3 -N, leading to higher N 2 O emissions, compared to conventional practices. • Biochar increased biological N 2 -fixation, grain yield and NUE, compared to conventional practices. • Climate smart agriculture offers more benefits in low N rates than high N rates, compared to conventional agriculture. [ABSTRACT FROM AUTHOR]

In the Dry Chaco region, agriculture expansion has caused significant land use change hotspots. However, the post-impact of land use change on nitrous oxide (N 2 O) emissions and carbon (C) budgets remains unknown. This study aimed to contrast the impacts of the main land use systems on N 2 O emissions related to its C inputs and C budgets by comparing them with those of a native forest at two sites of the Dry Chaco region of Argentina. At Site 1, the land use system were soybean-fallow-soybean and maize-fallow-maize sequences, whereas at Site 2, it was a soybean-wheat sequence. Measurements of soil N 2 O and carbon dioxide (CO 2) fluxes were carried out monthly using the static chamber method. The C budgets of each system were determined for the annual crop-fallow cycle by the difference between the C inputs (from annual aboveground (ABG), belowground (BG), and rhizodeposition) and C outputs (defined as cumulative CO 2 -C emissions). At Site 1, the native forest showed 168 and 50 % more cumulative N 2 O emissions than maize and soybean, respectively. However, most land use differences were based on C inputs. Thus, when the cumulative N 2 O emissions of each system were related to their C inputs, the N 2 O emissions per ton of C entered of the native forest were lower than those of soybean and similar to those of maize. The C budgets (± standard error) at Site 1 were 6.4 ± 1.3, 1.0 ± 0.3 and −0.7 ± 0.6 t C ha−1 yr−1 for native forest, maize and soybean, respectively. At Site 2, they were 3.1 ± 0.7 and −4.0 ± 0.6 t C ha−1 yr−1 for the native forest and the soybean-wheat sequence, respectively. This paper proposes a comprehensive approach that integrates C inputs and budgets when evaluating N 2 O emissions from different land uses as a guide to define mitigating management practices and considers a native vegetation system to unmask the real impacts of agroecosystems. [Display omitted] • How do changes in land use affect N 2 O emissions and C budgets in the Dry Chaco region. • C-scaled N 2 O emissions can change the point of view of agroecosystem impacts. • Maize and the native forest had similar N 2 O emissions per unit of assimilated C. • The approach of C budgets allows determining sustainable crop rotation. • Better N 2 O emissions and C budgets start improving at a 5-ton C input threshold. [ABSTRACT FROM AUTHOR]

The majority of people in Sub-Saharan Africa (SSA) live in rural communities and practice subsistence farming. Variations in climate and other environmental factors affect the stability of local food production. This instability makes the adoption of efficient farming techniques critical in helping farmers achieve food, income, and livelihood security. Agricultural water conservation techniques called water harvesting are being implemented to increase crop yields in SSA. These techniques have been shown to increase water productivity, nutrients, and organic matter in the soil. This paper uses high-resolution imagery to identify and differentiate between farms using conventional and water-harvesting farm methods. An ordinary least-squares regression model was used to correlate seasonal maximum normalized difference vegetation index (NDVI) values with environmental factors for the different farming methods. The results suggest that water harvesting farm techniques have higher crop yields and are less dependent on precipitation than conventional farming methods. The methodology presented in this paper can be used to map use of water harvesting over large areas and monitor associated differences in productivity. [ABSTRACT FROM AUTHOR]

A healthy riparian ecosystem is essential to maintain instream water quality, decrease stream bank erosion, increase bank stability and prevent soil loss within river systems, which in turn may affect coastal water quality. The presence of cattle within the riparian zone is a common feature of grazing ventures, but can negatively impact on the functionality of riparian ecosystems. Therefore, the provision of offstream watering points (OSWPs) as an alternative watering source for cattle may lessen or prevent the impact cattle have on the riparian zone. A systematic review was conducted to identify: 1) which factors influence how cattle use OSWPs, and 2) if the provision of an OSWP is an effective best management practice to reduce the time cattle spent in riparian zones, potentially limiting the impact cattle may have on instream water quality and riparian habitat particularly stream bank vegetation. A total of 37 from 1135 research papers satisfied the initial selection criteria for the review with seven providing sufficient information to conduct a meta-analysis. Out of the 37 papers a total of seven factors and five sub-factors influencing cattle’s use of OSWPs were identified. There is evidence that OSWPs did reduce the time cattle spent in riparian zones, however with great variation (63.7%) among studies. The review further highlights that substantial knowledge gaps exist within the literature linking the interaction of cattle, OSWPs and riparian habitats indicating the need for further research. [ABSTRACT FROM AUTHOR]

The integration of cover crops (CCs) in low-input systems is a widely adopted practice to re-capture surplus nitrogen (N) and avoid excessive losses to the environment by leaching or N 2 O emissions. Closing the N cycle within an agricultural system is therefore economically beneficial and lowers the negative impact of inorganic N on soil and water bodies. However, it is debated if pollution swapping occurs to some extent and if N 2 O emissions increases as a result of decreased N leaching. An experiment was conducted to systematically evaluate grass vs. non-grass CCs, frost tolerant vs. non-frost tolerant CCs as well as high residual N vs. low residual N from the pre-crop, in a low input system which receives no additional fertilizer. Furthermore, the extent to which N 2 O losses occur from different seeded CC species and mixtures (Sinapis alba / Vicia sativa , Brassica rapa / Vicia villosa and Lolium perenne / Trifolium repens) was investigated over two experimental years on a sandy soil located in northern Germany. The annual N 2 O emissions were investigated on a weekly basis using the static closed chamber method. The non-grass CCs had the highest annual N 2 O emissions (2.5 kg N 2 O-N ha−1) compared to grass (1.9 kg N 2 O-N ha−1). The frost-killed CC led to higher N 2 O emissions (3.3 kg N 2 O-N ha−1), especially after the first year when high residual N was still present due to the pre-crop. This indicates that the type of CC used, frost tolerance as well as residual N from the pre-crop will affect N 2 O emissions. The low N 2 O emissions observed in the current study indicate that pollution swapping as a result of avoided N leached due to the use of CCs, as shown in a previous paper from the same experiment, is not occurring under these low-input systems. Furthermore, grass used as CC has low N 2 O emissions and a high N uptake and therefore the potential to close the N cycle and improve on-farm N budgets. • Crop residues act as source for N 2 O emissions. • Freezing/thawing cycles increases risk for N 2 O emissions. • N 2 O emissions were kept low using ryegrass as cover crop. • Cover crops can help close the N gap in low input systems. • Cover crops helped mitigate N 2 O emissions from sandy soils. [ABSTRACT FROM AUTHOR]

This paper estimates the welfare impacts of adoption of maize-soybean rotation in eastern Zambia using data from on-farm trials and household survey data collected from over 800 households. The on-farm trials were conducted from 2012 to 2015 while the household survey was conducted in 2012. The study evaluated maize-soybean rotation where soybean was grown with and without inoculants and inorganic fertilizer, whereas continuous maize cropping was used as a control. The paper estimated household level income changes and poverty reduction due to adoption of maize-soybean rotation using market level economic surplus as well as household level analyses to allocate economic surplus changes to individual households. The results showed that several factors influence the adoption of maize-soybean rotation, including land ownership, education, and age of the household head. Results also showed that adoption of maize-soybean rotation reduced per-unit production costs by between 26 and 32% compared to continuous maize. Ex-ante welfare impact analysis showed significant potential income gains and poverty reduction following adoption of maize-legume rotation in eastern Zambia. The paper concludes with implications for policy to promote wider adoption of soil fertility management practices such as maize-soybean rotation for increased maize productivity in Zambia. [ABSTRACT FROM AUTHOR]

Strawberry (Fragaria x ananasa Duch.) is the most economically important soft fruit worldwide. While self- and wind-pollination is possible for strawberry, without biotic pollination (animal pollinators, including artificial pollination by humans) rate of strawberry flowers rarely exceeds 60% and thus fruit production is decreased. At a time of widely recognized decline of pollinators and increasing global demand for balanced food, we need a comprehensive understanding of the worldwide valuation of these ecosystem services. In this paper, we use a transparent and systematic review process to detect gaps in the available literature. By applying multilevel meta-analytic models, we quantified the contribution of biotic pollinators and different pollinator types to strawberry fruits. Our review showed that research on strawberry pollination is clearly concentrated in European countries, with limited information for Asia – the largest strawberry producer. Additionally, we detected disproportions across research topics, stressing the need for further research on pollinator preferences between strawberry cultivars and the occurrence of managed and wild bee communities. The overall estimate of pollination benefit to strawberry crops is on average a 25% reduction in fruit weight for plants not receiving a biotic pollination treatment. This benefit is similar regardless of the pollinating species. The mean amount globally (2011–2020) receivable by producers from purchasers due to biotic pollination is $5.36 billion per year. Moreover, we demonstrated that strawberry plants that are dependent on self- or wind-pollination set on average 43% fewer seeds (fertilized achenes) than biotically pollinated plants. Such a huge reduction in seed set can cause fruit deformation and reduce the commercial value of strawberries. Together, these findings indicate the critical role of biotic pollination in strawberry production and quality. To ensure pollination services in strawberry farms and produce the best-quality fruits, growers should take action to sustain healthy pollinator communities and utilize them with the optimal cultivar. • Biotic pollination has fundamental importance to strawberry production and quality. • Besides honeybees, a huge diversity of species are involved in strawberry pollination. • Pollination benefits are comparable regardless of the pollination species. • Without biotic pollination fruits are smaller and produce fewer fertilized achenes. • Growers should take action to sustain healthy pollinator communities. [ABSTRACT FROM AUTHOR]

Global models of biodiversity and ecosystem services base their calculations on land use classifications, where agricultural land is only divided into a few categories of management intensity. These land use classifications were not developed to underpin biodiversity models. This is why crop diversity and the presence of non-crop plants or livestock in agricultural land are not considered in these classifications, despite the effect they have on agrobiodiversity and the supply of ecosystem services. Therefore, the use of these classifications in models results in neglecting current diversified agricultural systems and the effect of diversification practices on biodiversity and ecosystem services. In this paper, we present a new global classification of agricultural land management systems organized as a matrix of diversity and intensity ranges. The classification is based on a literature review and expert interviews and is illustrated by examples of agricultural systems around the world. This classification is a first step to build land use and land cover maps that consider diversified agricultural systems, which could then be used by global biodiversity and ecosystem services models. The matrix structure of the classification makes it flexible and adjustable to use for different purposes, such as exploring the potential of preserving biodiversity in agricultural land through land-use scenarios or assessing trade-offs between intensity and diversity. • Agricultural diversity and intensity classification to improve biodiversity models. • Mixture of crops, livestock and non-crop species characterize cropland diversity. • Pesticide use, fertilizer type and amount, and irrigation characterize intensity. • Grazing intensity, sowing and mowing management and age characterize grasslands. [ABSTRACT FROM AUTHOR]

Arable plant diversity has been dramatically declining due to agriculture intensification, with several arable species currently included in national Red Lists. This is particularly relevant in the case of plant communities of the traditional Mediterranean agricultural systems. Despite the current knowledge about the factors affecting this diversity, it is not clear how these communities, which have likely evolved under the pressure of ploughing for millennia, depend on this regular soil disturbance. This is an important issue nowadays, because current management practices focused on the conservation of the ground vegetation cover, to protect soil and other biological groups, often exclude ploughing. In this paper, we test the hypothesis that traditional ploughing is favourable to more specialist arable plants, predictably more dependent on the regular soil disturbance. We address this issue in a Mediterranean agricultural system, the traditional olive groves of Southern Portugal, which is characterized by the annual ploughing of soil. A total of 90 plots containing 1350 sampling quadrats were sampled, and all plant species identified. We categorized plants in four target groups of conservation interest, and then used a joint species distribution model to model their occurrence in relation to three management practices: ploughing, cultivation and low-intensity grazing, using abandoned olive groves as reference level. Results suggest that ploughing is a key factor for the maintenance of arable plant diversity. Ploughing had a positive effect on the occurrence of rare arable plants, archaeophytes and on several Red listed species. In order to conserve these high value plant communities and endangered plant species, we recommend incentivizing ploughing using reduced tillage techniques (e.g. chisel ploughing) on these traditional Mediterranean agricultural systems. • Traditional ploughing promoted the occurrence of specialist arable plants. • Low-intensity cultivation and grazing had a detrimental effect on threatened species. • The exclusion of ploughing may cause the declining of threatened species populations. • Conservation tillage should include ploughing with reduced tillage techniques. [ABSTRACT FROM AUTHOR]

Solitary bees are receiving increasing attention as they are very effective crop pollinators. However, widespread implementation of pollination management with solitary bees is hampered by a lack of targeted and practical guidelines. Indeed, little evidence-based guidelines exist about the preferred type of nesting material, how to control nest-associated macroparasites and how to promote a healthy offspring with sufficient female bees. This study investigated whether different types of artificial nesting materials – paper straws and wooden grooved boards – are preferred by the European orchard bee (Osmia cornuta). In addition, we explored how the bee nesting success and infestation of macroparasites are influenced by type of nesting material, landscape complexity and timing throughout the active nesting period of O. cornuta. We found that O. cornuta preferred to nest in paper straws compared to wooden grooved boards. The number of produced brood cells and the offspring sex-ratio (i.e. the ratio of female:male bees) were higher in wooden grooved boards. Number of brood cells, successful cocoon development and the sex-ratio all decreased throughout the nest-construction period of the bees. The sex-ratio also increased with increasing landscape complexity. Paper straws had a reduced infestation rate of kleptoparasitic mites. In addition, the infestation rate of both kleptoparasitic mites and kleptoparasitic drosophilid flies increased with time throughout the bees' nest-construction period. These findings present relevant evidence to aid successful implementation of solitary bees for crop pollination. Utilization of paper straws, or similar materials, over wooden grooved boards and closing the nests near the end of the bees' active nest-construction period should be recommended practices. Implementation of these practices will reduce parasite infestation and enhance bee nesting success. Furthermore, conservation of semi-natural habitat or planting pollinator-friendly vegetation around fields is also advised to promote the proportion of female bees in the offspring. • O. cornuta prefers to nest in paper straws compared to wooden grooved boards. • Paper straws reduced the infestation rate of kleptoparasitic mites. • Bee nesting success decreased throughout the nest-construction period of the bees. • Infestation of mites and drosophilid flies increased through the nesting period. • The offspring's sex-ratio increased with increasing landscape complexity. [ABSTRACT FROM AUTHOR]

Cultivated plants are often much more susceptible to insect herbivores than wild-type plants. In addressing this observation, much attention has focused on a trait-based approach, and especially on how artificial selection via domestication has modified morphological and chemical traits, in particular levels of defensive secondary metabolites. However, larger scale ecological processes, such as the spatial distribution and diversity of species in a plant community, also determine how insects locate and exploit their food plants, and these differ profoundly between natural and agricultural ecosystems. In this paper we discuss these two approaches to better understand differences in levels of insect herbivory between agricultural and natural ecosystems. We argue that studies investigating the effects of secondary metabolites on insect herbivory are compromised by the methodological approach that is often used. Insect feeding assays testing the effect of reduced concentrations of secondary metabolites in domesticated plants rely on testing a limited subset of insect species, usually those that can easily be reared in the laboratory and often are agricultural pest species. The responses of these insects do not reflect the full range of responses of the species present in the plant's natural habitat. This may explain why reduced levels of secondary metabolites in crop plants may only partially explain increased susceptibility to herbivory. Hypotheses explaining larger scale patterns of insect herbivore abundance are often based on studies in agricultural settings. In our opinion, developing broad ecological hypotheses based on studies in agricultural systems do not necessarily apply to natural systems and vice versa. To fully understand how susceptibility or resistance to insect herbivory is affected by plant traits and habitat heterogeneity, these have to be studied together in both natural and agricultural settings. • Cultivated plants are often more susceptible to insect herbivores than wild-type plants. • To explain this, research has been focused on plant traits, especially chemical traits. • Landscape and plant community characteristics also determine how insects locate and exploit food plants. • Susceptibility to insect herbivory should be studied considering both aspects simultaneously. • These should be studied together in both natural and agricultural settings [ABSTRACT FROM AUTHOR]

Permanent grasslands cover 34% of the European Union's agricultural area and are vital for a wide variety of ecosystem services essential for our society. Over recent decades, the permanent grassland area has declined and land use change continues to threaten its extent. Simultaneously, the management intensity of permanent grasslands increased. We performed a systematic literature review on the multifunctionality of permanent grasslands in Europe, examining the effects of land use and management on 19 grassland ecosystem service indicators. Based on the evidence in 696 out of 70,456 screened papers, published since 1980, we found that both land use change and intensification of management decreased multifunctionality. In particular, preventing conversion of permanent grasslands to croplands secured the delivery of multiple ecosystem services. A lower management intensity was associated with benefits for biodiversity, climate regulation and water purification, but impacted the provision of high-quality animal feed. Increasing the number of species in the sward enhanced multifunctionality of permanent grassland without significant trade-offs such as losses in production. Our review covered many aspects of land use, management and ecosystem services, but we also identified areas with no or only few studies. The most prominent gaps were related to comparisons between permanent and temporary grasslands, and effects of management practices on the provision of cultural values, and on erosion and flood control. We suggest that, despite apparent changes in human dietary preferences, the protection of permanent grasslands in Europe must be prioritised. At the same time, considering the need to reduce ruminant livestock's contribution to climate change, the time seems ripe to increase support for low-intensity grassland management to optimise the provision of essential ecosystem services from Europe's permanent grasslands. • In recent decades, Europe's permanent grassland area has declined and land use change continues to be a threat. • We performed a systematic literature review on ecosystem services delivery from permanent grasslands. • Our findings are based on evidence in 696 out of 70,456 screened papers on 19 ecosystem service indicators. • Land use change and intensification decrease the multifunctionality of permanent grasslands. • Despite calls to reduce meat and dairy consumption, the protection of permanent grasslands has to be prioritized. [ABSTRACT FROM AUTHOR]

Abstract: This introductory paper provides an overview of the contributions to this special issue, addressing four key questions related to conservation agriculture (CA) in Sub-Saharan Africa and South Asia: What is the impact of CA on yields? What is the impact of adopting CA on farmers’ profits? What are the environmental impacts of adopting CA? How well does CA fit with wider agricultural, social, economic and political contexts for small-scale farmers? Papers in this special issue find that yield increases under CA are possible but uncertain given the low average yields that pertain in these regions, and yield gains are more likely to be observed after several years. CA is not widely adopted in Sub-Saharan Africa and South Asia owing to a lack of economic incentive for smallholder farmers—that the process of conversion to CA is not profitable over planning horizons of most farmers. There is no clear trend for greater carbon sequestration under CA, so the potential for subsidizing farmers to adopt CA using payments for ecosystem services/carbon credit schemes seems limited in scope. There is early evidence that farmers perceive a benefit from CA adoption in regions that are prone to erratic rainfall, suggesting a potential risk mitigation role. In addition, throughout this overview paper we offer a commentary on some of the scientific issues that constrain our ability to understand the performance of CA in these systems more comprehensively. [Copyright &y& Elsevier]

Massive grasslands on the Qinghai-Tibetan Plateau(QTP) provide vital ecosystems services, which have been decreased by land degradation associated with global change. Effective efforts and actions of restoration and management are required to promote the sustainable development of these grassland ecosystems with global importance. This special issue collected numerous papers to address share the innovative theoretical foundations and practical approaches for restoring and protecting QTP's grassland ecosystems in the era of global change. The findings from the collected papers of this special issue stated that the ecosystems services of the QTP's grasslands are declining due to weakened interfaces among soil, plant and grazing animals in the QTP's grassland ecosystems by climate and land use changes. Applicable actions such as climate change mitigation and adaptation, close-to-nature restoration, rotational grazing regime with moderate grazing intensity should be taken to enhance the ecosystem services through rebuilding rational soil-plant-animal interfaces. • Both climate change and human activities led to grassland degradation. • Grassland degradation have weakened the ecosystem services. • Restoration and rational grazing can enhance sustainability of grasslands. [ABSTRACT FROM AUTHOR]

Abstract: Landscape ecology has emphasized the key role of spatial heterogeneity as a driver of ecological processes, which has led to a shift from a patch-matrix to a landscape mosaic representation of landscapes. However, in agricultural landscapes, the role of heterogeneity for biodiversity is often studied by considering (semi-) natural elements regardless of the functional heterogeneity of the cultivated mosaic. This mosaic, which emerges from the organization of cropping systems by farmers, is not just heterogeneous in space but also strongly dynamic (i.e. temporally heterogeneous) due to crop phenology, management and sequence. In this paper, based on agronomic and ecological literature we highlight the heterogeneous properties of the cropping system mosaics in space and time, and the implications of this “hidden” heterogeneity for controlling of arthropod population dynamics and persistence. An illustration is then given to propose different methodological approaches to map the hidden heterogeneity of agricultural landscapes. This conceptual and methodological framework concerns various species in agro-ecosystems, including crop and multi-habitat species, as well as species that only disperse through the crop mosaic. This paper suggests that the design of the cropping system mosaics could be complementary to the design of natural areas to manage populations, notably for species of economic interest (pests, natural enemies or pollinators). More empirical work on this topic is crucial, which will require new methodological approaches. [Copyright &y& Elsevier]

This paper introduces the contents of a special issue of Agriculture, Ecosystems and Environment dedicated to “Agrobiodiversity & Africa”. Placed within the context of the scientific literature on agricultural biodiversity, its contribution to sustainable production and its importance in Africa, this special issue starts off with background articles which reviewed major agroecosystems in Africa, descriptions of their biodiversity resources, management, limitations and concerns. The follow-up scientific papers covered major components of biodiversity for agriculture namely soil biota, species diversity and germplasm diversity. The soil biota papers report research and findings on arbuscular mycorrhizal fungi in the rhizosphere, termite and bacterial communities and evidence on the influence of their diversity on crop production. The crop species diversity papers provide evidence on the role of the diversity in influencing soil microbial properties as well as managing pest and diseases in crop production. Scientific evidence on the role and interactions of germplasm diversity and provenance with the environment are also presented. [ABSTRACT FROM AUTHOR]

This paper reviews the agroecosystems and agricultural biodiversity in Southern Africa and highlights the importance of the agricultural landscape in biodiversity conservation and the important role that the traditional farming systems play in conserving biodiversity. The review established that agrobiodiversity is of great importance to both small scale and large commercial farmers in Southern Africa through its provision of ecosystem services. The paper also highlights the significant loss of agrobiodiversity as a result of human population pressure and the transition from traditional mixed farming systems which is characterized with high agrobiodiversity, to modern monoculture farming resulting in decline of species diversity. Although concerted efforts are being made to promote the sustainable use and management of this agrobiodiversity, there need to have a multi-stakeholder approach so that conservation efforts are successful, a role that is currently played by the SADC Plant Genetic Resources Centre in Southern African conservation of agrobiodiversity. [ABSTRACT FROM AUTHOR]

Abstract: A meta-analysis is a statistical treatment of a dataset derived from a literature review. Meta-analysis appears to be a promising approach in agricultural and environmental sciences, but its implementation requires special care. We assessed the quality of the meta-analyses carried out in agronomy, with the intent to formulate recommendations, and we illustrate these recommendations with a case study relative to the estimation of nitrous oxide emission in legume crops. Eight criteria were defined for evaluating the quality of 73 meta-analyses from major scientific journals in the domain of agronomy. Most of these meta-analyses focused on production aspects and the impact of agriculture activities on the environment or biodiversity. None of the 73 meta-analyses reviewed satisfied all eight quality criteria and only three satisfied six criteria. Based on this quality assessment, we formulated the following recommendations: (i) the procedure used to select papers from scientific databases should be explained, (ii) individual data should be weighted according to their level of precision when possible, (iii) the heterogeneity of data should be analyzed with random-effect models, (iv) sensitivity analysis should be carried out and (v) the possibility of publication bias should be investigated. Our case study showed that meta-analysis techniques would be beneficial to the assessment of environmental impacts because they make it possible to study between site-year variability, to assess uncertainty and to identify the factors with a potential environmental impact. The quality criteria and recommendations presented in this paper could serve as a guide to improve future meta-analyses made in this area. [Copyright &y& Elsevier]

Abstract: Results from the UK were reviewed to quantify the impact on climate change mitigation of soil organic carbon (SOC) stocks as a result of (1) a change from conventional to less intensive tillage and (2) addition of organic materials including farm manures, digested biosolids, cereal straw, green manure and paper crumble. The average annual increase in SOC deriving from reduced tillage was 310kg C±180kgCha−1 yr−1. Even this accumulation of C is unlikely to be achieved in the UK and northwest Europe because farmers practice rotational tillage. N2O emissions may increase under reduced tillage, counteracting increases in SOC. Addition of biosolids increased SOC (inkgCha−1 yr−1 t−1 dry solids added) by on average 60±20 (farm manures), 180±24 (digested biosolids), 50±15 (cereal straw), 60±10 (green compost) and an estimated 60 (paper crumble). SOC accumulation declines in long-term experiments (>50 yr) with farm manure applications as a new equilibrium is approached. Biosolids are typically already applied to soil, so increases in SOC cannot be regarded as mitigation. Large increases in SOC were deduced for paper crumble (>6tCha−1 yr−1) but outweighed by N2O emissions deriving from additional fertiliser. Compost offers genuine potential for mitigation because application replaces disposal to landfill; it also decreases N2O emission. [Copyright &y& Elsevier]

• Methane emissions were found to be markedly lower than IPCC estimations. • Calculated net carbon balance at system level is close to equilibrium. • Extensive beef herds may be environmentally viable. • Farming interventions may reduce the carbon footprint of extensive beef production systems. The savannas of eastern Colombia located in the Orinoco river basin represent 18% of the Latin American neotropical savannas, and those areas that are tillable and closer to markets are subject to considerable anthropic pressure in the quest for intensification. Historically, and even today, beef cattle production constitutes the main land use, and much of it is subjected to extensive management. This paper describes for the first time, the use of cattle grazing experiments to assess methane (CH 4) emissions from neotropical savanna-based beef breeding systems, and with the support of published research conducted next to them, estimates of the carbon (C) footprint in carbon dioxide equivalents (CO 2 -eq) for the whole system. Over 5 years and covering complete reproductive cycles, a conventional weaning (CW) herd system was compared to an early weaning (EW) herd system, that represented a modest degree of more intensive savanna management. Differences were found between the two management practices in total CH 4 emissions, emission intensities [kg CH 4 kg –1 calf born and kg CH 4 kg –1 liveweight gain (LWG)] and emission efficiencies (kg CO 2 -eq kg –1 calf born and kg CH 4 kg –1 LWG), that mostly associated with the different lactation lengths. When both herd systems were carried over until calves, later yearlings, reached to 25 months of age, the differences in favor of EW breeding herd system were diminished. The calculated C footprint in (CO 2 -eq) of both management practices was near neutral subjected to a number of assumptions and the use of limited published information on savanna C stocks and CH 4 and nitrous oxide (N 2 O) emissions from soil, and it is posited that both herd systems were nearly in equilibrium. The available data and results show the need for further information on the neotropical savanna C stocks and C sequestration potential of soils of the Orinoco river basin. More reliable datasets regarding below-ground C inputs and CH 4 and N 2 O emissions from soil are needed to provide a useful basal benchmark for, and approach to, future analyses of environmental impact of more intensive beef herd systems in the region. [ABSTRACT FROM AUTHOR]

• Literature review found few papers addressing plant-soil dynamics in organic pastures. • Little evidence that organic pasture management results in altered plant or soil processes. • Principles of managed grazing for non-organic pastures critical for organic livestock management. Organic livestock production in the U.S. requires that a significant amount of feed comes from grazed pasture. While principles of grazing management for temperate grasslands are well known, organic livestock production may result in unique plant-soil dynamics with ramifications for farmer decision-making and management. We reviewed the literature for direct or indirect evidence that organic pasture management results in altered plant-soil dynamics and assessed whether organic management might necessitate modifications or additions to managed grazing principles. The literature directly addressing these questions is sparse. We found some evidence that organic management can stimulate soil biota but no evidence for grassland yield, soil stocks, or soil transformation rate differences between organic and non-organic pastures. Given the constraint on fertilizer and herbicide inputs in organic management, established principles of managed grazing – rotating livestock frequently through paddocks such that plants are uniformly grazed but left with significant residual biomass and time for regrowth – are critical for maintaining dense, productive swards in organic pasture management. [ABSTRACT FROM AUTHOR]

• Diverging socio-economic environments and vulnerabilities to erosion found in Rwanda. • Uniform adoption of soil erosion control despite contrasting agro-ecological zones. • Adoption of soil erosion control as a catalyzer to improve farm management practices. Rwanda, the land of thousand hills, hosts a large diversity in environmental conditions, regionally classified into agro-ecological zones (AEZs). This paper aimed to explore the current perceptions of farmers on soil erosion processes, soil erosion control (SEC) and their impacts on the adopted farming systems within two watersheds from contrasting AEZs, i.e. Murehe in the Eastern plateau and Tangata in the Buberuka highlands, using participatory survey data from 300 households collected during face-to-face interviews in 2017. Both zones differed in socio-economic environment, the short distance to the capital favouring higher education levels in Murehe, while the production of cash crops in the well aroused and more fertile, yet also more steeply sloping Tangata watershed offered higher incomes. Despite these differences, adoption of SEC measures proved uniform across both zones reflecting strong but seemingly low-differentiated governmental supported action. Diversity in available erosion control measures within both zones was large, but dominated by combined structural and vegetative measures. Most farmers relied on government support for the installation of bench terraces, but adopted also other SEC such as progressive terracing and agroforestry. SEC adoption furthermore changed the agricultural systems heading to crop rotation, contour tillage and combined application of (in)organic fertilizers, albeit mainly fostered through subsidies. Despite these efforts, SEC seemed to be only partly effective in the highlands where erosion continued to have multiple high impact consequences affecting the entire landscape. High rainfall amounts and steep slopes were held responsible. The potential contribution of land management to erosion was generally less recognized, except for the tillage practices. Erosion was considered most prominent in the mid-season periods on Acrisols located at vulnerable landscape positions. These research results might question the effectiveness of the adopted control practices in particular AEZs. However, it can also pinpoint to the need of a much more integrated watershed management approach. The long-standing exposure of the surveyed population to diverse erosion control measures offers a unique insight that can be useful for other tropical highland countries. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Plastic pollution in agricultural soil is a growing environmental concern. • We tested different types of biodegradable plastic mulches (BDMs) in field experiments. • BDMs compared favorably against polyethylene mulch. • Effects of different BDMs on soil health were not consistent over time and site. • BDMs are a promising alternative to polyethylene, but longer-term testing is needed. Abstract Plastic pollution in agricultural soils, caused by the incomplete removal of polyethylene mulch after usage, is a growing environmental concern. There has therefore been increased interest in biodegradable plastic mulches as alternative to polyethylene mulch; however, little is known about their impact on soil health. We evaluated the effects of four biodegradable plastic mulches on soil health at two sites (Knoxville, TN and Mount Vernon, WA) under pie pumpkin (Cucurbita pepo) production. Cellulosic paper, polyethylene, and no-mulch served as controls. Soil health was first assessed in May 2015, and then every six months until May 2017, by measuring 19 soil properties (physical, chemical, and biological). Soil properties were converted to index scores and aggregated into six soil health indicators and five soil functions. The results showed poor correlations and high spatial variations for most of the soil properties. We performed repeated measure analyses using raw values and change scores to account for the initial variations. The soil properties, soil health indicators, and soil functions were affected more by site and time than by the mulch treatments. Nonetheless, we did observe significant effects of some of the mulch treatments on six soil properties (aggregate stability, infiltration, soil pH, electrical conductivity, nitrate-N, and exchangeable potassium), four soil health indicators (hydraulic, biological, fertility, and salinity & sodicity), and one soil function (nutrient cycling). However, these effects were not consistent among all the biodegradable plastic mulches, across the two sites, and the sampling times. Overall, biodegradable plastic mulches may be a viable alternative to polyethylene. However, evaluation under long-term studies is needed to better establish their effects on soil health. [ABSTRACT FROM AUTHOR]