Arable Cropping Systems Research Articles

Long term response of water and nitrogen fluxes to Good Agricultural Practices at field and catchment scales

Facing the nitrate pollution problem, the European Union has encouraged a code of “Good Agricultural Practices” (GAP) in order to recover a good chemical and ecological status of waterbodies. In this study, we hypothesized that the systematic application of GAP in time and space would allow to meet the EU standard of nitrate concentration (50 mg NO3 L−1) under arable cropping systems. Water and nitrogen fluxes were determined in an agricultural catchment (187 ha) during 22 years after GAP implementation, at field and catchment scales. The aquifer outlet is a set of springs which were monitored for water flow and nitrate concentration. GAP management mainly consisted in adjusting N fertilization rates and establishing catch crops. Crop N uptake, soil water and mineral N were measured respectively two and three times per year on 36 sites representing soil variability. These data were used to initialize the STICS model which simulated the fluxes of infiltrated water and nitrate leached below the rooting zone at field scale. The elementary fluxes (calculated for each site-year) were then used as independent inputs of the hydrological model MODCOU which made the integration at catchment scale. Simulations of agricultural scenarios allowed to calculate the cost/efficiency ratio of GAP implementation per soil type. The mean amounts of infiltrated water and N leached calculated below rooting depth in agricultural fields were 179 mm yr−1 and 19 kg N ha−1 yr−1, respectively, yielding a mean weighted nitrate concentration of 41 mg NO3 L−1 during 22 years over the whole catchment. The mean residence time of water in the catchment was estimated at 17–22 years using tritium and CFC tracers. The observed nitrate concentration in the main spring declined 11 years after GAP implementation and levelled off to 49 mg NO3 L−1. The agro-hydrological model satisfactorily predicted water flow and nitrate concentration in springs but overestimated their response time. It predicted a positive impact of GAP application on water quality. GAP management appeared to be efficient on the long term with a low cost/efficiency ratio. A more flexible and motivating management could consist in including GAP as a first step in a loop progress towards agro-ecological systems.

Measuring and Monitoring the Impact of Precision Land Levelling and Arable Cropping Systems on Aggregate Associated Carbon Fractions and Soil Carbon Stock in Sub-tropical Ecosystems

The Long term experiment (2009-10 to-2018-19) was conducted to study the effects of precision land levelled (PLL) versus traditional land levelled (TLL) systems on aggregate-associated soil organic carbon (SOC) in a farmers participatory fields under sub-tropical ecosystems (Western Uttar Pradesh) of Indian conditions. The significance of this study mainly focus to determine the suitability of various labile carbon fractions as indicators of soil quality and the stability of aggregates plays a vital role in preserving and long term storing of soil organic carbon by implementing Precision Land Levelling under various arable cropping system. The treatment comprised of sixteen alternative arable cropping systems strategies viz. R-WPLL, R-WTLL, S-WPLL, S-WTLL, R-P-MbPLL, R-P-MbTLL, R-P-OPLL, R-P-OTLL, R-C-OPLL, R-C-OTLL, O-W-MbPLL, O-W-MbTLL, M-W-MbPLL, M-W-MbTLL, M-P-MbPLL, and M-P-MbTLL etc were taken with recommended dose of fertilizers and various observations were recorded. The results indicated that the M-P-MbPLL produced 79.5 kgha-1day-1 productivity and used only 110 cm irrigation water which was 48.1 per cent less than irrigation water used for R-WPLL. The land use efficiency under R-P-MbPLL, R-P-OPLL, R-P-MbPLL, R-C-OPLL and M-P-MbPLL were recorded as 86.2, 85.1, 84.8, 84.6 and 83.9%. However, energy value in terms total input energy and energy productivity were 39.9 and 218.5 GJ ha-1 over existing R-W system (32.9 & 105.7 GJ ha-1). The quantity of water used in the R-C-O, M-W-Mb, M-P-Mb, and O-W-Mb were 46.1, 44.9, 40.1 and 36.3 per cent less than quantity of water used for R-W system. Aggregate-associated SOC contents in 0-15 cm depth were recorded highest SOC at 15-30 cm depth in PLL systems as 9.4% for both M-P-MbPLL and M-W-MbPLL. Highest PON change in arable cropping system (30.9 & 40.1%) was found in O-W-Mb with precision land levelling (T11) plots followed by R-P-O with precision land levelling (T7) plots (26.1 & 35.8%) as compared to R-W and S-W system. The values of LFOC in surface soil were 194.7, 187.9, 176.2, 170.9, 168.5, 150.6, 132.8 and 123.8 mgkg−1 in R-P-O, R-C-O, M-W-Mb, O-W-Mb, M-P-Mb, R-P-Mb, R-W and S-W with precision land levelling treatments. Higher SOC sequestration was observed with precision land leveling along with alternative arable cropping systems with O-W-MbPLL, R-C-OPLL, R-P-OPLL, O-W-MbPLL and M-P-MbPLL respectively. Therefore, PLL systems had greater soil surface aggregation and carbon storage, land levelling did not affect SOC patterns across aggregates, but changed the distribution of aggregate size, reflecting that land levelling mainly influenced soil fertility by altering soil structure.

Floristic Response of Herbaceous Flora to Intensive Cropping Systems: A Case of Ajibode-sasa Arable Agroecosystem, Ibadan, Southwest Nigeria

Agriculture a most significant land use types which alter natural ecosystem dynamics. Arable farming exerts much pressure on plant biodiversity, especially when practiced intensively in urban centers. There is dearth of information on floristic changes due to intensive arable farming in urban agroecosystems in developing countries. The study therefore assessed floristic changes resulting from and intensive farming practices at Ajibode-Sasa agricultural landscape. Ajibode-Sasa agroecosystem is a complex mix of arable cropping system between latitude N07°28′, E003°53′ and longitude N07°28′, E003°54. Comparative floristic surveys were conducted in 2016 and 2020 using quadrats (1 m2) systematically laid on 18 Transects ranging from 50 – 250 m long. A total of 224 and 184 quadrats were laid in 2016 and 2020 respectively. Reduction in numbers of quadrats laid resulted from physical anthropogenic development after the 2016 survey. Species identification followed standard procedures, and quantitative occurrence data were collected for determination of species composition and computation of relative importance values (RIV) and diversity indices. Land-use changes over four years period was determined using Google earth and QGIS. Herbacous plant composition with 123 cumulative number of species in both years reduced from 98 species in 2016 to 85 species in 2020 species RIV of species ranged from 0.038 – 14.803. Tridax procumbens had the highest RIV (14.803) in 2016, while it was Acmella brachyglossa (13.248) 2020. Species richness and floral diversity was high with Shannon-Weiner Index (3.081 and 3.088) and Dominance (0.09388 and 0.08746) in 2016 and 2020 respectively. Intensive cultivation favoured introduction and spread of invasive species like Tridax procumbens and Tithonia diversifolia. Eight introduced and invasive species were newly enumerated in 2020, with a total of 38 herbaceous species no longer encountered in 2020. Concerted efforts should be made to conserve native flora on the agroecosystem through sustainable practices like crop rotation and short fallow.

Legacy effects of soil fertility management on cereal dry matter and nitrogen grain yield of organic arable cropping systems

The yields of crops in organic farming are typically lower than in conventional farming, although this depend greatly on local climatic conditions and on crop and soil management. A long-term study over three consecutive 4-year cropping cycles at three locations in Denmark compared organic arable cropping systems varying in fertilization management (green manure crops, cover crops, livestock manure) to study the long-term effects of soil fertility management on crop yields. The analysis of the results showed that the nitrogen (N) derived from cover crops has a legacy effect on the dry matter and N grain yield of spring barley being traceable 5-8 years back in time. The net N input of crop residues and manure for the crop cycles 1-4 and 5-8 years prior to the winter wheat had a significant effect on both the dry matter and N grain yield of wheat.The management of organic cropping systems should focus on reducing the weed pressure, promoting soil fertility and increasing the soil N supply to optimize crop yields. For both winter wheat and spring barley, the weed pressure reduced both crop dry matter and the N grain yield. A cover crop as pre-crop had a significant positive effect on both dry matter and N yield of spring barley, while a cover crop in the rotation did not significantly affect grain yield of winter wheat. For both winter wheat and spring barley, manure application was most effective in increasing crop yields. However, N in applied crop residues also had considerable yield-enhancing effects. For winter wheat, the N inputs from crop residues from previous crop rotation cycles (1-4 and 5-8 years) significantly increased yields, while for spring barley, N input in crop residues from incorporated cover crop and the long-term crop rotation cycle (5-8 years) significantly enhanced both dry matter and N grain yield. These legacy effects of soil fertility management through enhancing and retaining organic N inputs of organic arable cropping suggest that a holistic approach to soil and crop management is necessary, and this needs to focus on increasing weed suppression, soil fertility and targeting manure inputs for enhanced N uptake.

The response of weed and crop species to shading. How to predict their morphology and plasticity from species traits and ecological indexes?

To assess the competitive ability of plant species, ecologists describe many species from contrasting habitats with traits that are proxies of ecophysiological functions whereas agronomists describe few species from similar habitats with process-based parameters. Here, we combined both approaches and compared many contrasting crop and weed species of temperate European arable crops in terms of competition for light, to understand weed response to shading by crop canopies and to choose light-competitive crop species and varieties. We (1) measured species parameters that drive light-competition processes in 26 crop and 35 weed species of temperate European arable cropping systems, (2) related the parameter values to species features that are easier to measure or available in databases. Early plant-growth parameters (relative growth rate RGR, initial leaf area) were measured in optimal light and nutrient conditions in a greenhouse with automatic non-destructive measurements. Potential plant morphology in unshaded conditions (specific leaf area SLA, leaf biomass ratio LBR, plant height and width per unit biomass HM and WM, vertical leaf distribution) was measured in garden plots in optimal light and nutrient conditions and harvested at 4–5 stages. Shading response was measured by comparing potential morphology to that of plants grown under shading nets. We confirmed well-known relationships (lower SLA and LBR in legumes vs non-legumes…), included new species features (base temperature, photosynthetic pathway…), and established relationships for the new shading-response parameters (weeds respond more to shade than crops, by increasing LBR, SLA, HM and WM…). Some correlations reported in ecology (RGR vs SLA…) were not verified on our species pool from arable temperate fields. Shade-response parameters explained species responses to habitat described by Ellenberg indexes, e.g., when shaded, shade-loving species (low Ellenberg-L values) increased SLA and HM to increase light interception.

Nonchemical control of a perennial weed, Cirsium arvense, in arable cropping systems. A review

Cirsium arvense (L.) Scop. is one of the most problematic perennial weeds in European countries, causing notable yield losses in both conventional and organic arable cropping systems. C. arvense control is essential because its infestation spreads rapidly and has negative impacts for several years due to its biological characteristics. Herbicidal treatments are the main control methods used in conventional input-based systems, but they are not always more effective than cultural practices. However, the cultural practices currently employed in arable cropping systems are often expensive and time-consuming. To guarantee the efficiency of these control practices, knowledge of C. arvense biology is essential. This review synthesizes the key points from the previous literature on C. arvense biology that can be mobilized to this end and analyzes the literature on different strategies of C. arvense control without herbicides. These strategies are (1) limitation of C. arvense dispersal, (2) weakening of root reserves, (3) extraction of roots, (4) competition with cultivated species, and (5) physical destruction. There is also a review of reported experiences using these strategies for C. arvense control, and relevant information is presented on associated biological processes to optimize the efficacy of each practice. The benefits and drawbacks of these strategies for C. arvense control are also emphasized, as well as the possibility of combining them in cropping systems, even though some knowledge gaps remain. This review confirms that one individual practice, implemented in 1 year only, is not sufficient to provide satisfactory, long-term control of C. arvense; therefore, further studies on combinations of control strategies and processes are required. There is a particular lack of knowledge about the duration of the effect of C. arvense control strategies.

Has compost with biochar applied during the process added value over biochar or compost for increasing soil quality in an arable cropping system?

Previous research showed that adding biochar at the onset of the composting process alleviates this process and reduces emissions. The objective of this study was to evaluate in a field trial whether this compost with biochar applied during the process (i.e., biochar-blended compost) has added value compared to compost or biochar alone on chemical, physical and biological soil properties and crop yield. A single application of biochar, compost and biochar-blended (BB) compost increased the C content of the top soil in the long term, but only compost and biochar-blended compost had a lasting effect on pH and the K content. Two to 4 years after a single application of all three amendments in the field, the soil microbial biomass, richness, diversity and community composition remained unchanged. Due to intensive soil tillage, biochar migrated to subsoil already after 2 growing seasons, thus increasing the C sequestration in subsoil. We conclude that in general, the biochar-blended compost outperformed biochar and had a similar effect as the compost.

Similar specific mineralization rates of organic carbon and nitrogen in incubated soils under contrasted arable cropping systems

No tillage is often thought to mitigate greenhouse gas emissions from agricultural land by increasing soil carbon storage, because of a reduced mineralization of soil organic carbon (SOC) and nitrogen (SON). Regrettably, most available references on this topic come from laboratory incubations of disrupted soil from superficial soil layer. Here, we compare SOC and SON mineralization rates in the long-term experiment of La Cage (France) under conventional (CON), low input (LI), conservation agriculture (CA) or organic (ORG) management. Disturbed soil samples from the 0−27 cm soil layer of all treatments were laboratory incubated for four months, while undisturbed CON and CA soil cores were incubated to account for tillage effects. Physical disturbance decreased SOC and SON mineralization. Model fitting showed that the size of the C labile pool and the C and N mineralization rates of the slow pool were 1.5–2.3-fold greater in undisturbed soil cores than in disturbed ones, which may be due to a higher abundance of labile SOC (e.g. plant residues) in undisturbed soil cores. All cropping systems exhibited similar specific rate of mineralization, expressed per unit of SOC, SON or microbial biomass C, both for disturbed and undisturbed soils. Similar mineralization in CA and CON undisturbed soil cores may result from the balance between higher amount of labile OM and less favourable soil structure for decomposition in CA. Similar mineralization rates in disturbed soil cores suggest that OM decomposability and environmental conditions for decomposers were similar between cropping systems. Overall, these results confirmed the hypothesis previously made in silico to explain the differences in SOC storage in this experiment (Autret et al., 2016). Our results together with the increased SOC stocks observed in CA and ORG treatments suggest that increased biomass returns to soil or changes in microbial physiology may be the main drivers of SOC storage.

Legacy effects of leguminous green manure crops on the weed seed bank in organic crop rotations

Leguminous green manure crops are important for accumulating nitrogen by means of biological nitrogen fixation and for building up soil fertility in organic arable cropping systems. Whole-year green manure crops are also known to deplete the soil weed seed bank, e.g. by decaying and predation, but there is uncertainty about the magnitude of the legacy effect after termination of the green manure crop. This study sampled soil for weed seed bank assessment upon termination of a two-year leguminous green manure crop and then one, two and three years afterwards. The samples were taken from two five-year crop rotations (2011–2015) in a long-term organic crop rotation experiment in Denmark. One rotation (O2) had a two-year green manure crop followed by three years of annual cash crops, and the other rotation (O4) consisted only of annual cash crops, with four crop sequences in both rotations represented every year. In general, the weed seed bank of rotation O2 was 54 % lower than O4, with 5475 seeds m−2versus 11,967 seeds m−2. Similarly the aboveground amount of weed biomass in O2 was lower than in O4 over the course of the five years. The legacy effect of the green manure crop showed a negative exponential rise in weed seed numbers with the increase in years after termination of the green manure crop. A biennial leguminous green manure crop can mitigate weed problems in organic annual crops. This effect adds to the benefits of including nitrogen fixing leys in crop rotations with limited access to animal manures.

Cover crops as a tool to reduce reliance on intensive tillage and nitrogen fertilization in conventional arable cropping systems

Cover crops are often recommended as a valuable practice to develop more sustainable cropping systems but, despite many benefits, their adoption in practice is still limited mainly because the effects on productivity and economic return are variable. Furthermore, it is still unclear under which combinations with other management practices (e.g. tillage, fertilization, weed control) cover crops can provide the highest paybacks.Here we tested whether cover crops are a suitable management tool to reduce fertilizer input, tillage intensity and herbicide use in Swiss arable cropping systems. We compared the effects of four different cover crop treatments (fallow, radish, subterranean clover and hairy vetch) on maize at two fertilization levels combined with three levels of tillage intensity. To unravel the effects of cover crops on maize growth, we assessed vegetation dynamics using the Normalized Differential Vegetation Index (NDVI) from aerial spectral imagery.Cover crops on average increased yields by 12 % (+7 % to +20 %) and cover crop effects depended on tillage intensity, fertilization level and cover crop treatment for most of the assessed maize parameters. Best results were obtained with hairy vetch, which increased maize N uptake by 79 kg ha−1 on average. As a consequence, at least combinations of two of the three targeted inputs (tillage, fertilization and herbicides) could be successfully reduced, e.g. tillage and fertilization under no tillage or tillage and herbicides under reduced tillage. Even under intensive tillage, both legume cover crops allowed a reduction of fertilization without compromising yield. Spectral imagery analysis showed that legume cover crops compensated for delayed N availability in reduced and no tillage systems and cover crops contributed to enhanced N uptake and crop growth later in the season.We provide evidence that cover crop based cropping systems can be used to reduce synthetic inputs and tillage without compromising yield, thus presenting an example of ecological engineering. We highlight the importance of considering the whole set of management practices when adopting cover cropping in order to maintain or increase productivity with reduced anthropogenic inputs under conventional cropping.

Impact of short‐rotation coppice with poplar and willow on soil physical properties

AbstractAs the land area of short‐rotation coppice (SRC) increases, their soil physical impacts have to be evaluated. The objective of this study was to detect the effects of long‐term SRC with poplar and willow on the vertical distribution of soil physical properties (bulk density, water retention, penetration resistance) and on solute transport patterns. An 18‐year‐old SRC located in northeastern Germany was compared to an adjacent continuous arable cropping system by means of soil sampling, penetrologger measurements and dye tracer experiments. The topsoil's bulk density was significantly lower under SRC than under cropland. This effect was especially pronounced in the uppermost 10 cm, where also the air capacity and the plant‐available water content were higher under SRC. The penetration resistance in 25–50 cm depth was reduced under SRC compared to the cropland, indicating a loosening of the plough pan. Dye tracer experiments showed that the importance of preferential flow was higher under SRC due to tree root channels and an increasing colonisation with invertebrates. SRC has ecologically advantageous effects on soil physical properties of the topsoil, however, combined with an enhanced risk of preferential solute transport upon application of agrochemicals.

Mass balance and long-term soil accumulation of trace elements in arable crop systems amended with urban composts or cattle manure during 17 years

Organic waste products (OWP) application to crop lands makes possible nutrients recycling. However, it can result in long-term accumulation of trace elements (TE) in soils. The present study aimed at (i) assessing the impact of regular applications of urban composts and manure on the TE contents of topsoils and crops in a long-term field experiment, (ii) comparing the TE mass balances with the stock variations of TE in soils, and (iii) proposing a prospective evaluation of this practice, based on estimated soil safe threshold values and simulations of soil TE accumulation for 100 years. In the long-term field experiment, physico-chemical properties and TE contents (Cd, Cr, Cu, Hg, Ni, Pb and Zn) have been measured in OWP, soils, plants and leaching waters for the period 1998–2015, and used for mass balance calculations and long-term simulations of TE accumulations. The composts of green wastes and sludge (GWS) and of municipal solid waste (MSW) were the OWP with the largest TE contents, while the farmyard manure tended to have the lowest. Repeated application of OWP led to significant accumulation of Zn and Cu in the topsoil layer (not for Cr, Cd, Hg, Ni, Pb), especially with GWS, without overpassing calculated protective threshold values. No effect of repeated application of OWP has been observed on TE contents in grains (wheat, maize, barley). The positive mass balance has been dominated by the input flux of TE through OWP and resulted in the observed increases of soil stocks for Cu and Zn. Prospective simulation of soil content evolution until 2100 showed that soil content reached 0.4 mg Cd kg−1 soil (GWS, MSW), 38 mg Cu kg−1 soil (GWS) and 109 mg Zn kg−1 soil (GWS), which remained lower than protective threshold values.

Diversified Arable Cropping Systems and Management Schemes in Selected European Regions Have Positive Effects on Soil Organic Carbon Content

In the last few decades, various crop diversification strategies and management practices have been promoted to improve or at least maintain environmental quality and agroecosystem services. We conducted a data-analysis to evaluate the effectiveness of alternatives for crop diversification and environmentally friendly farming management for arable crops in four selected European pedoclimatic regions and typical cropping systems in the Atlantic, Boreal, Mediterranean North, and Mediterranean South regions. The dataset was retrieved from 38 references and included data on site-specific environmental conditions, soil tillage, crop rotation, fertilization, and final soil organic carbon content (SOC). No tillage (NT) was more effective (7%) in increasing SOC content than minimum tillage (MT) across the studied depths (from 5 to 40 cm). Conservation tillage as whole, including NT, MT, and rotational tillage (RT) positively affected SOC content in the top 10 cm (28%) in comparison with conventional tillage (CT). Compared to monoculture, longer crop rotations (3–5 years) and the introduction of legumes resulted in higher increases in SOC contents (18%), that were higher in semiarid conditions (11%) than under humid and sub-humid climates (3.2%). The effect of fertilization on SOC contents was higher in the Mediterranean North region (28%), and organic fertilization showed the highest increases (25%) compared to the control with mineral fertilization. Higher increases in SOC contents with tillage and fertilization management were found in sites with lower SOC contents in the control treatment (conventional tillage and mineral fertilization respectively). The data analysis indicated that various European arable agroecosystems benefit both from diversified cropping systems and the adoption of environmentally friendly farming management and are thereby capable to increase SOC contents.

Autumn-based vegetation indices for estimating nitrate leaching during autumn and winter in arable cropping systems

Nitrate leaching losses from arable cropping systems cause severe damage to environmental services worldwide. There is a considerable need for methods that allow rapid, easy and area covering detection of nitrate leaching to guide nitrogen (N) management. We used three years of data from the 5th cycle of a long-term crop rotation experiment in Denmark to quantify the relationships between nitrate leaching in autumn and winter and field conditions in autumn as defined by three vegetation indices [VIs; Ratio Vegetation Index (RVI), Normalized Difference Vegetation Index (NDVI), Ratio Red Edge (RRE)] in autumn. Following cereal crops, cover crops significantly reduced nitrate leaching in autumn and winter, whereas this was only the case for one out of the three years after faba bean. In autumn and winter, a negative relationship was found between nitrate leaching and cover crop aboveground biomass or aboveground N, and the thresholds were ∼2 Mg ha−1 for aboveground cover crop biomass and 60 kg N ha−1 for aboveground cover crop N, above which nitrate leaching was low and stable. A significant positive linear relationship was found between nitrate leaching and soil water nitrate concentration in autumn and winter with a slope of 4.0 kg N ha−1 per mg L−1 of nitrate-N in the soil. Although all three VIs showed significant negative relationships with nitrate leaching during autumn and winter, the sensitivities of RVI and NDVI to estimated nitrate leaching were lost sharply when nitrate leaching exceeded 100 kg N ha−1 and 50 kg N ha−1, while RRE exhibited consistent low noise equivalent values for the nitrate leaching in autumn and winter. These results provide evidence for the scope of assessing risk of nitrate leaching from agricultural soils based on newly launched satellite remote sensing platforms with NDVI and red edge bands. To maximize the application of these technologies it will be necessary to combine remote sensing with information on cropping systems and biophysical conditions.

Trade-offs of gaseous emissions from soils under vegetable, wheat-maize and apple orchard cropping systems applied with digestate: An incubation study

ABSTRACTLand application of digestate from anaerobic digestion causes various gaseous emissions. A soil core incubation experiment was carried out in the laboratory to investigate the trade-offs of NH3, N2O and CH4 emissions from soils collected from vegetable, arable and orchard cropping systems. Digestate derived from liquid cattle manure was applied to the soil cores through the surface (SA) and incorporation application (IA) methods under three soil moisture conditions (40%, 60%, and 80% water-filled pore space, WFPS). Gaseous emissions from vegetable soil were significantly greater (P< .05) than those from soils under the other two cropping systems under similar conditions, particularly under a high moisture condition. The greenhouse gas emissions (GHG, in term of CO2-equivalents) of all soils increased with the increasing soil moisture contents, mainly due to rapidly increasing N2O emissions. Trade-offs in the emissions of these three gases were observed between SA and IA. As expected, SA was characterized by greater NH3 and CH4 but lower N2O emissions compared to IA. The increase in GHG under IA could be offset only somewhat by the reduced NH3 (and this reduced indirect N2O) and CH4 emissions under lower moisture conditions (<60% WFPS), which indicates a requirement for other strategies to control gaseous emissions from wet soils applied with digestate. In conclusion, an environmentally friendly strategy for digestate application should consider the soil moisture, types of soils and application methods, and all the presented suggestions need to be verified in the field in the future.Implications: This study shows that digestate incorporation can decrease NH3 but increase GHG emissions verse the surface application method, where the increased GHG could only be offset by the NH3 reductions at relatively dry soil condition, indicating an urgent requirement to mitigating GHG emissions under moist soil condition.

Plant identity control on soil food web structure and C transfers under perennial bioenergy plantations

Conversion from arable cropping systems to perennial bioenergy crops is increasing across Europe to meet market energy demands, but our understanding of how this land use change is affecting below-ground diversity and C allocation remains limited. Here, we assessed the impact of conversion from arable cropland to Miscanthus and Short Rotation Coppice (SRC) willow in UK bioenergy commercial plantations on earthworm community structure and abundance. At this same location we then conducted an in-situ 13CO2 pulse-chase labelling experiment in the two bioenergy plantations to trace the fate of recently photosynthetically assimilated carbon into roots, bulk soil, soil microbial (PLFA) and earthworm communities. Results showed that land conversion from annual arable crops to both Miscanthus and SRC willow perennial bioenergy crops led to severe reductions of soil earthworm abundance and biomass. SRC willow had higher microbial biomass relative to Miscanthus, whereas Miscanthus provided a better habitat for a more functionally diverse earthworm community. Transfer of labile C compounds to soil pools was faster under Miscanthus supporting activity of bacterial grazers in the soil food chain, whereas a fungal-driven detrital decomposition processes dominated under SRC willow plantations. Taken together, these findings indicate that plant identity in land conversions have a strong influence not only on the abundance and structure of soil communities but also on which basal resources (root exudates, dead organic matter or microbial derived compounds) are preferentially consumed, and ultimately on the rates of mobilisation of these different C pools.

Soil Phosphorus Modeling for Modern Agriculture Requires Balance of Science and Practicality: A Perspective.

The use of phosphorus (P) fertilizers in arable crop and pastoral systems is expected to change as modern agriculture is challenged to produce more food with fewer inputs. Agricultural systems models offer a dual purpose to support and integrate recent scientific advances and to identify strategies for farmers to improve nutrient efficiency. However, compared with nitrogen and carbon, advances in P modeling have been less successful. We assessed the potential opportunity of P modeling to increase P efficiency for modern agriculture and identified the current challenges associated with modeling P dynamics at the field scale. Three major constraints were (i) a paucity of detailed field datasets to model strategies aimed at increasing P use efficiency, (ii) a limited ability to predict P cycling and availability under the local effects of climate change, and (iii) a restricted ability to match measured soil P fractions to conceptual and modelable pools in soils with different mineral properties. To improve P modeling success, modelers will need to walk a tightrope to balance the roles of assisting detailed empirical research and providing practical land management solutions. We conclude that a framework for interdisciplinary collaboration is needed to acquire suitable datasets, continually assess the need for model adjustment, and provide flexibility for progression of scientific theory. Such an approach is likely to advance P management for increased P use efficiency.

Whole-Systems Analysis of Environmental and Economic Sustainability in Arable Cropping Systems: A Case Study

The long-term sustainability of crop production depends on the complex network of interactions and trade-offs between biotic, abiotic and economic components of agroecosystems. An integrated arable management system was designed to maintain yields, whilst enhancing biodiversity and minimising environmental impact. Management interventions included conservation tillage and organic matter incorporation for soil biophysical health, reduced crop protection inputs and integrated pest management strategies for enhanced biodiversity and ecosystem functions, and intercropping, cover cropping and under-sowing to achieve more sustainable nutrient management. This system was compared directly with standard commercial practice in a split-field experimental design over a six-year crop rotation. The effect of the cropping treatment was assessed according to the responses of a suite of indicators, which were used to parameterise a qualitative multi-attribute model. Scenarios were run to test whether the integrated cropping system achieved greater levels of overall sustainability relative to standard commercial practice. Overall sustainability was rated high for both integrated and conventional management of bean, barley and wheat crops. Winter oilseed crops scored medium for both cropping systems and potatoes scored very low under standard management but achieved a medium level of sustainability with integrated management. In general, high scores for environmental sustainability in integrated cropping systems were offset by low scores for economic sustainability relative to standard commercial practice. This case study demonstrates the value of a ‘whole cropping systems’ approach using qualitative multi-attribute modelling for the assessment of existing cropping systems and for predicting the likely impact of new management interventions on arable sustainability.

Whole-Systems Analysis of Environmental and Economic Sustainability in Arable Cropping Systems: A Case Study

Whole-Systems Analysis of Environmental and Economic Sustainability in Arable Cropping Systems: A Case Study

Reviews and syntheses: Review of causes and sources of N&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;O emissions and NO&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt; leaching from organic arable crop rotations

Abstract. The emissions of nitrous oxide (N2O) and leaching of nitrate (NO3) from agricultural cropping systems have considerable negative impacts on climate and the environment. Although these environmental burdens are less per unit area in organic than in non-organic production on average, they are roughly similar per unit of product. If organic farming is to maintain its goal of being environmentally friendly, these loadings must be addressed. We discuss the impact of possible drivers of N2O emissions and NO3 leaching within organic arable farming practice under European climatic conditions, and potential strategies to reduce these. Organic arable crop rotations are generally diverse with the frequent use of legumes, intercropping and organic fertilisers. The soil organic matter content and the share of active organic matter, soil structure, microbial and faunal activity are higher in such diverse rotations, and the yields are lower, than in non-organic arable cropping systems based on less diverse systems and inorganic fertilisers. Soil mineral nitrogen (SMN), N2O emissions and NO3 leaching are low under growing crops, but there is the potential for SMN accumulation and losses after crop termination, harvest or senescence. The risk of high N2O fluxes increases when large amounts of herbage or organic fertilisers with readily available nitrogen (N) and degradable carbon are incorporated into the soil or left on the surface. Freezing/thawing, drying/rewetting, compacted and/or wet soil and mechanical mixing of crop residues into the soil further enhance the risk of high N2O fluxes. N derived from soil organic matter (background emissions) does, however, seem to be the most important driver for N2O emission from organic arable crop rotations, and the correlation between yearly total N-input and N2O emissions is weak. Incorporation of N-rich plant residues or mechanical weeding followed by bare fallow conditions increases the risk of NO3 leaching. In contrast, strategic use of deep-rooted crops with long growing seasons or effective cover crops in the rotation reduces NO3 leaching risk. Enhanced recycling of herbage from green manures, crop residues and cover crops through biogas or composting may increase N efficiency and reduce N2O emissions and NO3 leaching. Mixtures of legumes (e.g. clover or vetch) and non-legumes (e.g. grasses or Brassica species) are as efficient cover crops for reducing NO3 leaching as monocultures of non-legume species. Continued regular use of cover crops has the potential to reduce NO3 leaching and enhance soil organic matter but may enhance N2O emissions. There is a need to optimise the use of crops and cover crops to enhance the synchrony of mineralisation with crop N uptake to enhance crop productivity, and this will concurrently reduce the long-term risks of NO3 leaching and N2O emissions.