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Mid-term (MTEs, 5-20 years) and long-term (LTEs, 20+ years) field experiments are key sources of information to design future climate-smart agriculture. Within the European Joint Program SOIL (EJP SOIL), we built the EJP SOIL-MTE/LTE metadataset that contains metadata from 240 MTEs/LTEs across Europe. Metadata collected included precise descriptions of the treatments (combination of factors such as tillage, crop type/rotation, amendments/fertilizers, grazing and pest/weed management), soil and crop measurements and pedo-climatic information. Using different figures and dashboards, an overview of those MTEs/LTEs is presented and specific research themes (tillage systems, residue management, amendment type and cover crops) are further analysed within their pedo-climatic context. An interactive web portal developed in collaboration with the BonaRes project (https://lte.bonares.de), enables users to explore the metadataset and find relevant MTEs/LTEs for specific combinations of practices (e.g. all MTEs/LTEs that investigate cover crops on a Cambisol in no-tillage system). Finally, a SWOT (Strengths, Weaknesses, Opportunities, Threats) analysis of the metadataset was carried out to highlight the potential contribution of MTEs/LTEs to a harmonized European soil observation and monitoring approach. We propose that the metadataset could be elaborated with metadata from other existing MTEs/LTEs in Europe or even worldwide. [ABSTRACT FROM AUTHOR]

Soil compaction is one of the main limiting factors for sustainable agriculture. Efficient methods for detecting the distribution of soil compaction at a field scale are urgently needed in precision agriculture. We evaluated the possibility to detect soil compaction from measurements of apparent electrical conductivity (ECa) by using electromagnetic induction (EMI) and maize traits at a ~1 ha field parcel. The soil was Luvisol, and soil compaction‐related properties, such as bulk density (BD), penetration resistance (PR), soil texture, soil salinity, soil moisture and maize traits, were measured at ten locations across the field based on ECa variability. In this site‐specific study, no good correlation between soil compaction properties (i.e. BD and PR) and ECa was found but soil clay content was positively related to ECa in the sublayer (P = 0.08). The variation in the unmanned aerial vehicle (UAV)‐derived maize canopy height was significantly negatively correlated with soil compaction and a negative relationship between dry above‐ground biomass and BD and PR existed at 25–50 cm layer. In addition, ECa and UAV‐derived maize canopy height was negatively correlated (Spearman's rank correlation coefficients of −0.67 in the 0–25 cm layer) under the rather dry conditions prevailing during this study. Overall, as could be expected, detecting soil compaction with ECa was challenging under heterogeneous terrains, while maize traits had a better correlation with spatial variability of soil compaction. Owing to its sensitivity to the integral variation of multiple soil properties, ECa was a good indicator of maize canopy height. [ABSTRACT FROM AUTHOR]

Soil compaction forms a major threat to the well-functioning of agricultural soils. This threat is primarily driven by the increasing wheel loads of modern farming machinery and the increased frequency of field operations in periods when the soil is moist to wet and thus more prone to compaction. The application of slurry in early spring can have a highly detrimental impact, certainly for a crop like sugar beet, which is sensitive to soil compaction. A one-year experiment was set up on silt loam soil in the Belgian loess belt to assess the short-term impact of this field operation on soil under conventional ploughing and under non-inversion tillage. Two types of farming machinery were compared: a widely used tractor-trailer combination and a less common self-propelled slurry spreader, with the latter having higher wheel loads. Both machines were operated according to common or standard practice and a practice that aims at preventing soil compaction. For the tractor-trailer, this was with tyre inflation pressure recommended for road traffic and field traffic, respectively, corresponding with high and low tyre inflation pressure. The self-propelled slurry spreader was operated under standard and crab steering, respectively. Lowering the tyre inflation pressure to the recommended level for field traffic limited soil compaction and sugar beet yield loss. Although the effects of crab steering were less pronounced, it lowered the impact on the soil by limiting the number of passages. The overall machinery effect remained limited. The heavier self-propelled slurry spreader did not significantly increase the level of soil compactness and reduce sugar beet yield compared to the more common tractor-trailer combination. Soil under conventional ploughing showed more soil compaction, while the effectiveness of reducing tyre inflation pressure as a prevention strategy was lower compared to non-inversion tillage. The tillage practice, however, did not have any overall influence on sugar beet yield. [ABSTRACT FROM AUTHOR]

Over the last two decades, there has been growing interest on the effects of agricultural practices on soil biology in Europe. As soil biota are known to fluctuate throughout the season and as agro-environmental conditions may influence the effect of agricultural practices on soil organisms, conclusions cannot be drawn from a single study. Therefore, integrating the results of many studies in order to identify general trends is required. The main objective of this study was to investigate how soil biota are affected by repeated applications of organic amendments (i.e. compost, farmyard manure and slurry) or reduced tillage (i.e. non-inversion tillage and no till) under European conditions, as measured in multiyear field experiments. Moreover, we investigated to what extent the effects on soil biota are controlled by soil texture, sampling depth, climate and duration of agricultural practice. Experimental data on earthworm and nematode abundance, microbial biomass carbon and bacterial and fungal communities from more than 60 European multiyear field experiments, comprising different climatic zones and soil texture classes, were extracted from literature. From our survey, we can conclude that adopting no tillage or non-inversion tillage practices and increasing organic matter inputs by organic fertilization were accompanied by larger earthworm numbers (an increase between 56 and 125% and between 63 and 151% for tillage and organic amendments, respectively) and biomass (an increase between 108 and 416% and between 66 and 196% for tillage and organic amendments, respectively), a higher microbial biomass carbon content (an increase between 10 and 30% and between 25 and 31% for tillage and organic amendments, respectively), a marked increase in bacterivorous nematodes (an increase between 19 and 282% for organic amendment) and bacterial phospholipid-derived fatty acids (PLFA; an increase between 31 and 38% for organic amendment). Results were rarely influenced by soil texture, climate and duration of practice. [ABSTRACT FROM AUTHOR]

Farmers have to combine several measures to balance carbon contents in the top soil to preserve soil quality but potentially increasing the risk for N and P losses by leaching. We studied the effect of a combination of several measures on topsoil C content, nutrient leaching and soil quality in a multi-year field trial. Soil quality was defined as the result of the interaction between chemical, physical and biological soil characteristics, and included an assessment of disease suppressiveness as well. Initially, the soil had a suboptimal C content (i.e. 0.81%). Soil organic carbon (SOC) levels were maintained and slightly increased by applying slurry and good agricultural practices such as the use of cover crops and the incorporation of cereal straw (on average +0.04 percentage point). Only with a yearly extra plant-based farm compost amendment SOC levels were substantially increased after a period of four years (on average +0.17 percentage point). This application of 8.3 Mg C ha −1 also improved chemical, physical and biological soil quality. Our research demonstrates that farmers can use compost, for at least 4 years, on top of cattle or pig slurry application to soils with suboptimal C levels to increase C content in the top soil, without inducing higher N and P leaching. Repeated compost application increased the microbial biomass (measured by means of PLFA) and disease suppressiveness against Botrytis cinerea on lettuce. There was no effect on the abundance of the plant-parasitic nematode Pratylenchus penetrans in the soil, nor on disease severity caused by Dickeya solani , Streptomyces scabies and Rhizoctonia solani after a potato cropping. Differences between tillage practices were most obvious in the 0–10 cm soil layer as non-inversion tillage (compared to ploughing) resulted in an increase in SOC, Total N, hot-water extractable C and P, plant-available P and K, aggregate stability, earthworm abundance and bacterial and fungal populations in this layer. [ABSTRACT FROM AUTHOR]

Inherent in the concept of good agricultural practice (BMP) is that it improves resource use efficiency, mitigates environmental impact or increases farm profitability. However, it is usually impossible to achieve all the objectives, and trade-offs need to be accepted, such as a reduction in productivity together with a reduction in costs or an increase of soil organic matter. A European FP7 project, Catch-C (http://www.catch-c.eu) analyses the effects that different management practices have on productivity, mitigation of climate change and chemical, physical and biological soil fertility, based on simple indicators. Such indicators were collected from international literature, national scientific or technical journals, or grey literature that dealt with long-term field trials in Europe. We collected and analysed data from more than 350 experiments. This paper presents the overall results of the effects of a series of BMP have on crop productivity, soil nitrogen (N) uptake, N use efficiency end N balance. Important interactions with soil and climate types, crop and duration of the experiment were noticed for most BMPs. Rotations, also including double cropping, were among practices with more positive effects of productivity and N indicators. A slight reduction of yield counteracted benefits to soil quality and to climate change mitigation of minimum and no tillage, and of organic fertilisers. [ABSTRACT FROM AUTHOR]

Highlights: [•] Long-term field experiment studying the effect of repeated farm compost amendment. [•] Chemical, biological and physical properties were integrated into a soil quality index. [•] Farm compost increased soil quality and crop yields. [•] Causal relationship between soil quality and crop production. [•] SOC was pointed out as the most important indicator influencing crop production. [Copyright &y& Elsevier]

Intensification of agriculture can have negative consequences such as increased erosion, reduced biodiversity and a reduction in soil organic matter content resulting in a decline in the quality of agricultural soils. The application of compost can contribute to agricultural sustainability. Most of the research on compost done so far has focused on the use of municipal solid waste compost. Farm compost (FC) is another type of compost that is made of ingredients which are available on the farm like wood chips and bark, manure, straw, crop residues, mowed grass and soil. The use of FC is popular in organic farming and there is a growing interest to use it in non-organic farming. However, there is a lack of information on the agronomic value and environmental impact of FC. Therefore, a long-term field experiment was started to assess the influence of repeated FC applications on crop yields and soil quality. Repeated applications of FC increased soil organic carbon content, hot-water extractable carbon, earthworm numbers, microbial biomass-C and reduced soil bulk density. Furthermore the effect of FC on crop yields became significant after the fourth year of compost application underscoring the ability of compost amendments to support crop yields over time. [ABSTRACT FROM AUTHOR]

This paper reports the results on the agronomic performance of organic amendments in the EU 7th FP project "FERTIPLUS—reducing mineral fertilizers and agro-chemicals by recycling treated organic waste as compost and bio-char". Four case studies on field-scale application of biochar, compost and biochar-blended compost were established and studied for three consecutive years in four distinct cropping systems and under different agro-climatic conditions in Europe. These included the following sites: olive groves in Murcia (Spain), greenhouse grown tomatoes in Almeria (Spain), an arable crop rotation in Oost-Vlaanderen (Merelbeke, Belgium), and three vineyards in Friuli Venezia Giulia (Italy). A slow pyrolysis oak biochar was applied, either alone or in combination with organic residues: compost from olive wastes in Murcia (Spain), sheep manure in Almeria (Spain), and compost from biowaste and green waste in Belgium and Italy. The agronomical benefits were evaluated based on different aspects of soil fertility (soil total organic carbon (TOC), pH, nutrient cycling and microbial activity) and crop nutritional status and productivity. All amendments were effective in increasing soil organic C in all the field trials. On average, the increase with respect to the control was about 11% for compost, 20% for biochar-blended compost, and 36% for biochar. The amendments also raised the pH by 0.15–0.50 units in acidic soils. Only biochar had a negligible fertilization effect. On the contrary, compost and biochar-blended compost were effective in enhancing soil fertility by increasing nutrient cycling (25% mean increase in extractable organic C and 44% increase in extractable N), element availability (26% increase in available K), and soil microbial activity (26% increase in soil respiration and 2–4 fold enhancement of denitrifying activity). In general, the tested amendments did not show any negative effect on crop yield and quality. Furthermore, in vineyards and greenhouse grown tomatoes cropping systems, compost and biochar-blended compost were also effective in enhancing key crop quality parameters (9% increase in grape must acidity and 16% increase in weight, 9% increase in diameter and 8% increase in hardness of tomato fruits) important for the quality and marketability of the crops. The overall results of the project suggest that the application of a mixture of biochar and compost can benefit crops. Therefore, biochar-blended compost can support and maintain soil fertility. [ABSTRACT FROM AUTHOR]

To evaluate the agronomic value of animal manure, we quantified the effects of pedo-climatic, crop and management factors on crop productivity, N use efficiency, and soil organic matter, described with simple indicators that compare manures with mineral fertilizers. We selected 80 European long-term field experiments that used bovine farmyard manure or bovine liquid slurry, alone (FYM and SLU) or combined with mineral fertilizers (FYMm and SLUm), and compared them to mineral fertilizer only reference treatments. We collected 5570 measurements from 107 papers. FYM produced slightly lower crop yields (−9.5%) when used alone and higher (+11.3%) yields when used in combination with N fertilizer (FYMm), compared to those obtained using mineral fertilizers only. Conditions promoting manure-N mineralization (lighter soil texture, warmer temperature, longer growing season, and shallower incorporation depth) significantly increased the effect of FYM/FYMm on crop yield and yield N. The production efficiency of FYM (yield:N applied ratio) was slightly lower than that of mineral fertilizers (-1.6%). The apparent N recoveries of FYM and FYMm were 59.3% and 78.7%, respectively, of mineral fertilizers. Manured soils had significantly higher C (+32.9% on average for FYM and FYMm) and N (+21.5%) concentrations. Compared to mineral fertilizers, yield was reduced by 9.1% with SLU, but not with SLUm. Influencing factors were similar to those of FYM/FYMm. Efficiency indicators indicated SLU (but not SLUm) was less effective than mineral fertilizers. Slurry significantly increased SOC (on average for SLU and SLUm by +17.4%) and soil N (+15.7%) concentrations. In conclusion, compared to mineral N fertilizers, bovine farmyard manure and slurry were slightly less effective on the crop, but determined marked increases to SOC and soil N, and thus, to long-term soil fertility maintenance. [ABSTRACT FROM AUTHOR]

Potato cyst nematodes (PCN), Globodera rostochiensis and G. pallida , are major constraints to potato crop production. We studied the effects of several soil amendments on PCN survival and reproduction in pot experiments. Pig slurry, cattle slurry, mineral nitrogen fertilizer (NH 4 NO 3 ), crab shell compost and wood chip compost at 170 kg N ha −1 reduced the number of viable eggs in cysts of both PCN species in the absence of potato. This resulted in fewer second-stage juveniles (J2) hatching from these cysts and penetrating potato roots than from cysts of non-amended soils. When potato was planted, the same amendments resulted in less reproduction than in non-amended soil. Most reduction of reproduction was achieved in soils amended with pig slurry (87%) and wood chip compost (82%). Adding biochar at 0.3 and 1% did not reduce the survival or the reproduction of any of PCN species; moreover, it inhibited the suppressing effect of wood chip compost and pig slurry on PCN reproduction when added together with these amendments. The release of ammonium and changes in soil microbial community, determined by phospholipid fatty acid (PLFA) analysis, are involved in nematode suppression in soil amended with pig and cattle slurries. However, the suppressing effect of wood chip and crab shell compost can only be explained by the changes in soil microbiota, while the effect of mineral nitrogen fertilizer can only be related with the production of ammonium. Ammonium and microorganisms most probably have affected PCN directly by killing the eggs and juveniles or indirectly by changing the physiology of the root as mentioned amendments reduced hatch and movement of J2, penetration of the roots and females’ fecundity. [ABSTRACT FROM AUTHOR]

Biochar, a solid coproduct of biomass pyrolysis, has recently been proposed as soil amendment in agriculture. We studied the effect of biochar on soil and substrate physicochemical properties, plant growth, disease susceptibility and rhizosphere microbiology in two contrasting cropping systems, i.e., lettuce grown in field soil and strawberry grown in white peat. For both systems, changes in the physicochemical properties of the plant growth media were observed. In the lettuce bio-assay, biochar addition had no effect on crop growth, crop health ( Rhizoctonia solani infection test) and rhizosphere microbiology. In contrast, in the strawberry bioassay, addition of 3% biochar to peat resulted in (i) a higher fresh and dry plant weight, (ii) a lower susceptibility for the fungal pathogen Botrytis cinerea on both leaves and fruits, and (iii) changes in the rhizosphere microbiology, analysed by Phospholipid Fatty Acid (PLFA) profiling and 16S rDNA amplicon sequencing. Biochar addition led to an increase of bacterial diversity and a shift in composition of the rhizosphere microbiota. Extra inorganic plant nutrition and lime added to the peat reduced these effects of biochar on the strawberry plants. We conclude that in certain plant growth media, biochar amendment can result in chemical changes that induce multiple responses in the plant, including shifts in the rhizosphere microbiome. Biochar can be beneficial for plant growth, especially in conditions of limited nutrient availability. [ABSTRACT FROM AUTHOR]

Biochar is often proposed to increase soil quality and crop yield, while sequestering carbon. Despite the growing number of studies in temperate regions, the claimed positive effects are still unsure for northwestern European soils. Moreover, there is a need to upscale results from lab and pot studies in these soil types to field experiments. The objectives of this study were therefore to investigate the effect of biochar application to a temperate agricultural soil on soil chemical, physical and biological properties, and on crop growth and nutrient uptake under field circumstances. A field trial, located in Merelbeke (Belgium), was established in October 2011 and monitored until August 2013. The biochar applied was produced from a mixture of hard- and softwood at 480 °C. The biochar dose was 0 (control) or 20 t ha −1 (on dry weight basis). Over two years, biochar addition to soil did not affect soil chemical properties, except for organic carbon content and C:N ratios. Effects on bulk density, porosity and soil water retention curves were non-consistent over time, possibly due to interaction with tillage operations. Biochar increased soil water content in 2012, although mostly not significantly. However, in 2013, when soil water content was overall lower compared to 2012, it was not affected by biochar addition. Soil temperature, as measured at a soil depth interval of 8–20 cm, was not changed by biochar addition. Furthermore, biochar addition to soil did only slightly influence soil microbiological community structure during the first year after biochar application, as only certain bacterial biomarker PLFAs were significantly affected by biochar addition, but no fungal biomarker PLFAs. Hence, it was not surprising that biochar addition did not affect crop yield, N or P uptake during the first two years after biochar application. [ABSTRACT FROM AUTHOR]