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Intensive agriculture has increased global food production, but also impaired ecosystem services and soil biodiversity. Organic fertilization, essential to organic and integrated farming, can provide numerous benefits for soil quality but also compromise the environment by polluting soils and producing greenhouse gases through animal husbandry. The need for reduced stocking density is inevitably accompanied by lower FYM inputs, but little research is available on the impact of these effects on the soil microbiome. We collected soil samples from winter wheat plots of a 42-year-old long-term trial comparing different farming systems receiving farmyard manure at two intensities and measured soil quality parameters and microbial community diversity through DNA metabarcoding. High-input fertilization, corresponding to 1.4 livestock units (LU) improved the soil's nutritional status and increased soil microbial biomass and respiration when compared to low-input at 0.7 LU. Bacterial and fungal alpha-diversity was largely unaffected by fertilization intensity, whereas their community structure changed consistently, accompanied by an increase in the bacterial copiotroph-to-oligotroph ratio in high-input systems and by more copiotrophic indicator OTUs associated with high than low-input. This study shows that reduced nutrient availability under low-input selects oligotrophic microbes efficiently obtaining nutrients from various carbon sources; a potentially beneficial trait considering future agroecosystems., FEMS Microbiology Ecology, 99 (6), ISSN:0168-6496, ISSN:1574-6941

We investigated the effects of biochar (BC) at 0 and 20 t ha-1, combined with two organic fertilizers (municipal solid waste compost, MC, and sewage sludge, SS), on soil organic matter (SOM) in a 9-year field experiment. To capture the protection by soil minerals and iron (Fe) against microbial decomposition, we fractionated SOM into particulate (POM) and mineral-associated organic matter (MAOM), and analyzed the fractions by iron (Fe) K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy.BC and the two organic amendments increased soil organic carbon (OC) content, but only the organic fertilizers significantly increased total nitrogen (N) content. BC increased particulate OC and total N contents, while the organic fertilizers only increased particulate total N content. BC significantly increased mineral-associated OC content, while the organic fertilizers increased both mineral-associated OC and total N contents. We found no interaction between BC and organic fertilizers on mineral-associated OC and total N contents. The Fe EXAFS data fitting showed that the Fe(III)-SOM content of the Fe phases in POM and MAOM in unamended soils were noticeably different. Hematite represented the main Fe oxide phase in the POM fractions from all the amended soils, and Fe(III)-SOM averaged around 15%. In the amended soils, besides hematite (also present in the unamended soil), ferrihydrite occurred in all MAOM fractions, although at a different proportion.

No-tillage systems are able to reduce the negative effects of agricultural intensification on soil properties. However, knowledge of long-term impacts of no-tillage systems on soil properties is insufficient. It is essential to know which soil quality indicators are the most sensitive to management practices in each particular environment. Therefore, the objective of this work is to determine which soil quality properties are more sensitive to the impact of two tillage systems in a vertic Argiaquoll soil from Buenos Aires, Argentina. This work started in 2006 and included crop rotation and tillage systems, including both tillage and no-tillage. Physical and chemical properties were measured in three consecutive years (2013–2015) at two depths (0–10 cm and 10–20 cm). The tillage system modified soil physical and chemical properties, mainly in the surface layer. No-tillage showed significantly higher bulk density (2013–2015 p

The development of resilient cropping systems with high yield stability is becoming increasingly important due to future climatic and agronomic challenges. Consequently, it is essential to compare the effects of different agronomic management practices, such as cropping sequences and nutrient supply, on the stability of crop yields. Long-term experiments are a valuable resource for investigating these effects, as they provide enough time to accurately estimate stability parameters. The objective of the current study was to compare the effects of different cropping sequencing (#1: continuous v. rotational), fertilization (#2: mineral v. organic) and straw management techniques (in the case of continuous wheat; #3: removal v. incorporation) on the yield stability of winter wheat; yield risk (the probability of yield falling below a threshold yield level) and inter-annual yield variability were used as stability indicators of the effects. Long-term yield data from the Broadbalk Wheat Experiment (Rothamsted, UK) were analysed using a mixed model. Overall, the results showed that rotational cropping combined with sufficient mineral N fertilizer, with or without organic manure, ensured stable wheat yields while reducing yield risk. In contrast, higher yield risks and inter-annual yield variabilities were found in continuous wheat sections with less mineral N fertilizer or with organic manure only.

Carbon sequestration has been proposed as a way to mitigate the impact of CO2 on the climate. At the COP21, the ‘4 per 1000 Soils for Food Security and Climate’ initiative was launched with the goal to increase global soil organic carbon (SOC) stocks by 4‰ per year. The Thyrow long-term field experiment DIV.2 was chosen to determine the feasibility of this 4 per 1000 goal under the dry and sandy conditions in Eastern Germany. The effects of different fertilizing regimes on SOC contents and winter rye yields were investigated. Winter rye is a representative crop for the region and grown as a monoculture in the experiment. The 4 per 1000 goal was achieved in all treatments including the unfertilized control, although ploughing takes place and straw is removed every year. The highest carbon sequestration of up to 0.5 t ha−1 a−1 was provided by a combination of mineral and manure fertilization. In three out of four years, no yield difference was observed between mineral-only fertilization (120 kg ha−1 N) and a combination of mineral and organic N (97.4 kg ha−1 plant available N) fertilization. Yields increased over the years in the treatment with pure organic N and decreased in all other treatments.

Cultivation practices alter the molecular status of the soil Humeome, meant as the ensemble of all heterogeneous humic molecules, whose changes need to be understood and monitored in order to maintain the sustainability of agricultural soils. We applied the Humeomics sequential chemical fractionation, coupled to characterization of separated fractions by GC-MS and high-resolution Orbitrap LC-MS, on soils subjected for 20 consecutive years to the following treatments: i) non cultivated and untilled soil (Control); ii) maize monoculture (Maize); iii) maize-leguminous (Vicia faba) rotation (Mix). Humeomics fractions revealed a greater amount of organic carbon (OC) than for the traditional alkaline humus extraction (eSOM), double chromatographic visibility and one order of magnitude more detectable empirical formulae. Humeomics indicated that the ratio of organosoluble to hydrosoluble components decreased significantly passing from Control to Mix and Maize soils, thus unveiling that the loss of humic hydrophobic compounds, such as long-chain esters and fatty acids, rendered more physically and chemically fragile soils under long-term maize monoculture than under crop rotation. Saccharides undetectable in eSOM became instead visible after cleavage of esters weakly bound to the humic matrix, confirming a mechanism of protection of polar compounds by hydrophobic humic components. The same was observed for nitrogen-containing compounds, such as amides and heterocyclic nitrogen, which were significantly detected in Humeomics fractions of cropped soils only after the HI step disrupted ether linkages and organo-mineral complexes. Most of N-containing compounds in cropped soils were found to be bound to iron, thus implying that different forms of nitrogen entering soil by either synthetic fertilizer or nitrogen fixation are progressively sequestered into recalcitrant organic pools. Our findings highlight that a detailed knowledge on the molecular dynamics of the Humeome of soils under long-term field trials allowed a further understanding of the organic matter molecular distribution and the mechanisms of its stabilization.

Made available in DSpace on 2021-06-25T10:24:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-05-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Nederlandse Organisatie voor Wetenschappelijk Onderzoek Unsustainable agricultural management practices such as non-conservationist tillage and overuse of fertilizers result in soil acidity and, in turn, soil degradation due to reduced carbon (C) concentrations and nutrient availability and increased aluminum toxicity. Application of lime (L) and phosphogypsum (PG) can overcome these constraints and improve soil quality, but the long-term effects of these amendments on both abiotic and biotic soil properties are not known, particularly when applied in combination. Here, we evaluated the effects of L (acidity corrective), PG (soil conditioner), and their combination (LPG) on soil organic matter (SOM) transformations, soil chemical and physical properties, and microbiome assembly in a long-term experiment under a no-till crop rotation system in a tropical soil. The Ca-based soil amendments increased C concentrations (labile and stable fractions), improved soil physicochemical properties, and changed the associations between several bacterial and fungal groups. Contrary to expectations, the acidic soil amended with PG exhibited greater number of significant shifts in the bacterial community than soil amended with L or LPG, as well as higher soil bulk density. By contrast, the fungal community underwent greater shifts in soil amended with L or LPG, which had higher macroporosity. L and LPG amendment shaped the fungal community and rearranged the SOM fractions at similar rates, suggesting an essential role of the altered fungi in SOM transformation. In addition, combining L with PG increased the relevance of many low-abundance microorganisms, especially fungi, compared with the control, indicating an increase in their ecological role in the soil. Finally, by applying general joint attribute modeling and sensitivity analysis, we determined that soil fertility increased most in LPG-amended soil, as the ensuing changes in the bacterial and fungal communities resulted in improved SOM fractions, soil physical characteristics and, ultimately, soil quality. College of Agricultural Sciences São Paulo State University (UNESP) Department of Crop Science Netherlands Institute of Ecology (NIOO-KNAW) Department of Microbial Ecology Ecology and Biodiversity Institute of Environmental Biology Utrecht University, Padualaan 8 Luiz de Queiroz College of Agriculture (ESALQ) University of São Paulo (USP) College of Agricultural Sciences São Paulo State University (UNESP) Department of Crop Science FAPESP: 2018/11063-7 FAPESP: 2019/12764-1 Nederlandse Organisatie voor Wetenschappelijk Onderzoek: 870.15.022

The polyfactorial long-term field experiment was conducted in 1983 on a calcareous chernozem soil in Hungary (Debrecen-Látókép experimental farm) to determine the long-term effect of different doses of chemical fertilizers and irrigation on the yield, nutrient uptake of maise (in monoculture production) and on soil parameters. Our aim was to analyse and compare the changes of soil chemical and microbiological caracteristics for 33 years NPK fertilizer application either in irrigated and or in non irrigated version. Soil pH, humus, nutrient content and some soil microbiological parameters were analyzed. The microbiological parameters sightly, the chemical parameters of soil significantly influenced by long term application of NPK fertilizers. In fertilized plots: the pH decreased, humus content increased. The availability of supplied nutrients, NPK improved, while non-supplied macronutrients, calcium and magnesium significantly decreased in fertilized plots compared to control. The significantly decrease in calcium content call attention, that the same effect in acidic sandy soil might be particularly harmful. In fertilized plots the number of bacteria tended to decrease, while the number of microscopic fungi and saccharase enzime activity significantly enhanced. The irrigation did not cause significant changes of measured microbiological parameters.

International audience; Developing more sustainable forage systems requires efficient decision support tools for fertilization management. Soil phosphorus (P) tests have long been used as decision support tools for fertilization management but, more recently, plant nutrition indices using the P concentration of shoot biomass were developed to assess the P nutrition status of grasslands. The objectives of this study were to (i) evaluate the relationship between the phosphorus nutrition index (PNI) and the yield response to P fertilization (ii) analyze relationships between PNI and soil plant-available P (SPAP) indicators, and (iii) evaluate PNI assets for P diagnosis in forage system. Five long-term (≥ 9 years) grassland P fertilization experiments under different soil and climate environments in Canada, Switzerland, France and Romania were used. Three SPAP indicators were tested: CP, the soil solution orthophosphate ions (oPion) concentration (mg P L−1), Olsen P (mg P kg−1), and, a process-based assessment (Qw + Pr) from the sum of oPion in the soil solution (Qw, mg P kg−1) and diffusive oPion with time and CP (Pr, mg P kg−1). PNI was calculated as sward P concentration divided by the critical P concentration. The cumulative effect of P fertilization resulted in a wide range of SPAP values. Overall, CP varied from 0.03 to 3.6 mg P L−1, (Qw + Pr60 min) from 6−52 mg kg−1, and Olsen P from 4−40 mg kg−1. The PNI varied from 48–94% in plots with no applied P, and from 83–121% in P-fertilized plots. A generally positive relationship between relative forage dry matter yield and PNI was established, with a critical PNI value of 92% that distinguishes P-limited and non-P-limited grassland nutrition. Positive relationships between PNI and the three SPAP indicators confirmed that the soil P status influenced the grassland P nutrition status. Critical values on a stock basis for a target PNI value of 92% were similar for Olsen P (12.9 kg P ha−1) and (Qw + Pr60 min) (13.5 kg P ha−1). This study opens perspectives for P diagnosis improvement in forage systems.

Repeated applications of organic waste products (OWP) are a source of trace elements (TE) inputs to agricultural topsoils. The present study aimed at (i) assessing the effects of repeated OWP inputs on the chemical properties of topsoils in two long-term field experiments (13 and 15 years, calcareous and non-calcareous soils), (ii) evaluating TE phytoavailability and their transfer to grain (winter wheat and maize) and (iii) identifying the underlying factors causing alterations of TE phytoavailability. In both field experiments, receiving compliant or slightly high doses of OWP in compliance with regulations, OWP and soil physicochemical properties and TE concentrations in soils and grains were determined. In situ phytoavailability of TE was assessed at two juvenile crop growth stages by analyzing TE concentrations in shoot plantlets. Depending on the OWP input amount, results showed that compared to the soil receiving no organic amendment, repeated OWP inputs significantly increased soil organic carbon content, pH, cation exchange capacity, total soil Cu, Mo and Zn concentration and the phytoavailability of Mo, while the phytoavailability of Cd, Mn, Ni and Tl was significantly reduced. No notable effect was observed for Cr, Cu, Hg, Pb and Zn phytoavailability. Statistical approaches suggested that due to the repeated OWP applications, increased soil organic carbon content and pH, were likely responsible for decreased TE phytoavailability (e.g., Cd).

Despite recent technological advances in molecular ecology, DNA extraction from soil remains a crucial step when quantifying and characterizing soil microbial communities. Potential biases could hamper fundamental understanding of the dynamic relationships between soil properties and microorganisms under different agricultural practices. In this study, we compared four different DNA extraction methods for their ability to discriminate microbial communities of an arable soil subjected to different fertilization managements for more than 50 years (Ultuna, Sweden). The abundance and the diversity of bacteria, archaea and fungi were studied using qPCR and molecular fingerprints, respectively. Overall, the choice of DNA extraction method had a more pronounced effect on the fungal and archaeal communities in comparison to bacterial ones. The assessment of the microbial diversity was more sensitive to DNA extraction methods in comparison with the quantification of the abundances. The DNA extraction method clearly affects the intensity of the correlations between the abundance and/or diversity of microbial communities and environmental variables (C, N and pH) according to the targeted taxon. This study highlights that long-term effects can be offset by biases in DNA extraction methods. Highlights Using different DNA extraction methods may alter soil microbial survey. Average DNA concentrations vary from 1 to 3 mu g.g(-1)according to the extraction method. Gene copies numbers vary up to 2 orders of magnitude among DNA extraction methods. Fungal communities diversity descriptors were the most affected by DNA extraction

International audience; Repeated applications of organic waste products (OWP) are a source of trace elements (TE) inputs to agricultural topsoils. The present study aimed at (i) assessing the effects of repeated OWP inputs on the chemical properties of topsoils in two long-term field experiments (13 and 15 years; calcareous and non-calcareous soils), (ii) evaluating TE phytoavailability and their transfer to grain (winter wheat and maize) and (iii) identifying the underlying factors causing alterations of TE phytoavailability. In both field experiments, receiving compliant or slightly high doses of OWP in compliance with regulations, OWP and soil physicochemical properties and TE concentrations in soils and grains were determined. In situ phytoavailability of TE was assessed at two juvenile crop growth stages by analyzing TE concentrations in shoot plantlets. Depending on the OWP input amount, results showed that compared to the soil receiving no organic amendment, repeated OWP inputs significantly increased soil organic carbon content, pH, cation exchange capacity, total soil Cu, Mo and Zn concentration and the phytoavailability of Mo, while the phytoavailability of Cd, Mn, Ni and Tl was significantly reduced. No notable effect was observed for Cr, Cu, Hg, Pb and Zn phytoavailability. Statistical approaches suggested that due to the repeated OWP applications, increased soil organic carbon content and pH, were likely responsible for decreased TE phytoavailability (e.g., Cd).

Addition of organic amendments is a commonly used practice to offset potential loss of soil organic matter from agricultural soils. The aim of the present study was to examine how long-term addition of organic matter affects the abundance of different soil biota across trophic levels and the role that the quality of the organic amendments plays. Here we used a 17-year-old fertilization experiment to investigate soil biota responses to four different organic fertilizers, compared with two mineral nitrogen fertilizers and no fertilization, where the organic fertilizers had similar carbon content but varied in their carbon to nitrogen ratios. We collected soil samples and measured a wide range of organisms belonging to different functional groups and trophic levels of the soil food web. Long-term addition of organic and mineral fertilizers had beneficial effects on the abundances of most soil organisms compared with unfertilized soil, but the responses differed between soil biota. The organic fertilizers generally enhanced bacteria and earthworms. Fungi and nematodes responded positively to certain mineral and organic fertilizers, indicating that multiple factors influenced by the fertilization may affect these heterogeneous groups. Springtails and mites were less affected by fertilization than the other groups, as they were present at relatively high abundances even in the unfertilized treatment. However, soil pH had a great influence on springtail abundance. In summary, the specific fertilizer was more important in determining the numerical and compositional responses of soil biota than whether it was mineral or organic. Overall, biennial organic amendments emerge as insufficient, by themselves, to promote soil organisms in the long run, and would need to be added annually or combined with other practices affecting soil quality, such as no or reduced tillage and other crop rotations, to have a beneficial effect.

Исследования с целью изучения влияния водорегулирующей лесной полосы на впитывающую способность почвы проводили на склоне западной экспозиции в полевом опыте по контурно-мелиоративному земледелию, заложенном на площади 146 га в 1982 г. в Курской области. Почва опытного участка - чернозём типичный среднемощный тяжелосуглинистый. Впитывающую способность определяли методом дождевания с использованием портативной дождевальной установки. Монолиты для дождевания отбирали в конце второй декады апреля с использованием металлических цилиндров высотой 0,203±0,002м и площадью 0,049±0,001 м2 на удалении 10,50 и 108 м выше и ниже по склону от лесной полосы, имевшей протяженность 194 м. Дождевание проводили в лабораторных условиях. Определяли плотность и влажность почвы, интенсивность дождя и количество воды, стекающей с поверхности. Результаты статистического анализа данных для всех расстояний удаленности от лесной полосы свидетельствуют о том, что величины плотности почвы (1,20±0,05 г/см3) и её влажности (24,4±0,9 %) варьируют в пределах погрешности 4 %, впитывающая способность почвы (0,71±0,13 мм/мин) в пределах погрешности 18 %. Лесная полоса не оказывает влияния на эти факторы. Для установления количественных зависимостей величин этих показателей от расстояния до лесной полосы необходимы более точные методы измерений. В качестве примера применения результатов исследований для естественных дождей проведен расчёт слоя поверхностного стока при выпадении на почву экстремального дождя.

Increased inorganic nitrogen (N) and phosphorus (P) additions expected in the future will endanger the biodiversity and stability of agricultural ecosystems. In this context, a long-term fertilizer experiment (37 years) was set up in the black soil of northeast China. We examined interaction impacts of elevated fertilizer and host selection processes on arbuscular mycorrhizal fungi (AMF) communities in wheat rhizosphere soil using the Illumina MiSeq platform. The soil samples were subjected to five fertilization regimes: no fertilizer (CK) and low N (N1), low N plus low P (N1P1), high N (N2), and high N plus high P (N2P2) fertilizer. Long-term fertilization resulted in a significant shift in rhizosphere soil nutrient concentrations. The N fertilization (N1 and N2) did not significantly change rhizosphere AMF species diversity, but N plus P fertilization (N1P1 and N2P2) decreased it compared with CK. Non-metric multidimensional scaling showed that the rhizosphere AMF communities in CK, N1, N2, N1P1 and N2P2 treatments were distinct from each other. The AMF communities were predominantly composed of Glomeraceae, accounting for 30.0-39.1% of the sequences, and the relative abundance of family Glomeraceae was more abundance in fertilized soils, while family Paraglomeraceae were increased in N1 and N2 compared with CK. Analysis shown that AMF diversity was directly affected by soil C:P ratio but indirectly affected by plant under long-term fertilization. Overall, the results indicated that long-term N and P fertilization regimes changed rhizosphere AMF diversity and community composition, and rhizosphere AMF diversity was both affected by soil C:P ratio and plant.

The purpose of this long-term experiment was on gaining more insights into the environmental behaviour of veterinary antibiotics in the subsurface after application with manure. Therefore, manure spiked with a bromide tracer and eight antibiotics (enrofloxacin, lincomycin, sulfadiazine, sulfamethazine, tetracycline, tiamulin, tilmicosin and tylosin) in concentrations of milligrams per litre were applied at an experimental field site. Their pathway was tracked by continuous extraction of soil pore water at different depths and systematic sampling of groundwater for a period of two years. Seven target compounds were detected in soil pore water of which four leached into groundwater. Concentrations of the detected target compounds were, with few exceptions, in the range of nanograms per litre. It was concluded that a large fraction of the investigated antibiotics sorbed or degraded already within the first meter of the soil. Further, it was inferred from the data that long and warm dry periods cause attenuation of the target compounds through increased degradation or sorption occurring in the soil. In addition, the comprehensive data-set allowed to estimate a retardation factor between 1.1 and 2.0 for sulfamethazine in a Plaggic Anthrosol soil, and to classify the individual compounds by environmental relevance based on transport behaviour and persistence. According to the distribution of resistant genes in the environment, sulfamethazine was found to be the most mobile and persistent substance.

The purpose of this long-term experiment was on gaining more insights into the environmental behaviour of veterinary antibiotics in the subsurface after application with manure. Therefore, manure spiked with a bromide tracer and eight antibiotics (enrofloxacin, lincomycin, sulfadiazine, sulfamethazine, tetracycline, tiamulin, tilmicosin and tylosin) in concentrations of milligrams per litre were applied at an experimental field site. Their pathway was tracked by continuous extraction of soil pore water at different depths and systematic sampling of groundwater for a period of two years. Seven target compounds were detected in soil pore water of which four leached into groundwater. Concentrations of the detected target compounds were, with few exceptions, in the range of nanograms per litre. It was concluded that a large fraction of the investigated antibiotics sorbed or degraded already within the first meter of the soil. Further, it was inferred from the data that long and warm dry periods cause attenuation of the target compounds through increased degradation or sorption occurring in the soil. In addition, the comprehensive data-set allowed to estimate a retardation factor between 1.1 and 2.0 for sulfamethazine in a Plaggic Anthrosol soil, and to classify the individual compounds by environmental relevance based on transport behaviour and persistence. According to the distribution of resistant genes in the environment, sulfamethazine was found to be the most mobile and persistent substance.

Soil organic matter (SOM) consists of various labile and stable fractions, which are differently influenced by agricultural activities and land-use change. This study, aimed at investigating the feasibility of achieving 4p1000 goals on conventionally tilled plough-land, was carried out in a 42 years-old long-term field experiment (LTE), in which the effect of three farmyard manure (FYM) doses and the FYM equivalent NPK mineral fertiliser rates can be examined, together with that of mineral fertiliser with and without ploughed-in plant residues. The soil total organic carbon (SOC) and nitrogen (SN) and the labile hot-water soluble C (HWC) and N (HWN) fractions were determined (0–0.3 m) and used as indicators. The parameters of the tilled area were compared with those of a grassland area with similar characteristics. The suitability of these parameters for use as soil quality indicators (SQI) was also examined in terms of soil fertility. The results showed that the most sensitive fraction for the detection of treatment effects were HWC and HWN. Increases in these labile organic fractions were significantly related to the gains of SOC stocks. Based on the close correlation between these factors and both SOC and crop yield it is recommended that they should be used as indicators for the prediction of changes in SOC and in studies on soil fertility or soil quality. The initial C stock of 40.46 Mg ha−1 became 40.27–47.05 Mg ha−1 on the tilled soil after four decades, while on the grassland it rose to 69.31 Mg ha−1. The carbon sequestration rate (CSR) in the various fertilisation systems exhibited the following order: plant residue incorporation >FYM addition > mineral fertilisation (0.147–0.156, 0.101–148 and –0.021–0.065 Mg ha−1 yr−1, respectively), while an outstandingly high value of 0.687 Mg ha−1 yr−1 was recorded for the grassland. Despite the fact that the carbon sequestration potential (CSP) remained high (55.36–62.48%), the achievement of 4 per 1000 aims can only be ensured in treatments involving high rates of organic matter and only in the short term.

Phosphorus (P) is an essential plant nutrient. However, our understanding of the complex interactions between soil P availability, environment, management and crop growth is still limited. We used unique historic and recent soil and crop data spanning more than a century combined with a process-based crop model to analyze the impact of P fertilizer omission and P fertilization on the biomass production of five crops. The long-term field experiment at Dikopshof, Germany, was established in 1904 with a 5-year crop rotation of sugar beet, winter wheat, winter rye, clover and oat/potato (potato replaced oat in 1953) on a fertile Luvisol. Averaged over the period from 1906 to 2018, the yield loss due to P omission was low for winter wheat and winter rye (7-8 %). In contrast, yield losses for sugar beet, clover and potato were relatively high (15-24 %). The yield loss from P fertilizer omission in comparison to the reference treatment (rotation mean excluding oat/potato) increased until the middle of the last century from 7% to 18 %, but subsequently decreased to 13 %. Trend and correlation analyses suggest that this decrease was related to an increase in air temperatures in especial during spring and a lower yield loss under P omission. Crop model simulations showed decreasing topsoil organic carbon concentrations after the 1930ies as manure was discontinued in 1942 but also due to increasing air temperatures. The increase in plant-available topsoil P concentrations during the last decades was one of the main factors offsetting yield losses despite P fertilizer omission. Our study suggests that climate change and, in particular, a marked increase in temperature since the middle of the last century most likely influenced soil P dynamics with a significant impact on crop production.

Nitrogen (N) loss from fertilization in agricultural fields has an unavoidable negative impact on the environment and a better understanding of the major pathways can assist in developing the best management practices. The aim of this study was to evaluate the fate of N fertilizers applied to acidic red soil (Ferralic Cambisol) after 19 years of mineral (synthetic) and manure fertilizer treatments under a cropping system with wheat-maize rotations. Five field treatments were examined: control (CK), chemical nitrogen and potash fertilizer (NK), chemical nitrogen and phosphorus fertilizer (NP), chemical nitrogen, phosphorus and potash fertilizer (NPK) and the NPK with manure (NPKM, 70% N from manure). Based on the soil total N storage change in 0–100 cm depth, ammonia (NH 3 ) volatilization, nitrous oxide (N 2 O) emission, N plant uptake, and the potential N leaching loss were estimated using a mass balance approach. In contrast to the NPKM, all mineral fertilizer treatments (NK, NP and NPK) showed increased nitrate (NO 3 − ) concentration with increasing soil depth, indicating higher leaching potential. However, total NH 3 volatilization loss was much higher in the NPKM (19.7%) than other mineral fertilizer treatments (≤4.2%). The N 2 O emissions were generally low (0.2–0.9%, the highest from the NPKM). Total gaseous loss accounted for 1.7, 3.3, 5.1, and 21.9% for NK, NP, NPK, and NPKM treatments, respectively. Estimated N leaching loss from the NPKM was only about 5% of the losses from mineral fertilizer treatments. All data demonstrated that manure incorporation improved soil productivity, increased yield, and reduced potential leaching, but with significantly higher NH 3 volatilization, which could be reduced by improving the application method. This study confirms that manure incorporation is an essential strategy in N fertilization management in upland red soil cropping system.

Цель. В многолетнем стационарном опыте в четырёхпольном зернопропашном севообороте проследить динамику численности и видового разнообразия сорняков в посевах озимой пшеницы при применении классической вспашки и технологии прямого посева. Методы. Мониторинг агрофитоценозов в условиях двух постоянно воспроизводимых обработок почвы проводили методом сеточного картографирования засорённости посевов дважды за сезон в течение 10 лет. Результаты. Составлены пространственные карты засорённости посевов и зон разной продуктивности агрофитоценозов, связанные с неравномерностью почвенных условий и применяемых технологий возделывания культур. Показано, что на варианте Прямой посев численность и видовое разнообразие сорняков в среднем в дватри раза выше, чем на варианте Вспашка. Осеннее применение гербицидов Линтур (1,8 кг/га) или Алистер Гранд (0,8 л/га) на озимой пшенице в фазу кущения существенно снижает численность сорняков на весь период вегетации. Однако на варианте Прямой посев численность сорных растений остается высокой, на уровне 4080 шт./м. Заключение . За десять лет наблюдений в агрофитоценозах многолетнего опыта Центра точного земледелия было зафиксировано 84 вида нежелательной растительности, из них 69 сорных видов, 7 древесных видовзасорителей и 8 видов культурных растений засорителей. В один сезон вегетационный встречается в среднем 3540 видов. Засорённость посевов по варианту Нулевая обработкапрямой посев (двукратная обработка гербицидом) в среднем в три раза выше, чем по варианту Вспашка (однократная обработка гербицидом)., Aim . The objectives of this study were to compare of the number and species diversity of weeds in the winter wheat crops in the longterm field crop rotation experiment under two plant technology classical plowing and direct seeding. Methods . Monitoring of agrophytocenoses under two constantly reproduced soil treatments was carried out twice per season for 10 years by the method of grid mapping of weeds distribution in winter wheat crops. Results . Spatial maps of weeds distribution and areas of different productivity of agrophytocenoses associated with uneven soil conditions and applied technologies of cultivation of crops. It was shown that the number and species diversity of weeds under zerotill technology was on average two to three times higher than under plowing. Autumn use of herbicides Lintur (dicambatriasulfuron) (1.8 kg/ha) or Alistair Grand (Mesosulfuronmethyliodosulfuronmethylsodiumdiflufenicanmefenpyrdiate) (0.8 l/ha) on winter wheat in the tillering phase significantly reduces the number of weeds for the entire vegetation period. However, under zerotillage the number of weed plants remains high, approximately 4080 PCs.m. Conclusions . For ten years of observations in agrophytocenoses of longterm experience of the Center of precision agriculture there were recorded 84 species of undesirable vegetation: 69 weed species, 7 species treeweeds and 8 species of cultivated plants. During every vegetation season, the survey found an average of 3540 species. The weeds frequency under zerotillage (double treatment with herbicide) is on average three times higher than under plowing (single treatment with herbicide)., №148(148) (2019)

Recycling organic residues in agrosystems presents several benefits but faces the question of contaminants, among them a few trace metals which eventually accumulate in soils following regular applications of organic waste products (OWP) and represent an ecological risk. The increase of total trace metal contents in amended topsoils can be predicted by a mass balance approach, but the evolution of their available fractions is a more intricate issue. We aimed at modelling this evolution by using the dataset of a long-term field experiment of OWP applications (manure and three urban waste composts). Two operationally-defined fractions of 6 trace metals have been quantified in the OWP and amended topsoils between 2002 and 2015: the soluble and potentially available metals, extracted in 0.01 M CaCl2 and 0.05 M EDTA solutions, respectively. The potentially available metals have progressively increased in amended topsoils, at rates depending on elements and types of OWP. For Zn, these increases corresponded in average to inputs of potentially available Zn from OWP. But the soil stocks of potentially available Cu increased faster than from the inputs of EDTA-extractable Cu, showing linear regression slopes between 1.4 and 2.5, depending on OWP type. The influence of OWP has been provisionally interpreted in the light of their efficiency to increase soil organic matter and their inputs of reactive oxides. Soluble copper has increased with repeated amendments. But soluble cadmium, nickel and zinc have generally decreased, as they are influenced by changing soil variables such as pH and organic matter. Statistic models were used to unravel the relationships between soluble and EDTA-extractable metals and other soil variables. For Cu, the most satisfactory models just relate soluble and potentially available Cu. Developing such models could contribute to predict the long-term effects of a precise scenario of agricultural OWP recycling upon available trace metals in soils.

Background Intensively cultivated agricultural landscapes often suffer from substantial pollinator losses, which may be leading to decreasing pollination services for crops and wild flowering plants. Conservation measures that are easy to implement and accepted by farmers are needed to halt a further loss of pollinators in large areas under intensive agricultural management. Here we report the results of a replicated long-term study involving networks of mostly perennial flower strips covering 10% of a conventionally managed agricultural landscape in southwestern Germany. Results We demonstrate the considerable success of these measures for wild bee and butterfly species richness over an observation period of 5 years. Overall species richness of bees and butterflies but also the numbers of specialist bee species clearly increased in the ecological enhancement areas as compared to the control areas without ecological enhancement measures. A three to five-fold increase in species richness was found after more than 2 years of enhancement of the areas with flower strips. Oligolectic bee species increased significantly only after the third year. Conclusions In our long-term field experiment we used a large variety of seed mixtures and temporal variation in seeding time, ensured continuity of the flower-strips by using perennial seed mixtures and distributed the measures over c. 10% of the landscape. This led to an increase in pollinator abundance, suggesting that these measures may be instrumental for the successful support of pollinators. These measures may ensure the availability of a network of diverse habitats and foraging resources for pollinators throughout the year, as well as nesting sites for many species. The measures are applied in-field and are suitable for application in areas under intensive agriculture. We propose that flower strip networks should be implemented much more in the upcoming CAP (common agricultural policy) reform in the European Union and promoted more by advisory services for farmers. Electronic supplementary material The online version of this article (10.1186/s12898-018-0210-z) contains supplementary material, which is available to authorized users.

To compare how different analytical methods explain crop yields from a long-term field experiment (LTFE), we analyzed the grain yield of winter wheat (WW) under different fertilizer applications in M&uuml, ncheberg, Germany. An analysis of variance (ANOVA), linear mixed-effects model (LMM), and MP5 regression tree model were used to evaluate the grain yield response. All the methods identified fertilizer application and environmental factors as the main variables that explained 80% of the variance in grain yields. Mineral nitrogen fertilizer (NF) application was the major factor that influenced the grain yield in all methods. Farmyard manure slightly influenced the grain yield with no NF application in the ANOVA and M5P regression tree. While sources of environmental factors were unmeasured in the ANOVA test, they were quantified in detail in the LMM and M5P model. The LMM and M5P model identified the cumulative number of freezing days in December as the main climate-based determinant of the grain yield variation. Additionally, the temperature in October, the cumulative number of freezing days in February, the yield of the preceding crop, and the total nitrogen in the soil were determinants of the grain yield in both models. Apart from the common determinants that appeared in both models, the LMM additionally showed precipitation in June and the cumulative number of days in July with temperatures above 30 &deg, C, while the M5P model showed soil organic carbon as an influencing factor of the grain yield. The ANOVA results provide only the main factors affecting the WW yield. The LMM had a better predictive performance compared to the M5P, with smaller root mean square and mean absolute errors. However, they were richer regressors than the ANOVA. The M5P model presented an intuitive visualization of important variables and their critical thresholds, and revealed other variables that were not captured by the LMM model. Hence, the use of different methods can strengthen the statement of the analysis, and thus, the co-use of the LMM and M5P model should be considered, especially in large databases involving multiple variables.

Annual C input to soil is a major factor affecting soil organic carbon (SOC) dynamics. However different types of C-sources can have different behaviour, in relation to their chemical characteristics and how they interact with soil. Root-derived C, in particular, should be more efficient than other organic materials as a result of the physicochemical and biological characteristics of the surrounding environment, leading to a reduction in the C decomposition rate. To test this hypothesis, we considered a long-term experiment underway in Northern Italy since 1962, comparing permanent meadow and 6 different crop rotations over a wide range of nutrient inputs, in both organic and inorganic forms. C inputs from amendments were measured and those from crops were calculated using allometric functions and crop and residues yields. The time evolution of SOC was studied through a single-pool, first-order kinetic model, allowing the estimation of humification coefficients for residues, roots, farmyard manure and cattle slurries. The highest value of the humification coefficient was estimated for farmyard manure, which confirmed its high efficiency in stabilising SOC content. Root C presented a humification coefficient 1.9 times higher than above-ground plant materials while slurries were intermediate, with a humification coefficient roughly half that of farmyard manure and even lower that of roots. The quality of C input thus seems of fundamental importance for evaluating the sustainability of different cropping systems in terms of SOC dynamics.

Several studies have reported that biochar can improve soil properties which are linked with higher crop yields and this effect is long-term. This paper aimed to study the effects of biochar (0, 10 and 20 t ha&minus, 1) and its combinations with N-fertilization (zero, first and second level of N-fertilization) after 3 and 4 years of its application on improving soil characteristics of loamy Haplic Luvisol and crop yields (Doln&aacute, Malanta, Slovakia). The results indicated an increase in soil pH (+7%), improvement in sorption properties (hydrolytic acidity decreased by 11%, sum of basic cations and base saturation increased by 20% and 5%, respectively) and soil organic carbon rose by 27% with increasing biochar rate in the soil. N-fertilization applied to biochar treatments was a stabilizing moment in C sequestration even in the case of its labile forms. Overall, humus stability and quality were not significantly changed, however in biochar treatments without N-fertilization, the humus stability and quality decreased 3 and 4 years after biochar application. Yield parameters differed with relation to climate conditions during both vegetation crop seasons, however the combination of 20 t ha&minus, 1 of biochar with the first and second level of N-fertilization had the highest potential to increase the grain yield.

Potassium is an essential nutrient for plant growth and development. Clay minerals in soils represent an important reservoir of plant-available K. Extraction of fixed K from the interlayer space of micaceous 2:1 minerals can lead to an increase in the layer-to-layer distance which can be measured by X-ray diffraction. Samples from the Morrow Plots continuous corn (C) and corn-oats-hay (R) experiment, from fertilised (F) and non-fertilised (U) subplots for the years 1904, 1957, 1980, 1997 and 2013-2014 were subjected to sequential size-fractionation to obtain the silt fraction (50-2 um) and clay-sized subfractions (2-0.2, 0.2-0,05 and, Le potassium est un nutriment essentiel à la croissance et au développement des plantes. Les minéraux argileux dans les sols représentent un important réservoir de K disponible pour les plantes. L'extraction de K fixé à partir de l'espace interfoliaire des minéraux micacés 2:1 peut entraîner une augmentation de la distance feuillet à feuillet qui peut être mesurée par diffraction des rayons X . Des échantillons de l'expérience Morrow Plots continue avec du maïs (C) ou du maïs-avoine-foin (R), provenant de sous-parcelles fertilisées (F) et non fertilisées (U) pour les années 1904, 1957, 1980, 1997 et 2013-2014, ont été soumis au fractionnement granulométrique séquentiel pour obtenir la fraction limoneuse (50-2 um) et les sous-fractions argileuses (2-0,2, 0,2-0,05 et

По результатам многолетних исследований (1967–2008 гг.) в типичных условиях сухой степи сделан обобщенный анализ отклика гумусного состояния почвы на традиционные приемы возделывания культур. Исследования проводили в трех стационарных многолетних полевых опытах Бурятского научно-исследовательского института сельского хозяйства на каштановой почве. Комбинированная обработка почвы в традиционном зернопаровом севообороте (пар чистый – пшеница – овес – овес на зеленую массу) позволила поддерживать близкое к исходному гумусное состояние почвы за счет вновь образованных гумусовых веществ с хорошим качественным составом. Одновременно происходило увеличение мощности гумусового горизонта. Бездефицитный и положительный баланс гумуса в зернопаровом севообороте обеспечивали только варианты с внесением навоза. Повышение содержания общего углерода и расширение отношения гуминовых кислот к фульвокислотам росло в ряду вариантов: без удобрений → N40P40К40 → 10 т/га навоза + N50Р25К60 (эквивалент 10 т/ га навоза) → навоз 20 т/га → навоз 40 т/га. Занятые и сидеральные донниковые пары по своему влиянию на содержание и качество гумуса не уступали традиционному виду органических удобрений – навозу в дозе 10 т/га севооборотной площади. Динамика изменения содержания гумуса каштановой почвы в зависимости от вида и длительности (n = 28...42) сельскохозяйственного использования аппроксимируется экспоненциальными уравнениями с низкими средними ошибками, отличающимися высокой прогностической значимостью., Based on the results of many years of research (1967–2008), the response of the humus soil state to traditional methods of cultivation was generally analyzed under typical conditions of the dry steppe. The investigations were carried out in three stationary long-term field experiments on the chestnut soil in Buryatia Research Agricultural Institute. Combined soil cultivation in a traditional grain-fallow crop rotation (bare fallow, wheat, oat, oat for green mass) allowed maintaining the humus condition close to the initial state due to newly formed humic substances with good quality composition. Simultaneously the thickness of the humus horizon increased. A lack of deficit and a positive balance of humus in the grain-fallow crop rotation were provided only by variants with the application of manure. The increase in the content of total carbon and the expansion of the ratio of humic acids to fulvic acids increased in a number of variants: without fertilizers – N40P40K40 – 10 t/ha manure + N50P25K60 (the equivalent of 10 t/ha manure) – manure 20 t/ha – manure 40 t/ ha. Seeded and green manure fallow were not inferior to the traditional type of organic fertilizers – manure in a dose of 10 tons per hectare of crop rotation area in their influence on the content and quality of humus. The dynamics of the humus content of the chestnut soil, depending on the type and duration (n = 28–42) of agricultural use, is approximated by exponential equations with low mean errors, which are highly predictive.

Temporary (ley) grassland introduced into cropping cycles has been advocated as being beneficial for the delivery of ecosystem services by agricultural soils. The management of these temporary grasslands has unknown effects on soil organic matter (SOM) concentrations and biogeochemical properties of the cropland soils following the grassland phase. Here, we investigated the legacy effect of differently managed temporary grasslands, i.e. change of soil properties lasting beyond three years of crop. We assessed soil organic carbon (SOC) quantity and SOM biogeochemical signature (composition of soil neutral carbohydrates and lignin), as well as microbial activities (potential C and N mineralization and denitrification). We used a long-term field experiment on Cambisol with temperate climate in western France, where temporary grassland management practices differed in terms of duration (3 or 6 years) and presence or absence of N fertilisation. Topsoil (10 cm) samples were collected after a 3-yr crop rotation (maize, wheat, barley). Our results showed that N fertilisation during the grassland phase was necessary to maintain soil C and N concentrations beyond three years of crop. Temporary grassland management may affect microbial activities as indicated by contrasting polysaccharide and lignin composition. It had however, no effect on potential CO2 and N2O emissions during laboratory incubations. The biogeochemical signature of SOM was close to continuous grassland only in treatments with 6 yrs of fertilized temporary grassland. We thus, conclude that the legacy effects of a grassland phase on SOC quantity and properties of SOM depend on its management.

The paper describes the influence of liming to phosphorus and potassium accumulation in soil. The research has been carried out at the Institute of Agronomy of Latvia University of Agriculture in the long-term subsurface drainage field established in Skrīveri in 1981. The experimental field was established with four rates of mineral fertilizers: without fertilizers (F0), N45P30K45 (F1); N90P60K90 (F2), N135P90K135 (F3) and four rates of lime: without liming (L0), 2.58 (L1), 5.70 (L2), 11.40 (L3) t ha-1 CaCO3. Primary liming was done in 1981 (Estonian oil shale ashes), the maintenance liming was performed in 1994 (dolomitic limestone) and 2014 (BALTKALK). After 35 years of trial similar soil parameters showed significantly different content of phosphorus and potassium related to the different rates of liming in all fertilizing levels. Without fertilizers, the liming provided the increase of phosphorus content in soil from 14 to 36 mg kg-1, but the increase of potassium – from 55 to 72 mg kg-1. On a low background of fertilizers (N45P30K45) the content of phosphorus and potassium under liming increased respectively from 20 to 32 mg kg-1 for phosphorus and 75 to 96 mg kg-1 for potassium. At the fertilizers level N90P60K90 the content of phosphorus and potassium increased respectively from 94 to 81 mg kg-1 for phosphorus and 115 to 165 mg kg-1 for potassium. At the fertilizers level N135P90K135 the content of phosphorus and potassium increased respectively from 174 to 203 mg kg-1 for phosphorus and 166 to 214 mg kg-1 for potassium.

Soil organic carbon (SOC) is one of the main carbon reservoirs in the terrestrial ecosystem. It is important to study SOC dynamics and effects of organic carbon amendments in paddy fields because of their vest expansion in south China. A study was carried out to evaluate the relationship between the SOC content and organic carbon input under various organic amendments at a long-term fertilization experiment that was established on a red soil under a double rice cropping system in 1981. The treatments included non-fertilization (CK), nitrogen-phosphorus-potassium fertilization in early rice only (NPK), green manure (Astragalus sinicus L.) in early rice only (OM1), high rate of green manure in early rice only (OM2), combined green manure in early rice and farmyard manure in late rice (OM3), combined green manure in early rice, farmyard manure in late rice and rice straw mulching in winter (OM4), combined green manure in early rice and rice straw mulching in winter (OM5). Our data showed that the SOC content was the highest under OM3 and OM4, followed by OM1, OM2 and OM5, then NPK fertilization, and the lowest under non-fertilization. However, our analyses in SOC stock indicated a significant difference between OM3 (33.9 t ha−1) and OM4 (31.8 t ha−1), but no difference between NPK fertilization (27 t ha−1) and non-fertilization (28.1 t ha−1). There was a significant linear increase in SOC over time for all treatments, and the slop of linear equation was greater in organic manure treatments (0.276–0.344 g kg−1 yr−1) than in chemical fertilizer (0.216 g kg−1 yr−1) and no fertilizer (0.127 g kg−1 yr−1).

В статье приводится анализ изменений плодородия лугово-бурых отбеленных почв, произошедших за восемь ротаций севооборота в длительном стационарном опыте при внесении минеральных удобрений, извести и регулярном поступлении свежего органического вещества с запашкой клевера. Длительное выращивание культур в севообороте без удобрений способствует уменьшению содержание гумуса (к концу восьмой ротации севооборота его содержание снизилось с 3,67 % до 2,96 %) и по этой причине получен его отрицательный баланс, при этом годовой дефицит составил 0,08 % (2,0 т/га). Запашка в почву органической массы клевера два раза за ротацию севооборота не способствовала сохранению бездефицитного баланса гумуса. Содержание подвижного фосфора за семь ротаций севооборота достигло высокого и очень высокого уровня (15,0 35,4 мг/ 100 г) на навозно-известково-минеральном фоне, особенно с удвоенными нормами минеральных удобрений. Однако, применение различных систем удобрения в восьмой ротации севооборота не обеспечили улучшение фосфатного режима почвы. На содержание обменного калия в почве оказало положительное влияние использование агрохимических средств. Накопление подвижного калия в почве достигло максимума на навозно-известково-минеральном фоне в конце седьмой ротации 26,2 мг/100 г, в конце восьмой ротации20,5 мг/ 100 г. Внесение одних минеральных удобрений в двойных дозах оказывает небольшое подкисляющее действие в пределах 0,05 единиц. Выявлено что, совместное внесение навоза с известью и минеральными удобрениями за семь ротаций севооборота обеспечило большее снижение кислотности почвы, чем применение одной извести с минеральными удобрениями., The article presents the analysis of fertility change of the meadow-brown bleached soils which took place during eight years of the plant rotation in the course of long-term stationary experiment with application of mineral fertilizers, lime and regular introduction of fresh organic matter taken from plowed clover. Cultivation of crops applying crop rotation during long time without fertilizers promotes decrease of humus (by the end of the 8-th crop rotation its content decreased from 3,67 % tol 2,96 %) and for this reason, it got a negative balance and its annual deficit amounted to about 0,08 % (2,0 t/ha). Plowing of organic matter of clover into the soil twice in crop rotation has not contributed to preservation of deficit-free humus balance. Mobile phosphorus content during seven crop rotations has reached a high and a very high level (15.0 35.4 mg / 100 g) against the manure-lime-mineral background, especially with double norms of mineral fertilizers. However, application of various fertilizer systems in the 8-th crop rotation failed to improve the phosphate regime of the soil. Usage of agrochemicals made a positive effect upon exchangeable potassium content in the soil. Accumulation of mobile potassium in the soil peaked against the manure-lime-mineral background: 26.2 mg / 100 g at the beginning of the crop rotation and 20.5 mg / 100 g at the end of the rotation. Application of the same fertilizer of double doses has a slight acidifying effect within 0.05 units. It has been revealed that the joint application of manure with lime and mineral fertilizers during seven crop rotations had provided greater reduction in soil acidity than the use of lime only with mineral fertilizers.

Background and aims Arbuscular mycorrhizal (AM) fungi play a significant role in P nutrition of crops in agriculture, but P accumulation in the soil, e.g., application of P-fertilizer, generally reduces AM fungal colonization. The impact of long-term application of chemical fertilizer on AM fungal communities was investigated with respect to the time scale. Methods Soils were collected from four plots with different fertilizer management in the long-term experimental field established in 1914. Lotus japonicus was grown in the soils in a greenhouse, while Glycine max was grown in the plots in the field. DNA was extracted from their roots, and the diversity and community compositions were analyzed based on occurrence of the AM fungal phylotypes defined by sequence similarity in the LSU rDNA. Results The 90-year-application of N and K in the absence of P increased AM fungal diversity and resulted in formation of a distinctive fungal community compared with those in the other treatments. This effect was not cancelled by single application of P. Whereas the impact of balanced application of N, P, and K was ambiguous. Conclusion These observations suggest that the presence/absence of P-fertilizer has a major impact on AM fungal communities, but the action may appear only on a long time scale. Electronic supplementary material The online version of this article (doi:10.1007/s11104-012-1398-x) contains supplementary material, which is available to authorized users.

Interaction of organic matter (OM) with soil mineral components plays a critical role in biophysical organization (aggregate structure) as well as in biogeochemical cycling of major elements. Of the mineral components, poorly-crystalline phases rich in iron (Fe) and aluminum (Al) are highly reactive and thus contribute to both OM stabilization and aggregation. However, the functional relationship among the reactive metal phases, C stability, and aggregation remains elusive. We hypothesized that relatively young C acts as a binding agent to form the aggregates of weak physical stability, whereas the reactive metal phases and older C bound to them contribute to stronger aggregation. Using four surface horizons of Andisols having a gradient of soil C concentration due to decadal OM management, we conducted sequential density fractionation to isolate six fractions (from 2.5 g cm−3) with mechanical shaking, followed by selective dissolution and radiocarbon analysis. After 28 years of no-till with litter compost addition, not only C and N but inorganic materials including the reactive metal phases (pyrophosphate-, oxalate-, and dithionite-extractable metals) showed clear shifts in their concentrations towards lower-density fractions (especially

Este trabalho teve por objetivo avaliar e comparar os teores e as características químicas das substâncias húmicas (SHs) de um Planossolo háplico submetido a diferentes sistemas de cultivos de arroz. Amostras de solo foram coletadas em um experimento de longa duração (19 anos) nas profundidades de 0-0,025, 0,025-0,05, 0,05-0,20m e no topo do horizonte B. Os tratamentos avaliados foram: APC-Sistema de cultivo contínuo de arroz (preparo convencional) e controle de invasoras com herbicida, APD-Sucessão de azevém x arroz sob plantio direto e SN-Solo mantido em condições naturais (pastagem nativa). As SHs e a fração não-húmica (NH) foram obtidas por meio de fracionamento químico. O teor de carbono do solo e na forma de SHs e NH foram determinados, respectivamente, pelos métodos Walkley-Black e espectrofotométrico. As características químicas e moleculares das SHs foram avaliadas por espectroscopias de infravermelho e UV/Vis e por análise elementar. Em comparação ao solo natural, o sistema APD preservou os teores de carbono orgânico total e de todas as frações húmicas, enquanto que o sistema APC provocou perdas de carbono orgânico total e de todas as frações húmicas nas camadas superficiais (The objective of this study was to evaluate and compare the content and chemical characteristics of humic substances (SHs) of an Albaqualf under different soil management systems. Soil samples were collected in a long-term field experiment (19 years) from the 0-0.025; 0.025-0.05 and 0.05-0.20m layers and from the top of the B horizon. The following treatments were evaluated: APC-continuous rice crop system under conventional tillage and weed control with herbicides; APD-no-tillage system with rye-grass in the winter and rice in the summer, and SN-soil under natural condition with native grassland. The SHs and the non-humic fraction (NH) were obtained by chemical fractioning. The content of total soil carbon and those occurring as SHs and NH were determined by the Walkley-Black and spectrophotometric methods, respectively. To determine the chemical and molecular characteristics of the SHs, UV-visible and infrared spectroscopy techniques and elementar analyses were employed. In comparison to the soil under natural condition (SN), the no-tillage system (APD) maintained total soil organic carbon concentrations as well as the content of SHs. The conventional tillage reduced soil total organic carbon and the content of SH in the upper layers (

Spring barley (grain, straw), grass-clover (two cuts), winter wheat (grain, straw) and silage maize grown in the Askov long-term experiment with different levels (0, ½, 1, 1½, 2) of mineral fertiliser (NPK) and animal manure (AM) had concentrations of As, Pb, Cd and Hg below the EC maximum permissible levels for feeds. The content of As was barely detectable even in crops grown with double rate of NPK. This was also true for Hg and Ni in cereal grains. The Cd content increased linearly with NPK rate but only in crops with fresh dressings of NPK. Yet, cereal grains were low in Cd. Contents of Cd in crops grown on unmanured soil and soil with AM were similar and below that of crops grown with NPK. For a range of other elements including Cr and Ni, we found no general relationship between fertilisation rate and their concentration in the crops. Except for Cd, no systematic differences were found in the analysed metal contents between crops grown with NPK and AM. Crop contents of uranium and thallium were below the analytical detection limits regardless of nutrient source and addition rate. Thus in a farming context similar to that of the Askov experiment, the long-term application of standard rates of NPK and AM does not pose a threat in terms of feed quality. However, the long-term accumulation of heavy metals added with mineral fertilisers and animal manure is essentially irreversible and may threaten soil quality. Spring barley (grain, straw), grass-clover (two cuts), winter wheat (grain, straw) and silage maize grown in the Askov long-term experiment with different levels (0, ½, 1, 1½, 2) of mineral fertiliser (NPK) and animal manure (AM) had concentrations of As, Pb, Cd and Hg below the EC maximum permissible levels for feeds. The content of As was barely detectable even in crops grown with double rate of NPK. This was also true for Hg and Ni in cereal grains. The Cd content increased linearly with NPK rate but only in crops with fresh dressings of NPK. Yet, cereal grains were low in Cd. Contents of Cd in crops grown on unmanured soil and soil with AM were similar and below that of crops grown with NPK. For a range of other elements including Cr and Ni, we found no general relationship between fertilisation rate and their concentration in the crops. Except for Cd, no systematic differences were found in the analysed metal contents between crops grown with NPK and AM. Crop contents of uranium and thallium were below the analytical detection limits regardless of nutrient source and addition rate. Thus in a farming context similar to that of the Askov experiment, the long-term application of standard rates of NPK and AM does not pose a threat in terms of feed quality. However, the long-term accumulation of heavy metals added with mineral fertilisers and animal manure is essentially irreversible and may threaten soil quality.

International audience; Archived soil samples from the beginning and end of three long-term field trials conducted in central France were analysed for total uranium (U) and thorium (Th) contents to evaluate the effect of 15–30 yr of phosphorus (P) fertilizer treatments on the accumulation of these elements in the topsoil. For comparison, the soil samples were also analysed for total P. Three treatments were compared: no P application (P0), 26 kg P/ha/yr (P26) and 52 kg P/ha/yr (P52). Significant effects of P fertilizer were observed on U content and, to a lesser extent, on Th content as a result of the P52 treatment at two of the field trials. This effect was demonstrated both in the analyses at the end of the field trials [P52–P0: +0.25 and +0.44 mg U/kg soil, +0.58 (not significant) and +1.03 mg Th/kg soil] and when considering the changes in U and Th contents between the beginning and the end of the field trials (end–start: +0.18 and +034 mg U/kg soil, +0.35 and +0.45 mg Th/kg soil). The P fertilizer effect was also supported by the correlations of U and Th with total levels of P in the soil. However, in one of the three trials, no significant accumulation of U or Th because of fertilizer could be seen, suggesting either that less U and Th were applied using a different P fertilizer and/or that soil heterogeneity masked significant effects.

The objective of this study was to compare the effects of repeated field applications of three urban compost amendments and one farmyard manure amendment over a 9-year period on aggregate stability in a silty loam soil initially characterized by low clay and initial organic matter contents and poor aggregate stability. Three different aggregate stability tests with increasing disruptive intensities (fast wetting > mechanical breakdown > slow wetting tests) and different disaggregation mechanisms, were used. All of the amendments, which were applied at approximately 4 Mg C ha−1 every other year, increased the organic carbon content and improved the stability of the aggregates against the disruptive action of water, as determined by each of the stability tests. However, the year-to-year variations in the aggregate stability that related to factors other than the organic inputs were greater than the cumulative increase in aggregate stability relative to the control. The positive effects of the tested amendments on aggregate stability were linked to their contribution to soil organic C contents (r = 0.54 for the fast wetting test and r = 0.41–0.42 for the mechanical breakdown and slow wetting tests; p

The aim of this work was to estimate the changes in contents of different sulfur (S) fractions in soils under lowering inputs of S from emissions together with the influence of organic and mineral fertilizing. Soil samples from long-term field experiments were used for this purpose. The samples were taken from 10 sites from precise long-term field experiments with different soil-climatic conditions in the Czech Republic. The samples were analyzed using the following fractionation: i) water soluble S (H2O extracts), ii) sorbed S (0.032M NaH2PO4 extracts) and iii) S occluded with carbonates (1M HCl extract). Furthermore, the concentration of total S (Stot) and organic S (Sorg) was determined. Soil samples were taken in the years 1981 and 2007. During 26 years a decreases of Stot by about 3-8%, water soluble S by 65-68 % and sorbed S by 39-44 % was observed in the topsoil of the evaluated soils. Furthermore, a low increase in the organic S content (Sorg) was observed. The estimated ratio of Sorg reached 78.7-80.9% from Stot in the year 1981 and 87.7-89.8 % in 2007. Farmyard manure (40 t.ha-1) applied every 4 years did not have a significant influence on S fractions and Stot contents in soils. Intensive S fertilizing increased Stot and mobile S forms contents in the soils.

The effects at medium term of repeated compost spreading on cultivated soil on the physico-chemical characteristics and biologicalactivity, including soil microflora and earthworm population, have been studied in a field experiment started in 1998. The composts areorganic amendments that increased soil fertility. They brought also small concentrations in heavy metals (HM) and organic micropollutants(Polycyclic aromatic hydrocarbons, PAH). Their repeated applications could disturb the biological functioning of a soil, in relationwith progressive accumulation of pollutants. After 9 years of experimentation, 5 spreading of sludge compost and municipal solid wastecompost have modified physico-chemical characteristics of soil such as pH, organic matter contents… Total Cu and Zn concentrationsin soil also significantly increased. Such evolution was not noticeable for the other HM and PAH. The PAH concentration in soil correspondedto usual concentrations found in cultivated soils. The particulate organic matter [50 μm -5 mm] increased in soil after compostapplication, mainly with sludge compost. The HM and PAH concentrations were larger in this particulate organic matter compared to totalsoil. The fraction of HM extractable with EDTA increased compared to control more than total HM in soil receiving composts. Howeverthe exchangeable fraction of HM (< 1 % total HM) was mitigated by the effect of compost on soil pH. The effects of compost applicationon microflora and earthworm population are presented in other papers of the present journal., Se evaluaron los efectos a mediano plazo del reciclaje en agricultura de compostes sobre las características físico-químicas y el componentebiológico de los suelos cultivados, incluyendo microflora y fauna en un ensayo de campo establecido en 1998. Los compostesestán sobre todo materias orgánicas cuyas aporte aumenta la fertilidad y la actividad biológica del suelo. Pero están también vectoresde contaminantes orgánicos y metálicos (ETM) en pequeñas concentraciones. Sus aplicaciones repetidas podrían tener un efectoperturbador sobre el funcionamiento biológico de los suelos, en razón del cúmulo de pequeñas dosis de contaminantes. Después de9 años de experimentación, 5 esparcimientos de compostes de lodo (DVB) y de basuras domesticas residuales (OMR) condujeron auna diferenciación de las características físico-químicas de los suelos como el pH, los contenidos en C y N orgánico. Los aportes decompostes aumentaron significativamente contenidos en Cobre y en Zinc total en los horizontes de superficie. Esta evolución está pocoo no visible para los otros ETM.Los esparcimientos de compostes aumentan el compartimento de materia orgánica particular (50 μm – 5 mm) liviana, separada porfraccionamiento granulo-densimétrico, sobre todo en el tratamiento DVB. Esta fracción está más rica en materia orgánica y en ciertosETM. Los aportes de compostes aumentan los ETM extractables al EDTA (fracción potencialmente disponibles de manera más marcadaque los ETM totales). En cambio, las proporciones d’ETM intercambiables los mas disponibles (menos de 1 % de los ETM totales), semodulan por los efectos de los compostes sobre el pH del suelo., Les effets à moyen terme du recyclage en agriculture de composts sur les caractéristiques physico-chimiques et la composante biologique de sols cultivés, incluant microflore et faune, ont été évalués dans un essai au champ mis en place en 1998. Les composts sont avant tout des matières organiques dont l’apport augmente la fertilité et l’activité biologique du sol. Mais ils sont aussi vecteurs de polluants organiques et métalliques (ETM) en faibles concentrations. Leurs applications répétées pourraient avoir un effet perturbateur sur le fonctionnement biologique des sols, en raison du cumul de faibles doses de polluants. Après 9 ans d’expérimentation, 5 épandages de composts de boue (DVB) et d’ordures ménagères résiduelles (OMR) ont conduit à une différenciation des caractéristiques physico-chimiques des sols comme le pH, les teneurs en C et N organique. Les apports de composts ont augmenté significativement les teneurs en Cuivre et Zinc total dans les horizons de surface. Cette évolution est peu ou pas visible pour les autres ETM.Les épandages de composts augmentent le compartiment de matière organique particulaire [50 μm -5 mm] légère, séparée par fractionnement granulo-densimétrique, surtout dans le traitement DVB. Cette fraction est plus riche en matière organique et en certains ETM. Les apports de composts augmentent les ETM extractibles à l’EDTA (fraction potentiellement mobilisable) de façon plus marquée que les ETM totaux. En revanche, les proportions d’ETM échangeables les plus disponibles (moins de 1 % des ETM totaux), sont modulées par les effets des composts sur le pH du sol. Les concentrations en HAP sont de l’ordre de grandeur des concentrations mesurées dans les sols cultivés. Les concentrations en HAP sont supérieures dans les matières organiques particulaires qui concentrent ces polluants sans différence significative entre les traitements. Les résultats des effets sur les composantes biologiques du sol sont présentés dans 2 autres articles de cette même revue.

Este trabalho teve por objetivo avaliar e comparar os teores e as características químicas das substâncias húmicas (SHs) de um Planossolo háplico submetido a diferentes sistemas de cultivos de arroz. Amostras de solo foram coletadas em um experimento de longa duração (19 anos) nas profundidades de 0-0,025, 0,025-0,05, 0,05-0,20m e no topo do horizonte B. Os tratamentos avaliados foram: APC-Sistema de cultivo contínuo de arroz (preparo convencional) e controle de invasoras com herbicida, APD-Sucessão de azevém x arroz sob plantio direto e SN-Solo mantido em condições naturais (pastagem nativa). As SHs e a fração não-húmica (NH) foram obtidas por meio de fracionamento químico. O teor de carbono do solo e na forma de SHs e NH foram determinados, respectivamente, pelos métodos Walkley-Black e espectrofotométrico. As características químicas e moleculares das SHs foram avaliadas por espectroscopias de infravermelho e UV/Vis e por análise elementar. Em comparação ao solo natural, o sistema APD preservou os teores de carbono orgânico total e de todas as frações húmicas, enquanto que o sistema APC provocou perdas de carbono orgânico total e de todas as frações húmicas nas camadas superficiais (

8 pages, figures, and tables statistics., We studied the effects of long-term organic and mineral fertilization on soil microarthropods and soil chemical parameters in a field experiment under semi-arid conditions in Central Spain. Two different regimes of organic manuring, i.e. farmyard manure applied once in 3 years versus annual manuring with crop residues were compared. Soil carbon and nitrogen contents were increased markedly by farmyard manure, whereas straw and green manure had no significant effect. In contrast, the abundance of soil microarthropods was increased by annual application of straw and green manure, but not by farmyard manure last applied 2.5 years before sampling.We conclude that in the field experiment under study the abundance of soil microarthropods was influenced by the immediate food supply rather than by soil chemical parameters, such as carbon and nitrogen content or the pH. Biodiversity of soil microarthropods, as estimated by the Shannon index, was not affected significantly by straw and green manure. Obviously, other management practices, especially tillage, are limiting the species composition of soil microarthropods and thereby overshadow possible effects of fertilization on diversity., We are grateful to Dr. Elke Schulz (Centre for Environmental Research, Leipzig-Halle) for doing the soil chemical analysis and to the staff of ‘‘La Higueruela’’ experimental station for supporting us during our field work. The first author was supported by the German Academic Exchange Service (code D/01/02687).

Genetically modified microorganisms (GMMs) with enhanced biocontrol activity are attractive to apply in agriculture. To investigate potential ecological risks of field introduction of GMMs, effects of P. putida strain WCS358r and two genetically modified derivatives of this strain on the indigenous microflora of wheat were investigated. The two modified strains produce phenazine-1-carboxylic acid (P. putida WCS358r::phz) or 2,4-diacetylphloroglucinol (P. putida WCS358r::phl), compounds known to be active against plant pathogenic microorganisms. The strains were applied as seed coating on wheat seeds and field trials were performed in 1999, 2000, 2001, and 2002. Treatments were introduced in the same plots in all years. The effects of the GMMs on the microflora were compared with effects of the parental strain, an untreated control and effects resulting from a common agricultural practice, crop rotation of wheat and potato. Denaturing gradient gel electrophoresis (DGGE) was used to detect changes in community profiles. In the first year, all bacterial treatments transiently affected the composition of the bacterial communities, without differences between the wild-type and the GMMs. After reintroduction, the DAPG-producing GMM influenced the bacterial microflora significantly different from the wild type in the following years. The PCA-producing derivative of WCS358r showed an effect different from the parental strain only after four consecutive introductions. Cropping potato in alternation with wheat had a lasting effect on the bacterial communities compared to continuous wheat cropping. Throughout this long-term field trial, effects of the GMMs never exceeded those of the crop rotation. Specific bacterial species that were affected by the introduction of GMMs were also identified by using additional molecular techniques. PCR-amplified DNA of rhizosphere samples was hybridized to Affymetrix GeneChips® containing 16S rDNA sequences of approximately 9000 operational taxonomic units (OTUs), representative of specific bacterial species. Cluster analysis of DGGE banding patterns and GeneChip data gave similar results, in agreement with the data described in Chapter 3. Neither P. putida WCS358r, nor the GMMs led to loss of any bacterial species identified. Some bacterial species were even stimulated by all bacterial treatments; a few were stimulated only by the DAPG-GMM. Bacteria-specific 16S rDNA amplicons of rhizosphere samples from 2002 treated with the wild type or the DAPG-producing strain were also analyzed using suppression subtractive hybridization (SSH). With this technique it is possible to identify unique sequences in one of two DNA samples. In a test system it was demonstrated that SSH can be applied to rhizosphere samples, since unique DNA sequences derived from digested phage ? X174 were detected after subtraction of a rhizosphere sample spiked with phage DNA against a non-spiked rhizosphere sample. However, when SSH was applied to rhizosphere samples treated with the wild type or the DAPG-producing strain, no obvious differences were detected. Apparently, this technique is not sufficiently optimized to identify shifts in microbial communities in these selected samples. Repeated introduction of genetically modified, antibiotic-producing Pseudomonas bacteria led to only transient effects on the soil microflora that are minor compared to natural variation in soil properties and crop species grown.

Genetically modified microorganisms (GMMs) with enhanced biocontrol activity are attractive to apply in agriculture. To investigate potential ecological risks of field introduction of GMMs, effects of P. putida strain WCS358r and two genetically modified derivatives of this strain on the indigenous microflora of wheat were investigated. The two modified strains produce phenazine-1-carboxylic acid (P. putida WCS358r::phz) or 2,4-diacetylphloroglucinol (P. putida WCS358r::phl), compounds known to be active against plant pathogenic microorganisms. The strains were applied as seed coating on wheat seeds and field trials were performed in 1999, 2000, 2001, and 2002. Treatments were introduced in the same plots in all years. The effects of the GMMs on the microflora were compared with effects of the parental strain, an untreated control and effects resulting from a common agricultural practice, crop rotation of wheat and potato. Denaturing gradient gel electrophoresis (DGGE) was used to detect changes in community profiles. In the first year, all bacterial treatments transiently affected the composition of the bacterial communities, without differences between the wild-type and the GMMs. After reintroduction, the DAPG-producing GMM influenced the bacterial microflora significantly different from the wild type in the following years. The PCA-producing derivative of WCS358r showed an effect different from the parental strain only after four consecutive introductions. Cropping potato in alternation with wheat had a lasting effect on the bacterial communities compared to continuous wheat cropping. Throughout this long-term field trial, effects of the GMMs never exceeded those of the crop rotation. Specific bacterial species that were affected by the introduction of GMMs were also identified by using additional molecular techniques. PCR-amplified DNA of rhizosphere samples was hybridized to Affymetrix GeneChips® containing 16S rDNA sequences of approximately 9000 operational taxonomic units (OTUs), representative of specific bacterial species. Cluster analysis of DGGE banding patterns and GeneChip data gave similar results, in agreement with the data described in Chapter 3. Neither P. putida WCS358r, nor the GMMs led to loss of any bacterial species identified. Some bacterial species were even stimulated by all bacterial treatments; a few were stimulated only by the DAPG-GMM. Bacteria-specific 16S rDNA amplicons of rhizosphere samples from 2002 treated with the wild type or the DAPG-producing strain were also analyzed using suppression subtractive hybridization (SSH). With this technique it is possible to identify unique sequences in one of two DNA samples. In a test system it was demonstrated that SSH can be applied to rhizosphere samples, since unique DNA sequences derived from digested phage ? X174 were detected after subtraction of a rhizosphere sample spiked with phage DNA against a non-spiked rhizosphere sample. However, when SSH was applied to rhizosphere samples treated with the wild type or the DAPG-producing strain, no obvious differences were detected. Apparently, this technique is not sufficiently optimized to identify shifts in microbial communities in these selected samples. Repeated introduction of genetically modified, antibiotic-producing Pseudomonas bacteria led to only transient effects on the soil microflora that are minor compared to natural variation in soil properties and crop species grown.

A long-term field experiment was conducted to determine the effect of the additions of urban waste compost on the physical and chemical properties and enzymatic activities in a calcareous soil (Fluventic Xerochrept). Total Porosity (pores >50 pm measured on thin soil sections from undisturbed samples by image analysis) was greater in the plots treated with compost than the control plots due to a larger amount of elongated pores. In the amended plots total and humified organic C, Pb, Cu, and Zn showed a significant increase compared with nonamended plots. Enzymatic activities (L-asparaginase, arylsulphatase, dehydrogenase, phosphodiesterase, and alkaline phosphomonoesterase) were significantly enhanced by the compost addition thus indicating no inhibiting influence of the heavy metals present. The increased levels of the arylsulphatase, dehydrogenase, phosphodiesterase, and phosphomonoesterase activities were significantly correlated with total porosity: the first three with pores ranging from 50 to 1000 {mu}m, mainly with pores 50 to 200 {mu}m in size and phosphomonoesterase only with pores whose size was