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Abstract: Tillage treatments had impact on total soil nitrogen (N) storage and consequently on soil carbon (C) sequestration. The objective of this study was to assess effects of long-term (1992–2010) tillage practices, including a partial-width tillage system (paraplow) on N concentration and stratification. The tillage treatments were: no-tillage (NT), minimum tillage (18–22cm depth) with chisel plow (MT), conventional tillage (25–30cm depth) with mouldboard plow (CT) and zone-tillage subsoiling (25–30cm) with a paraplow (ZT) applied in alternate years in rotation with NT. The soil was a Calcic Haploxeralf from Central Spain. The crop rotation was chick pea (Cicer arietinun L.) cv. Inmaculada/barley (Hordeum vulgare L.) cv. Volley. The equivalent mass approach was used to compare N stocks in the various tillage methods. Tillage treatments had significant effects on soil bulk density and no-till increased soil bulk density of the top layer. At the end of 19 years, the stocks of N had increased under NT compared with MT and CT. Most changes occurred within the 0–5cm layer, where plots under NT had 0.48MgNha−1 and 0.53MgNha−1 greater than in MT and CT, respectively. Zone tillage maintained most of the long-term benefit of NT in increasing N stocks in the top layer (0–5cm). At the end of the experiment, total N concentration in the 0–5cm depth under ZT was 42% and 53% higher that under MT and CT, respectively. Stratification ratios of N from 1992 to 2000 showed no significant differences between NT, MT and CT. In contrast, from 2001 onwards, all stratification ratios were significantly higher in NT than in the other two tillage systems. In addition, in 2010 the stratification ratio of N in NT was >2 and more than 2-fold those obtained in MT and CT. Values of stratification ratios under ZT followed the same trend than under NT and were significantly greater than under MT or CT. These greater stratification ratios of N observed under NT and ZT confirm, in the soil studied, not only the benefits associated with the long-term application of no-till in increasing total N in the top layer, but also the positive impact of the use of a paraplow as a rotational tillage system. [Copyright &y& Elsevier]

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

Abstract: The paper describes a simplified carbon balance model, derived from the CANDY model, which works in annual time steps requiring only clay content, soil type of the German classification system “Reichsbodenschätzung”, average air temperature and rainfall as site characteristics, a value for organic carbon content as the initial value as well as crop yield and organic matter amendments as management data. The Candy Carbon Balance (CCB) model has been validated using a dataset from 40 long-term experiments situated in Central Europe including 391 treatments with a total number of 4794 Corg observations. Statistical measures to prove model validity were mean error (ME=−0.001) and root mean square error (RMSE=0.119). In addition a number of tests were performed to make sure that the model has no systematic error for different types of site conditions and management activities. After this successful validation the CCB model is considered applicable for advisory service for arable fields on a wide range of site conditions. Due to the poor representation of clay soils in this study some more model tests on these soils would be recommendable. [Copyright &y& Elsevier]

Abstract: Sandstone samples of the Stuttgart Formation at Ketzin have been experimentally treated with CO2 and synthetic reservoir brine in high-quality steel autoclaves at simulated in situ P-T conditions of 5.5 MPa and 40 °C. In order to observe mineralogical changes induced by CO2, untreated samples are compared to CO2-treated ones. Samples show a comparable petrography of mainly quartz and plagioclase. Heterogeneities are related to minor mineral phases, such as K-feldspar, hematite, muscovite, biotite, illite, chlorite, and opaque phase(s). This variability of the Stuttgart Formation is primarily attributed to the sandstone sedimentation in a meandering, fluvial environment. The samples are weakly consolidated. Analcime, anhydrite and dolomite are only found as cement phases. SEM micrographs of CO2-treated samples show corrosion textures on mineral surfaces of anorthitic plagioclase and K-feldspar, as well as euhedral albite crystals. Overall, the data indicate preferred dissolution of calcium-rich plagioclase, K-feldspar and anhydrite, and stabilization or precipitation of albite. The petrophysical properties of the sandstone samples also show slight changes. Nuclear magnetic resonance (NMR) and mercury injection measurements indicate a slightly increased porosity and a shift to larger pore sizes; both suggesting dissolution processes. [Copyright &y& Elsevier]

Copyright of Journal of Central European Agriculture is the property of Journal of Central European Agriculture and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: Carbon sequestration in tropical soils has potential for mitigating global warming and increasing agricultural productivity. We analyzed 26 long-term experiments (LTEs) in different agro-climatic zones (ACZs) of India to assess the potential and cost of C sequestration. Data on initial and final soil organic C (SOC) concentration in the recommended N, P and K (NPK); recommended N, P and K plus farmyard manure (NPK+FYM) and unfertilized (control) treatments were used to calculate carbon sequestration potential (CSP) i.e., capacity to sequester atmospheric carbon dioxide (CO2) by increasing SOC stock, under different nutrient management scenarios. In most of the LTEs wheat equivalent yields were higher in the NPK+FYM treatment than the NPK treatment. However, partial factor productivity (PFP) was more with the NPK treatment. Average SOC concentration of the control treatment was 0.54%, which increased to 0.65% in the NPK treatment and 0.82% in the NPK+FYM treatment. Compared to the control treatment the NPK+FYM treatment sequestered 0.33MgCha−1 yr−1 whereas the NPK treatment sequestered 0.16MgCha−1 yr−1. The CSP in different nutrient management scenarios ranged from 2.1 to 4.8MgCha−1 during the study period (average 16.9 yr) of the LTEs. In 17 out of 26 LTEs, the NPK+FYM treatment had higher SOC and also higher net return than that of the NPK treatment. In the remaining 9 LTEs SOC sequestration in the NPK+FYM treatment was accomplished with decreased net return suggesting that these are economically not attractive and farmers have to incur into additional cost to achieve C sequestration. The feasibility of SOC sequestration in terms of availability of FYM and other organic sources has been discussed in the paper. [ABSTRACT FROM AUTHOR]

Abstract: Changes in the agricultural management can potentially increase the accumulation rate of soil organic carbon (SOC), thereby sequestering CO2 from the atmosphere. In a long-term experiment (1992–2008) we examined the effects of various tillage intensities: no-tillage (NT), minimum tillage with chisel plow (MT), and conventional tillage with mouldboard plow (CT), on the topsoil profile distribution (0–30cm) of SOC, on a semi-arid loamy soil from Central Spain. The crop sequence established was cheap pea (Cicer arietinun L.) cv. Inmaculada/barley (Hordeum vulgare L.) cv. Volley. Soil organic carbon in the various tillage treatments was expressed on a content bases and the equivalent soil mass approach. Measurements made at the end of 17 years showed that in the 0–30cm depth, stocks of SOC had increased under NT compared with MT and CT. Most dramatic changes occurred within the 0–5cm layer where plots under NT had 5.8 and 7.6Mgha−1 more SOC than under MT or CT respectively. No-tillage plots, however, exhibited strong vertical gradients of SOC with concentrations decreasing from 0–5 to 20–30cm. Stratification ratios of SOC in 1992 showed no significant differences between tillage systems. On the contrary, from 1993 onwards all stratification ratios were significantly higher in NT than in the other two tillage systems. In addition, since 2003 stratification ratios of SOC obtained under NT were systematically >2 and more than 2-fold those obtained under MT and CT. Stratification ratios >2 are uncommon under degraded conditions and could suggest that NT management system may have the most benefits to soil quality in semi arid regions with low native soil organic matter. [Copyright &y& Elsevier]

Abstract: No-till (NT) management greatly reduces soil physical disturbance and can result in a stratification of nutrients and organic matter in the soil profile due to the retention of crop residues on the soil surface potentially affecting the dynamics of microbial interactions in the soil. Microbial abundance and diversity can be used to assess the relative impact of management on the long-term sustainability of cropping systems. The objective of this study was to assess the impact of long-term NT vs. conventional tillage (CT) management on soil microbial community structure at four different sites on the Canadian prairies using phospholipid fatty acid analysis (PLFA) and DNA fingerprinting. Analysis of 16S and 18S rDNA using denaturing gradient gel electrophoresis revealed high inherent variability within bacterial and fungal community fingerprints among replicate field plots. Differences in bacterial and fungal phylogeny were related to depth in the soil profile but not to tillage management. Abundance of individual PLFA biomarkers were 7 to 86% greater in NT surface soils (0- to 5-cm depth), except at the Ellerslie site in 2005 where biomass was greater in CT. Responses at the 5- to 10-cm and 10- to 15-cm depths were more varied, in some cases with greater biomass in CT than NT soils. Ordination analysis of PLFA profiles showed clear community separation with depth but not tillage. Physiological stress biomarkers were correlated with simple measures of nutrient concentration and indicated that resource availability was likely the main factor determining community structure. It was concluded that tillage disturbance was not an overriding factor in determining microbial community composition in the long-term NT and CT soils studied. Further study of the interaction of cropping frequency with tillage management is needed to understand the effects of tillage disturbance on microbial turnover of plant derived residues. [ABSTRACT FROM AUTHOR]

Abstract: For carbon sequestration estimates it is necessary to evaluate effects of management practices on soil organic carbon (SOC) and nitrogen (SON) dynamics in a wide range of production systems and climatic zones. At higher latitudes with cold temperate climate, crop rotations dominated by forage are common and often highly productive—and the climate as well as the forage cropping systems favour large stocks of SOC and SON. The objective of this study was to estimate SOC and SON stock dynamics in the arable layer (0–25cm) for different 6-year forage-based rotations using sampling data from three long-term field experiments in Northern Sweden. At the site with the lowest initial amount of SOC (8.2kgCm−2), SOC stocks increased by 12gCm−2 yr−1 over a 50-year period for the continuous forage rotation (‘A’), which received ca. 10Mgha−1 of cattle manure per year (wet mass). At the same site, SOC stocks were more or less at steady state in rotation ‘B’ with 4 years of forage and 2 years of annuals, receiving the same amount of manure. For rotation ‘C’ with 3 years of forage and receiving ca. 6.5Mgha−1 of manure, the SOC stocks decreased by 18gCm−2 yr−1, while the SOC stocks for rotation ‘D’ with only annuals and no manure application decreased by 24gCm−2 yr−1. At the other two sites, with higher initial SOC stocks (12.1 and 12.8kgCm−2), the SOC stocks in all treatments decreased during a 30-year period, at a rate ranging from 11 to 95gCm−2 yr−1. Similar trends were found for the change in SON stocks, although they were more variable. The topsoil SOC stocks were high compared to southern Sweden and regions of similar climate in northeast Canada, in particular for rotation A. These results indicate that the estimates of SOC and SON storage rate changes for a particular management system van vary widely within a small region of a given climatic zone. [Copyright &y& Elsevier]

Common agricultural practices such as excessive use of agro-chemicals, deep tillage and luxury irrigation have degraded soils, polluted water resources and contaminated the atmosphere. There is increasing concern about interrelated environmental problems such as soil degradation, desertification, erosion, and accelerated greenhouse effects and climate change. The decline in organic matter content of many soils is becoming a major process of soil degradation, particularly in European semi-arid Mediterranean regions. Degraded soils are not fertile and thus cannot maintain sustainable production. At the same time, the production of urban and industrial organic waste materials is widespread. Therefore, strategies for recycling such organic waste in agriculture must be developed. Here, we review long-term experiments (3-60 years) on the effects of organic amendments used both for organic matter replenishment and to avoid the application of high levels of chemical fertilizers. The major points of our analysis are: (1) many effects, e.g. carbon sequestration in the soil and possible build-up of toxic elements, evolve slowly, so it is necessary to refer to long-term trials. (2) Repeated application of exogenous organic matter to cropland led to an improvement in soil biological functions. For instance, microbial biomass carbon increased by up to 100% using high-rate compost treatments, and enzymatic activity increased by 30% with sludge addition. (3) Long-lasting application of organic amendments increased organic carbon by up to 90% versus unfertilized soil, and up to 100% versus chemical fertilizer treatments. (4) Regular addition of organic residues, particularly the composted ones, increased soil physical fertility, mainly by improving aggregate stability and decreasing soil bulk density. (5) The best agronomic performance of compost is often obtained with the highest rates and frequency of applications. Furthermore, applying these strategies, there were additional beneficial effects such as the slow release of nitrogen fertilizer. (6) Crop yield increased by up to 250% by long-term applications of high rates of municipal solid waste compost. Stabilized organic amendments do not reduce the crop yield quality, but improve it. (7) Organic amendments play a positive role in climate change mitigation by soil carbon sequestration, the size of which is dependent on their type, the rates and the frequency of application. (8) There is no tangible evidence demonstrating negative impacts of heavy metals applied to soil, particularly when high-quality compost was used for long periods. (9) Repeated application of composted materials enhances soil organic nitrogen content by up to 90%, storing it for mineralization in future cropping seasons, often without inducing nitrate leaching to groundwater. [ABSTRACT FROM AUTHOR]

Abstract: Loss of organic C from tilled agricultural soils has generated interest in C-sequestration in soils. The effects of nutrient and organic inputs on soil organic carbon (SOC) and total nitrogen (TN) stocks were studied in three 23–25-year-old long-term conventional tillage fertility experiments (LTFEs) in the Nepal terai. The sites differed in soil texture and were cropped annually to rice (Oryza sativa L.) and wheat (Triticum aestivum L.). Treatments were control (unfertilized), recommended NPK, and farmyard manure (FYM; 4Mgdrywt./crop) at all sites, plus FYM (4Mgha−1 year−1) or chopped wheat straw (8Mgdrywt.ha−1 year−1) plus N to rice and NPK to wheat at Parwanipur. Small areas of unfertilized grassland created at the same time as the LTFEs were sampled to provide a no-tillage comparison. Soil samples were collected at 15cm intervals to a depth of 60cm. In general, SOC and TN stocks were highest in the FYM treatment and the grassland, intermediate in treatments with residue return or reduced FYM inputs and lowest in the control and NPK treatments. Differences in SOC and TN stocks were found in the top 30cm of soil at Bhairahawa but only in the top 15cm at the other two sites. Application of inorganic nutrients increased SOC and TN only at Bhairahawa, which had the highest silt+clay content and where severe P deficiency was observed without fertilization. SOC stocks to 60cm at Bhairahawa were 33.5, 36.8 and 53.1MgCha−1 for the control, NPK, and FYM treatments, respectively, on an equal soil mass basis. The SOC stock in the NT-grassland was 51.8Mgha−1, similar to that in the FYM treatment. Stocks of SOC and TN were anomalously high at Tarahara but differences between treatments were similar to those at Parwanipur, which had a similar soil texture. Retention of added carbon over the duration of the experiment was about 10% for FYM and 4.5% for wheat straw. It was estimated that 47% of the original soil C under native forest had been lost from the NPK treatments at Bhairahwa and Parwanipur and that recovery was to 71–76% of the forest value with addition of FYM. However, the rates of FYM used would not be achievable at a landscape scale. Given these results, shifting to no-tillage agriculture is probably the most practical option for increasing SOC and TN stocks. [Copyright &y& Elsevier]

Abstract: In agricultural systems, soils are subjected to a range of stresses which may affect soil physical and biological properties and compromise the ability of the soil to function. How the soil responds to stress both initially and over time defines resistance and resilience respectively and is key to sustainable soil management. As soil organic matter (OM) is a fundamental soil property, we hypothesised that resilience would be controlled, in part, by this. As soil OM is itself affected by long-term soil management, we therefore sought to establish a direct link between this and resilience to physical and biological stresses. Fifteen soils were taken from a range of arable and grassland sites in England, including the Broadbalk and Highfield long-term experiments at Rothamsted. The soils were subjected to physical (uniaxial compaction stress) or biological (transient heat stress or persistent Cu stress) stresses in the laboratory and the effects on general physical (void ratio) and biological (substrate-induced respiration) functions were monitored over a recovery period of up to 28 days. Wet–dry and freeze–thaw cycles were also imposed on the soils following the initial recovery after compression. The initial recovery of void ratio following compression was greater in grassland soils (0.28–0.80) than arable soils (0.16–0.58) which was probably related to the elastic effect of particulate OM and the redistribution of the greater water content in the former soils. Wet–dry and freeze–thaw cycles had an additional effect in soils with clay contents greater than 26%. The transient heat stress reduced respiration rates in the grassland soils by up to 45%. Grassland soils are less likely to have been subjected to heat stress in the field since they carry a greater vegetation covering than arable soils. The more persistent Cu stress reduced respiration rates in arable soils by up to 85% but only up to 30% in grassland soils. The difference was ascribed to the greater microbial biomass and diversity in grassland soils and buffering by the OM. We defined resistance and resilience indices as the absolute value of the measured soil functions at maximum stress and after the recovery period respectively. Reasonable linear regressions (adjusted R 2 up to 0.68) were established for resistance or resilience as a function of soil OM content, used as a proxy index of soil management. Expressed in this way, grassland soils were more resistant and resilient to the physical and biological stresses than the arable soils. Linear relationships were also found to link physical and biological resistance and resilience (adjusted R 2 up to 0.96). An arable soil with 65% clay was found to be highly resilient also. We found large differences in physical and biological resilience to stress between arable and grassland soils. We attributed this primarily to the effect of soil management on the OM content, although we recognised the importance of clay content. [Copyright &y& Elsevier]

A recent report of widespread declines in soil organic C (SOC) in the UK over the 10–25 years until the early 2000s has focussed attention on the importance of resampling previously characterized sites to assess long-term trends in SOC contents and the importance of soils as a potentially volatile and globally significant reservoir of terrestrial C. We have used two sets of long-term experimental plots which have been under constant and known management for over a century and for which historical data exist that allow comparison over recent decades to determine what, if any, changes in SOC content have occurred. The plots used are the Palace Leas (PL) Meadow Hay Plots in north-east England (UK) established in 1897, and from the Park Grass (PG) Continuous Hay experiment established in 1856 at Rothamsted in south-east England. Collectively, these plots represent the only grassland sites in the UK under long-term management where changes in SOC over several decades can be assessed, and are probably unique in the world. The plots have received different manure and fertilizer treatment and have been under known management for at least 100 years. In 1982, total SOC contents were determined for the 0–27 cm layer of six of the PL plots using measurements of SOC concentrations, bulk density and soil depth. In 2006, the same six PL plots were resampled and SOC contents determined again. Four of the plots showed no net change in SOC content, but two plots showed net loss of SOC of 15% and 17% (amounting to decreases of 18 and 15 t C ha−1) since 1982. However, these differences in total SOC content were in a similar range to the variations in bulk density (6–31%) with changing soil water content. In 1959, the soil masses and SOC concentrations to 23 cm depth were measured on six PG plots with fertilizer and manure treatments corresponding closely with those measured on PL. In 2002, the SOC concentrations on the same plots were measured again. On three of the PG plots, SOC concentrations had declined by 2–10%, but in the other three it had increased by 4–8% between 1959 and 2002. If it is assumed that the soil bulk density had not changed over this period, the losses of SOC from the top soils ranged range from 10 to 3 t C ha−1, while the gains ranged from 4 to 7 t C ha−1. When the differences with time in SOC contents for the six PL and the six PG plots were examined using paired t-tests, that is, regarding the plots as two sets of six replicate permanent grasslands, there were no significant differences between 1982 and 2006 for the PL plots or between 1959 and 2002 for the PG plots. Thus, these independent observations on similar plots at PL and PG indicate there has been no consistent decrease in SOC stocks in surface soils under old, permanent grassland in England in recent decades, even though meteorological records for both sites indicate significant warming of the soil and air between 1980 and 2000. Because the potential influences of changes in management or land use have been definitively excluded, and measured rather than derived bulk densities have been used to convert from SOC concentrations to SOC amounts, our observations question whether for permanent grassland in England, losses in SOC in recent decades reported elsewhere can be attributed to widespread environmental change. [ABSTRACT FROM AUTHOR]

Aim Western mosquitofish ( Gambusia affinis) have been linked with the decline of native fish and amphibians throughout the world. Separation along the temperature niche axis may promote the long-term coexistence of introduced western mosquitofish, with native species in temperate regions. Recent research has shown that western mosquitofish can reduce the recruitment of native least chub ( Iothichthys phlegethontis) endemic to the Bonneville Basin. We tested the hypotheses that cold temperatures (≤ 15 °C in the summer, freezing winters) would: (1) reduce the aggressive and predatory effects of western mosquitofish on least chub, and (2) eliminate the overwinter survival and recruitment of western mosquitofish while having little effect on least chub recruitment. Location Bonneville Basin of Utah, USA. Methods We used short-term tests in the laboratory at the level of individuals and manipulated temperature (warm, cold and seasonal treatments) in long-term experiments using mesocosms at the population level. Results Cold temperatures (≤ 15 °C) reduced the aggression and predation of western mosquitofish on least chub at the level of individuals. At the population level, however, cool summers (≤ 15 °C) eliminated recruitment in both species because they required warm summers ( c. 20–30 °C) to survive freezing winters. Although least chub had an overwinter advantage in survival (75% least chub, 45% western mosquitofish), it was overwhelmed by the rapid reproduction of western mosquitofish as temperatures increased in the summer. Main conclusions Studies at the level of populations are necessary to understand the ultimate effects of introduced species on native taxa. Separation along the temperature niche axis was not sufficient to promote coexistence between these species in habitats with warm summers ( c. 30 °C). Although coexistence may be possible in habitats with cool summers (≤ 20 °C) and freezing winters, the ability of niche separation to promote long-term coexistence between native and introduced species may ultimately depend on their respective rates of evolution. Long-term coexistence may not be possible if introduced species can adapt to new environmental conditions faster than native species can evolve mechanisms to reduce their harmful effects. [ABSTRACT FROM AUTHOR]

No-till farming and manure application are means of storing carbon in soil and increasing soil quality. However, the organic fertilization of no-till soils may sustain subtropical agroecosystems for only a limited period until the soil quality declines. The C, N, P, and other nutrient cycles are perturbed due to the nutrient imbalance in manures and their application on the soil surface, which poses a risk for nutrient dispersion into the environment. Long-term N-based manure application also impacts the apparent nutrient recovery (ANR) by crops and, hence, the crop quality. Our objective was to monitor changes in soil quality and to measure nutrient recovery from N-based organic fertilization in a Brazilian agroecosystem. A long-term experiment was established in May 2004 on Typic Hapludalf soil in Southern Brazil. The experiment comprised two periods: 2004–2009 and 2009–2020. The treatments were unfertilized (control), pig slurry, pig deep litter (swine manure and rice husk), cattle slurry, and mineral fertilizer (urea, triple superphosphate, and K chloride). Grain and cover crops were grown. The maize grain yield and oat biomass were used as indicators of productivity. The application of cattle slurry, pig deep litter, and pig slurry increased the grain production by 20% on average compared to mineral fertilization. Organic manuring increased the soil pH by up to one unit, while urea acidified the soil. The highest crop yields were obtained with pig deep litter, which increased the levels of P, K, Ca, Mg, and C in the soil test. Pig deep litter showed the highest N-ANR for the aboveground part of the plants. The ANRs for P, K, Ca, and Mg were also highest when pig slurry had been applied. The ANR values for the micronutrients varied widely among the organic sources but indicated large marginal offtake gains compared to mineral fertilization. The N-based fertilization with animal manures increased the rate of nutrient uptake by plants but led to an accumulation of nutrients in the soil, threatening the sustainability of the system. Manure applications must be monitored regularly to avoid the accumulation of nutrients that could impair the soil quality and become an environmental problem in the future. [ABSTRACT FROM AUTHOR]

Organic amendment (OA) has positive effects on rice yield in literature, but few studies have reported positive effects on rice yield trend in a region, which need to be distinguished for the development of sustainable agriculture in terms of management of organic resources available in agroecosystems. The objectives of the present study were to examine the long-term effects of OA on rice yield, yield trends and soil fertility change under the same double rice cropping system at three experimental sites established in 1980s in subtropical China. Organic amendments at the sites covered different strategies in use of locally available green manure, rice straw and farmyard manure to partially substitute inorganic fertilizers at different doses of recommended N, P and K in combination at Jinxian, Jiangxi Province, to partially substitute inorganic N at rates of 30%, 50% and 70% of the recommended rate at Nanchang, Jiangxi Province, and to fully substitute single element of inorganic N, P and K at Qiyang, Hunan Province. The actual rice yield showed no significant time trends at Jinxian and Nanchang and negative trends in the treatments with low N application rates at Qiyang. Analysis of the relative yield trends showed significant positive effects of OA on the yield trends for either first or second rice crop in the treatments except for those without sufficient nutrient supply. The positive effects can be attributed mainly to the increased soil organic carbon and soil nutrient capacity due to the long-term application of OA. The results suggest that the organic amendments strategies should be encouraged as partial substitution of inorganic fertilizers for the consideration long-term yield trends and soil fertility. [Copyright &y& Elsevier]

Nitrogen (N) budgets can be used to quantify the flows of N in agroecosystems and to account for differences in losses and retention of N. The objective of our study was to develop 24-year N budgets for three diverse cropping systems on a boreal soil at Breton, Alberta, Canada: AER – an agroecological 8-year rotation, with N inputs from legumes [fababean (Vicia faba L.), red clover (Trifolium pratense L.), alfalfa (Medicago sativa L.)] and manure; CF – a continuous perennial grass–legume forage system, with N inputs from fertilizer (18kgNha−1 yr−1) and white clover (Trifolium repens L.); and CG – a continuous annual grain system, with N fertilizer (90kgNha−1 yr−1). We were able to compile detailed N budgets, demonstrate accumulation of soil N, and attribute differences in N flow and permanence to treatment effects. For AER and CG, net inputs almost exactly matched gains in soil N. The AER system had the highest N flow and the largest net N accumulation. Soil total N mass to 30cm depth increased in all systems during 1980–2005, but increases were smaller in CG (0.59MgNha−1) than in AER (1.90MgNha−1) and CF (1.63MgNha−1), showing the effect of legumes, perennial species, and manure in the latter systems. The proportion of total N inputs retained as soil N with organic N inputs in AER (44%) was about twice that with synthetic N fertilizer in CG (23%). The CF system had the lowest productivity and the least N loss to the environment (4kgNha−1 yr−1, compared to 28 for AER and 24 for CG). The proportion of N inputs lost to the environment was 16% for AER and 24% for CG. In CF, gains of soil N exceeded apparent net N inputs, perhaps because we under-estimated N inputs from clover. Estimate of legume N input was one of the larger sources of uncertainty. The study affirmed the value of N budgets in evaluating agroecosystem performance, and identified AER and CF as productive and sustainable systems due to their minimal reliance on external N inputs and small N losses to the environment. [Copyright &y& Elsevier]

Copyright of Latvian Journal of Agronomy / Agronomija Vestis is the property of Latvian Journal of Agronomy and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of this study was to critically assess the accumulation and depletion in total contents of trace elements from non-point pollution areas, specifically agricultural fields. Enrichment or depletion of trace elements was assessed using Al, Fe and V (control topsoil and B horizon) as reference elements. We found that various reference elements and selecting reference horizons could give contradictory results and lead to different assessments of the effects of various agricultural practices in Lithuanian soils. Cultivation on naturally acid soils in east and west Lithuania led to enrichment in some trace elements, predominantly Ag, Mn and Sr in sandy loams or loams of west Lithuania and B, Cu and Sr in sandy loams of east Lithuania. Differential fertilization led to Sr accumulation in calcareous silt loams of central Lithuania. Many experiments revealed Sr accumulation, which means that Sr concentrations have profoundly changed during decades of soil fertilization and liming in Lithuanian soils. Subsoil reference indicated a greater number of affected elements in almost all the cases. It is probable that other regional factors (such as atmospheric pollution and precipitation chemistry) influence differences in enrichment factors (EFs) between topsoils and subsoils. Research findings accord with earlier published results on changes of mobile element forms after liming and adds knowledge on the total amounts of affected elements. We suggest that assessment protocols using a few reference elements and soil layers allow filtering of datasets and indicate reliable changes in enrichment factors (EFs). However, changes occurred in other specific elements in specific circumstances, and these reference elements merit special attention. Reference selection procedures also merit further investigation and discussion. [ABSTRACT FROM AUTHOR]

Abstract: A judicious combination of agricultural soil management and conservation practices can help to increase carbon and nitrogen levels in the soil. This study examines the effect of five olive-grove soil-management systems (tillage, T; non-tillage with bare soil, NC; cover crops+herbicides, CH; cover crops+mower, CM; cover crops+mower+one pass of the disk harrow, CMD) on soil organic carbon and nitrogen content, evaluated over a 28-year trial in southern Spain (Jaén). The large quantity of biomass generated in all the treatments except NC, together with textural differences, modified the bulk density of the soil. With the CM and CH treatments, the concentration of soil organic carbon (SOC) was high at the surface and decreased with depth whilst T, NC and CMD resulted in more homogeneous concentrations at all the depths studied. The soil organic carbon pool correlated well with the clay pool in treatments applied to soils with more homogeneous textures and less biomass containing (CMD and NC). The highest SOC pool values appear on the surface (0–5cm) with cover treatments (between 10.2 and 12.2Mgha−1). When the entire profile is taken into account (0–30cm), CMD and T present the highest values (42.1 and 39Mgha−1). The lowest values are those of NC (22.8Mgha−1). The N pool behaves in a similar way. Olive-grove cover crop systems (CH, CM and CMD) must therefore be considered as an efficient agronomic practice for soil carbon fixation. [Copyright &y& Elsevier]

Abstract: Simulation models are widely used to assess the impacts of management and environmental variables on soil organic matter dynamics, to address questions on ecosystem sustainability and carbon cycling under global change. We tested the Century ecosystem model for two long-term experiments in north-eastern Italy: one (SF) comparing nutrient management treatments in small confined plots containing widely contrasting soil types (i.e., sandy, clay and peat) and the other (CR) involving a field study with crop rotation, nutrient, and management intensity variables. The organic matter changes in the SF experiment, showed a strong, linear relationship with C inputs from crop residues and added manures in the sand and clay soils, which was closely mimicked by the model. There was a net loss of soil C for all treatments in the peat soil, but the rate and overall magnitude of C losses were accurately simulated by the model, which suggested that treatment effects on soil C inputs was the major determinant of SOC dynamics in all three soils. In the CR experiment the model reasonably simulated the large initial decline (averaging about 30% of initial levels) in SOC observed in all treatments, as well as mean treatment effects over the course of the experiment. The model predicted a general pattern of higher SOC in the high management intensity, high fertility treatment combinations and lower SOC in the low management intensity, low fertility treatments; however, observed soil C did not show a clear pattern related to the treatments. Simulated soil C contents were linearly related to C input levels in the different treatments while there was no significant relationship between measured soil C and C inputs based on observed data. [Copyright &y& Elsevier]

Abstract: Long-term trends of crop yields have been used as a means to evaluate the sustainability of intensive agriculture. Previous studies have measured yield trends from long-term rice–rice and rice–wheat experiments in different sites from the slopes of individual site regressions of yield over time. The statistical significance of each site regression was determined but not that of the aggregate trend, which could give an indication of the magnitude and significance of global yield change. The random regression coefficient analysis (RRCA) and meta-analysis were used in this study to analyze the aggregate yield trend from several long-term experiments (LTE) across the Indo-Gangetic Plains (IGP) and outside the IGP. Both methods show that there has been a significant (p <0.05) declining trend in rice yield in rice–wheat LTEs in South Asia including China with the recommended rates of nutrients, but that there has been no significant change in wheat and system (rice+wheat) yields. There was no significant year×region (IGP versus non-IGP) interaction in rice and wheat yields. However, RRCA showed that the average yield trend was significantly negative (−41.0kgha−1 yr−1) only in the IGP. In the rice–rice LTEs, there was a significant year×site (IRRI versus non-IRRI sites) interaction during the dry season but not the wet season. Rice yields declined throughout Asia in the wet season. The average system (dry+wet season rice) yield trends were significantly negative in both IRRI and non-IRRI sites (−170.1 and −52.8kgha−1 yr−1, respectively) but the magnitude of yield decline was significantly greater in the IRRI sites than in the non-IRRI sites. Rice in the rice–wheat LTEs showed a significantly positive yield trend with the addition of farmyard manure (FYM) but the initial yield was generally lower with FYM than without FYM. After 15 years, yield increase due to FYM was not evident in most of the LTE. [Copyright &y& Elsevier]

Abstract: In south Asian countries, production fatigue has been observed as yields which have started declining or stagnating under long-term experiments in multiple cropping systems due to continuous cultivation. We examined the potential impact of continuous cultivation of crops in rotation, and fertilizer and manure application on yield trends, soil organic carbon (SOC) storage, soil quality parameters (active fractions of SOC in particular) and sustainable yield index (SYI). Crop rotations included in the study were: rice–wheat–jute, soybean–wheat and sorghum–wheat system at Barrackpore (Typic Eutrochrept), Ranchi (Typic Haplustalf) and Akola (Typic Haplustert), respectively. Field treatments included unfertilized (control), 100% N, 100% NP, 100% NPK and 100% NPK+FYM. The negative yield trend was observed in unbalanced use of inorganic N and NP application at all the three sites. The positive yield trend was observed in the NPK and NPK+FYM treatments at Ranchi and Akola. However, significantly negative-yield trends were observed in these treatments at Barrackpore under rice-based system. Results showed that the SOC in the unfertilized plot (control) decreased by 41.5, 24.5, and 15.5% compared to initial values in Barrackpore, Ranchi and Akola, respectively, wherein the treatment receiving NPK and NPK+FYM either maintained or improved it over initial SOC content in these sites. The estimated annual C input values in NPK+FYM treatments were 4392, 4159 and 3113kgha−1 year−1 in rice–wheat–jute, sorghum–wheat and soybean–wheat system, respectively. Active fractions of SOC, viz., water-soluble carbon and hydrolysable carbohydrates, soil microbial biomass C and N, dehydrogenase and alkaline phosphatase activity, improved significantly with the application of NPK and NPK+FYM. The content of SOC significantly (p ≤0.05) correlated with SYI and active fractions of SOC, which support better sustainable productivity. Results suggest that current fertilizer recommendations of 100% recommended NPK are adequate for maintaining SOC and its active fractions as well. The causes of yield decline are mostly location specific but depletion of SOC and its active fractions seems to be a general cause. [Copyright &y& Elsevier]

In long-term experiments in awake guinea pigs ( n=12), distortion product otoacoustic emissions (DPOAEs) at various frequencies were measured repeatedly over 6–8 months. About 9 weeks after the first measurement, the animals were exposed to industrial noise (car industry, maximal intensity about 110 dB SPL) for 2 h. The amplitudes of DPOAE were measured prior to noise exposure and 10 min, 70 min, 1 day and 2 days after the noise exposure and then once every week. Three to four months after noise exposure, the animals were killed, and the cochleae were prepared for scanning electron microscopy. The row of inner hair cells (IHCs) was complete in all animals, while the rows of outer hair cells (OHCs) showed a considerable hair cell loss in some of the animals without a correlation to the change in amplitudes of DPOAE. However, a closer relationship between the decline of amplitudes of DPOAE and the number of missing and changed OHCs (fused stereocilia bundles, missing tip links) could be established. The number of lost OHC does not reflect the decline in DPOAE in all cases. This discrepancy must be considered when the degree of hearing loss needs to be established from changed DPOAE. [ABSTRACT FROM AUTHOR]

Abstract: Soil management practices such as crop rotations and crop production inputs can affect soil microbial communities. Carbon substrate utilization patterns have been used to distinguish microbial community functional activity in different ecosystems. Microbial community functional activity from a long-term crop rotation experiment (HRE) and from Pennsylvania farms was evaluated by analysis of microbial community-level physiological profiles (CLPP) based on Gram-negative Biolog® plate reactions. Principal component analysis (PCA) and cluster analyses of substrate reactions were analyzed after 72h of incubation. In the HRE, treatments with manure and crop rotations formed a different cluster than treatments with no manure and continuous corn. Farms with routine organic amendments formed a different cluster than farms with few or no organic additions. Whole plate metrics—mean plate intensity (MPI), number of C substrate reactions—were particularly effective as indicators of soil management impacts on microbial community activity. Substrate utilization diversity was different in treatments with manure additions and crop rotations treatments of HRE, but not for farms with different management. Although not without limitation, microbial community-level physiological profiling can be used as a tool to explore the impacts of different soil management on the functional activity of soil microbial communities. [Copyright &y& Elsevier]

The soil is the basis of existence of humans. Therefore, sustainable land use is the most important task. Soil processes run very slowly and are often only measurable and/or quantifiable after decades. Long- term field experiments are an indispensable basis of our knowledge of predominantly practical solutions for sustainable land use. A large proportion of up to now still insufficiently solved problems can be clarified exclusively using long-term experiments. These are among others: questions of the supply of soils with organic matter, crop rotation, carbon sequestration, interrelations between soil, plant and environment, influence of climatic changes. At present there are world-wide around 600 long-term experiments, including grass land, with a duration of more than 20 years, 25 of them > 100 years. An overview is given and selected results are demonstrated. [ABSTRACT FROM AUTHOR]

Organic inputs can help maintain soil fertility by improving chemical and biological soil properties. The effects of 40 years of organic, mineral and mixed fertilisations on soil organic properties were evaluated in a continuous maize system. The following properties were analysed: total organic carbon (TOC), humic carbon (HC) and its molecular weight distribution, HC/TOC and the hormone—(auxin and gibberellin-like) activities of the humic substances and their effects on two key enzymes (nitrate reductase (NR) and glutamine synthetase (GS)) involved in nitrate assimilation in maize seedlings.Farmyard manure fertilisation sustained TOC in the top layers while mineral treatments alone or mixed with organic exhibited a minor influence on the organic matter evolution: over 40 years the average TOC depletion was 23% with liquid manure and mixed fertilisations, 43% with mineral fertilisers alone and 51% in the control.The different treatments also influenced the HC molecular complexity. Farmyard fertilisations improved the production of humus with a high degree of policondensation, a fraction usually linked to soil fertility; the absence of organic fertiliser inputs determined the opposite, with a higher percentage of non-complex and light-weight humus.The hormone-like and biochemical activities of humus substances were evident with the organic and mixed fertilisations. The humus extracted by the soil treated with farmyard manure exhibited the best gibberellin-like activity and the highest increases of NR (+42%) and GS (+49%) activities with respect to the control. The other treatments showed intermediate stimulations as in the case of mixed fertilisations (NR + 22% and GS + 24%), or no activities as in the case of mineral inputs. [Copyright &y& Elsevier]

Many biological functions of soil organisms are replaced in intensive agricultural systems, but earthworms and other soil invertebrates may continue to have significant effects on nutrient cycling in these disturbed systems. We investigated the influence of earthworms on leaching of water and nitrogen in corn (Zea maysL.) agroecosystems in a long-term (6-year) field experiment in Wooster, Ohio, USA. We employed a split-plot experimental design in which main plots received one of three nutrient treatments (cow manure, legume-grass mixture, inorganic fertilizer) and contained three 4.5 × 4.5-m field enclosures in which earthworm populations were increased, decreased, or unmodified. We installed zero-tension lysimeters beneath enclosures with increased or decreased populations and collected leachates regularly in 1996, analyzing them for water volume and concentrations of NH4+, NO3-, and dissolved organic nitrogen (DON). Earthworms did not influence concentrations of inorganic N or DON but greatly increased leachate volume. The total flux of N in soil leachates was 2.5-fold greater in plots with increased earthworm populations than in those with decreased populations. Earthworm population density was positively correlated with total N leaching flux (r2 = 0.49). Leaching losses of N to a depth of 45 cm were greater in the inorganically fertilized than in the organically fertilized plots, possibly due to greater inorganic N concentrations and lower immobilization potential in inorganically fertilized systems. Our results indicate that earthworms can increase the leaching of water and nitrogen to greater soil depths, potentially increasing N leaching from the system. [ABSTRACT FROM AUTHOR]

Soil organic matter (SOM) and its different pools have key importance in nutrient availability, soil structure, in the flux of trace gases between land surface and the atmosphere, and thus improving soil health. This is particularly critical for tropical soils. The rates of accumulation and decomposition of carbon in SOM are influenced by several factors that are best embodied by simulation models. However, little is known about the performance of SOM simulation model in an acid tropical soil under different tillage systems including no-tillage (NT). Our objective was to simulate soil organic matter dynamics on an Acrisol under no-tillage and different plowed systems using Century model. Tillage systems consisted of no-tillage, disc plow, heavy disc harrow followed by disc plow, and heavy disc harrow. Soil C stocks simulated by Century model showed tendency to recovery only under no-tillage. Also, simulated amounts of C stocks of slow and active pools were more sensitive to management impacts than total organic C. The values estimated by Century of soil C stocks and organic carbon in the slow and passive pools fitted satisfactorily with the measured data. Thus fitted, except for the active pool, Century showed acceptable performance in the prediction of SOM dynamics in an acid tropical soil. [Copyright &y& Elsevier]

Long-term experiments in Müncheberg, Braunschweig and Livada were used to understand the complex issue of carbon sequestration in soil. The investigations were focused on: effects of land use changes on the fate of soil organic carbon; options of agronomic practices to maintain or to increase soil organic carbon; relationships between organic fertilization and changes in soil organic carbon. The long-term observations showed that the amount of soil organic matter is primarily a function of the prevailing land use. Clearly marked differences were observed between long-term arable farming with lower and short-term with higher soil organic carbon content. Agricultural practices lead to a decrease of soil organic carbon with the result that arable soils are rather sources of carbon than sinks. The carbon sequestration potential is caused by the agronomic management to different extents. The combination of organic and mineral fertilization increased the soil organic carbon content compared to exclusive mineral fertilization. Optimum values of organic fertilizer application for maintaining soil organic carbon were calculated. Liming reduced the soil carbon pool when applied in large amounts. Long-term fertilization experiments are a useful tool for calculating the carbon sink or source potential of arable soils. [ABSTRACT FROM AUTHOR]

The importance of the soil organic matter (SOM) in the environmental protection, particularly its relation to the global carbon and nitrogen cycle come increasingly into the foreground. The evaluation of the influence of SOM on the environment requires the knowledge of optimal SOM content. Several authors estimated the necessary amount of primary organic matter (POM) for preservation of the optimal SOM content in soil on basis of the results from 10 long-term field experiments at eight different locations. An average demand for farmyard manure (FYM) was determined to be 10 t.ha -1 .a -1. The difference in the organic carbon content between the unfertilized variant and the optimum fertilized variant ranged between 0.11% C org on a sandy soil and 0.51% Corg on loess black soil. A higher level of organic fertilization brings no yield advantages and it is connected with higher N-losses. The utilization of FYM nitrogen is around 30% lower in comparison with mineral N. The reduction of the CO2 concentration in the atmosphere by means of carbon sequestration in mineral soils is practically impossible. The input of primary organic matter to soil exceeds by large C quantity which can be accumulated. [ABSTRACT FROM AUTHOR]

The annual input and output of nitrogen (N) to and from agricultural land is relatively small compared with the total stock of organic N in soil. However, the long-term humus N pool dynamics is seldom considered in fertilisation planning, and thus N surpluses in budgets are considered as losses. In this paper, we analyse the consequences of this assumption and investigate how observed data precision affect the precision of model projections. We used available data sets from long-term agricultural field experiments in Sweden (topsoil C and N concentrations, crop yields as well as soil type and climate data) for calculating topsoil C and N mass dynamics. ICBM/2N, a simple C and N soil model (available at: www.mv.slu.se/vaxtnaring/olle/ICBM.html), was used for calculating soil organic matter balances. We parameterised this model for two field trials, and for specific crops, using available data and educated guesses and compared the results with those obtained from the conventional approach, not including humus pool C and N dynamics. In spite of the corrections for bulk densities, etc., the soil carbon measurements were too variable for a critical model validation or a sensitive test of the effects of including pool dynamics. In other words, we had to rely on the model assumptions for the projections and soil data could only be used to obtain general means, e.g., for the whole duration of the experiment. We think this is a general problem, not limited to this data set and model. We also show, at least in principle, how estimates of organic N pool dynamics can be used to produce improved N balance sheets for individual crops. For example, the apparent N use efficiency by sugar beet increased from 58 to 99% when organic N pool dynamics were included. [Copyright &y& Elsevier]

Opinions differ as to the importance of organic amendments (OA) for sustaining crop productivity in the intensive, irrigated rice systems of Asia. Our objectives were to (1) quantify the effects of farmyard manure (FYM) and straw incorporation on yield trends in long-term experiments (LTEs) with rice–rice (R–R) (Oryza sativa L.) and rice–wheat (R–W) (Triticum aestivum L.) systems and (2) assess the potential effects of OA on profitability, taking into account long-term effects on yield. We analyzed yield trends in 25 LTE (seven R–R, 18 R–W systems) across a wide geographical range in Asia. Three main conclusions emerged from this analysis. First, application of either manure or straw did not improve grain yield trends in R–R and R–W cropping systems. Second, depending on socio-economic conditions, use of manure or straw in these cropping systems may be profitable, provided these OA are used as a complement to a recommended dose of inorganic NPK (i.e. organic materials should not be used as the primary nutrient source). Third, current experimental designs to assess the suitability of OA need to be improved in order to allow a better comparison of the relative advantages of inorganic and organic fertilizers. The major shortcoming of current designs is that they do not properly adjust mineral fertilizer rates in the inorganic treatments to account for the macronutrient input from OA. Thus, our tentative estimates of the profitability of OA may be overstated. [Copyright &y& Elsevier]

The results of investigation of soil organic matter (SOM), its mobile and more strongly bound forms in long-term experiments on loamy soddy podzolic and grey soils of Russia and Loess-Chernozem of the Static Fertilization Experiment at Bad Lauchstädt in Germany are presented. The method of fractionation using successively 0.1 n sodium hydroxide (fraction 1), the mixture 0.1 m sodium pyrophosphate (fraction 2) and finally 0.02 n sodium hydroxide extraction on water bath (fraction 3) has been applied for isolation of humic substances differently bound with mineral part of soil. The results show that mineral and organic fertilizers differ in their effect on the composition of humic substances. The above mentioned properties of bound SOM fractions may possibly serve as indicators of manuring intensity and accumulation of decomposable SOM in dark soils of temperate climatic conditions initially characterized by predominance of humic substances with high optical density. The results show the importance of an optimum level of decomposable organic matter in soil and corresponding optimum fertilizer systems for every crop in rotation. [ABSTRACT FROM AUTHOR]

It is established that radon concentration in dwellings is connected with the geological structure of the Upper Silesian Coal Basin, as well as the intensity and the depth of carrying out mining operations. The measurements revealed that radon level is higher in buildings located on outcropped Triassic layers than in those ones on Tertiary and Quaternary sediments. It is shown that the syncline regions are the zones of increased radiation hazard. [ABSTRACT FROM AUTHOR]

In an experiment conducted over 8 years at the research farm of the National Research Centre for Weed Sciences, Jabalpur, we investigated the effects of mineral fertilizer and organic manures on K balances and non-exchangeable K release kinetics in a Typic Haplustert under a rain-fed rice (Oryza sativa L.) and irrigated wheat (Triticum vulgare L.) system. Each year, rice was grown with variable levels of fertilizer N with and without organic manures, while recommended rates of 26 kg P ha−1 and 33 kg K ha−1 were applied to both the crops. Wheat was grown without organic manure but with the same levels of fertilizer N as for rice. The apparent K balance was measured as the difference between total K added and that removed by the crop. Increasing levels of fertilizer N resulted in an increase in the negative K balance from 56 kg ha−1 yr−1 (control) to 103 kg ha−1 yr−1 at 90 kg N ha−1 and 156 kg ha−1 at 180 kg N ha−1. Incorporation of farmyard manure (FYM) or green manure (GM) with fertilizer N reduced the negative K balance. Repeated extraction of soil with 0.01 M CaCl2 revealed that continuous cropping for 8 years either without fertilizer N (control) or with 90 kg N ha−1 reduced the cumulative K release. However, the application of 180 kg ha−1 of fertilizer N not only maintained the cumulative K release but also improved it. Incorporation of 5 t FYM or 6 t GM ha−1 with 90 kg N ha−1 resulted in an increase in K release by 58 and 37 mg kg−1 soil, respectively, over the values measured in a soil sample collected at the onset of the experiment. A parabolic diffusion equation described the release rate of the non-exchangeable K. The equation suggested that the application of fertilizer N reduced the release rate of K, whereas the incorporation of manure, with fertilizers, increased it over the values obtained from soil collected at the onset of the experiment. The large cumulative K release at 180 kg N ha−1 was due to the amount of K released initially. Continuous cropping at a fertilizer level of 33 kg K ha−1 may pose a threat to the sustainability of the rice–wheat system. Recycling of crop residue or application of higher levels of fertilizer K may provide long-term sustainability to the system. [Copyright &y& Elsevier]

From a global point of view the aims of sustainable, agricultural land use are high and rising yields per hectare to secure the nutrition of the constantly growing population of the world and for the production of energy and raw materials. However, at the same time it is equally important to avoid environmental impacts by nutrients and pollutants released into the groundwater or into the atmosphere. On the basis of the results of numerous long-term field experiments, organic farming (OF) and integrated farming (IF) were compared regarding yield and environmental impacts. The following results were obtained: With renunciation of mineral nitrogen fertilization and chemical plant protection less than 70% of the ecologically and economically justifiable maximum yields are achieved, which can be obtained with combined organic-mineral fertilization. Thus, for the production of same quantities of food more than 40% additional land is needed. The nitrogen regime in OF is connected with the risk of larger N losses, the carbon balances fails more unfavourably. Compared to OF in about one ton carbon more per hectare will be carried from the atmosphere. Often baking quality and N content of grains are insufficient in OF. Quality advantages of OF products have not been proved. The evaluation of different management systems according to the "Kriterien Umweltgerechte Landwirtschaft (KUL)" or the model "REPRO" ensures a sufficient security check and is recommended. [ABSTRACT FROM AUTHOR]

In Hungary the AL-method using ammonium lactate acetic acid as extractants has been widely used for serial analysis of soil potassium and phosphorous available to plants in the last 30y. Because of the considerable increase of the price of fertilizers and decline of the economic situation, there is a pressing need for cost-effective fertilizer use. Recently this highlighted the importance of nutrient recommendations based on soil analyses. Small plot long-term field fertilization. Long-term data sets can reveal on which soil type which crop responds most favourably to the different fertilizer doses and nutrient ratios under different, long-term balanced soil nutrient levels. Since the experimental data of the National Long-Term Field Trials reflect the agro-ecological conditions of nine experimental sites representing different soil types of Hungary, these experiments provide excellent opportunity to study this topic. The trials were set up in 1967 with 20 fertilization treatments including three increasing N-and P-levels each, two K-levels and their different combinations. From the experimental data of great number only those of four sites will be shown. Winter wheat, maize, and pea have been grown as test plants. In the experiment selected for presentation, maize had Statistically proved responses to K-fertilization. The efficiency of K-fertilizer on different soil types shows, however, significant differences, which can not be completely explained with the results of K-analysis gained with AL-method. [ABSTRACT FROM AUTHOR]

Organic matter is the life of soil. It enables a soil to perform efficiently its primary function of supporting plant growth. Its endemic deficiency in tropical soils, particularly those under the influence of arid, semiarid and sub-humid climates, is a major factor contributing to their low productivity. Research over the past 30 years, formatted as long-term experiments, has conclusively proven that those treatments and practices that supported organic matter build-up, also favored sustainable productivity. Since sustenance of organic matter necessitates regular additions, bolstering its supplies in sufficient quantities is a strategy suggested for the future. While in-situ cultivation and non-competitive use are the common elements of an overall scheme on reinforcing an organic matter reservoir, traversal routes for harnessing, however, vary with the kind of organic resource being aimed at. For instance: with cattle dung and human excrements, conversion into biogas is considered necessary; farmer participatory appraisal and emphasis on dual purpose legumes are found to be essential in spreading green manures, and non-palatability to cattle with a pre-composting step seem vital to succeed with crop residues. Possible research, development and policy initiatives are outlined to enlarge supply and efficient use of different types of organic resources. [ABSTRACT FROM AUTHOR]

The fate of phosphorus (P) derived from mineral fertilisers and organic manures, and the effective P balance, have been assessed in three long-term field experiments at Rothamsted (UK), Bad Lauchstaedt (Germany) and Skierniewice (Poland). This paper discusses the plant availability, uptake and overall utilisation of P over the last 30 years, based on soil test P ‘availability indices’ and crop analyses determined by the standard methods used in each of the three countries. The data suggest that differences in soil type significantly influence the dynamics of P at the three locations, but most significantly between a loess Chernozem at Bad Lauchstaedt with a high organic matter content and the soils at the other two locations which have a low organic matter content. The application of P either as inorganic fertiliser or organic manure had a considerable influence on the availablity, uptake, leaching or fixing of P, but the crop recovery rate of P from mineral fertiliser did not exceed 35% with the smallest recovery (average 18%) occurring in the soil with the highest clay content at Rothamsted. At Bad Lauchstaedt and Rothamsted the most efficient utilisation of P (averages of 47% and 37%, respectively) was from soils treated with farmyard manure (FYM), with the greater quantity of P either leached or fixed (8 and 25 kg ha-1 y-1, respectively) occurring in soils treated with superphosphate. At Skierniewice, however, the reverse was true. Overall, the most efficient crop utilisation from mineral P (30% average) was from the loamy sand at Skierniewice. P balances for the three locations show that quantitatively, for the same P input, the amount of P either leached from or fixed in the plough layer of Broadbalk field, Rothamsted, was 2–3 times greater than at Skierniewice and 3–6 times greater than at Bad Lauchstaedt. The results suggest that differences in the soil physico-chemical properties, climate, the availability of other major nutrients, and the form in which P is applied, all influence the effectiveness of P fertilisation and P balance. The investigation highlights the importance of maintaining long-term field experiments and archived soil and crop samples on a world-wide basis for understanding nutrient cycling and fertility dynamics. [ABSTRACT FROM AUTHOR]

Agricultural Long-Term Experiments (LTEs) are crucial agricultural research infrastructures for monitoring the long term effects of management and environment on crop production and soil resources. We have compiled the meta-information of 616 LTEs from 30 different countries across Europe with a duration of typically 20 years, including clustered information of the European LTEs in different categories (management operations, land use, duration, status, etc.). It consists of the updated version of the dataset published by Grosse et al., (2020) but is extended by further LTE metadata, categories and research themes. Each set of metadata consists of up to 49 different attributes (categorical or numeric). Collected attributes were analyzed according to several research themes, including fertilization, crop rotation and tillage treatments. The collection of individual metadata was enlarged by the recent agreement between the BonaRes (www.bonares.de) and EJP SOIL (www.ejpsoil.eu) groups into the most comprehensive dataset in Europe, providing access to LTE and other, shorter running experiments. This dataset centralized past and existing information usually dispersed across several national actors. As such, it provides an extensive database that can be used by decision-makers, scientists, LTE owners and the public. The dataset can be updated in the future to foster networking and information exchange continuously., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have influenced the work reported in this paper., (© 2022 The Authors. Published by Elsevier Inc.)

In broadly conceived long-term experiments, tobacco was grown in monoculture and with different crop rotations. This paper presents results in terms of the yields achieved and the major yield components for the crops grown, and the proportion of particular tobacco quality classes obtained. In addition to tobacco monoculture (initially only fertilized and later also unfertilized) as the key crop, different types of crop rotations included, besides tobacco, the following crops: winter wheat, maize, soybean, oil-seed rape, and red clover. Experiments involved two 2-year and two 4-year crop rotations, and a 3-year, a 5-year, and a 6-year crop rotation. Experiments were set up on luvic semigley on multilayered Pleistocene sands. Average 10-year results suggest that there is an advantage of crop rotation over monoculture for tobacco leaf yields. The influence of different crop rotation types on yields of other crops was variable, tending towards higher values as the number of crops in rotation was increased. Values obtained for yield components should be considered from two angles: some of the values were primarily influenced by genetic factors, while others were influenced by ecological factors, including crop rotation as an overall biological buffer. With regard to quality classes (IB-III), the growing of flue-cured tobacco in crop rotation represents a great advancement relative to its growth in monoculture, even in a narrower crop rotation. [ABSTRACT FROM AUTHOR]