Effects Of Agricultural Management Practices Research Articles

Effect of agricultural management practices on rice yield and greenhouse gas emissions in the rice–wheat rotation system in China

Agricultural management practices (AMPs) have the potential to significantly enhance crop yield, albeit with the possible side effect of escalating greenhouse gas emissions. Few studies have undertaken a comprehensive quantification of the impact of AMPs on crop production and soil GHG, particularly in identifying the optimal AMPs for rice cultivation within rice-wheat rotation system. Here, we combined data analysis and keyword search methods on 1433 individual experimental observations from 172 studies on diverse soil types in the subtropical monsoon climate zone of China to assess the impact of AMPs on rice yield, CH4 and N2O emissions, total greenhouse gas emissions (TGHGE). We focused on four key AMPs: mineral N fertilizer management (including ordinary N fertilizer and slow−/controlled-release fertilizer (SCRF)), organic material management (incorporating organic fertilizer, biochar amendment, and straw return), water-saving irrigation, and no-tillage. Our result showed the rice yield ranged from 2525 to 31,196 kg ha−1, and mineral N fertilizer and organic material management boosted rice yield by 2.84–16.19 % and 2.47–8.52 %, respectively. In terms of N2O emissions, biochar amendment resulted in a decrease of 13.05 %, while ordinary N fertilizer, organic fertilizer, and water-saving irrigation led to increases of 63.16 %, 136.66 %, and 37.41 %, respectively. The implementation of SCRF, water-saving irrigation, and no-tillage significantly curtailed CH4 (6.83 %–35.91 %) and TGHGE (6.22 %–20.59 %). Conversely, organic fertilizer and straw return significantly escalated CH4 emissions by 102.20 % and 33.64 % and TGHGE by 85.03 % and 32.40 %. Rice yield and GHG emissions are mainly influenced by variables such as soil bulk density, pH, soil organic carbon, soil texture, mean annual temperature, and total nitrogen. Our study demonstrates that the application of SCRF, water-saving irrigation, and no-tillage can effectively reduce GHG without compromising yield. These practices are particularly effective under climatic and soil conditions of rice-wheat rotation systems in China, thereby contributing to the sustainable rice farming.

Methane uptake rates across different soil types and agricultural management practices in Denmark

Upland terrestrial soils play a crucial role in the global methane (CH4) cycle, although their potential as sinks for CH4 remains inadequately quantified. This study investigated CH4 uptake rates spanning two full years at four locations representing typical soil types and crop rotations in Denmark. The sampling campaigns included a total of more than 5000 manual static chamber flux measurements. All locations were, on average, small net sinks for CH4 while displaying significant differences between locations ranging from −1.5±0.3 g CH4-C ha−1 day−1 on the loamy soils to −3.8±0.3 g CH4-C ha−1 day−1 on the sandy soil with the lowest bulk density. A significant negative effect of soil moisture on CH4 uptake was also identified across the locations. Therefore, this study highlights the importance of soil texture and moisture as key controlling variables for CH4 uptake and emphasizes the need for local estimates of sink capacity. Overall, there were no detectable effects of agricultural management practices and fertilisation events did not affect the CH4 flux except for some high emissions following cattle slurry application on coarse sandy soil, which needs some consideration.

Effect of agricultural management practices on diversity, abundance, and infectivity of arbuscular mycorrhizal fungi: a review

Effect of agricultural management practices on diversity, abundance, and infectivity of arbuscular mycorrhizal fungi: a review

Major contributions of agricultural management practices to topsoil organic carbon distribution and accumulation in croplands of East China over three decades

Multiple natural and anthropogenic factors jointly drive the spatial distribution of soil organic carbon (SOC) and its dynamics in croplands. Among these factors, agricultural management practices have caused considerable impacts. Previous studies on the driving factors of SOC in croplands have provided significant understanding on this matter. However, whether and how the effects and interplay of these drivers change over time is often unknown, especially agricultural activities. To measure the effects of agricultural management practices on the spatial distribution and temporal change of SOC incorporating the network relationships with other natural drivers at the regional scale, we conducted partial least squares path analysis on the topsoil organic carbon content using two historical soil datasets from cropland samples in East China obtained during the 1980s and the 2010s. Eight indicators and their temporal changes reflecting climate, agricultural management, and edaphic conditions were used to quantify the driving mechanisms of the spatial distribution and temporal change of SOC. The drivers of SOC distribution showed that high SOC was mostly distributed in soils with a relatively low pH and high clay content in warm humid climates. High SOC was associated with the application of N fertilizer, crop residue input, and agricultural machinery in the 1980s and 2010s. The effect of N fertilization on SOC distribution increased from the 1980s to the 2010s, whereas the total edaphic effects significantly decreased from 0.62 to 0.25 (P < 0.01). Regarding the drivers of SOC change over the three decades, the edaphic effects presented the strongest effect (path coefficient of 0.74, P < 0.01), including the negative effects of topsoil acidity and baseline SOC level, as well as the positive effects of total nitrogen (TN) and clay content change. Croplands with lower intensity of management practices in the 1980s generally attained more development in agricultural modernization, which led to a considerable SOC increase. Our research revealed the importance of agricultural management practices on the spatial distribution and temporal change of cropland SOC at the regional scale. The results emphasize the need to measure the changing driving mechanisms of SOC dynamics. The findings indicate that indicators reflecting the effects of agricultural management practices should be included in digital mapping and process-based modeling of soil carbon at different spatiotemporal scales to improve prediction accuracy.

Assessing the effects of agricultural management practices and land-use changes on soil organic carbon stocks

Soil organic carbon (SOC) stocks have profound effects on climate change, sustainable agricultural development, and environmental management. Our objectives were to propose a conceptual framework and quantify the impact of land use change (LUC) and agricultural management practices (AMPs) on SOC stocks. By comparison, we choose the Kriging-based spatial prediction model to estimate SOC stocks based on the field sampled soil data (depth of 0–30 cm) in 2005 and 2019. Film mulching, drip irrigation, and fertilizer application were selected to represent the regional AMPs. Our results indicate that SOC stocks increased by 12.7% in the Sangong river basin from 2005 to 2019. From the proposed conceptual framework, we notice that the transition between different land-use types may cause both losses (e.g., −9.49 Gg C caused by expansion of construction land) and gains (e.g., +3 Gg C caused by the conversion of cultivated land to grassland) of SOC storage. Benefiting from improved AMPs (e.g., film mulching, drip irrigation, and fertilizer application), the “stable cultivated land” category contributes the most (+36.0 Gg C) to the growth of SOC stocks.

Management‐induced shifts in rhizosphere bacterial communities contribute to the control of pathogen causing citrus greening disease

AbstractIntroductionCitrus greening (aka Huanglongbing, HLB) caused primarily by the bacterial pathogen Candidatus Liberibacter asiaticus (CLas) has devastating effects on the global citrus industry. Agricultural management‐induced changes in microbial communities are hypothesised to contribute toward HLB resistance by reducing pathogen titre and increasing root and soil health. However, we have a limited understanding of the impacts of management practices on the soil microbiome, making the extent of HLB management uncertain.Material and MethodsHere we investigated the effect of agricultural management practices on reducing CLas titer via changes in rhizosphere‐associated bacterial communities. Rhizosphere and root samples were collected from two sites in Florida where different management practices (e.g., metalized reflective mulch ground covers, compost application and microbial inoculations) are currently being implemented to prevent HLB. Management‐induced changes in the rhizosphere bacterial community were assessed using amplicon sequencing. qPCR assays were used to quantify the titer of the pathogen CLas in roots. In addition, we measured soil properties and the activities of microbial enzymes involved in soil nutrient cycling.ResultsOur results indicated that certain management practices lead to shifts in the community structure of rhizosphere bacterial communities that negatively interact with the HLB pathogen. Management practices improved soil quality and reduced CLas titer. Additionally, we found that Actinobacteria were frequently enriched in the successful treatment sites, suggesting that Actinobacteria taxa could be indicators for HLB suppression properties in the soil.ConclusionOur results suggest that microbiome manipulation, either through changes in the management practices or microbial amendment, can increase the suppressive potential of soils, resulting in the reduction in CLas titer and potentially leading to HLB suppression in citrus groves.

Water-Saving Potential of Different Agricultural Management Practices in an Arid River Basin

Water scarcity threatens food security in arid areas, highlighting the importance of water-saving agriculture for food production. Agricultural management practices are developed to improve water-use efficiency, and their water-saving effects are generally evaluated at the field scale rather than the regional scale. To figure out the regional water-saving potential of irrigation methods and mulching practices, the FAO AquaCrop model was first calibrated and validated at the three experimental stations. With aggregating spatial information, a distributed model was constructed and validated in a typical arid river basin of northwest China. Twelve combinations of soil mulching (plastic and straw) and irrigation methods (basin, furrow, drip, and subsurface drip) were simulated using the model to evaluate the effect of agricultural management practices on crop evapotranspiration (ET), crop water productivity, and regional water consumption. The results showed that soil mulching, advanced irrigation methods, and their combinations reduced noneffective soil evaporation (E) and the E/ET ratios and improved crop water productivity. Plastic mulching combined with subsurface drip irrigation is the most promising practice, increasing the crop water productivity of seed maize and spring wheat by 18.2% and 11.1% on average and reducing regional crop water consumption by 7.7% (75.0 million m3) and 7.4% (72.7 million m3), respectively. The reduction in irrigation water extraction ranged from 20.6% under furrow irrigation with straw mulching to 68.7% under subsurface drip irrigation with plastic mulching. This study quantitatively assessed the water-saving potential of soil mulching, irrigation methods, and their combinations to reduce agricultural water use, offering practical implications for the management and development of water-saving agriculture in arid areas.

Effects of Agricultural Management Practices on the Temporal Variability of Soil Temperature under Different Crop Rotations in Bad Lauchstaedt-Germany

To investigate the effects of management practices on the dynamics of soil temperature, during 2014–2017, a field experiment was carried out in Bad Lauchstaedt, Germany. In this study, four management systems are compared for determining management-induced changes in soil temperature at different depths: (i) conventional tillage (TC) with the standard rate of N fertilizer (P1N1), (ii) conventional tillage with the half-standard rate of N fertilizer (P1N0), (iii) reduced tillage (TR) with the standard rate of N fertilizer (P0N1), and iv) reduced tillage with the half-standard rate of N fertilizer (P0N0). Temporal analysis of soil temperature is assessed to examine data observed at a specific time to achieve a better understanding of the soil temperature dynamic that occurs at different time scales. The results showed that the soil temperature has decreasing amplitudes and increasing phase shifts with increasing soil depth, i.e., the deeper the measurement depth, the smoother the soil temperature changes cycle and the smaller the variability. Results showed that the diurnal temperature variation is found up to 45 cm depth of soil whereas annual temperature variation is up to a depth of 180 cm. The results, moreover, revealed that soil temperature dynamic was affected by tillage systems and fertilization and a time lag is observed between the temperature fluctuations at the surface and deeper layers, due to induced management effects on plant cover, residues, and soil properties. Although higher soil temperature at the sowing stage under TR is contributed to higher amounts of surface crop residues in crop rotations, the effect of residues on soil temperature variation reduces with an increase in percent plant cover and shading of soil, which happens in the last stage of plant growth. At the last stage of crop development regardless of tillage systems, applying more N fertilization increased crop yield, resulting in cooling soil temperature.

Assessment of the effects of agricultural management practices on soil erosion and sediment yield in Rib watershed, Ethiopia

Assessment of the effects of agricultural management practices on soil erosion and sediment yield in Rib watershed, Ethiopia

Near‐surface soil property changes affected by management practices in a long‐term, wheat–soybean, double‐crop system

AbstractLong‐term agricultural sustainability and productivity are controlled by the integrative effects of different management practices on the soil. Many Arkansas producers use the double‐crop system to grow soybeans [Glycine max (L.) Merr] and wheat (Triticum aestivum L.). The objective of this study was to evaluate the effects of agricultural management practices (including residue level, tillage, irrigation, and burning) and soil depth on the change in various soil properties from 2010 to 2020 in a long‐term, wheat–soybean, double‐crop system on a silt‐loam soil (Glossaquic Fraglossudalfs) in eastern Arkansas. Soil nutrients tended to accumulate over time, the most in the top 10 cm, whereas soil nutrient contents in the 10‐to‐20‐cm depth interval tended to not significantly change over time. Soil bulk density (BD) generally decreased across all treatments over time. Soil organic matter (SOM) content increased under all treatment combinations by 0.097 kg ha−1. Soil BD decreased and SOM numerically increased the most in the no‐tillage/no‐burn treatment in the top 10 cm of the soil. Total C was 9.2 times greater, whereas total N was 48 times greater in the top 10 cm of the soil. Soil pH was 1.9 times greater under irrigation than under nonirrigated treatments. Quantifying changes in soil‐properties over time will help producers to better understand the long‐term effects of various residue and water management practices and to find reasonable, more sustainable alternative practices.

Effects of Agricultural Management Practices on Soil Properties in the Sahelian Zone of Burkina Faso

Agro-ecosystem degradation is a real socio-environmental problem in the Sahel. Face to the declining of yields from cultivated soils, populations are adopting various adaptation strategies. This study was conducted to assess the impact of three agricultural technologies on the evolution of soil fertility in the Sahel area of Burkina Faso. Soil was sampled from the agro-systems and submitted to physico-chemical and biological analyzes in laboratory. We evaluated soil infiltration capacity , inventoried herbaceous vegetation.Also grasses biomass was measured, and millet straw and grains were weighted in the field. Results from this study showed that plowing + bund + organic manure (LDF) treatment was the best management option in the Sahel. It reduces soil infiltration time by 1.65%, increase soil fine elements (clay and silt), chemical elements (N, P and K), exchangeable bases and cation exchange capacity. In addition, soil respiration under LDF treatment is significantly higher (P = 0.001) than other treatments. Simple plowing, is not recommended in the Sahel. It must necessarily be accompanied by measures to improve the nutrient content of soils, especially with manure. These results could guide agricultural actors (farmers, agricultural extension agents, NGOs) for sustainable farming in the Sahel areas.

Total Organic Carbon Assessment in Soils Cultivated with Agave tequilana Weber in Jalisco, Mexico

The Agave tequilana Weber is an important commercial crop in the State of Jalisco, Mexico. However, the agave cultivation generates significant soil loss. For that reason, knowledge about the implementation of the agriculture management practices, such as manure application and the combination of inorganic fertilizers and manure, are relevant. The objective of this research was to determine the effect of agricultural management practices on the total organic carbon (TOC) in the soil in three study locations: Arandas, Tepatitlán, and Acatic in the Altos Sur region of Jalisco. A random sampling was carried out in each study location, 12 samples were obtained for each location at 0–30 cm deep, and a total of 36 samples were analyzed. The evaluated parameters were the potential hydrogen (pH), electrical conductivity (EC), bulk density (BD), soil-water saturation (SWS), total nitrogen (TN), and total organic carbon (TOC). Basic statistics and correlations between parameters were generated. In addition, to estimate TOC from a multivariate analysis, models were developed based on the lowest Akaike information criterion (AIC) and of the classification and regression trees (CART). ANOVA and Tukey test were determined. Results demonstrated a significant difference in the TOC percentages between the study locations. The Tukey test showed that there is no difference in TOC content between the Tepatitlán and Arandas sites, but there is a difference between these two sites and the Acatic. The latter resulted with the lowest values of TOC. Long-term studies are recommended to develop crop management strategies.

Legacy Effects of Agricultural Practices Override Earthworm Control on C Dynamics in Kiwifruit Orchards

In Galicia (NW Spain), kiwifruit (Actinidia chinensis var. deliciosa) is intensively produced using conventional practices (CONV) that ensure high yields, despite the fact that the excessive use of agrochemical inputs leads to soil organic matter depletion, increased water pollution and biodiversity losses. Although more sustainable practices have been implemented in the area (i.e. integrated, INT and organic farming, ORG), it remains unclear how these practices will affect C dynamics mediated by soil biota. Therefore, in this study, we investigated the effects of agricultural management practices and earthworm additions (macrofauna) on soil C losses (CO2 emissions and dissolved organic carbon (DOC)) in relation to the amount of bioavailable soil carbon (salt extractable organic carbon (SEOC) and microbial carbon indicators (microbial biomass or Cmic and the Cmic/Corg ratio)). The experimental design consisted of a 105-days laboratory incubation of intact soil cores collected in the field (40 from each agroecosystem) and earthworm additions over ambient (2.43 ± 0.05 g/earthworm) to half of the experimental units (+EW), with the remaining half acting as controls. Our results showed that earthworm additions led to significant increases in their abundance in all three management treatments, but with the ORG soils sustaining the greatest population sizes. However, no significant effect on soil C transformations were observed in response to these earthworm increases, and instead, legacy agricultural practices overrode macrofauna control on C turnover. Consequently, more C was lost from the CONV treatments than from the ORG ones (on average, 60% more CO2 and 53% more DOC) as a result of CONV practices promoting microbial-mediated processes and hence, amplifying C mineralization versus C stabilization. Furthermore, C release from the INT soils was intermediate between the other two treatments, which suggests that more sustainable farming practices could help in achieving climate change mitigation. These findings provide clear evidence of how local adaptation (at farm level) towards a more environmentally friendly land management could represent a promising strategy to increase soil C sequestration. Future agricultural approaches would need to incorporate the potential benefits from other agroecosystem services beyond those derived from productivity and market values.

Effect of Organic Fertilizers on Antioxidant Activity and Bioactive Compounds of Fenugreek Seeds in Intercropped Systems with Buckwheat

Antioxidants and flavonoids are beneficial compounds used in the pharmaceutical and food industries that are derived from natural sources. A two-year field experiment was undertaken to investigate the effect of agricultural management practices on the trigonelline content, antioxidant activity measured with DPPH (2,2-Diphenyl-1-Picrylhydrazyl) and FRAP (Fe+++-Reduction, Ferric reducing antioxidant power), total phenolic content, total flavonoids content, and specific flavonoid contents of fenugreek seeds. The treatments examined were sole fenugreek (Sole F) and three intercropping ratios with buckwheat (B) (F:B = 2:1, 1:1, and 1:2), each with three types of fertilizer (chemical fertilizer, integrated fertilizer, and broiler litter). The highest trigonelline content of fenugreek seeds was obtained in F:B = 2:1 fertilized with broiler litter. Compared to Sole F, the fenugreek seeds harvested in the intercropped treatments had higher antioxidant activity, total phenolic content, vitexin, isovitexin, orientin, and isoorientin. The treatment F:B = 2:1 enhanced the antioxidant activity and the content of bioactive compounds. Overall, the addition of organic manure to fenugreek seeds was highly effective at promoting all compounds analyzed in both the sole and the intercrop systems. Our study found that harvested fenugreek seeds from plants that were intercropped with buckwheat and with the application of organic fertilizer enhanced the seed content of antioxidants and flavonoids.

Modeling maize above-ground biomass based on machine learning approaches using UAV remote-sensing data

BackgroundAbove-ground biomass (AGB) is a basic agronomic parameter for field investigation and is frequently used to indicate crop growth status, the effects of agricultural management practices, and the ability to sequester carbon above and below ground. The conventional way to obtain AGB is to use destructive sampling methods that require manual harvesting of crops, weighing, and recording, which makes large-area, long-term measurements challenging and time consuming. However, with the diversity of platforms and sensors and the improvements in spatial and spectral resolution, remote sensing is now regarded as the best technical means for monitoring and estimating AGB over large areas.ResultsIn this study, we used structural and spectral information provided by remote sensing from an unmanned aerial vehicle (UAV) in combination with machine learning to estimate maize biomass. Of the 14 predictor variables, six were selected to create a model by using a recursive feature elimination algorithm. Four machine-learning regression algorithms (multiple linear regression, support vector machine, artificial neural network, and random forest) were evaluated and compared to create a suitable model, following which we tested whether the two sampling methods influence the training model. To estimate the AGB of maize, we propose an improved method for extracting plant height from UAV images and a volumetric indicator (i.e., BIOVP). The results show that (1) the random forest model gave the most balanced results, with low error and a high ratio of the explained variance for both the training set and the test set. (2) BIOVP can retain the largest strength effect on the AGB estimate in four different machine learning models by using importance analysis of predictors. (3) Comparing the plant heights calculated by the three methods with manual ground-based measurements shows that the proposed method increased the ratio of the explained variance and reduced errors.ConclusionsThese results lead us to conclude that the combination of machine learning with UAV remote sensing is a promising alternative for estimating AGB. This work suggests that structural and spectral information can be considered simultaneously rather than separately when estimating biophysical crop parameters.

Effects of tillage intensity on pore system and physical quality of silt-textured soils detected by multiple methods

Understanding the effects of agricultural management practices on soil functionality is an ongoing challenge in environmental science and agricultural practice. In the present study we quantified the effects of changes in tillage intensity on soil physical quality and pore size distribution after 6, 10 and 23 years. At three long-term tillage experimental sites in central Europe we analysed soils under four different soil management systems: conventional mouldboard tillage; chiselling + rotary harrow; rotary harrow; and no till. These treatments differed in mechanical intensity and depth. Pore size distributions were calculated from soil water retention curves based on high-resolution measurements. Subsequently, fractions of functional pore size classes and indicators of soil physical quality were determined and compared between the treatments. In addition, we evaluated the performance of two calculation approaches for pore size distribution: (1) fitting of a smoothing cubic spline; and (2) a bimodal van Genuchten function. The parametric function yielded a higher proportion of storage pores by approximately 3–5%. The combination of multiple measurement and evaluation methods enabled detailed comparison of soil physical characteristics between different tillage treatments. No-till soils showed a distinct lack of transmissive pores and higher bulk density, but similar plant-available water capacity, compared with the other treatments. Under all soil management systems, aeration deficits were observed, emphasising the high vulnerability for compaction of silt-dominated arable soils with a low organic matter content. Hence, the design of agricultural soil management strategies on such soils needs to consider the risks of compaction as thoroughly as erosion or chemical degradation.

Delineation of tile-drain networks using thermal and multispectral imagery—Implications for water quantity and quality differences from paired edge-of-field sites

As part of the Great Lakes Restoration Initiative, paired edge-of-field sites were established in high priority subwatersheds to assess the effectiveness of agricultural management practices. One pairing was in Black Creek, a tributary to the Maumee River and Lake Erie. These fields were paired because of similarity in soils, topography, and agricultural management. Following two years of baseline data collection from these fields, consistent differences in water quantity and quality were observed for tile networks draining the fields, despite these fields being adjacent and managed together. Consequently, it was hypothesized that differences in subsurface water movement, specifically tile-drain density and connectivity, were the source of the observed differences. Our objective was to map the tile-drain network using remote sensing methodology in order to improve the understanding of nutrient and water transport as well as management on these fields. A combination of multispectral and thermal imagery, collected in spring of 2017, was incorporated to delineate the tile-drain network within each field. This imagery led to locating a cracked tile, which provided a direct path for overland flow to enter the tile-drain system and suggested that a tile-drain segment under the road connected the two fields. A ground-penetrating radar survey verified multiple tile locations, including the tile segment under the road. The distribution of these tiles helps explain the difference in water quantity and quality in the two fields.

Evaluation of the RothC model as a prognostic tool for the prediction of SOC trends in response to management practices on arable land

RothC is an established model for predicting soil organic carbon (SOC) changes in response to environmental conditions and management. The model lacks algorithms for carbon input estimation and a differentiated consideration of carbon input sequestration from organic amendments commonly used in agriculture. Moreover, it does not consider the higher stability of below-ground crop residues in relation to above-ground crop residues.RothC was combined with two empirical approaches for quantifying carbon inputs from above- and below-ground crop residues and tested on 439 SOC data series from 36 arable long-term field experiments in Central and Northern Europe. Effects of carbon input quality on model fit were quantified with linear mixed models based on the analytical solution of RothC. Model parameters that describe the stability of incoming carbon were calibrated using a multi-site approach and Bayesian calibration. A second calibration study combined the determination of partitioning of incoming carbon into pools with different turnover rates and model responses to temperature and soil water content. With this calibration we showed that the contribution of above-ground residues to SOC is lower than when estimated with default RothC paramerization. We also show that the relative contribution from roots to SOC is higher than that from above-ground residues. Moreover, the degradability of organic amendments was highly variable between amendment categories and increased for all model configurations in the following order: farmyard manure < farmyard compost < sawdust < sewage sludge < peat. The proposed RothC partition coefficients for above-ground residues, roots and several commonly used organic amendments as estimated for this large data set should be useful for other studies in temperate climates. We also show that the analytical solution of RothC is closely related to the much simpler empirical humus balancing approaches used by farm advisory services. This provides opportunities to build bridges between the more process-oriented SOC models used in research and the well established instruments used by the farming community to assess the effects of agricultural management practices on SOC changes.

Total and available metal concentrations in soils from six long-term fertilization sites across China.

Approximately 19% of agricultural soils in China are contaminated by heavy metals. However, the effects of agricultural management practices on soil contamination are not well understood. Taking advantage of six long-term (23-34years) field sites across China, this study examined the effects of different agricultural fertilization treatments, including control (no fertilization), inorganic nitrogen, phosphorus and potassium fertilization (NPK), manure fertilization (M), and NPK plus manure fertilization (NPKM), on the total and available metal concentrations in soils. The results showed that after 23-34years of fertilization, the M and NPKM treatments significantly increased the total concentration of cadmium (Cd), copper (Cu), and zinc (Zn) in soils compared with the concentrations measured for the control and NPK treatments. In contrast, the fertilization treatments had almost no influence on soil lead (Pb) and nickel (Ni) concentrations. The results of analysis via diffusive gradients in thin films demonstrated that long-term sheep or cattle manure fertilization increased the available metals, especially Cd, Cu, and Zn, but long-term swine manure application decreased the available metals, except for Cu and Zn, in soils. Further analysis revealed that the manure source, soil pH level, and biogeochemical properties of metals affected the availability of Cd, Cu, Pb, Zn, and Ni in soils. Collectively, organic fertilizers had the potential to reduce metal uptake by crops, but caution should be taken to reduce metal concentrations in manure.

Effects of agricultural management practices on soil quality: A review of long-term experiments for Europe and China

In this paper we present effects of four paired agricultural management practices (organic matter (OM) addition versus no organic matter input, no-tillage (NT) versus conventional tillage, crop rotation versus monoculture, and organic agriculture versus conventional agriculture) on five key soil quality indicators, i.e., soil organic matter (SOM) content, pH, aggregate stability, earthworms (numbers) and crop yield. We have considered organic matter addition, no-tillage, crop rotation and organic agriculture as “promising practices”; no organic matter input, conventional tillage, monoculture and conventional farming were taken as the respective references or “standard practice” (baseline). Relative effects were analysed through indicator response ratio (RR) under each paired practice. For this we considered data of 30 long-term experiments collected from 13 case study sites in Europe and China as collated in the framework of the EU-China funded iSQAPER project. These were complemented with data from 42 long-term experiments across China and 402 observations of long-term trials published in the literature. Out of these, we only considered experiments covering at least five years. The results show that OM addition favourably affected all the indicators under consideration. The most favourable effect was reported on earthworm numbers, followed by yield, SOM content and soil aggregate stability. For pH, effects depended on soil type; OM input favourably affected the pH of acidic soils, whereas no clear trend was observed under NT. NT generally led to increased aggregate stability and greater SOM content in upper soil horizons. However, the magnitude of the relative effects varied, e.g. with soil texture. No-tillage practices enhanced earthworm populations, but not where herbicides or pesticides were applied to combat weeds and pests. Overall, in this review, yield slightly decreased under NT. Crop rotation had a positive effect on SOM content and yield; rotation with ley very positively influenced earthworms’ numbers. Overall, crop rotation had little impact on soil pH and aggregate stability − depending on the type of intercrop; alternatively, rotation of arable crops only resulted in adverse effects. A clear positive trend was observed for earthworm abundance under organic agriculture. Further, organic agriculture generally resulted in increased aggregate stability and greater SOM content. Overall, no clear trend was found for pH; a decrease in yield was observed under organic agriculture in this review.