湿地土壤质量退化的模糊综合评价

Wetland soil quality degradation caused by large-scale agricultural reclamation on the Sanjiang Plain of Northeast China has been widely reported. A relative soil quality evaluation (RSQE) model and a projection pursuit evaluation (PPE) model based on real-coded accelerating genetic algorithm were introduced to evaluate quality variations in top layers of the main wetland soils on the Sanjiang Plain in 1999 and 2003, respectively. As soil quality degradation boundaries were vague, this study established two fuzzy synthetic evaluation (FSE) models based on the original data and criteria used in the RSQE and PPE models. The outputs of the two FSE models were obtained by choosing two fuzzy composite operators M (∧,∨) and M (?,⊕). Statistical analysis showed that the results of the FSE, RSQE, and PPE models were correlated. In particular, outputs of the FSE model using M (?,⊕) were significantly correlated with those of the RSQE model with r = 0.989 at P < 0.01. Compared with RSQE and PPE models, the FSE model may be more objective in showing soil quality variations and was closer to the natural situation, showing the feasibility and applicability of the FSE model in evaluating soil quality degradation. However, the choice of composite operator was of critical importance. The study of wetland soil quality degradation on the Sanjiang Plain was of scientific and practical significance for protection and management of soils and for sustainable development of agriculture in this area in the future.     

集约化管理的温室土壤养分现状研究

Nine districts covering the main greenhouse vegetable areas in Tianjin Municipality of the North China Plain were selected for the soil investigation in 2010 to survey the current soil nutrient status (soil available N, P and K), acidification and salinization due to excessive input of fertilizers in greenhouses in Tianjin. The study showed that, in particular, soil available P content increased with the age of greenhouses. In contrast, our results did not reveal higher K accumulation and lowered pH in the greenhouse soils compared with cultivation in open fields. Over-fertilization, causing high NO 3 accumulation, most likely resulted in salinity problems in the greenhouses. Ninety percent of the investigated greenhouse soils had electrical conductivity values of saturated paste extracts of 2-10 d S m-1 , which might affect the yields of vegetable crops like green bean, pepper, cabbage, carrot, eggplant, lettuce, spinach, celery, cucumber and tomato. The findings of our survey of the current fertility and salinity problems in greenhouse soils suggest that there is an urgent need to improve the farmers’ practices and strategies in fertilization management in greenhouses of China. Because education and the agricultural technical extension services may play a more important role in avoiding overuse of fertilizers, we suggest that current nutrient management practices should be improved in the near future through training of local farmers in farmers’ schools and through strengthening the agricultural extension services with practical techniques.     

不同种植模式和土壤类型条件下土壤健康的定量评价

Soil health assessment is an important step toward understanding the potential effects of agricultural practices on crop yield, quality and human health. The objectives of this study were to select a minimum data set for soil health evaluation from the physical, chemical and biological properties and environmental pollution characteristics of agricultural soil and to develop a soil health diagnosis model for determining the soil health status under different planting patterns and soil types in Chongming Island of Shanghai, China. The results showed that the majority of the farmland soils in Chongming Island were in poor soil health condition, accounting for 48.9% of the survey samples, followed by the medium healthy soil, accounting for 32.2% of the survey samples and mainly distributed in the central and mid-eastern regions of the island. The indicators of pH, total organic carbon, microbial biomass carbon and Cd exerted less influence on soil health, while the soil salinization and nitrate accumulation under a greenhouse cropping pattern and phosphate fertilizer shortage in the paddy field had limited the development of soil health. Dichlorodiphenyltrichloroethanes, hexachlorocyclohexanes and Hg contributed less to soil health index (SHI) and showed no significant difference among paddy field, greenhouse and open-air vegetable/watermelon fields. The difference of the SHI of the three soil types was significant at P = 0.05. The paddy soil had the highest SHI values, followed by the gray alluvial soil, and the coastal saline soil was in a poor soil health condition, indicating a need to plant some salt-tolerant crops to effectively improve soil quality.     

长期施肥对土壤中硒的累积及其生物有效性的影响

Continuous applications of organic and inorganic fertilizers can affect soil and food quality with respect to selenium(Se) concentrations.A long-term(over 20 years) experimental field study,started in 1989,was conducted to investigate the changes in soil Se fractions and its uptake by crops,as affected by different fertilizer practices,in the North China Plain with an annual crop rotation of winter wheat and summer maize.The long-term experiment was arranged in a complete randomized block design consisting of 4replications with 7 fertilizer treatments:1) organic compost(OC),2) half organic compost plus half N-P-K chemical fertilizers(OC+ NPK),3) N-P-K fertilizers(NPK),4) N-P fertilizers(NP),5) P-K fertilizers(PK),6) N-K fertilizers(NK),and 7) an un-amended control.Soil samples from the surface(20 cm) were collected in 1989,1994,1999,2004 and 2009 to characterize Se and other soil properties.In 2009,the average soil Se concentrations in the treatments(149 ± 8 μg kg~(-1)) were higher than those in the soil samples collected in 1989 at the beginning of the experiment(112 ± 4 μg kg~(-1)),and decreased in the order of OC OC + NPK NPK≈NP PK ≈NK control.Sequential extraction showed the oxidizable fraction(50.06%± 3.94%) was the dominant form of Se in the soil,followed by the residual fraction(24.12%± 2.89%),exchangeable fraction(15.09%± 4.34%) and Fe-Mn oxides fraction(10.73%± 4.04%).With an increase of soil K,the exchangeable Se concentrations in the soil increased.The Se concentrations in the soil tillage layer(0-20 cm) were mainly related to soil organic carbon(SOC),although different contributions came from atmospheric deposition,irrigation and fertilizers.With the accumulation of SOC,the uptakes of soil Se by two crops were inhibited.For the OC and OC + NPK treatments,Se concentrations in wheat grains were lower than the critical standard of Se in stable food(100 μg kg~(-1)).Additionally,Se concentrations in grains were also decreased by the deficiencies of major soil nutrients,especially P.     

亚热带湿润地区城市公园重建强度对其土壤酸化和土壤中重金属的影响

Soil quality is a major concern in the management of urban parks. In this study, the soils at 0–3, 3–13, and 13–23 cm depths were sampled from six urban parks, differing in reconstruction intensity(mainly changes made during conversion of natural forests into parklands), in the Pearl River Delta, China to determine how reconstruction intensity influenced the extent of acidification and heavy metal levels in the soils of urban parks in a humid subtropical environment. High reconstruction intensity(HRI) was practiced in three parks and low reconstruction intensity(LRI) in three other parks. The LRI soils were strongly to extremely acidic(with low exchangeable Ca, Mg, and K concentrations) while the HRI soils were much less acidic. Both total and extractable concentrations of soil heavy metals were related to the specific management practices and age of the park, but did not differ significantly between LRI and HRI parks or among soil depths. Soil p H was significantly related to soil exchangeable cation concentrations and base saturation but was weakly related or unrelated to soil heavy metal levels. Our results suggest that high intensity but not low intensity reconstruction significantly reduces the extent of soil acidification in the urban parks in a humid subtropical environment.     

土壤碳氮对多年生能源草、覆盖作物和氮施肥的响应

Cover crop and nitrogen(N) fertilization may maintain soil organic matter under bioenergy perennial grass where removal of aboveground biomass for feedstock to produce cellulosic ethanol can reduce soil quality. We evaluated the effects of cover crops and N fertilization rates on soil organic carbon(C)(SOC), total N(STN), ammonium N(NH_4-N), and nitrate N(NO_3-N) contents at the0–5, 5–15, and 15–30 cm depths under perennial bioenergy grass from 2010 to 2014 in the southeastern USA. Treatments included unbalanced combinations of perennial bioenergy grass, energy cane(Saccharum spontaneum L.) or elephant grass(Pennisetum purpureum Schumach.), cover crop, crimson clover(Trifolium incarnatum L.), and N fertilization rates(0, 100, and 200 kg N ha~(-1)). Cover crop biomass and C and N contents were greater in the treatment of energy cane with cover crop and 100 kg N ha~(-1) than in the treatment of energy cane and elephant grass. The SOC and STN contents at 0–5 and 5–15 cm were 9%–20% greater in the treatments of elephant grass with cover crop and with or without 100 kg N ha~(-1)than in most of the other treatments. The soil NO_3-N content at 0–5 cm was 31%–45% greater in the treatment of energy cane with cover crop and 100 kg N ha~(-1)than in most of the other treatments.The SOC sequestration increased from 0.1 to 1.0 Mg C ha~(-1)year~(-1)and the STN sequestration from 0.03 to 0.11 Mg N ha~(-1)year~(-1)from 2010 to 2014 for various treatments and depths. In contrast, the soil NH_4-N and NO_3-N contents varied among treatments,depths, and years. Soil C and N storages can be enriched and residual NO_3-N content can be reduced by using elephant grass with cover crop and with or without N fertilization at a moderate rate.     

玉米-大豆轮作中耕作方式和磷肥施用对土壤磷组分冬季变化特征的影响

Determining how agricultural management practices affect soil phosphorus(P) over the winter may further our understanding of the soil P cycle under specific environmental conditions in eastern Canada. This study assessed changes over winter for soil P fractions and other selected chemical properties as affected by tillage and P fertilization. In 1992, a long-term corn(Zea mays L.) and soybean(Glycine max L.) rotational experiment was established in the province of Quebec, Canada. Soil samples(0–15 cm) were collected in fall 2001 and 2007 after a soybean harvest, and in the following spring 2002 and 2008 before corn seeding, in main plots under moldboard plow and no-till managements and selected subplots fertilized with 0, 17.5, or 35 kg P ha-1and 160 kg N ha-1. Soil samples were analyzed for P fractions and other chemical properties to assess changes over winter for 2001–2002 and 2007–2008. Changes over winter of all soil P fractions were significant for the two periods, indicating the occurrence of soil P transformation and movement over winter. The Mehlich-3-extractable Fe, Al, Ca, and Mg decreased during the two studied periods. Tillage had no significant effect on all soil P fractions. The resin-extractable P in 2001–2002 and Na HCO3-extractable inorganic P and Na OH-extractable organic P during the two winters were significantly increased under P fertilization. This study demonstrated that P in cultivated soils changed during winter as a result of changes in labile P fractions possibly due to the solubilization of residual fertilizer P combined with environmental factors.     

约旦河谷土壤含盐量变化对其灌溉农业可持续发展的潜在危害研究

The integrated effect of irrigation and agricultural practices on soil salinity in the Jordan Valley （JV）, where over 60% of Jordan’s agricultural produce is grown, was investigated in this study during 2009-2010. Due to the differences in agricultural operations, cropping patterns, irrigation management, and weather conditions, 206 top- and sub-soil samples were taken every 1 to 3 km from representative farms along a north-south （N-S） transect with 1 to 2 km lateral extents. Soil electrical conductivity of saturated extract (EC_se), Ca, Mg, K, Na, Cl, and Na adsorption ratio （SAR） were determined in saturated paste extracts. Results indicated that about 63% of soils in the JV are indeed saline, out of which almost 46% are moderately to strongly saline. Along the N-S transect of the JV, EC_se increased from 4.5 to 14.1 dS m^-1 in top-soil samples. Similar increase was observed for the sub-soil samples. The major chemical components of soil salinity; i.e., Ca, Mg, and Cl, also showed a similar increase along the N-S transect of the valley. Moreover, compared to previous field sampling, results showed that changes in soil salinity in the JV were dramatic. In addition, it was found that Cl imposed an existing and potential threat to sensitive crops in 60% of the soils in the JV, where Cl concentrations were greater than 710 mg L^-1. Under the prevalent arid Mediterranean conditions, improving the management of irrigation water, crops, and nutrient inputs and increasing water and fertilizer use efficiencies should be indispensable to conserve and sustain the already fragile agricultural soils in the JV.     

聚合果属生物炭引起的咸水灌溉下土壤养分有效性和番茄生长变化

Thermally modified organic materials commonly known as biochar have gained popularity of being used as a soil amendment.Little information, however, is available on the role of biochar in alleviating the negative impacts of saline water on soil productivity and plant growth. This study, therefore, was conducted to investigate the effects of Conocarpus biochar(BC) and organic farm residues(FR) at different application rates of 0.0%(control), 4.0% and 8.0%(weight/weight) on yield and quality of tomatoes grown on a sandy soil under drip irrigation with saline or non-saline water. The availability of P, K, Fe, Mn, Zn and Cu to plants was also investigated. The results demonstrated clearly that addition of BC or FR increased the vegetative growth, yield and quality parameters in all irrigation treatments. It was found that salt stress adversely affected soil productivity, as indicated by the lower vegetative growth and yield components of tomato plants. However, this suppressing effect on the vegetative growth and yield tended to decline with application of FR or BC, especially at the high application rate and in the presence of biochar. Under saline irrigation system, for instance, the total tomato yield increased over the control by 14.0%–43.3% with BC and by 3.9%–35.6% with FR. These could be attributed to enhancement effects of FR or BC on soil properties, as indicated by increases in soil organic matter content and nutrient availability. Therefore, biochar may be effectively used as a soil amendment for enhancing the productivity of salt-affected sandy soils under arid conditions.     

森林生态系统中土壤有机质组分的固态13C核磁共振波谱表征

Forest management practices such as prescribed burning and thinning in forest ecosystems may alter the properties of soil organic matter (SOM).In this study,surface soils from field plots in the Bankhead National Forest,Alabama,USA,were used to investigate possible SOM transformations induced by thinning and burning.Elemental analysis and solid-state 13C cross polarization magic angle spinning nuclear magnetic resonance (13C CPMAS NMR) spectroscopy were used to characterize SOM fractions in whole soils,humic substances,and density fractions.Our data revealed that the changes in SOM fractions due to the repeated burning carried out in the forest ecosystem studied were involved mainly with alkyl C,O-alkyl C,and carbohydrate functional groups,implying that most prominent reactions that occurred involved dehydrogenation,de-oxygenation,and decarboxylation.In addition,burning and thinning might have also affected the distribution and composition of free and occluded particulate SOM fractions.The limited structural changes in SOM fractions suggested that low-intensity prescribed fire in the forest ecosystem studied will not create major structural changes in SOM fractions.     

不同蔬菜生产模式对日光温室土壤质量的影响

有机农业作为常规农业的一种替代模式,其对土壤及作物的影响研究逐渐受到学术界的关注。该文通过对日光温室有机、无公害和常规生产模式的比较试验,分析有机生产模式对土壤养分、土壤微生物碳氮以及土壤酶活性的影响。结果表明,经过6年的试验,有机生产模式可显著提高土壤全碳、全氮含量以及土壤微生物量碳、氮含量,并提高土壤主要酶的活性,各项指标均表现为有机模式优于无公害模式优于常规模式。有机生产模式能够显著提高土壤质量,有利于土壤的可持续利用。3种生产模式下夏茬番茄产量有机模式高于无公害模式高于常规模式,且随着种植年限的增加有机模式秋茬作物产量呈增加趋势。     

集约化大棚蔬菜种植条件下土壤硒有效性的影响因子分析

Soil properties dramatically change after long-term greenhouse vegetable cultivation, which further affects soil selenium (Se) nutritional status and plant Se uptake. An evaluation of Se availability after long-term greenhouse vegetable cultivation (GVC) can help in better understanding its influential factors under GVC conditions and will also facilitate further regulation of soil Se nutrition in GVC systems. Two typical GVC bases were chosen: one with clayey and acidic soil in Nanjing, southern China, and the other with sandy alkaline soil in Shouguang, northern China. Twenty-seven surface soil samples at the Nanjing base and 61 surface soil samples at the Shouguang base were collected according to cultivation duration and cultivation intensity. Soil properties including soil available Se (PO₄^3--Se) and total Se (T-Se) were analyzed. The results showed that soil PO₄^3--Se was significantly and negatively correlated with soil Olsen-P, available K (A-K), and electrical conductivity (EC) at the Nanjing base. At the Shouguang base, however, no significant correlation was found between soil PO₄^3--Se and Olsen-P and EC, and soil PO₄^3--Se increased with increasing soil organic matter (OM). Intensively utilized greenhouse vegetable cultivation caused significant changes in soil properties and further affected soil Se availability. Due to different management practices, the dominant factors affecting Se availability varied between the two GVC bases. At the Nanjing base, the dominant influential factor on soil Se availability was soil nutritional status, especially Olsen-P and A-K status. At the Shouguang base, where organic fertilizers were applied at high rates, soil OM was the dominant influential factor.     

新疆绿洲区连续五年施用沼液对农田土壤质量的影响

以施用化肥为对照,通过5年田间小区试验,研究沼液灌溉对绿洲设施蔬菜地土壤质量的影响。试验结果表明:连续施用沼液能够有效调节绿洲农田耕层土壤酸碱度,有利于改良碱性土壤;沼液灌溉能够显著提高设施蔬菜地土壤肥力,尤其是表层土壤中有机质和全氮、全磷、速效氮、有效磷、速效钾、钙、铁、锌和铜等植物必需营养元素含量;然而,连续施用沼液也会导致表层土壤电导率显著升高,土壤中重金属元素显著积累,虽然5年内设施蔬菜地土壤盐分和重金属等有害元素含量均在蔬菜种植允许范围内,但随着沼液灌溉年限的增加,土壤存在次生盐渍化现象和重金属超标风险,尤其以Cd、As和Ni的风险最大。     

IBQS: A synthetic index of soil quality based on soil macro-invertebrate communities

We developed a synthetic index of biological soil quality (IBQS) based on soil macro-invertebrate community patterns to assess soil quality. In 22 sites representing the diversity of agroecosystems encountered in France, invertebrate communities co-varied significantly with a set of 14 parameters describing the physical and chemical properties of soil (co-inertia, p < 0.001; RV = 0.70). Using hierarchical classification, sites could be separated into four homogeneous groups and, using the ‘indicator value’ method, 46 indicator taxa characteristic of one or another of these groups were identified. We then used a formula that takes into account the abundance of indicator species and their respective indicator values to score soils from 1 to 20. IBQS was able to detect the effects of management practices on soil quality. Soil quality varied from 6 to 20 in forests, 7 to 9 in pastures and 2 to 9 in crops respectively. This suggests that well-managed crops and pastures may have better soil quality than some forests. Our results confirm that soil macro-invertebrates provide an integrative measure of soil quality and that the proposed index can be used either in short- or long-term monitoring, provided that it is calibrated and validated with respect to the regional context of the study.     

Relationship between soil chemical properties and microbial metabolic patterns in intensive greenhouse tomato production systems

ABSTRACT

Intensive greenhouse production involving excessive fertilizer and organic manure application rates may affect soil chemical and biological quality. Soil samples from 50 commercial greenhouses for tomato production in northern China were collected for the evaluation of the status of soil fertility and identification of the soil chemical factor that exerts the strongest influence on microbial functional diversity. The soil total nitrogen content showed high soil fertility and was 68% higher than 1000 mg kg^?1 and 14% higher than 1500 mg kg^?1. Differential soil pH values caused statistically significant shifts in microbial metabolic activity (average well color development, AWCD) and Shannon’s diversity index using Biolog^TM ECO plates assay. The highest soil microbial functional diversity was observed at near neutral pH values. When individual data points were plotted against soil organic matter (SOM), significant positive associations with soil microbial biomass nitrogen and AWCD were observed. The canonical correspondence analysis confirmed that shifts in the soil microbial functional diversity were associated with changes in pH, total nitrogen, and SOM. This study indicated that excessive fertilization changed the community-level physiological profile of the soil microorganisms, and this effect can be a consequence of changes in soil pH under intensive greenhouse management.     

Impact of soil solarization on the ciliate community structure of a greenhouse soil

Soil solarization is an ecologically friendly method of controlling various plant pathogens and pests, but also affects non-pathogenic members of the soil biota. Here, we studied the impact of soil solarization on the community structure of soil ciliates using a culture-independent molecular approach, namely denaturing gradient gel electrophoresis (DGGE) of targeted 18S rRNA gene fragments. Greenhouse soil with added organic fertilizers was solarized for 33 days at an average temperature of 47–48°C. Solarization caused a drastic change in the ciliate community. The variation between replicates was large, which suggested that the distribution of ciliates was spatially heterogeneous in the soil, probably due to their decreased numbers. In contrast, non-solarized soil had a stable and homogeneous ciliate community during the experimental period. In solarized soil, most of the original ciliate community recovered 76 days after solarization. Sequence analysis of DGGE fragments indicated that both r-selected and K-selected species of ciliates were affected by solarization but recovered with time after solarization. Our results demonstrated both the vulnerability and resilience of the ciliate community to soil solarization and also the utility of using molecular-based analysis of ciliate communities as bioindicators of soil stress caused by solarization.     

Effects of organic,low input,conventional management practices on soil nematode community under greenhouse conditions

A comparative study of organic, low input, conventional vegetable greenhouse systems was conducted to assess the effect of management practices on the soil nematode community. Bacterivores were the most dominant trophic group in all three systems with a mean proportion of over 80%, followed by omnivore-carnivores. In general, organic management practices increased the abundance of total nematodes, bacterivores, fungivores, and omnivore-carnivores in comparison with low input and conventional management practices. Though inhibitory effects of plant feeders were found in organic and low input systems, these effects were more evident in organic systems. However, small differences were observed in the composition of trophic groups and fauna analysis. All three systems displayed enriched soil conditions and structured food webs. We inferred that the bottom-up effect resulting from organic input in the soil food web may play a more important role than the disruption effects under our high input greenhouse conditions. The Shannon index (H′) and genus dominance (λ) suggested that in greenhouse conditions, excessive manure input would cause a decrease in nematode diversity but increase the dominance, particularly for enrichment opportunists. We concluded that management practices under greenhouse conditions were more influential on nematode biomass (including trophic groups) than community structure.     

Effects of biochar amendment on greenhouse gas emissions,net ecosystem carbon budget and properties of an acidic soil under intensive vegetable production

Biochar addition to soils has been frequently proposed as a means to increase soil fertility and carbon (C) sequestration. However, the effect of biochar addition on greenhouse gas emissions from intensively managed soils under vegetable production at the field scale is poorly understood. The effects of wheat straw biochar amendment with mineral fertilizer or an enhanced‐efficiency fertilizer (mixture of urea and nitrapyrin) on N₂O efflux and the net ecosystem C budget were investigated for an acidic soil in southeast China over a 1‐yr period. Biochar addition did not affect the annual N₂O emissions (26–28 kg N/ha), but reduced seasonal N₂O emissions during the cold period. Biochar increased soil organic C and CO₂ efflux on average by 61 and 19%, respectively. Biochar addition greatly increased C gain in the acidic soil (average 11.1 Mg C/ha) compared with treatments without biochar addition (average ?2.2 Mg C/ha). Biochar amendment did not increase yield‐scaled N₂O emissions after application of mineral fertilizer, but it decreased yield‐scaled N₂O by 15% after nitrapyrin addition. Our results suggest that biochar amendment of acidic soil under intensive vegetable cultivation contributes to soil C sequestration, but has only small effects on both plant growth and greenhouse gas emissions.     

Low-cost interventions for big impacts in dryland production systems

A study at selected action sites in semi-arid region of Andhra Pradesh, India, showed widespread land degradation due to low levels of soil organic carbon (78% of fields) and deficiencies of available nutrients like phosphorus (34%), sulfur (93%), calcium (33%), zinc (84%), boron (73%), and copper (33%). Soil test-based addition of deficient micro- and macronutrients increased food grain production by 30–40% and straw (which is used as fodder) production by 10–30%. Micro-watershed scale low-cost cement-lined farm-ponds at smallholder farm level proved a scalable technology for drought-proofing of crops resulting into additional crop yield by more than 30% during 2015. Augmentation of water sources also facilitated farmers’ to successfully diversify the production system. Shared machinery resources improved the operational and economic efficiency of farm sowing operations through higher crop yields by around 10%. We conclude that a mix of low-cost critical interventions if out-scaled in a large number of dryland small holdings through policy support may not only improve productivity and livelihoods, but also enhance their abilities to effectively cope with the climatic aberrations.     

大棚土壤盐分累积特征与调控措施研究

通过对昆明地区不同年限的大棚土壤的管理现状调查分析及采集次生盐渍化严重的土壤做调控盐分的盆栽模拟试验，研究了保护地大棚土壤次生盐渍化的形成特征以及土壤调理剂对大棚土壤盐分的调控效果，结果表明：随着大棚年限的增长，耕层土壤的盐分在增加，盐分组成以Ca²⁺和NO^-₃为主，0～60 cm土层的盐分剖面由露地的直筒型向倒锥形发展，由泥炭、沸石、锯末等改良材料组合成的土壤调理剂控盐效果显著，耕层土壤全盐含量降幅在19％～32％之间。