长期施肥对潮土硫、钙和镁组分与平衡的影响

本文以在潮土进行的 2 0年的长期肥料试验为例进行研究 .结果显示 ,单施化肥处理土壤有效硫出现耗竭趋势 ,而施用有机肥的处理则保持较高有效硫水平和由于所含钙磷肥和有机肥以及灌溉水中含有数量可观的钙 ,土壤水溶态钙和交换态钙含量除对照外 ,各处理间十分接近 ,各处理的钙均有赢余 ;由于有机肥对土壤镁素的补充作用 ,水溶态镁、交换态镁、酸溶态镁和全镁含量均表现为原始土 >单施有机肥 >对照 >化肥与有机肥配施 >单施化肥 ,即使在施用有机肥条件下 ,土壤镁素仍然亏缺     

Isolating the effect of soil properties on agricultural soil greenhouse gas emissions under controlled conditions

Agricultural soils are important sources of greenhouse gases (GHGs). Soil properties and environmental factors have complex interactions which influence the dynamics of these GHG fluxes. Four arable and five grassland soils which represent the range of soil textures and climatic conditions of the main agricultural areas in the UK were incubated at two different moisture contents (50 or 80% water holding capacity) and with or without inorganic fertiliser application (70 kg N ha⁻¹ ammonium nitrate) over 22 days. Emissions of N₂O, CO₂ and CH₄ were measured twice per week by headspace gas sampling, and cumulative fluxes were calculated. Multiple regression modelling was carried out to determine which factors (soil mineral N, organic carbon and total nitrogen contents, C:N ratios, clay contents and pH) that best explained the variation in GHG fluxes. Clay, mineral N and soil C contents were found to be the most important explanatory variables controlling GHG fluxes in this study. However, none of the measured variables explained a significant amount of variation in CO₂ fluxes from the arable soils. The results were generally consistent with previously published work. However, N₂O emissions from the two Scottish soils were substantially more sensitive to inorganic N fertiliser application at 80% water holding capacity than the other soils, with the N₂O emissions being up to 107 times higher than the other studied soils.     

Leaf position and genotype differences for mineral element concentrations in sorghum grown on tropical acid soil 1

Mineral element deficiencies and toxicities are common problems associated with sorghum [Sorghum bicolor (L.) Moench] production on acid soils. To better understand some of the mineral element problems and the analysis of plant tissue of sorghum plants grown on acid soils, four sorghum genotypes were grown on an acid Oxisol at Carimagua, Colombia limed with dolomite at 2 and 6 Mg ha^‐1.

Samples for mineral element analyses were obtained from leaves at different positions on the four genotypes. Concentrations of P and Mg were highest in the flag leaf (Leaf No. 1) and decreased as the position on the plant declined from the top of the plant for plants grown at 2 Mg lime ha^‐1. Similar decreases in P, Mg, K, and Zn concentrations occurred in plants grown with 6 Mg lime ha^‐1. Concentrations of Ca, S, Si, Mn, Fe, Cu, and Al increased as leaf position declined from the flag leaf for plants grown at 2 and 6 Mg lime ha^‐1. The higher lime supply enhanced Ca and reduced Mn and Fe concentrations in leaves. Differences in mineral element concentrations for the four genotypes used were fairly extensive. The elements to show the greatest range among genotypes were Al and Si and the elements to show the least range among genotypes were P, K, and S. Care should be used in collecting leaf samples for plant analysis and genotypic differences for accumulation of mineral elements should be considered in interpretation of results.     

通过光谱辐射方法测定估算土壤化学性质

The contents of nitrogen and organic carbon in an agricultural soil were analyzed using reflectance measurements （n = 52） performed with an ASD FieldSpee-Ⅱ spectroradiometer. For parameter prediction, empirical models based on partial least squares （PLS） regression were defined from the measured reflectance spectra （0.4 to 2.4 μm）. Here, reliable estimates were obtained for nitrogen content, but prediction accuracy was only moderate for organic carbon. For nitrogen, the real spatial pattern of within-field variability was reproduced with high accuracy. The results indicate the potential of this method as a quick screening tool for the spatial assessment of nitrogen and organic carbon, and therefore an appropriate alternative to time- and cost-intensive chemical analysis in the laboratory.     

Combined effect of biochar and soil moisture on soil chemical properties and microbial community composition in microplastic-contaminated agricultural soil

Accumulation of microplastics (MPs) in agricultural environments has caused growing concern in recent years because of its detrimental impacts on soil quality, crop productivity and ecosystem function. This study was conducted to assess the impact of biochar on soil chemical and microbial properties in a MP-contaminated soil under two moisture regimes. Soil was contaminated with 1% (w/w) of low-density polyethylene MPs. Four types of standard biochar, that is, oil seed rape (OSR) biochar produced at 550°C (OSR 550) and 700°C (OSR 700) and soft wood pellet (SWP) biochar produced at 550°C (SWP 550) and 700°C (SWP 700), were applied at a rate of 5% (w/w). The control was maintained without MP addition. The samples were incubated in soil with two moisture regimes, that is, at 30% and 70% of the water holding capacity, and the soil chemical and microbiological properties were assessed after 100 days of incubation. OSR biochar application significantly increased soil pH (8.53–8.81) and electrical conductivity (0.51–0.58 dS/m) in both moisture regimes. The effect of biochar application on soil enzyme activity and microbial community composition did not show a clear trend. However, SWP 700 biochar improved soil enzyme activity compared with that of the control and improved bacterial diversity and evenness compared with those of other biochars, which was attributed to the high surface area available for microbial colonization. Low soil moisture content significantly reduced enzyme activity and bacterial richness even with biochar amendment, except for SWP 550 biochar. This study implies the suitability of biochar for improvement of soil quality in MP contaminated soil under both moisture regimes. However, further long-term studies are needed to get a clear understanding on the impact of different types of biochar on MP-contaminated soil.     

污泥及其混合堆肥对番茄土壤性质和N_2O排放的影响

目前关于污泥及其生物质堆肥的土地利用过程中土壤性质变化和温室气体排放数据十分缺乏,难以满足农田土壤氮素保存和温室气体减排的需求。该研究通过在番茄种植过程中添加800 kg/hm2新鲜污泥(S-H)、400 kg/hm2新鲜污泥(S-L)、800 kg/hm2秸秆堆肥(VM-S)和800 kg/hm2猪粪堆肥(VM-M),开展土壤性质、无机氮形态、作物生长以及N2O排放特征的研究。结果表明:堆肥处理显著增加了土壤电导率(electric conductivity,EC)(P0.05),其中猪粪堆肥时土壤EC值最大。添加污泥和堆肥都使土壤p H值显著上升(P0.05),最终趋于中性,且VM-M对土壤酸化的抑制效果略优于VM-S。污泥和堆肥处理时土壤NO3--N浓度显著高于对照,且各处理组NO3--N浓度均随时间逐渐下降,NO3--N主要被番茄吸收,部分NO3--N从土壤上层淋溶至下层;NH4+大多数被氧化为NO3-,部分NH4+被植物吸收。在施入的无机氮量相等情况下,VM-M、VM-S、S-H处理组中番茄地上部分生物量分别为1 515、1 383、1 103 g/株,株高分别为56.8、54.5、51.3 cm,对番茄生长的促进效果为VM-MVM-SS-H,而S-H比S-L多施入的氮肥对番茄生长并未起到明显促进作用(P0.05)。与对照相比,污泥或生物质堆肥都显著提高了土壤N2O的排放(P0.05),各处理组N2O的排放均集中于施肥后的前20天,且土壤N2O的排放通量大小顺序为S-L(0.76 kg/(hm2·a))VM-M(0.95 kg/(hm2·a))VM-S(1.19 kg/(hm2·a))S-H(1.71 kg/(hm2·a))。因此,在进行污泥及其生物质堆肥的土地利用时,应考虑有机肥的种类及其施用量,以在提高作物产量的同时改善土壤并减少温室气体排放,在进行污泥的农田利用时可先将污泥与畜禽粪堆肥。     

Elemental and/or cation ratio efficiency of corn hybrids grown on an infertile soil inadequate in magnesium

Abstract

Magnesium deficiency in corn (Zea mays L.) is often attributed to the low levels of Mg in soils. This study was conducted to determine elemental and/or cation balance efficiency of corn hybrids grown on a soil low in available Mg, Among the 15 hybrids tested, no differential efficiency in ear leaf concentration of P was found at two planting dates. Leaf concentrations of Zn and Fe were influenced by planting date for all hybrids but interactions between hybrids and planting date were found only for K, Ca, Mg concentrations and the sum of the Meq Ca + Mg/100 g, the Meq K + Ca + Mg/100 g, and the K/Ca and K/Ca + Mg ratios. Planting dates did not Influence the K/Mg ratio among hybrids. Large differences in efficiency of K, Ca, and Mg were found but these cations were found to have large Interactions. Data show that Ca and Mg efficient hybrids are less efficient in K than Ca and Mg inefficient hybrids. It should be possible to breed corn hybrids for better cation balance efficiency for use on infertile soils low in avallable Mg.     

水耕年限对黄棕壤发育的水稻土的表面化学性质的影响

利用采自江苏省农业科学院果园的旱地黄棕壤(对照)和由黄棕壤发育水耕20年和60年的水稻土,研究了土壤黏粒和粉粒的矿物组成,胶体和土体的化学性质随水耕年限的变化.粉粒的X-射线衍射图谱表明,3种供试土壤发育母质相似,胶体的矿物组成随水耕年限的变化不大.动电电位和表面负电荷的测定结果也表明,胶体表面化学性质未发生明显变化.随水耕年限增加,土壤黏粒含量降低,导致土体性质发生明显变化,土壤CEC和结构电荷量随水耕年限增加显著减少.     

Diversity of rhizobia isolated from an agricultural soil in Argentina based on carbon utilization and effects of herbicides on growth

Seventy-six rhizobial isolates belonging to four different genera were obtained from the root nodules of several legumes (Vicia sativa, Vicia faba, Medicago sativa, Melilotus sp., Glycine max and Lotus corniculatus). The action of five commonly used herbicides [2,4-dichlorophenoxyacetic acid (2,4-D), glyphosate (GF), dicamba, atrazine and metsulfuron-methyl] on the growth of rhizobial strains was assessed. Subsequently, GF and 2,4-D were tested in a minimum broth as C and energy sources for 20 tolerant strains. The ability of these strains to metabolize different carbon sources was studied in order to detect further differences among them. Tolerance of the bacteria to agrochemicals varied; 2,4-D and GF in solid medium inhibited and diminished growth, respectively, in slow-growing rhizobial strains. Among slow-growing strains we detected Bradyrhizobium sp. SJ140 that grew well in broth + GF as the sole C and energy source. No strain was found which could use 2,4-D as sole C source. The 20 strains studied exhibited different patterns of C sources utilization. Cluster analysis revealed three groups, corresponding to four genera of rhizobia: Rhizobium (group I), Sinorhizobium (group II) and Mesorhizobium–Bradyrhizobium (group III). On the basis of the results obtained on responses to herbicides and C sources utilization by the isolates investigated, it was possible to differentiate them at the level of strains. These results evidenced a considerable diversity in rhizobial populations that had not been previously described for Argentinean soils, and suggested a physiological potential to use natural and xenobiotic C sources.     

土壤pH值和含水量对土壤硝化抑制剂效果的影响

硝化抑制剂如2-氯-6-三氯甲基吡nitrapyrin,通常与氮肥配施来抑制硝化作用提高农田中肥料的利用率,但是其抑制效果会受到土壤理化性质的影响。采用新工艺重新合成后的新型nitrapyrin纯度高达98%,由于杂质减少而具有更好的硝化抑制效果。为了研究土壤pH值和含水量对新型nitrapyrin抑制效果的影响,明确nitrapyrin适合施用的土壤条件,采用室内培养试验,研究了在不同的土壤pH值和含水量下nitrapyrin对无机氮含量动态变化和硝化作用强度的影响,以及其硝化抑制率的变化规律。结果表明:随着土壤pH值的升高,铵态氮含量降低,硝态氮含量和表观硝化率呈现上升的趋势,并且在所有pH值处理下氮肥配施nitrapyrin均显著地降低了矿质氮库铵态氮的转化量,均不同程度地抑制了硝化作用;在培养的第9天,nitrapyrin在pH值7.70处理下对硝化作用抑制效果最好,硝化抑制率达到91.53%,但硝化抑制率的降低速率在高pH值处理上更快;在培养的第45天,当pH值为4.66时,硝化抑制率为36.43%,显著高于其他处理;在整个培养过程中,施用nitrapyrin能显著抑制各处理的硝化作用,硝化抑制率在不同土壤含水量上的表现为:40%WHC60%WHC80%WHC。可见,nitrapyrin更加适合施用在酸性土壤以及旱地土壤上,该研究可以为新型硝化抑制剂nitrapyrin在农田中施用的最优条件提供理论依据。     

Effect of vegetation manipulation of abandoned arable land on soil microbial properties

 The effect of vegetation composition on various soil microbial properties in abandoned arable land was investigated 2 years after agricultural practice had terminated. Microbial numbers and processes were determined in five replicate plots of each of the following treatments: continued agricultural practice (monoculture of buckwheat in 1997), natural colonization by the pioneer community (arable weeds), and manipulated colonization from low (four species, three functional groups: grasses, forbs and legumes) or high diversity (15 species, three functional groups) seed mixtures from plant species that are characteristic of abandoned fields in later successional stages. The results indicated that differences in above-ground plant biomass, plant species composition and plant species diversity had no significant effect on soil microbial processes (net N mineralization, short-term nitrification, respiration and Arg ammonification), microbial biomass C and N (fumigation-incubation) or colony-forming units of the major microbial groups. Hence, there were no indications that soil microbial processes responded differently within 2 years of colonization of abandoned arable land by later successional plants as compared to that by plants from the natural pioneer weed community. Therefore, it seems that during the first few years after arable field abandonment, plants are more dependent on the prevailing soil microbiological conditions than vice versa. Received: 8 April 1999     

Effects of different lime application rates and time on some chemical properties of an acid soil in Ghana

Abstract. Finely ground calcium carbonate was applied at six rates (0–7.0 t/ha) to samples from four depths of an acid tropical soil (Oxisol). The mixtures were kept moist and maintained at 18 °C for a period of 30 days. There was a significant increase (> 28%) in soil pH at all the sampling depths. Extractable P also increased significantly (> 90%). Significant positive correlations between pH, extractable P and liming rate were obtained ( r > 0.9, P = 0.01). The effect of time was significant only on the 10th day after liming, when soil pH had stabilized. Exchangeable Al was completely eliminated on the 5th day after liming, when most of the soil samples had pH values > 5.0. The results clearly indicate that liming, as a management practice, could be used to alleviate or prevent acidification of Oxisols like the soil studied.     

Influence of water table level and soil properties on emissions of greenhouse gases from cultivated peat soil

A lysimeter method using undisturbed soil columns was used to investigate the effect of water table depth and soil properties on soil organic matter decomposition and greenhouse gas (GHG) emissions from cultivated peat soils. The study was carried out using cultivated organic soils from two locations in Sweden: Örke, a typical cultivated fen peat with low pH and high organic matter content and Majnegården, a more uncommon fen peat type with high pH and low organic matter content. Even though carbon and nitrogen contents differ greatly between the sites, carbon and nitrogen density are quite similar. A drilling method with minimal soil disturbance was used to collect 12 undisturbed soil monoliths (50 cm high, Ø29.5 cm) per site. They were sown with ryegrass (Lolium perenne) after the original vegetation was removed. The lysimeter design allowed the introduction of water at depth so as to maintain a constant water table at either 40 cm or 80 cm below the soil surface. CO₂, CH₄ and N₂O emissions from the lysimeters were measured weekly and complemented with incubation experiments with small undisturbed soil cores subjected to different tensions (5, 40, 80 and 600 cm water column). CO₂ emissions were greater from the treatment with the high water table level (40 cm) compared with the low level (80 cm). N₂O emissions peaked in springtime and CH₄ emissions were very low or negative. Estimated GHG emissions during one year were between 2.70 and 3.55 kg CO₂ equivalents m⁻². The results from the incubation experiment were in agreement with emissions results from the lysimeter experiments. We attribute the observed differences in GHG emissions between the soils to the contrasting dry matter liability and soil physical properties. The properties of the different soil layers will determine the effect of water table regulation. Lowering the water table without exposing new layers with easily decomposable material would have a limited effect on emission rates.     

Functional dependencies of soil CO2 emissions on soil biological properties in northern German agricultural soils derived from a glacial till

Agricultural soil CO₂ emissions and their controlling factors have recently received increased attention because of the high potential of carbon sequestration and their importance in soil fertility. Several parameters of soil structure, chemistry, and microbiology were monitored along with soil CO₂ emissions in research conducted in soils derived from a glacial till. The investigation was carried out during the 2012 growing season in Northern Germany. Higher potentials of soil CO₂ emissions were found in grassland (20.40 µg g^?1 dry weight h^?1) compared to arable land (5.59 µg g^?1 dry weight h^?1) within the incubating temperature from 5°C to 40°C and incubating moisture from 30% to 70% water holding capacity (WHC) of soils taken during the growing season. For agricultural soils regardless of pasture and arable management, we suggested nine key factors that influence changes in soil CO₂ emissions including soil temperature, metabolic quotient, bulk density, WHC, percentage of silt, bacterial biomass, pH, soil organic carbon, and hot water soluble carbon (glucose equivalent) based on principal component analysis and hierarchical cluster analysis. Slightly different key factors were proposed concerning individual land use types, however, the most important factors for soil CO₂ emissions of agricultural soils in Northern Germany were proved to be metabolic quotient and soil temperature. Our results are valuable in providing key influencing factors for soil CO₂ emission changes in grassland and arable land with respect to soil respiration, physical status, nutrition supply, and microbe-related parameters.     

稻壳深施改良苏打碱土理化性质长期效应

盐渍土是中国重要耕地土壤,由于土壤中盐基离子含量高,影响植物生育,为此改良盐渍土意义重大。该研究以黑龙江省苏打碱土为供试土壤,采用土层置换犁将稻壳埋于20~30cm土层中,以单独的机械耕作不埋稻壳为对照,田间作业8 a后再次调查土壤理化性质,研究结果:土壤有机碳、速效氮、磷、钾含量与对照比有增加趋势,各层土壤pH值降低0.37~0.41,Na~+降低40.68~212.35 mg/kg;土壤固相率约40%,与对照比下降了3.68%~8.86%,土壤总孔隙度增加到57.38%~60.58%之间,有效孔隙比例大,占总孔隙的22.7%~26.8%,对照有效孔隙占总孔隙的19.0%~23.7%;土壤通气、透水性分别是对照的10~121 5倍和118~173 5倍,0~30 cm土层水库容量高于对照18.58 mm;速效水库容高于对照10.71 mm;稻壳深施持续后效长,改善苏打碱土比单一机械耕作有效,是适合盐渍土改良的一项技术,而且可以通过机械手段得以实现。     

Effect of chemical composition on the release of nitrogen from agricultural plant materials decomposing in soil under field conditions

Summary In two field experiments, plant materials labelled with ¹⁵N were buried separately within mesh bags in soil, which was subsequently sown with barley. In the first experiment, different parts of white clover (Trifolium repens), red clover (T. pratense), subterranean clover (T. subterraneum), field bean (Vicia faba), and timothy (Phleum pratense) were used, and in the second, parts of subterranean clover of different maturity. The plant materials were analysed for their initial concentrations of total N, ¹⁵N, C, ethanol-soluble compounds, starch, hemicellulose, cellulose, lignin, and ash. After the barley had been harvested, the bags were collected and analysed for their total N and ¹⁵N. In the first experiment the release of N was highest from white clover stems + petioles (86%) and lowest from field bean roots (20%). In stepwise regression analysis, the release of N was explained best by the initial concentrations of lignin, cellulose, hemicellulose, and N (listed according to decreasing partial correlations). Although the C/N ratio of the plant materials varied widely (11–46), statistically the release of N was not significantly correlated with this variable. The results of the second experiment using subterranean clover of different maturity confirmed those of the first experiment.     

The influence of winter soil cover on spring nitrous oxide emissions from an agricultural soil

In temperate regions, a majority of N₂O is emitted during spring soil thawing. We examined the influence of two winter field covers, snow and winter rye, on soil temperature and subsequent spring N₂O emissions from a New York corn field over two years. The first season (2006-07) was a cold winter (2309 h below 0 °C at 8 cm soil depth), historically typical for the region. The snow removal treatment resulted in colder soils and higher N₂O fluxes (73.3 vs. 57.9 ng N₂O-N cm⁻² h⁻¹). The rye cover had no effect on N₂O emissions. The second season (2007-08) was a much milder winter (1271 h below freezing at 8 cm soil depth), with lower N₂O fluxes overall. The winter rye cover resulted in lower N₂O fluxes (5.9 vs. 33.7 ng N₂O-N cm⁻² h⁻¹), but snow removal had no effect. Climate scenarios predict warmer temperature and less snow cover in the region. Under these conditions, spring N₂O emissions can be expected to decrease and could be further reduced by winter rye crops.     

长期施用化肥对作物产量和土壤性质的影响

１４年定位试验结果表明,在砂姜黑土、白散土和灰潮土上,以适量氮磷钾化肥配合施用,冬小麦、夏玉米、夏大豆、夏花生的增产效果最好,而单一施用一种化肥的肥效逐年降低。施肥提高了土壤有机质和氮磷钾养分的含量,而降低了ｐＨ值,土壤铜、锰、铁的有效性提高。土壤磷素积累,但降低了锌的有效性,故需隔年施用锌肥。     

不同施肥方式对农田土壤CO2和N2O排放的影响

采用静态箱/气相色谱法研究不同施肥方式以及环境因子对农田土壤CO2和N2O排放通量的影响,结果表明,不同施肥方式对农田土壤CO2排放的季节模式无明显影响,但是影响了N2O排放的季节模式。不同施肥方式对土壤CO2排放通量影响不明显,主要影响土壤N2O排放,整个小麦、玉米生长季,分两次施肥的F2与分四次施肥的F1相比,土壤N2O排放量增加,化肥配合有机肥施用(MF)的土壤N2O通量大于单纯的化肥处理,秸秆还田降低了土壤N2O的排放。相关分析结果表明,土壤CO2排放与大气温度、地表温度、土壤温度和土壤水分均呈显著正相关关系(P<0.01)。由于肥料施用的影响,土壤N2O排放和土壤温度、水分的相关分析并不显著。土壤N2O排放受土壤硝态氮和铵态氮变化的影响。     

Effects of different land use on soil chemical properties, decomposition rate and earthworm communities in tropical Mexico

The effects of land use on soil chemical properties were evaluated, and earthworm communities and the decomposition rate of three typical land use systems in tropical Mexico, namely banana plantations (B), agroforestry systems (AF) and a successional forest (S) were compared.The study was carried out from November 2005 to April 2006. A completely randomized sampling design was established in six sites (B1, B2, AF1, AF2, S1 and S2). Soil properties and chemical characteristics (texture, pH, organic carbon (Corg), nutrients, and available Zn and Mn), earthworm communities and the decomposition of Bravaisia integerrima and Musa acuminata litter were analyzed over a period of 8 weeks.All soils were loamy clays with a medium to high content of nutrients. Three principal clusters were generated with the soil chemical properties: a first cluster for forest soils with high Corg and Ntot and low available Zn content, a second cluster for AF1 and a third cluster for B1, B2 and A2.The decomposition of B. integerrima litter was significantly faster (half-life time: 1.8 (AF2)–3.1 (B1) weeks) than that of M. acuminata (4.1 (AF2)–5.8 (S2) weeks). However, the decomposition rates did not differ significantly among the different sites.The greatest earthworm diversities were observed in AF2 and B1. Native species were dominant in the forest soils, whereas exotic species dominated in AF and in the banana plantations. The abundance and biomass of certain earthworm species were correlated to physical and chemical soil parameters. However, litter decomposition rates were not correlated with any of the soil physical–chemical parameters.While none of the land use systems studied led to a decrease in nutrient status, earthworm biodiversity and abundance, or in litter decomposition rate, they did result in a change in earthworm species composition.