Comparison of postharvest practices used for cereal straw decomposition in a clay loam soil

ABSTRACT

During 2008–2011, model field experiments were carried out at the Joni?k?lis Experimental Station of Lithuanian Research Centre for Agriculture and Forestry on a clay loam Endocalcaric Endogleyic Cambisol. The study was aimed to establish the comparison of various postharvest practices (mineral nitrogen fertiliser alone or together with a bioactivator Penergetic k, livestock slurry, red clover biomass and straw incorporation in the soil by a stubble cultivator at a 10 cm depth) on the acceleration of the initial (nine-month period) decomposition of winter wheat straw. During this period, straw mass decomposition intensity was 20.7–29.1%, carbon (C) concentration decreased by 6.5–22.8%, while an increase in nitrogen (N) by 1.1–2.2 times was observed. The highest straw decomposition rate was recorded when after straw incorporation autumn was warm and humid. That year straw mass C to N ratio (C/N) was 38–46. Under less-favourable autumn conditions, the highest decomposition of straw was achieved, having applied mineral N (with and without Penergetic) and livestock slurry and having incorporated the straw in the soil (C/N = 40–55). A slower decomposition rate was observed for the straw spread on the soil surface with mineral N addition or on undersown red clover.     

Improving mineral nitrogen control by combining catch crops,fertilisation, and straw management in a clay loam soil

This experiment was conducted on a clay loam Cambisol and set out to determine the effects of combining catch crops, variable fertilisation levels, and straw management on the productivity of a spring barley-catch crop agrosystem, on the enrichment of soil with organic matter and nitrogen (N), and on soil mineral N control. Research was carried out in a spring barley (Hordeum vulgare L.) crop without catch crops, with undersown red clover (Trifolium pratense L.), and with post-crop white mustard (Sinapis alba L.). The barley was unfertilised, fertilised at moderate rates or at high rates. Straw was managed by either removing it from the field or chopping and spreading it. The quantity of organic matter and N incorporated into the soil depended on the fertilisation level of the barley crop. Soil mineral N stocks in the spring were reduced when straw was used together with red clover. When white mustard mass was incorporated alone in the autumn during ploughing, soil mineral N was reduced in the spring; however, when it was incorporated with straw, the effect was the opposite. Soil mineral N content is controllable when organic matter components are combined according to their decomposition rates, masses, and incorporation times.     

Effect of legume and legume-festulolium mixture and their mulches on cereal yield and soil quality in organic farming

ABSTRACT

Research was conducted to determine the effects of perennial legume and their mulches on cereal grain yield and the alterations to clay loam Cambisol properties. The perennial legumes (Trifolium pratense L., Medicago sativa L.) as well as their mixtures with festulolium (x Festulolium) were studied in conjunction with their aboveground biomass management methods: removal from the field (cut twice for forage), mixed management (the first cut was for forage, the second and third cuts were mulched) and mulching (four times) in an organic arable farming system. Mulching of legumes biomass resulted in a higher total nitrogen (N) used for green manure. A similar amount of N was accumulated for lucerne and lucerne-festulolium mulch when using mulching and mixed management. Legumes used for mulching caused the amount of mineral N in soil to increase in late autumn (62.7–82.9 kg ha^–1) and decrease in spring (39.5–64.0 kg ha^–1). This mineral N had a positive impact on crop yield (r = 0.68–0.71*); however, mineral N in autumn had a negative impact on soil sustainable organic compounds (r = ?0.71*). The results indicate that the most suitable treatment was the legume-festulolium mixture, which used the biomass under mixed management.     

不同耕作方式对中国东北黑土有机碳的短期影响

A tillage experiment, consisting of moldboard plow （MP）, ridge tillage （RT）, and no-tillage （NT）, was performed in a randomized complete block design with four replicates to study the effect of 3-year tillage management on SOC content and its distribution in surface layer （30 cm） of a clay loam soil in northeast China. NT did not lead to significant increase of SOC in topsoil （0-5 cm） compared with MP and RT; however, the SOC content in NT soil was remarkably reduced at a depth of 5-20 cm. Accordingly, short-term （3-year） NT management tended to stratify SOC concentration, but not necessarily increase its storage in the plow layer for the soil.     

Effect of some cations,anions, and organic residues on potassium leaching and fractionation in calcareous sandy loam soil

Potassium (K) is one of the essential elements for plants. There has been enough research to determine pollution of nitrogen (N), phosphorus (P), and heavy metals in soil. However, by comparison research on the storage and transport of K has been neglected. Chemical fertilizer usage leads to serious environmental problems in Iran. Leaching of K can be affected by type of anions and cations present in the chemical fertilizers. Potassium leaching experiments were performed using 10 mM NH₄Cl, (NH₄)₂HPO₄, NH₄H₂PO₄, NH₄NO₃, NH₄OAC, CaCl₂, Ca(NO₃)₂, NaNO₃, and CO(NH₃)₂. The leaching experiment was lasted for 20 days (15 pore volumes). In addition, a set of experiments were conducted, where potato and wheat residues and poultry manure and sheep manure were added to soil at the rate of 5% and distilled water was used as the leaching solution to investigate impacts of organic residues on K leaching. In general, maximum K release was observed using NH₄Cl (566 kg ha^?1). Potato and wheat residues had maximum and minimum impacts on K leaching, respectively. Potassium fractionation was carried out after the end of the leaching experiment. The results indicated that leaching of soil in the presence of soluble salts and organic residues altered K distribution in different parts of soil.     

Chemical and spectroscopic characteristics of humic acid from a clay loam soil in Ontario after 52 years of consistent fertilization and crop rotation

Long-term fertilization and crop rotation can influence both organic C sequestration as well as the C composition of soils and the more resistant organic C compounds contained in humic acid(HA). This study examined the effects of fertilization and cropping type(monoculture corn(MC) and Kentucky bluegrass sod(KBS) and corn-oat-alfalfa-alfalfa rotation(RC)) on the HA composition of soil from a 52-year field study in southern Ontario, Canada. Humic acid samples were extracted from soil, and elemental analysis, infrared spectroscopy, solid state 13C nuclear magnetic resonance spectra, and electron paramagnetic resonance methods were used to determine the influence of the cropping type on the characteristics of HA. Both fertilization and cropping type affected the chemical characteristics of HA. Fertilization led to a 5.9% increase in C, a 7.6% decrease in O, and lower O/C and(N + O)/C ratios in HA as compared to the corresponding non-fertilized treatments. Rotation resulted in a lower proportion of C(48.1%) and a greater(N + O)/C ratio(0.7) relative to monoculture cropping. Infrared spectroscopy analysis showed that HA contained more C-O groups in fertilized soil than in non-fertilized soil under MC and KBS. Fertilization increased the O-alkyl-C, phenolic-C, and free radical contents of HA relative to non-fertilization treatments. Rotation decreased the aliphatic and carboxyl groups and increased the O-alkyl, carbohydrate, aryl, and phenolic groups and free radicals, relative to MC and KBS. Both long-term crop rotation and fertilization dramatically modified the soil HA composition. Significant relationships were observed between the molecular composition of HA and soil organic C. Hence, humic acid characterization could be used as an indicator of the long-term sustainability of crop management practices.     

不同施肥管理对红壤性水稻土有机碳、氮形态的影响

A long-term experiment beginning in 1981 in Jinxian County of Jiangxi Province, subtropical China, was conducted in a paddy field under a double rice cropping system with four different fertilization regimes, including 1) no fertilizer as control (CK), 2) balanced chemical N, P, and K fertilizers (NPK), 3) organic manure using milk vetch and pig manure in the early and late rice growing season, respectively (OM), and 4) balanced chemical fertilizers combined with organic manure (NPKM). Samples (0-17 cm) of the paddy field soil, which was derived from Quaternary red clay, were collected after the late rice harvest in November 2003 for determination of total organic carbon (TOC) and total nitrogen (TN) and fractions of organic C and N. Results showed that TOC and TN in the NPKM and OM treatments were significantly higher than those in other two treatments (CK and NPK). Application of organic manure with or without chemical fertilizers significantly increased the contents of all fractions of organic C and N, whereas chemical fertilizer application only increased the contents of occluded particulate organic C (oPOC) and amino acid N. In addition, application of organic manure significantly enhanced the proportions of free particulate organic carbon (fPOC) and oPOC in total C, and those of amino sugar N and amino acid N (P < 0.01) in total N. In contrast, chemical fertilizer application only increased the proportions of oPOC and amino acid N (P < 0.05). There were no significant differences in either contents or proportions of soil organic C and organic N fractions between the NPKM and OM treatments. These indicated that organic manure application with or without chemical fertilizers played the most significant role in enhancing soil organic C and N quantity and quality in the paddy field studied.     

Phosphorus and nitrogen turnover and risk of waterborne phosphorus emissions in crop rotations on a clay soil in southwest Sweden

Abstract. Nutrient losses from arable land are important contributors to eutrophication of surface waters, and phosphorus (P) and nitrogen (N) usually act together to regulate production of Cyanobacteria. Concentrations and losses of both nutrients in drainage water from pipe drains were studied and compared in 15 crop rotations on a clay soil in southwest Sweden. Special emphasis was placed on P and it was possible to evaluate critical components of the crop rotations by flow-proportional water sampling. Total P concentrations in drainage water were generally small (0.04–0.18 mg L⁻¹), but during two wetter years out of six, high P concentrations were measured following certain management practices, including ploughing-in lucerne ( Medicago sativa L.) and fertilizing in advance without incorporation into the soil to meet the needs of several subsequent crops. This resulted in average flow-weighted concentrations of total P between 0.3 and 0.7 mg L⁻¹. In crop rotations containing green manures, green fallow or leguminous leys, there was also a risk for increased P losses after these crops were ploughed in. The losses increased in the order: cash crops < dairy with grass < dairy with lucerne < monoculture with barley < organic farming with cattle slurry < stockless organic farming with green manure. P balances varied between −9 and +8 kg P ha⁻¹ and N balances between +4 and +35 kg N ha⁻¹. The balances were not related to actual leaching losses. Phosphorus losses in drainage from set-aside were 67–82% of those from cash crops grown in ploughed and P-fertilized soil at the same site, indicating a high background P loss from this clay soil.     

Nitrogen and phosphorous in a loam soil of central Italy as affected by 6 years of different tillage systems

Tillage practices can influence content and dynamics of soil N and P. A field study was conducted on a loam soil (Typic Udifluvent) in Italy, to determine mineral and organic N and P concentrations at the end of 6 years of different tillage systems. Maize (Zea mays L.) was cropped since 1970, and managed since 1994 with deep ploughing (DP) to 40 cm, ripper subsoiling (RS) to 40 cm, shallow ploughing (SP) to 20 cm and minimum tillage with harrow disk (MT) to 10 cm. At the end of the sixth year, soil was collected in 10 cm increments to a total depth of 40 cm. Surface concentration of total N was higher with MT than with RS, SP and DP, but differences disappeared at lower depths. Soil water content was lower under DP and SP treatments than under MT and RS. Residual NO₃-N in the soil profile was not different among tillage treatments. During 6 years, MT increased soil quality, by enrichment of organic N and improvement of soil water content at the surface. Moldboard ploughing was a less sustainable tillage system in this environment.     

The consequences of wheel-induced soil compaction and subsoiling for silage maize on a sandy loam soil in Belgium

In Belgium, growing silage maize in a monoculture often results in increased soil compaction. The aim of our research was to quantify the effects of this soil compaction on the dry matter (DM) yields and the nitrogen use of silage maize (Zea mays L.). On a sandy loam soil of the experimental site of Ghent University (Belgium), silage maize was grown on plots with traditional soil tillage (T), on artificially compacted plots (C) and on subsoiled plots (S). The artificial compaction, induced by multiple wheel-to-wheel passages with a tractor, increased the soil penetration resistance up to more than 1.5 MPa in the zone of 0–35 cm of soil depth. Subsoiling broke an existing plough pan (at 35–45 cm of soil depth). During the growing season, the release of soil mineral nitrogen by mineralisation was substantially lower on the C plots than on the T and S plots. Silage maize plants on the compacted soil were smaller and flowering was delayed. The induced soil compaction caused a DM yield loss of 2.37 Mg ha⁻¹ (−13.2%) and decreased N uptake by 46.2 kg ha⁻¹ (−23.2%) compared to the T plots. Maize plants on compacted soil had a lower, suboptimal nitrogen content. Compared with the traditional soil tillage that avoided heavy compaction, subsoiling offered no significant benefits for the silage maize crop. It was concluded that avoiding heavy soil compaction in silage maize is a major strategy for maintaining crop yields and for enhancing N use efficiency.     

Effects of soil management practices and tillage systems on surface soil water conservation and crust formation on a sandy loam in semi-arid Kenya

The effect of different soil management practices on crust strength and thickness, soil water conservation and crop performance was investigated on a ferric lixisol in a semi-arid environment of eastern Kenya.

The study proved that manure and mulching with minimum tillage have a greater effect on the water balance of crusted soils and maize emergence. There was increase in steady infiltration rates, amount of soil water stored in the soil and better drainage. The physical effect of mulch was less important in the rehabilitation of crusted soils in the study site when it was incorporated into the soil. Manure and surface mulch with minimum tillage should therefore be taken into account in land management and water conservation in the semi-arid areas of Kenya. The response of crops to the improved water availability due to manure with minimum and with conventional tillage and surface mulch was very clear. These management practices should be recommended when considering the effectiveness of soil and water management techniques in the study area.     

长期不同施肥措施下黑土作物产量与养分平衡特征

为了明确长期不同施肥措施下黑土作物产量及养分平衡特征,利用开始于1979年的哈尔滨黑土肥力长期定位试验,以小麦-大豆-玉米轮作(3a)为一个周期,选取对照(不施肥,记作CK)、常量氮磷钾化肥配施(小麦施N、P2O5量分别为150、75 kg/hm2,大豆施N、P2O5量分别为75、150 kg/hm2,玉米施N、P2O5量分别为150、75 kg/hm2,K2O共施75 kg/hm2,记作NPK)、常量有机肥(施肥18 600 kg/hm2,记作M)、常量化肥有机肥配施(化肥施量同NPK,有机肥施量同M,记作MNPK)和二倍量氮磷化肥有机肥配施(小麦施N、P2O5量分别为300、150 kg/hm2,大豆施N、P2O5量分别为150、300 kg/hm2,、玉米施N、P2O5量分别为300、150 kg/hm2,有机肥共37 200 kg/hm2,记作M2N2P2)5个处理,研究了不同作物的平均产量、产量年际变化和土壤养分表观平衡。结果表明:1)较CK,长期平衡施用化肥或化肥配施有机肥提高了作物产量,多年平均增产率分别在82.5%~91.6%(小麦)和35.6%~40.9%(玉米)之间。长期不同施肥措施增产效果表现为M2N2P2MNPKNPKM,有机无机肥配施与单施化肥处理间作物产量差异不显著。2)长期不施肥处理小麦和玉米产量随试验年限推移呈下降趋势,降幅分别为13.93和42.61 kg/(hm2·a),大豆则以7.409 kg/(hm2·a)的速率增加。施肥处理小麦、大豆和玉米产量随试验年限的增加呈总体上升的趋势。3)在该试验条件下,长期施用常量化肥处理(NPK)和常量化肥有机肥配施处理(MNPK)土壤氮亏缺量分别为29.7和17.5 kg/hm2,磷盈余量分别为33.4和61.2 kg/hm2。各处理土壤中钾素均表现为亏缺,亏缺量在30.4~73.0 kg/hm2之间。MNPK处理氮、钾供应状况有所改善,较NPK处理分别增加12.2和27.6 kg/hm2。4)作物产量与土壤有机质、碱解氮、有效磷、降雨量、生育期日平均气温呈显著正相关关系(P0.05)。5)在黑土小麦-大豆-玉米典型轮作制度下,基于土壤养分平衡特征提出"稳氮、减磷和增钾"的施肥策略。该研究为评价和建立长期施肥模式、促进粮食持续生产提供依据。     

Residual nitrogen effects on a succeeding oat (Avena sativa L.) Crop of clover species and ryegrass (Lolium perenne L.) undersown in winter wheat (Triticum aestivum L.)

The aim of the present investigation was to study the effect of white clover (var. Milka and Donna), red clover (var. Fanny) and ryegrass (var. Tove) undersown in winter wheat on a succeeding oat crop. Under the climatic conditions prevailing in Sweden, growing a catch crop after winter cereals is of particular interest because the latter are usually followed by a spring sown crop, leaving the ground bare during autumn and winter. Field trials were carried out during three growing seasons in an integrated farming system and for one year in an organic farming system. Competition from the dense wheat crop in the integrated farming system had a negative effect on the undersown species, and at harvest of the wheat they showed quite poor growth in all three years, with nitrogen contents under 5 kg ha^?1. No significant yield increase was measured without added nitrogen when the averages for all three years were calculated. On average, the grain yields were improved by 750 kg ha^?1 (14% moisture content) for the treatments with undersown clover for all three years when 90 kg N ha^?1 were added. The experiment within the organic system showed a different pattern with a better development of the undersown clover species, with nitrogen contents approximately 25 kg ha^?1 and an improvement in oat grain yield, from around 2?000 kg ha^?1 for the control to almost 3?500 kg ha^?1 with clover undersown the previous year.     

Comparison of the effect of Cow manure,Vermicompost, and Azolla on safflower growth in a saline-sodic soil

ABSTRACT

Soil salinity and sodicity are two important factors in land degradation, especially in arid and semi-arid regions of the world. Application of soil amendments, such as organic matter, can be a suitable method for improving the fertility of saline-sodic soils. In this research, a saline-sodic soil was chosen, mixed with three levels of 1%, 3%, and 5% (weight) of Cow manure, Vermicompost, and Azolla, and incubated for 5 months at field capacity and a temperature of 20°C. Then, safflower seeds were planted and treatments were placed in a greenhouse for two months. After this period, plant indices were measured. The results showed that the addition of treatments caused differences in safflower growth in comparison to the control treatment. The noted differences were mostly negative for the treatment of cow manure, they were negligible for Azolla, and were positive for Vermicompost. Vermicompost applied at 5% level provided the most suitable substrate for safflower growth in saline-sodic soil.     

Modeling vertical movement of organic matter in a soil incubated for 41 years with C labeled straw

The distribution of organic matter (OM) in the soil profile reflects the balance between inputs and decomposition at different depths as well as transport of OM within the profile. In this study we modeled movement of OM in the soil profile as a result of mechanisms resulting in dispersive and advective movement. The model was used to interpret the distribution of ¹⁴C in the soil profile 41 years after the labeling event. The model fitted the observed distribution of ¹⁴C well (R²=0.988, AIC_c=−82.6), with a dispersion constant of D=0.71 cm² yr⁻¹ and an advection constant of v=0.0081 cm yr⁻¹. However, the model consistently underestimated the amount of OM in the soil layers from 27 to 37 cm depth. A possible explanation for this is that different fractions of OM are transported by different mechanisms. For example, particulate OM, organomineral colloids and dissolved OM are not likely to be transported by the same mechanisms. A model with two OM fractions, one moving exclusively by dispersive processes (D=0.26 cm² yr⁻¹) and another moving by both dispersive (D=0.99 cm² yr⁻¹) and advective (v=0.23 cm yr⁻¹) processes provided a slightly better fit to the data (R²=0.995, AIC_c=−83.6). More importantly, however, this model did not show the consistent underestimation from 27 to 37 cm soil depth. This corroborates the assumption that differing movement mechanisms for different OM fractions are responsible for the observed distribution of ¹⁴C in the profile. However, varying dispersion, advection, and decay of OM with depth are also possible explanations.     

Responses of soil microbial communities to manure and biochar in wheat cultivation of a rice-wheat rotation agroecosystem in East China

Soil contamination in agroecosystems remains a global environmental problem. Biochar has been suggested as an organic amendment to alleviate soil pollution, sequester carbon(C), and improve soil fertility. However, information on how bacterial and fungal communities in acidic bulk and rhizosphere soils respond to swine manure and its biochar is still lacking. In this study, biochar and swine manure were applied at two rates of 1.5 and 3 t ha^-1 in a rice-wheat rotation field to assess ...     

秸秆生物炭配施氮肥对潮土土壤碳氮含量及作物产量的影响

【目的】探讨玉米秸秆生物炭配施氮肥对华北潮土区土壤理化特性和作物产量的影响,阐明土壤和植株对生物炭和氮肥施用的响应,旨在为该区域秸秆资源高效利用、培肥土壤及作物增产提供科学依据。【方法】以华北冬小麦–夏玉米轮作区为研究对象,研究玉米秸秆生物炭 (缺氧条件下 450℃ 热裂解 1 小时获得) 配施氮肥对土壤养分含量、微生物量以及作物产量的影响。试验采用裂区设计,以秸秆生物炭施用量为主区,施氮量为副区。秸秆生物炭用量设 0、7.5 和 22.5 t/hm2 3 个水平 (以 BC₀、BC_7.5、BC_22.5 表示);氮肥用量设 0、150、225 和 300 kg/hm2 4 个水平 (以 N₀、N₁₅₀、N₂₂₅、N₃₀₀ 表示)。小麦在 2014 年 10 月 9 日播种,次年 6 月 8 日收获;玉米在 2015 年 6 月 10 日播种,当年 9 月 28 日收获。在作物成熟期进行产量测定,并采集 0—20 cm 土壤样品以及采用常规方法进行土壤有机碳 (SOC)、全氮 (TN)、可溶性有机碳 (DOC)、铵态氮 (NH₄+-N)、硝态氮 (NO₃–-N)、土壤微生物量碳 (MBC) 和微生物量氮 (MBN) 的测定。【结果】生物炭对土壤养分含量、微生物量碳氮及作物产量有极显著影响。生物炭用量增加,土壤 SOC、TN、DOC、NO₃–-N 含量以及土壤 SOC/TN 比值均显著增加,较 BC₀ 最大增加幅度分别为 165.0%、74.1%、39.1%、75.1% 和 44.0%。MBC、MBN 含量和作物产量均以 BC_7.5 处理达最大值,较 BC₀ 最大增加幅度分别为 49.2%、57.6% 和 46.1%,BC_22.5 较 BC_7.5 处理平均降低 12.1%、7.3% 和 9.7%;施用生物炭降低 NH₄+-N 含量,BC_7.5 和 BC_22.5 处理较 BC₀ 分别下降 18.4% 和 23.7%。随着氮肥施用量的增加,SOC、DOC、NH₄+-N、MBC、MBN 含量均先增后减,在施氮水平为 150 kg/hm2 时,其含量均达最大值,较 N₀ 最大增加幅度分别为 29.7%、22.9%、44.8%、79.4% 和 115.3%。所有施氮的处理作物产量较 N₀ 均显著增加,而三个施氮处理间其产量差异不显著 (P>0.05)。【结论】在维持作物产量不降低的情况下,短期内 N₁₅₀BC_7.5 处理对提升土壤肥力的效果最佳,是较为理想的施肥方式,但其有效机制及长期效果还需进一步试验研究。     

Effects of amendments on soil structural development in a clay soil-forming material used as a cap for landfill restoration

Abstract. Restoration of landfill sites to a vegetated after-use is severely compromised if soil-forming materials (SFMs) have to be used as substitute growing media for the restoration cap, owing partly to their poorly-developed structure. The effects of crushed brick material (brick), composted green-waste organic matter (OM) and potassium chloride salt (KCl) in a clay SFM were assessed at the Brogborough Landfill Site (Shank Group plc) in the county of Bedfordshire, UK. Soil structure was characterized three times in a two-year experimental period through measuring drainage water release and aggregate stability and size distribution. Crushed brick and composted OM at 100 t ha⁻¹ improved the ability of the clay to release water by drainage. In addition, the composted OM was associated with an increase in the size of stable aggregates, whereas the brick amendment reduced the overall aggregate stability. The KCl amendment had no consistent effect. Some beneficial structural improvements were thus associated with the brick and OM amendments, although these were rarely significant at the 5% level and the effects declined over time in the absence of vegetation and re-application. Nevertheless, incorporation of crushed brick and organic amendments may offer a potential structure-improving option in clay SFMs prior to vegetation establishment.     

节水控肥下有机无机肥配施对日光温室黄瓜–番茄轮作体系土壤氮素供应及迁移的影响

本试验以日光温室秋冬茬番茄-冬春茬黄瓜轮作体系为研究对象,采用田间小区试验,研究了5季节水控肥（冬春茬黄瓜和秋冬茬番茄季N-P2O5-K2O总投入量分别为600-300-525 kg/hm2和450-225-600 kg/hm2）有机无机肥配施对 040 cm（根区）土壤硝态氮供应、 40100 cm（根区以外）硝态氮残留和 0100 cm土体不同形态氮素淋失的影响,探索了设施蔬菜生产中节水节肥潜力,为构建设施蔬菜合理水肥管理下土壤肥力培育和土壤质量提升模式提供技术支持。试验结果表明, 1）农民习惯水肥管理节水节肥潜力较大; 节水控肥后0100 cm土体硝态氮积累量、 矿质氮和有机氮渗漏量均明显下降,种植蔬菜经济效益显著增加。2）商品有机肥猪粪与化肥在土壤无机氮供应方面的效果接近; 节水控肥1/41/2 猪粪氮替代1/41/2 化肥氮后,040 cm土体硝态氮供应和40100 cm土体硝态氮残留均无显著变化,但是随着猪粪氮配施比例的增加,土壤溶液渗漏量及养分淋失量呈增加趋势。3）施用秸秆促进了土壤无机氮固持,降低根区土壤硝态氮供应水平,提高土壤养分保蓄能力; 节水控肥1/2秸秆氮替代1/2化肥氮后,040 cm土壤硝态氮供应量平均下降34.3%~56.2%,40100 cm土体硝态氮残留量下降42.5%~87.8%, 0100 cm土体土壤溶液渗漏量下降65.0%,硝态氮淋失量下降 82.0%,而产量和经济收入无显著差异。根据本试验结果,对于新建温室可采用单施化肥、 化肥与猪粪配施方案,能在短时间内提高土壤无机氮供应强度,满足蔬菜氮素需求; 对于种植了一段时间的温室,可采用冬春茬黄瓜季化肥配施猪粪秋冬茬番茄季化肥配施秸秆方案,能固定积累于土壤中的无机氮,提高土壤养分容量,保证根层土壤氮素的稳定供应,降低环境风险,维护设施农业的可持续发展。     

Origin and fate of soil lipids in a Phaeozem under rye and maize monoculture in Central Germany

Although soil lipids are an important class of soil organic substances, which is involved in numerous soil processes, their origin and fate in soils is insufficiently known. Therefore, this study aimed at investigating the free lipid fraction in crop residues and farmyard manure (FYM), and soils which received these materials for long time. We sampled rye and maize stubble and roots, FYM, and Ap horizon soils from the ‘Unfertilized’ and ‘FYM’ plots of ‘Eternal Rye Cultivation’ experiment at Halle, Saxony-Anhalt, Germany. Free lipids were extracted by dichloromethane/acetone and analyzed by gas chromatography/mass spectrometry. Aliphatics were most abundant in all extracts, accounting for 61 to 77% of the total extractable lipids. By comparing the lipid composition of the added organic materials with that of the corresponding treated soil, the long-chain members of n-alkanols, n-alkanes, α,ω-alkanedioic acids, and unsaturated alkanoic acids from C₁₆ to C₁₉ did not disappear in soil whereas ω-hydroxyalkanoic acids and long-chain branched alkanoic acids were not extracted from soil probably because they were bound to nonextractable forms. It is suggested that the methodological approach can give information on decomposition and retention of free extractable lipids in soil. More information is needed to trace the fate of all lipids in the plant–soil system by the determination of bound molecules, which are nonextractable by organic solvents.