改良剂作用下滨海盐化潮土团聚体分布、稳定性及有机碳分布特征

通过对滨海盐化潮土小麦—玉米轮作2年田间定位试验,研究不同改良剂施用对土壤团聚体分布、稳定性及土壤团聚体中有机碳含量、各级团聚体有机碳对总有机碳贡献率的影响。试验共设置3个处理:对照(CK)、有机土壤改良剂(OSA)和有机—无机土壤改良剂(CSA),分析土壤团聚体分布、水稳性大团聚体(R_(0.25))、平均重量直径(mean weight diameter,MWD)、几何平均直径(geometric mean diameter,GMD)、分形维数(D)、有机碳储量(soil organic carbon storage,SOCS)和有机碳贡献率(contribution rate of organic carbon)。结果表明,滨海盐化潮土水稳性团聚体组成主要以0.25 mm粒径为主,改良剂施用后土壤R_(0.25)显著提高,其影响主要集中在5 mm和2～5 mm粒径级,OSA处理2个粒级团聚体含量较CK分别显著增加167.38%和59.00%,CSA处理分别显著增加89.17%和100.66%。施用OSA与CSA同时显著提高了土壤团聚体MWD和GMD值,说明2种改良剂的施用均有利于提高大团聚体数量及稳定性。施用改良剂2年处理土壤各粒级团聚体中有机碳含量均有所提高,OSA处理以1～2 mm粒级提高最多,CSA以2～5 mm粒级提高最多,且前者达显著水平。与CK相比,改良剂可促使土壤有机碳向大团聚体富集,显著提高1～2 mm粒级团聚体对土壤总有机碳的贡献率93.62%～109.76%,降低或显著降低1～2 mm粒级团聚体对土壤总有机碳的贡献率20.55%～24.92%。在小麦—玉米轮作模式下,改良剂施用不仅可以显著提高滨海盐化潮土水稳性大团聚体含量和稳定性,还可显著增加水稳性大团聚体有机碳含量与储量,是加强盐碱土壤有机碳库积累的有效措施。     

轮作休耕模式对土壤团聚体及有机碳含量的影响

为探究轮作休耕模式对红壤坡耕地团聚体稳定性及有机碳含量的影响,通过田间试验设置了休闲地、玉米单作、玉米-豌豆-玉米和玉米-苕子-玉米4个处理,分析了不同种植模式下土壤团聚体稳定性及有机碳含量,结果表明:(1)不同种植模式下土壤机械稳定性和水稳定性团聚体组成均以≥0.25 mm粒径占比最高,机械稳定性团聚体占比在80.68%以上,水稳定性团聚体达到了77.05%以上,且≥0.25 mm团聚体所占比例大小顺序为:休闲地>玉米-豌豆-玉米>玉米-苕子-玉米>玉米单作。(2)根据不同团聚体稳定指数(MWD,GMD,R_0.25和PAD)显示,休闲地的团聚体稳定性最好,与玉米单作之间差异显著,且休闲地和玉米轮作两种模式下团聚体稳定性均优于玉米单作。(3)玉米单作土壤团聚体有机碳含量最低,玉米轮作和休闲地能显著提高有机碳含量,并且玉米-苕子-玉米轮作效果最优; ≥0.25 mm粒径范围的团聚体储存的有机碳含量最高。(4)通过对土壤水稳性团聚体稳定指数与有机碳含量的相关性分析表明,4个不同团聚体稳定指数与有机碳含量都呈极显著正相关关系,与R_0.25相关程度最高。研究结果可为试验区域坡耕地水土流失防治提供理论依据。     

黄土高原吕梁山不同撂荒年限土壤团聚体稳定性及有机碳分布特征

为探究不同撂荒年限土壤结构及有机碳分布特征,试验选取黄土高原吕梁山自然撂荒1、2、3、5、10、15、20 a枣园土壤为研究对象,以清耕作业下的枣园土壤为对照(CK),利用干筛和湿筛法测定并分析各样地0～20 cm土层中土壤团聚体稳定性、团聚体有机碳与土壤总有机碳含量及其相关性。结果表明:撂荒初期,土壤团聚体含量呈波动变化趋势,撂荒3 a后土壤水稳性大团聚体含量(0.25 mm团聚体含量,R_(0.25))及团聚体平均重量直径(MWD)、几何平均直径(GMD)随撂荒年限的增加逐步提高。20 a撂荒地土壤水稳性大团聚体含量占团聚体总量的69.6%,较CK提高了55.2个百分点。土壤总有机碳、团聚体有机碳含量随撂荒年限的延长均呈先降低后增加的趋势,撂荒20 a土壤总有机碳含量达最大值7.88 g/kg;团聚体有机碳含量随团聚体粒径的减小呈先增加后降低的特点,主要集中于1～0.25 mm团聚体内。不同撂荒年限土壤中机械稳定性大团聚体有机碳对土壤总有机碳的贡献率为54.3%～82.2%,较CK(29.3%)提高25.0～52.9个百分点;水稳性大团聚体有机碳对土壤总有机碳的贡献率为17.7%～71.8%,除撂荒1 a和3 a土壤外,其他样地均高于CK (21.1%)。水稳性团聚体MWD、R_(0.25)与土壤总有机碳含量极显著相关(P0.01);水稳性团聚体GMD与土壤总有机碳含量显著相关(P0.05);水稳性团聚体R_(0.25)与2～1、1～0.25和0.25 mm水稳性团聚体有机碳含量极显著相关(P0.01),与5～2 mm团聚体有机碳含量显著相关(P0.05)。可见,撂荒恢复促进了土壤有机碳及水稳性团聚体有机碳含量的提高,从而提高了团聚体的稳定性。     

改良剂对复垦土壤团聚体组成及有机碳含量的影响

为探究改良剂对复垦土壤团聚体组成及有机碳含量的影响,采用田间微区的方法按表层0—20 cm土壤重量占比1%,3%,5%的比例添加泥炭、腐殖酸和蛭石,研究3种改良剂对复垦土壤团聚体组成、总有机碳、各粒级团聚体有机碳含量、土壤红外光谱特征的影响。结果表明:施用3种改良剂后各处理土壤机械稳定性团聚体均以>5 mm的最多,施用泥炭和腐殖酸后>5 mm团聚体含量随着改良剂施用比例的升高而增大,且MWD(平均质量直径)值均高于CK。其中,5%腐殖酸对调控>5 mm团聚体含量效果最佳,在6个月时>5 mm机械稳定性团聚体占比达到60.03%。而施用蛭石后>5 mm机械稳定性团聚体的占比与CK相比有所下降。施用3种改良剂后土壤水稳性团聚体以<0.053 mm团聚体含量最高,但其含量均随改良剂施用比例的升高而降低。泥炭和腐殖酸能够提高复垦土壤总有机碳的含量,增强抗侵蚀能力和团聚体的稳定性,而施用蛭石后有机碳含量减少。泥碳、腐殖酸和蛭石各处理下各粒级机械稳定性团聚体有机碳含量均以>5 mm最高,0.053~0.25 mm次之,<0.053 mm最少,有机碳含量贡献率也以>5 mm团聚体的最大,泥炭和腐殖酸处理下>5 mm团聚体有机碳含量贡献率均高于50%,<0.053 mm团聚体有机碳贡献率仅有0.63%~2.82%。从土壤的红外光谱特征峰可以看出,施用腐殖酸能够增加土壤中的多糖类物质,而多糖类物质有大量的—OH,能与黏粒矿物晶面上的氧原子形成氢键而把土粒团聚起来。     

化肥与有机物料配施对黄褐土团聚体分布及有机碳含量的影响

通过对黄褐土小麦/玉米轮作定位试验,研究了不同施肥模式对土壤团聚体分布、稳定性及团聚体中有机碳含量、各级团聚体对有机碳的贡献率的影响。结果表明:黄褐土的水稳性团聚体组成主要以0.25 mm粒径为主,施有机物料增加了0.25 mm水稳性团聚体,同时提高团聚体的稳定性。团聚体有机碳主要存在于0.25 mm水稳性团聚体中,并随着水稳性团聚体粒径的增大而明显增加。化肥配施秸秆对黄褐土水稳性团聚体影响较大,显著增加0.053 mm各粒径水稳性团聚体含量,降低0.053 mm水稳性团聚体含量,同时显著提高团聚体平均重量直径(MWD)、几何平均直径(GMD)和稳定率(R0.25),并且化肥配施秸秆对土壤中0.25 mm各粒径团聚体对有机碳的贡献率增加更为明显。而化肥配施鸡粪对土壤中0.25 mm各粒径团聚体中有机碳增加效果最好。     

施用生物质灰渣对柑橘园土壤团聚体及有机碳分布的影响

为探讨生物质灰渣施用对紫色丘陵区柑橘园土壤团聚体组成、稳定性以及不同土层各粒级团聚体有机碳分布的影响。以重庆市现代果树生态示范园为研究对象,采用沙维诺夫干筛法和湿筛法测定了土壤中各粒级团聚体含量,并用重铬酸钾外加热法测定其水稳定性团聚体的有机碳含量。结果表明:(1)干筛下,B处理(施用生物质灰渣21 260kg/hm~2)R_(0.25)含量高于A处理(对照),且A和B处理土壤团聚体主要以5mm粒径团聚体为主,其含量均大于70%;湿筛下,B处理20—40cm土层土壤R0.25含量高于0—20cm和40—60cm土层,分别增加了6.47%和11.60%,A处理也呈现相同的变化趋势,且A和B处理土壤水稳定团聚体主要以0.25mm粒径团聚体为主。(2)在0—20cm土层中,B处理在湿筛下的GMD和MWD均高于A处理,分别比A处理增加了0.87%和2.87%;在40—60cm中,B处理在干筛下的GMD和MWD达最大值,分别为4.54,4.81mm,可见配施生物质灰渣有利于提高土壤团聚体的稳定性,尤其有利于提高土壤表层(0—20cm)和亚表层(20—40cm)的团聚体稳定性。(3)与表层相比,A处理40—60cm土层5,5~2,2~1,1~0.5mm有机碳含量降幅分别是B处理的1.13,1.06,1.15,1.13倍,施用生物质灰渣能减小20—40cm和40—60cm土层有机碳的降幅;总体上,B处理各土层各粒级团聚体有机碳含量均高于A处理,提高土壤团聚体各粒级有机碳含量。(4)B处理0—60cm土层土壤团聚体有机碳总储量为4.318 8×10~5 kg/hm~2,比A处理高1.86%。配施生物质灰渣能够增加大团聚体的数量,提高土壤各粒级团聚体有机碳含量及有机碳储量,提高土壤有机碳水平。     

稻壳及稻壳生物炭对土壤团聚体稳定性及有机碳分布的影响

【目的】长期种植雷竹(Phyllostachys praecox)会导致土壤酸化加剧,土壤结构破坏。我们比较了施用不同量稻壳和稻壳生物炭对土壤理化性状和团聚体组成的影响,以寻求实现雷竹的可持续生产的有效措施。【方法】采用盆栽方法进行雷竹幼苗试验,供试土壤长期种植雷竹,pH为5.3。设置分别施用稻壳、稻壳生物炭10 t/hm² (10H、10B)和30 t/hm² (30H、30B)处理,以不施稻壳和稻壳生物炭的处理为对照(CK)。雷竹幼苗生长262天后,采集土样测定土壤基本理化性质,采用湿筛法筛分不同粒级土壤团聚体,测定各粒级团聚体中有机碳和全氮含量。【结果】30H和30B处理均显著降低了<0.053 mm粒级团聚体含量,显著提高了水稳性团聚体的平均重量直径(MWD)、几何平均直径(GMD)以及>0.25 mm粒级团聚体(R0.25)含量;10H和10B处理对水稳性团聚体的MWD、GMD以及R0.25含量均无显著影响。30B处理显著增加了>2 mm、0.25～2 mm、0.053～0.25 mm粒级团聚体中有机碳含量,其中增...     

生物质炭和秸秆长期还田对红壤团聚体和有机碳的影响

要 ：秸秆还田和施用生物炭是提高土壤有机碳含量和改良土壤团聚体结构的有效方法,但长期施用生物炭与秸秆还田改良土壤的效率研究仍然缺乏比较。本研究针对中亚热带典型的旱地红壤,基于等碳量不同碳源投入的5年野外定位试验,研究秸秆还田、秸秆-猪粪配施和生物炭还田对红壤团聚体组成、稳定性和有机碳分布的影响,为建立红壤地力快速提升的有机培肥措施提供科学依据。本试验共设置对照、单施化肥、秸秆还田、秸秆-猪粪配施和生物炭还田五个处理,采用干筛和湿筛法分析了连续施用不同碳源5年后对土壤团聚体组成、稳定性和有机碳分布的影响。研究表明,施用等碳量的不同有机碳源5年后显著增加了土壤有机碳含量,其增幅顺序为：生物炭还田>秸秆-猪粪配施>秸秆还田。干筛法分析结果表明：与单施化肥处理相比,秸秆-猪粪配施和生物炭还田处理显著增加>0.25 mm机械稳定性团聚体含量(R_0.25)、平均重量直径(mean weight diameter, MWD)和几何平均直径(geometric mean diameter, GMD);秸秆还田和生物炭还田处理显著增加了0.25-2 mm团聚体对土壤有机碳的贡献率。湿筛法分析结果表明：与单施化肥处理相比,秸秆还田和秸秆-猪粪配施处理显著增加R_0.25、MWD和GMD,但生物炭还田处理和单施化肥处理相比差异不显著;秸秆还田和秸秆-猪粪配施处理显著降低团聚体破坏率(PAD),生物炭还田处理显著增加了PAD;秸秆配施猪粪处理和秸秆还田处理显著增加了>2mm团聚体对土壤有机碳的贡献率。总体上,秸秆配施猪粪协同提高团聚体有机质含量和团聚体稳定性的作用比秸秆还田和生物炭还田要强。     

长期施肥与覆膜对半干旱区马铃薯农田土壤团聚体分布及其有机碳含量的影响

以国家土壤质量安定观测实验站黄绵土区的农田长期定位试验为研究平台,研究长期施肥与覆膜对半干旱区马铃薯农田土壤团聚体分布及其有机碳含量的影响。结果表明：耕层土壤团聚体占比随着粒径的减小呈先降低后增加的变化趋势,团聚体有机碳含量随粒径减小呈增加趋势。施肥显著影响马铃薯农田土壤团聚体分布及有机碳含量。长期化肥与有机肥配施（NPK+OM）和单施有机肥（OM）较单施化肥（NPK）显著增加>0.25 mm团聚体含量（R0.25）和平均质量直径（MWD）,显著提高大团聚体（>1 mm）对有机碳的贡献率。长期施用有机肥（NPK+OM和OM）较单施化肥（NPK）显著增加0～20 cm土层土壤团聚体有机碳储量,增幅达63.5%～82.8%。长期覆膜导致>2 mm粒径的大团聚体数量和MWD显著下降,覆膜与单施化肥（NPK）对团聚体有机碳含量及其储量影响不明显。综上所述,在西北黄土丘陵半干旱区和黄绵土质地条件下,长期化肥与有机肥配施（NPK+OM）或单用有机肥（OM）可显著提高耕层土壤大团聚体含量（R0.25）及其稳定性,促进新碳向大团聚体富集,增加团聚体有机碳储量,有利于农田土壤固碳。地膜...     

不同母质发育的柑橘园土壤团聚体及有机碳分布特征

作为土壤结构的基本单元和土壤肥力的组成部分,土壤团聚体对其物理、化学和生物学特性均具有重要影响。选取湖南省永兴县5种典型母质发育的柑橘园土壤,采用湿筛法研究不同成土母质的柑橘园土壤团聚体结构变化和有机碳分配规律。结果表明:(1)研究区不同母质发育土壤以>0.25 mm粒径团聚体为主,占85.94%～95.89%,其中板页岩风化物发育的黄泥土中大团聚体含量最高;(2)不同母质柑橘园土壤团聚体的水稳性大小为板页岩风化物(黄泥土)>第四纪红色粘土(红黄泥)>石灰岩风化物(灰红土)>砂砾岩风化物(红砂土)>河流沉积物(河砂泥);(3)不同母质柑橘园土壤团聚体有机碳含量、团聚体有机碳储量和团聚体对土壤有机碳的贡献率均随着团聚体粒径的减小而减少;(4)平均重量直径(MWD)、几何平均直径(GMD)、分形维数(D)和土壤可蚀性(K)与>2 mm团聚体间的相关系数最大,表明>2 mm团聚体含量是影响土壤团聚体稳定性的主要因子;(5)>2 mm团聚体有机碳贡献率与土壤团聚体MWD和GMD呈显著正相关,与土壤K值呈显著负相关,与土壤D值呈显著负相关。总体而言,目前南方柑橘果园施肥管理应注重增施有机肥,提高土壤结构的稳定性,从而降低水土流失的风险。     

Effective retention of litter-derived dissolved organic carbon in organic layers

This study aimed to gain insight into the generation and fate of dissolved organic carbon (DOC) in organic layers. In a Free Air CO₂ Enrichment Experiment at the alpine treeline, we estimated the contribution of ¹³C-depleted recent plant C to DOC of mor-type organic layers. In an additional laboratory soil column study with 40 leaching cycles, we traced the fate of ¹³C-labelled litter-DOC (22 and 45 mg l⁻¹) in intact Oa horizons at 2 and 15 °C. Results of the field study showed that DOC in the Oa horizon at 5 cm depth contained only 20 ± 3% of less than six-year-old C, indicating minor contributions of throughfall, root exudates, and fresh litter to leached DOC. In the soil column experiment, there was a sustained DOC leaching from native soil organic matter. Less than 10% of totally added litter-DOC was leached despite a rapid breakthrough of a bromide tracer (50 ± 7% within two days). Biodegradation contributed only partly to the DOC removal with 18-30% of added litter-DOC being mineralized in the Oa horizons at 2 and 15 °C, respectively. This was substantially less than the potential 70%-biodegradability of the litter-DOC itself, which indicates a stabilization of litter-DOC in the Oa horizon. In summary, our results give evidence on an apparent ‘exchange’ of DOC in thick organic layers with litter-DOC being retained and ‘replaced’ by ‘older’ DOC leached from the large pool of indigenous soil organic matter.     

Compositional characterization of soil organic matter and hot-water-extractable organic matter in organic horizons using a molecular mixing model

Purpose

Microbial decomposition of soil organic matter (SOM) is generally believed to be heterogeneous, resulting in the preferential loss of labile compounds such as carbohydrates and proteins and the accumulation of recalcitrant compounds such as lipids and lignin. However, these fractions are difficult to measure directly in soils. We examined patterns in the biomolecular composition of SOM and hot-water-extractable organic matter (HWEOM) by using a molecular mixing model (MMM) to estimate the content of carbohydrates, protein, lipids, and lignin.

Materials and methods

Organic-horizon soils from Spodosols at the Hubbard Brook Experimental Forest in NH, USA were analyzed for this study. The MMM uses data from elemental analysis (C, H, and N) and ¹³C nuclear magnetic resonance spectroscopy with cross-polarization and magic-angle spinning to estimate the percentage of total C in the various classes of biomolecules.

Results and discussion

Carbohydrate content decreased from about 50 % of the C in recent litter to approximately 35 % in the bottom of the humus layer. Lipids accounted for about 18 % of C in recent litter and increased to 40 % in the lower humus layers. The HWEOM fraction of SOM was dominated by carbohydrates (40–70 % of C). Carbohydrates and lipids in HWEOM exhibited depth patterns that were the opposite of the SOM. The results from the MMM confirmed the selective decomposition of carbohydrates and the relative accumulation of lipids during humus formation. The depth patterns in HWEOM suggest that the solubility of carbohydrates increases during decomposition, while the solubility of the lipid fraction decreases. The MMM was able to reproduce the spectral properties of SOM and HWEOM very accurately, although there were some discrepancies between the predicted and measured H/C and O/C ratios.

Conclusions

The MMM approach is an accurate and cost-effective alternative to wet-chemical methods. Together, carbohydrates and proteins account for up to 85 % of the C in HWEOM, indicating that the HWEOM fraction represents a labile source of C for microbes. Humification resulted in a decrease in carbohydrate content and an increase in lipids in SOM, consistent with investigations carried out in diverse soil environments.     

Recovery rate of organic c in organic matter fractions of Grantsburg soils

Abstract

Walkley‐Black method is a simple and rapid method for organic carbon analysis. Because of incomplete oxidation of organic carbon (C), the recovery of organic C is low with this method. Assuming the 77% recovery of organic C with Walkley‐Black method, the results are corrected with a correction factor of 1.30. The objective of this study is to determine the soil organic C recovery rate and appropriate correction factor for Walkley‐Black (wet combustion) method for tilled soils in southern Illinois. Soil samples were collected in 1995 and 1996 from a trial established in southern Illinois on a moderately well drained, Grantsburg (fine‐silty, mixed, mesic Oxyaquic Fragiudalf) soil. Organic C contents with the Leco analyzer (dry combustion) were significantly higher as compared to the Walkley‐Black method in different tillage systems (no‐till, chisel plow and moldboard plow), soil organic matter fractions (whole soil and mineral fraction) and soil depths (0–5 and 5–15 cm). The recovery percentage of organic C was lower than the assumed percentage with the Walkley‐Black method. No significant differences in organic C recovery percentage were found due to differences in tillage systems and depths, whereas the recovery percentage was lower in mineral fraction as compared to the whole soil. The lower organic C recovery percentage was due to the more stable organic C compounds in the mineral fraction. On the basis of these findings, correction factors of 1.35 and 1.41 are proposed for whole soil and mineral organic C analysis with Walkley‐Black method, respectively for tilled Grantsburg and other similar soils in southern Illinois.     

Effect of organic manure on organic phosphorus fractions in two paddy soils

We investigated the transformation of the organic P fractions from organic manure in two paddy soils (Ultisol, Entisol) and the influence of organic manure or cellulose on organic P under anaerobic conditions. The results obtained from the P fractionation experiment indicated that during the incubation labile and moderately labile organic P fractions increased in the Ultisol and decreased in the Entisol, which might be related to the difference in the organic matter content of both soils. Immediately after the application of organic manure, a large part of labile and moderately labile organic P supplied with the manure was transformed into moderately resistant organic P, possibly Ca- or Mg-inositol P were transformed into Fe-inositol P. During anaerobic incubation, the labile forms of organic P in the soils treated with organic manure were increased along with the incubation period in the first 4 weeks. The change in the moderately labile fraction was dramatic. It increased sharply in the first 2 weeks, then decreased, which was more pronounced in the soils treated with pig faeces. The moderately resistant fraction decreased during the whole incubation period. This indicated that under anaerobic conditions, the moderately resistant fraction can be transformed into labile and moderately labile organic P fractions, perhaps as Fe³⁺-inositol P is reduced to Fe⁺²-inositol P. Cellulose as an organic substrate had an increasing effect on organic P, especially when it was combined with inorganic P. Therefore, it is suggested that the application of inorganic P fertilizer combined with organic manure may be an effective way of protecting inorganic P against intensive sorption in soils.     

我国有机肥资源及产业发展现状

科学减施化肥用量，合理配施有机肥对土壤肥力提升、农产品增质和减轻面源污染有着重要的意义。我国农业有机废弃物资源丰富，有机养分总量达到约 7 519.5万 t，其中 N、P 2O5、K2O养分总量分别为 3 096.3万、1 174.1万、3 249.1万 t，但是目前资源利用率不足 40%，不仅造成优良有机养分资源的浪费，同时带来环境污染风险的问题。如何高效利用有机肥资源是我国目前亟需解决的问题。本文总结有机肥相关文献和他人研究结果，综述了我国有机肥资源数量、利用现状，针对施用的问题，对产业发展提出了一些建议。     

半干旱土添加有机改良剂后有机质的化学结构变化

A 9-month incubation experiment using composted and non-composted amendments derived from vine pruning waste and sewage sludge was carried out to study the effects of the nature and stability of organic amendments on the structural composition of organic matter (OM) in a semi-arid soil.The changes of soil OM,both in the whole soil and in the extractable carbon with pyrophosphate,were evaluated by pyrolysis-gas chromatography and chemical analyses.By the end of the experiment,the soils amended with pruning waste exhibited less organic carbon loss than those receiving sewage sludge.The non-composted residues increased the aliphatic-pyrolytic products of the OM,both in the whole soil and also in the pyrophosphate extract,with the products derived from peptides and proteins being significantly higher.After 9 months,in the soils amended with pruning waste the relative abundance of phenolic-pyrolytic products derived from phenolic compounds,lignin and proteins in the whole soil tended to increase more than those in the soils amended with sewage sludge.However,the extractable OM with pyrophosphate in the soils amended with composted residues tended to have higher contents of these phenolic-pyrolytic products than that in non-composted ones.Thus,despite the stability of pruning waste,the composting of this material promoted the incorporation of phenolic compounds to the soil OM.The pyrolytic indices (furfural/pyrrole and aliphatic/aromatic ratios) showed the diminution of aliphatic compounds and the increase of aromatic compounds,indicating the stabilization of the OM in the amended soils after 9 months.In conclusion,the changes of soil OM depend on the nature and stability of the organic amendments,with composted vine pruning waste favouring humification.     

有机农业生产肥料供应

简述了有机农业的基本概念、有机农业生产对肥料的特殊要求和我国肥料资源现状,指出进一步开发肥料资源,推动有机农业生产发展的途径。     

Qualitative and quantitative differences in particulate organic matter fractions in organic and conventional farming systems

To quantify functionally important differences in soil organic matter (SOM) that result from use of different farming practices, soils from 9 long-term trials comparing manure+legume-based organic, legume-based organic, and conventional farming systems were collected and particulate organic matter (POM) was fractionated to reflect its position within the soil matrix. The free, light POM (FPOM; <1.6 g cm⁻³) not occluded within aggregates and occluded POM (OPOM; <2.0 g cm⁻³) were compared to an undifferentiated POM fraction (coarse fraction, CF; >53 μm) obtained by wet sieving. Fraction C, N, and hydrolyzable N (quantified using the Illinois test (IL-N)) were determined. Organic farming systems had greater quantities of C and N in the OPOM and CF and, greater IL-N contents in all POM fractions considered. The OPOM's C:N ratio (16-19) and was least in the manure+legume-based organic, intermediate in the legume-based organic, and greatest in the conventional systems (P<0.10). Trends in OPOM C:N and IL-N abundance suggested occluded POM was most decomposed, and possibly a greater N reservoir, in the manured soils. The FPOM quality reflected the residues added to each system and its removal improved resolution of quality-based differences in POM associated with long-term management. Subdivision of POM revealed differences in its quality that were not evident using the undifferentiated CF. Quantification of hydrolysable N (IL-N) in POM did not enhance our understanding of management's affect on SOM quality. This multi-site comparison showed organic management simultaneously increased the size of the labile N reservoir and the amount of POM protected within aggregates; and that, occluded POM is more decomposed in manure+legume- than in legume-based organic systems. The characteristics of POM reveal how organic practices improve SOM and suggest the nutrient and substrate decay dynamics of organic systems may differ as a result of the N fertilization strategies they employ.     

Dynamic interactions of natural organic matter and organic compounds

Purpose

This article reviews our current understanding about how organic chemicals and water interact dynamically with, and therefore coevolve with, soil and sediment natural organic matter (NOM). NOM can be regarded as a polymer-like phase that responds to the input of organic compounds in ways analogous to synthetic polymers.

Methods

Sorption selectivity of organic compounds is shown to result in part from the three-dimensional microstructure of NOM related to its glassy character. Sorption to NOM conforms to polymer theory by exhibiting isotherm shape and irreversible behaviors characteristic of the glassy organic physical state. The glassy state is a metastable state characterized by the presence of excess free volume (holes).

Results

In polymers and NOM, incoming molecules preferentially occupy holes due to the absence of a cavitation penalty. Incoming molecules can enlarge existing holes and create new holes that do not relax completely when the molecules leave. The physical changes in NOM induced by sorption result in hysteresis in the isotherm that persists indefinitely at ambient temperature.

Conclusions

Sorption selectivity and hysteresis have important implications for the fate and bioavailability of contaminants.     

有机物料循环对红壤稻田系统有机质积累的贡献研究

中长期定位试验研究有机物料循环再利用对红壤稻田系统土壤有机质积累的贡献结果表明,红壤稻田系统有机物料自然归还量可达6 16 2kg/hm2 ,人为归还量可达13480kg/hm2 ;仅依靠系统内有机物料的自然归还,其土壤有机质亏缺为5 0 %左右,呈下降趋势;系统内可循环再利用的有机物料全部还田,土壤有机质盈余率可达80 %以上;预测结果显示有机物料循环再利用5 0年内可提高土壤有机质19.4～32 .6 g/kg ,增长率达83.6 %～14 0 .5 %