作物残茬翻埋对土壤性质的影响     

A. SCAGNOZZI  R. LEVI-MINZI  A. SAVIOZZI  R. RIFFALDI 《土壤圈》1994,4(3):209-215

Chemical transformation, nutrient release and changes in the energy content of decomposing rape, sunflower and soybean residues confined in buried fiberglass bags were assessed in a laboratory study during a 340-day incubation period. The organic C decreased by about 70% while total N, after initial decay, remained almost constant for each type of residue. The NH₄⁺-N was progressively oxidized and, consequently, the NO₃^--N increased. The C/N ratio narrowed with loss of C. Hemicellulose, cellulose and lignin decreased with different trends for each crop residue. The energy content, was reduced to about 25% in rape, 30% in sunflower and 20% in soybean residues. Total P, K, Ca and Mg contents decreased for each type of residue. The results suggest that the three residues could improve the nutrient pool of the soil.  相似文献   

Fitting plants to soil through mycorrhizal fungi: Mycorrhiza effects on plant growth and soil organic matter   总被引：5，自引：0，他引：5  

M. Quintero-Ramos  D. Espinoza-Victoria  R. Ferrera-Cerrato  G. J. Bethlenfalvay 《Biology and Fertility of Soils》1993,15(2):103-106

Summary Vesicular-arbuscular mycorrhizal (VAM) fungi affect diverse aspects of plant form and function. Since mycorrhiza-mediated changes in host-plant responses to root colonization by different VAM fungi vary widely, it is important to assess each endophyte for each specific effect it can elicit from its host as part of the screening process for effectiveness. Three species of VAM fungi and a mixture of species were compared with non-VAM controls for their effects on soil organic matter contents and on nutrition and morphology in two varieties (native and hybrid) of corn (Zea mays L.) and one of sunflower (Helianthus annuus L.) in P-sufficient and N-deficient soil in pot cultures. Differences in soil organic matter due to the fungal applications were highly significant with all host plants. Native corn responded more to VAM colonization than the hybrid did; differences in treatments were significant in leaf area, plant biomass, and root: shoot ratio in the former, but not in the latter. Responses in the sunflower were similar to those in the native corn. Significant VAM treatment-related differences in shoot N and P contents were not reflected in shoot biomass, which was invariant. Correlations between plant or soil parameters and the intensity of VAM colonization were found only in soil organic matter with the native corn, in specific leaf area in the hybrid corn, and in plant biomass in the sunflower. The presence of the different endophytes and not the intensity of colonization apparently elicited different host responses.  相似文献   

Soil organic carbon and phosphorus availability regulate abundance of culturable phosphate-solubilizing bacteria in paddy fields     

Arvind KUMAR  Lal Chand RAI 《土壤圈》2020,30(3):405-413

Low availability of phosphorus(P) is a major constraint for optimal crop production, as P is mostly present in its insoluble form in soil. Therefore,phosphate-solubilizing bacteria(PSB) from paddy field soils of the Indo-Gangetic Plain, India were isolated, and their abundance was attempted to be correlated with the physicochemical characteristics of the soils. Ninety-four PSB were isolated on Pikovskaya's agar medium, and quantitative phosphate solubilization was evaluated using NBRIP medium. The isolates solubilized P up to a concentration of 1 006 μg mL~(-1) from tricalcium phosphate with the secretion of organic acids. These isolates were identified by 16 S rRNA gene sequence comparison, and they belonged to Gammaproteobacteria(56 isolates),Firmicutes(28 isolates), Actinobacteria(8 isolates), and Alphaproteobacteria(2 isolates). Phylogenetic analysis confirmed the identification by clustering the isolates in the clade of the respective reference organisms. The correlation analysis between PSB abundance and physicochemical characteristics revealed that the PSB population increased with increasing levels of soil organic carbon, insoluble P, K~+, and Mg~(2+). The promising PSB explored in this study can be further evaluated for their biofertilizer potential in the field and for their use as potent bio-inoculants.  相似文献   

Water-extractable soil carbon in relation to the belowground carbon cycle   总被引：20，自引：0，他引：20  

R. Jandl  P. Sollins 《Biology and Fertility of Soils》1997,25(2):196-201

We investigated the role of water-extractable carbon (C-extr) as potential substrate for forest soil microorganisms by comparing belowground C fluxes at a plot with the forest floor removed (no-litter) and at a control plot. One-third lower soil respiration rates at the no-litter plot gave evidence that the forest floor was the source of considerable amounts of microbially degradable C. Laboratory incubation of C-extr, fractionated into neutral and acid moieties, showed that part of the C-extr was degraded rapidly, and that the high-molecular-weight acid fraction was much less degradable than the neutral C. To the extent that the degradable portion of the water-extractable C can be regenerated quickly, it may supply much of the substrate for heterotrophic soil respiration. Received: 11 December 1995  相似文献   

Agricultural and ecological aspects of a sandy soil as affected by the application of municipal solid waste composts   总被引：1，自引：0，他引：1  

J. Weber  A. Karczewska  J. Drozd  M. Licznar  S. Licznar  E. Jamroz  A. Kocowicz 《Soil biology & biochemistry》2007,39(6):1294-1302

We present the results of a plot experiment in which the changes in physical, chemical and physico-chemical properties of a sandy soil were examined after amending the soil with two different composts produced from municipal solid wastes. Triticale (X Triticosecale), cultivated in a 3-y monoculture, was used as a test plant. Both composts differed in their concentrations of heavy metals. Composts were applied non-recurrently in the spring before sowing, at the rates of 18, 36, and 72 t dry matter ha⁻¹. The plots without fertilization, and those fertilized annually with mineral nitrogen (N), phosphorous (P), and potassium (K) were used as controls. Soil samples were collected 1 month after compost application, as well as each year after harvesting. Application of both composts improved soil physical properties, associated with increasing content of organic carbon (OC). Statistically significant increases of total porosity, field water capacity and amounts of plant-available water were found only in the short time after compost application. Despite the fact that soil OC content decreased with time, a C:N ratio clearly increased in the third year after compost application, which was explained by a depletion of N reserve. Both composts caused a large increase of plant-available P, K, and magnesium (Mg), which was observed during the entire period of the experiment. Beneficial changes were also observed in soil humic substances composition. These were confirmed by increased humic acids content and humic/fulvic acid ratios. Soil cation exchange capacity and base saturation increased in all plots amended with composts. This effect was still observed 1 year after compost application, while in the third year it remained significant only at the highest compost rates. Compost originating from industrial areas, even if applied in low amounts, caused a significant increase in total concentration of soil heavy metals. This fact did not result, however, in any substantial changes in soil quality with regard to heavy metals content.  相似文献   

氮输入对森林土壤有机碳截存与损耗过程的影响   总被引：1，自引：0，他引：1  

程淑兰  方华军  马艳 《水土保持学报》2007,21(5):82-85

大气氮沉降对受氮限制的陆地生态系统碳截存/损耗的机理尚不清楚,尤其是对土壤有机碳(SOC)的输入、转化和输出过程的认识明显不足。本文论述了外源性氮素(氮沉降、人为增氮)对凋落物分解、土壤有机碳各组分周转的影响,以及土壤呼吸各组分(根系自养呼吸、根际微生物呼吸和SOM分解)对增氮的响应等领域的最新研究进展,指出了在上述研究领域中存在的问题,并提出拟解决的途径以及未来的可能研究方向,以期为该领域的研究提供参考。  相似文献   

Control of Rainfall-Induced Soil Erosion with Various Types of Polyacrylamide (8 pp)     

Majed Abu-Zreig 《Journal of Soils and Sediments》2006,6(3):137-144

Background   Several types of organic polymers with various molecular weights and surface charges are produced for various industrial and agricultural purposes, and recent studies have shown that high molecular weight anionic polymers are the most effective in reducing runoff and soil loss. However, anionic polyacrylamide (PAM) is marketed under various commercial names with variable molecular weight and length according to its chemistry (Barvenik 1994). Consequently, its interactions with soil and efficiency in reducing soil erosion are expected to vary. Moreover, types of PAM other than those recommended for erosion control may also be effective in reducing soil erosion. Objectives   The objective of this research is to test the influence of 9 types of polyacrylamide (PAM) on water infiltration and soil loss of an arid silt loam soil under simulated rainfall conditions. Method  logy. Nine types of organic polymers varied in surface charge, ranging from +20 to –75, and molecular weight ranging from very low to very high were used in this study. Soil plots with dimensions of 60 cm by 120 cm having moderate slope of3 to 5% were constructed in the field and equipped with runoff collection installations. A specific type of PAM was spread on soil plots at a rate of 10 kg/ha. Rainfall was supplied from a drip type rainfall simulator at constant intensity and duration of 80 mm/h and 50 min, respectively. Runoff, infiltration and soil loss were measured for each plot subjected to a specific type of PAM and compared to control plots. Results and Conclusions   Land application of PAMs significantly increased infiltration prior to runoff but had insignificant effect on total infiltration volume and final infiltration rate under the present experimental conditions. Experimental results confirmed that anionic polymers were more effective in reducing soil loss than that of non-ionic or cationic polymers. In fact the cationic, low molecular weight and low surface charge non-ionic PAMs had insignificant effect on soil loss. High molecular weight anionic PAM with 30% surface charge (A-130) was more effective(46% reduction) than those having a high molecular weight and a lower surface charge of 20% (A-110 and A-120) with an aver-age soil loss reduction of 24%. The PAM A-836, described assoil erosion polymer with 20% surface charge and high molecular weight, reduced soil erosion by 41%. Unexpectedly, the anionic PAM with low molecular weight but very high surface charge was also effective in reducing soil loss (47% reduction). Recommendations and Outlook   Land application of PAM improves water infiltration and highly reduces soil erosion thus improving agricultural production. Application of PAM could be the only viable way to improve arid land farming. It seemed that various types of PAMs, other than those specifically produced for erosion protection can be used to combat soil erosion. This means that farmers in poor countries can use any type of PAM that is available to them to improve agricultural production.  相似文献   

Organic C and N stabilization in a forest soil: Evidence from sequential density fractionation     

Phillip Sollins  Christopher Swanston  Timothy Filley  Susan Crow  Kate Lajtha 《Soil biology & biochemistry》2006,38(11):3313-3324

In mineral soil, organic matter (OM) accumulates mainly on and around surfaces of silt- and clay-size particles. When fractionated according to particle density, C and N concentration (per g fraction) and C/N of these soil organo-mineral particles decrease with increasing particle density across soils of widely divergent texture, mineralogy, location, and management. The variation in particle density is explained potentially by two factors: (1) a decrease in the mass ratio of organic to mineral phase of these particles, and (2) variations in density of the mineral phase. The first explanation implies that the thickness of the organic accumulations decreases with increasing particle density. The decrease in C/N can be explained at least partially by especially stable sorption of nitrogenous N-containing compounds (amine, amide, and pyrrole) directly to mineral surfaces, a phenomenon well documented both empirically and theoretically. These peptidic compounds, along with ligand-exchanged carboxylic compounds, could then form a stable inner organic layer onto which other organics could sorb more readily than onto the unconditioned mineral surfaces (“onion” layering model).To explore mechanisms underlying this trend in C concentration and C/N with particle density, we sequentially density fractionated an Oregon andic soil at 1.65, 1.85, 2.00, 2.28, and 2.55 g cm⁻³ and analyzed the six fractions for measures of organic matter and mineral phase properties.All measures of OM composition showed either: (1) a monotonic change with density, or (2) a monotonic change across the lightest fractions, then little change over the heaviest fractions. Total C, N, and lignin phenol concentration all decreased monotonically with increasing density, and ¹⁴C mean residence time (MRT) increased with particle density from ca. 150 years to >980 years in the four organo-mineral fractions. In contrast, C/N, ¹³C and ¹⁵N concentration all showed the second pattern. All these data are consistent with a general pattern of an increase in extent of microbial processing with increasing organo-mineral particle density, and also with an “onion” layering model.X-ray diffraction before and after separation of magnetic materials showed that the sequential density fractionation (SDF) isolated pools of differing mineralogy, with layer-silicate clays dominating in two of the intermediate fractions and primary minerals in the heaviest two fractions. There was no indication that these differences in mineralogy controlled the differences in density of the organo-mineral particles in this soil. Thus, our data are consistent with the hypothesis that variation in particle density reflects variation in thickness of the organic accumulations and with an “onion” layering model for organic matter accumulation on mineral surfaces. However, the mineralogy differences among fractions made it difficult to test either the layer-thickness or “onion” layering models with this soil. Although SDF isolated pools of distinct mineralogy and organic-matter composition, more work will be needed to understand mechanisms relating the two factors.  相似文献   

Soil carbon turnover in the McMurdo Dry Valleys, Antarctica     

J.E. Barrett  R.A. Virginia  D.H. Wall 《Soil biology & biochemistry》2006,38(10):3065-3082

  相似文献   

膨润土改善鸡粪厌氧消化产酸产甲烷特性   总被引：1，自引：4，他引：1  

潘君廷  马俊怡  郜天磊  邱凌  刘宏斌 《农业工程学报》2016,32(8):246-252

为探究膨润土对鸡粪厌氧消化过程中产甲烷特性和可溶性有机酸代谢特性的影响,采用L8(23)正交试验设计,以鸡粪添加量(有机负荷率)、膨润土添加量和接种量为三因素,每个因素设置2个水平,研究了中温条件下(35±1)℃膨润土添加对鸡粪厌氧消化过程中产酸和产甲烷特性的影响。结果表明:与对照组相比,低有机负荷条件下,膨润土添加能显著(P0.05)提高鸡粪挥发性固体(volatile solid,VS)产甲烷量,添加量为3.0%和1.5%时VS产甲烷量分别提升了22.72%、27.72%(膨润土添加量不同的组差异不显著(P0.05));高有机负荷条件下,膨润土添加能极显著(P0.01)提高鸡粪VS产甲烷量,添加量为3.0%和1.5%时VS产甲烷量分别提升了78.68%和55.41%(膨润土添加量不同的组差异显著(P0.05))。当鸡粪添加量为19.91 g挥发性固体,膨润土添加量为3.0%(占干基比)和接种量为80 m L(体积分数20%)时,单位挥发性固体产甲烷量最高为301.92 m L/g,比对照组高87.8%,此时可变成本也最低为2.43元/m~3,比两对照组分别低1.29和1.68元/m~3。方差分析表明:膨润土添加可提高鸡粪厌氧消化过程中挥发性脂肪酸,pH值,可溶性有机碳和可溶性无机碳的稳定性。膨润土可加强鸡粪厌氧消化系统的稳定性,降低产甲烷的可变成本,为膨润土强化鸡粪厌氧处理提供了试验验证据。  相似文献