Effects of Peat Extract on Crop Yields

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保水剂与不同化学材料配合对玉米生理特性的影响

通过盆栽实验对玉米幼苗生长及生理特性的监测,探讨了水分胁迫和正常供水条件下保水剂分别与泥炭、沸石和稀土复合应用的互作效应。结果表明,保水剂 泥炭在两种水分条件下均能复合应用,可有效促进玉米生长和提高水分利用效率;保水剂 沸石在正常供水条件下可进行复合应用,在水分胁迫时不适合复合应用;保水剂 稀土在两种水分条件下均不适合复合应用。     

Nitrogen mineralization in marsh meadows in relation to soil organic matter content and watertable level

The objective of the present study was to asses the effect of watertable level on N mineralization in a Histosol and a Humic Gleysol profile under natural meadows in Ljubljana marsh, Slovenia. The two soils differ significantly in organic matter content (27—40 % in Histosol and 14—20 % in Humic Gleysol) but not in C : N ratio (13—20) and pH (6.5—7.0). For each soil, the watertable was maintained at two levels (above or below 50 cm from the soil surface) for approximately one year. The four main plots, according to soil carbon content and watertable level were divided into 4 subplots, according to 4 fertilization treatments (unfertilized control, PK, PK + 50 kg N ha^—1, PK + 3 × 50 kg N ha^—1). Net N mineralization in unfertilized subplots was estimated from indices of N mineralization obtained by incubation of soil samples in the laboratory and by seasonal dynamics of mineral N content in the field. Annual uptake of N in herbage under the 4 fertilization treatments was also measured. Total mineral N content in topsoil was 20—80 % higher in Histosol than in Humic Gleysol. Similarly, aerobic N mineralization potentials along the entire soil profile (0—90 cm) were 20—130 % higher in Histosol than in Humic Gleysol. By contrast, anaerobic N mineralization potentials in subsoil were 10—60 % lower in Histosol than in Humic Gleysol. Both, aerobic and anaerobic N mineralization potentials strongly depended on watertable levels at sampling time. Seasonal dynamics of soil mineral N content as well as N mineralization potentials indicated that the N mineralization in the Histosol could be 10—40 % higher at low than at high watertable level. In the Humic Gleysol the N mineralization could be 10—100 % higher at high watertable level. Higher N availability in Histosol at low watertable and in Humic Gleysol at high watertable was also reflected in higher N uptake in herbage. These results indicate that N mineralization in Histosol and Humic Gleysol, was proportional to soil organic matter content, whereas in both soils, higher N mineralization rates can be expected at watertable levels between 40 and 60 cm below the soil surface, than at higher/lower watertable levels.     

Decomposition of peat,biogenic municipal waste compost,and shrub/grass compost added in different rates to a silt loam

An incubation experiment was carried out to test the effects of biogenic municipal waste (compost I) and shrub/grass (compost II) composts in comparison to peat on respiration and microbial biomass in soil. The amounts of these three substrates added were linearly increased in the range of field application rates (0.5%, 1.0%, 1.5%, 2.0%). The sum of CO₂ evolved during the incubation was markedly raised by the three substrates and increased with the rate of substrate concentration. However, the percentage of substrate mineralized to CO₂ decreased with the addition rate from 103 to 56% for compost I, from 81 to 56% for compost II, and from 21 to 8% for peat. During the first 25 days of incubation, compost I enlarged the biomass C content, which remained constant until the end. In contrast, compost II did not raise biomass C initially. But at the end of the incubation, the biomass C content of all 4 compost II treatments almost reached the level of the respective compost I treatment. The increase was significantly larger the more of the two composts was added. In contrast to the two composts, the addition of peat did not have any significant effect on microbial biomass C. The average qCO₂ values at day 25 declined in the order compost I > compost II > peat, at day 92 the order was changed to compost II > peat > compost 1. This change in the order was caused by a significant decrease in qCO₂ values of the compost I treatments, a significant increase in qCO₂ values of the peat treatments and constant qCO₂ values in the compost II treatments.     

草炭对砂质土壤保水特性的影响

通过比较草炭、砂土、草炭－砂土混合基质水物理特性和3种灌溉频率条件下基质蒸发量和水势的变化,分析了草炭对砂质土壤保水特性的影响。研究结果表明：用腐质化程度低的高位草炭改良砂土,改良基质的孔隙度、田间持水量、饱和含水率显著增加,基质保水能力提高;干旱处理过程中体积收缩程度也随基质中草炭含量的增加而增大。灌溉频率对基质蒸发量和水势也有显著影响,随着灌溉频率的增加,基质中草炭含量越高,表面蒸发越快。用较低的灌溉频率,纯草炭仍能保持更多的水分,为植物提供更多的有效水。     

Soil physical characteristics of peat soils

Drainage and intensive use of fens lead to alterations in the physical characteristics of peat soils. This was demonstrated using parameters of water balance (available water capacity) and the evaluated unsaturated hydraulic conductivity. Deriving the distribution of the pore size from the water retention curve was flawed because of shrinkage due to drainage, especially at high soil water potentials. These errors became greater as the peat was less influenced by soil‐genetic processes. The water retention curves (desorption) evaluated in the field and the laboratory satisfactorily corresponded. However, the wetting‐ and drainage‐curves obtained in the field differed up to 30 vol.‐% water content at same soil water potentials. These differences were largely due to a wetting inhibition.     

Bodenentwicklung am Rande oligotropher Moore im Raum Berlin

Soil development in the surrounding of oligotrophic mires in the Berlin region Polygenetic soils, surrounding oligotrophic kettle hole mires in the valley and aeolian sand areas of the Berlin region, were investigated. The typical soil catena is formed by the sequence of Ombric Histosol (Niedermoor), Ombric Histosol/Albi‐gleyic Podzol (Moor‐Podsol‐Gley), Albi‐gleyic Podzol (Nasspodsol‐Gley), Gleyic Podzol (Podsol‐Gley), and Dystri‐gleyic Arenosol (Gley‐Podsol‐Braunerde) (German soil classifications in parenthesis). Field and laboratory work showed, that the investigated soils were strongly related to each other and that their development depends on the trophy of the mire and groundwater fluctuations during the Holocene. Compared with the Bh‐horizon of terrestrial soils the Gh‐horizon is nearly free of Fe and Mn, but very rich in pedogenic Al‐oxides and rich in organic matter. The genesis of the soils is explained as follows: 1. The development of different Gleyic Podzols was due to rise of groundwater. Consequently the Bh and Bs horizons of Podzols surrounding the mire were converted to Gh and Gr horizons. 2. Humic substances and Al in the Gh and Gr horizons were not re‐mobilized due to the rise of groundwater, whereas Fe and Mn were reduced and removed by groundwater. 3. At the periphery of the mire Fe was enriched in the Go horizon of the Gley‐Podzols but not Mn. 4. The fact that the mire is completely surrounded by Podzol‐Gleys, indicates, that movement of the groundwater from the central parts of mires towards the periphery is an essential pedogenetic factor.     

Differences in the activity and bacterial community structure of drained grassland and forest peat soils

The microbial activity and bacterial community structure were investigated in two types of peat soil in a temperate marsh. The first, a drained grassland fen soil, has a neutral pH with partially degraded peat in the upper oxic soil horizons (16% soil organic carbon). The second, a bog soil, was sampled in a swampy forest and has a very high soil organic carbon content (45%), a low pH (4.5), and has occasional anoxic conditions in the upper soil horizons due to the high water table level. The microbial activity in the two soils was measured as the basal and substrate-induced respiration (SIR). Unexpectedly, the SIR (μl CO₂ g⁻¹ dry soil) was higher in the bog than in the fen soil, but lower when CO₂ production was expressed per volume of soil. This may be explained by the notable difference in the bulk densities of the two soils. The bacterial communities were assessed by terminal restriction fragment length polymorphism (T-RFLP) profiling of 16S rRNA genes and indicated differences between the two soils. The differences were determined by the soil characteristics rather than the season in which the soil was sampled. The 16S rRNA gene libraries, constructed from the two soils, revealed high proportions of sequences assigned to the Acidobacteria phylum. Each library contained a distinct set of phylogenetic subgroups of this important group of bacteria.     

不同容器基质苦楝的育苗效果及其评价

为寻求适宜苦楝种子育苗的容器基质,利用容器育苗成型技术,在泥炭中添加不同比例的珍珠岩和蛭石,研究不同容器育苗基质对苦楝种子出苗及生长的影响,并采用因子分析法对苦楝的育苗效果进行综合评价。结果表明：T3（V泥炭:V珍珠岩=1:1）和T5（V泥炭:V蛭石=2:1）处理苦楝叶片的光合速率和蒸腾速率显著低于其他处理,T4（V泥炭:V蛭石=3:1）处理的光合速率和蒸腾速率相对较强。T1（V泥炭:V珍珠岩=3:1）和T2（V泥炭:V珍珠岩=2:1）处理的苦楝出苗率最高,均达到了97.9%,T3、T5和T7（V泥炭:V蛭石:V珍珠岩=6:1:1）处理显著低于其他试验处理,分别仅为88.7%、85.4%和85.4%。多重比较结果表明,T2、T6（V泥炭:V蛭石=1:1）和T7的株高和地径显著大于其他试验处理,而T5处理则显著低于试验处理,T6处理的地上部生物量和地下部生物量相对较高,而T3和T5处理的生物量显著最低,各处理间不同指标的表现并不完全吻合。利用因子分析法综合评价不同容器育苗基质苦楝的育苗效果是适宜的。对苦楝的出苗率、株高、地径、地上部分和地下部分鲜重等5个指标进行因子分析,结果表明,T6为苦楝容器育苗最佳配比基质,其次为T7和T4,T3综合育苗效果最差。     

小兴安岭典型泥炭沼泽土壤水分物理性质研究

对小兴安岭5类典型泥炭沼泽土壤水分物理性质进行对比研究,结果表明:落叶松-杜香-泥炭藓沼泽土壤容重最小,非毛管孔隙最高,持水性最好;漂筏苔草沼泽和油桦-笃斯越桔-修氏苔草沼泽次之,修氏苔草沼泽和白桦-油桦-小叶章沼泽相对较差.落叶松-杜香-泥炭藓沼泽0～40 cm平均土壤容重为0.06g·cm-3,非毛管孔隙31.69%,总孔隙度高迭87.19%,平均土壤质量含水量、最大持水量、毛管持水量和最小持水量分别为1130.1%、1586.57%、1007.71%和882.70%,是对照林地的56.6倍、26.4倍、24.9倍和25.5倍.在5类泥炭沼泽中,白桦-油桦-小叶章沼泽0～40 cm平均土壤容重最高(0.74 g·cm-3),总孔隙度最低(62.02%),土壤各持水指标均最小,但其持水指标均显著高于对照林地.