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41.
平江县位于湖南省东北部,是一个典型的"老、山、边、穷、大"五位一体的农业大县,也是国家级贫困县。近几年来,平江县农业综合开发办公室不断总结经验教训,努力探索农业综合开发的新途径,逐步完善有关政策,使平江县农业综合开发迈上了一个新的台阶。 相似文献
42.
The Effectiveness and Feasibility of Using Ochre as a Soil Amendment to Sequester Dissolved Reactive Phosphorus in Runoff 总被引:1,自引:0,他引:1
Owen Fenton Laura Kirwan Daire Ó hUallacháin Mark Gerard Healy 《Water, air, and soil pollution》2012,223(3):1249-1261
Incidental losses of dissolved reactive phosphorus (DRP) to a surface waterbody originate from direct losses during land application
of fertilizer, or where a rainfall event occurs immediately thereafter. Another source is the soil. One way of immobilising
DRP in runoff before discharge to a surface waterbody, is to amend soil within the edge of field area with a high phosphorus
(P) sequestration material. One such amendment is iron ochre, a by-product of acid mine drainage. Batch experiments utilising
two grassland soils at two depths (topsoil and sub-soil), six ochre amendment rates (0, 0.15, 1.5, 7.5, 15 and 30 g kg−1 mass per dry weight of soil) and five P concentrations (0, 5, 10, 20 and 40 mg L−1) were carried out. A proportional equation, which incorporated P sources and losses, was developed and used to form a statistical
model. Back calculation identified optimal rates of ochre amendment to soil to ameliorate a specific DRP concentration in
runoff. Ochre amendment of soils (with no further P inputs) was effective at decreasing DRP concentrations to acceptable levels.
A rate of 30 g ochre kg−1 soil was needed to decrease DRP concentrations to acceptable levels for P inputs of ≤10 mg L−1, which represents the vast majority of cases in grassland runoff experiments. However, although very quick and sustained
metal release above environmental limits occurred, which makes it unfeasible for use as a soil amendment to control P release
to a waterbody, the methodology developed within this paper may be used to test the effectiveness and feasibility of other
amendments. 相似文献
43.
Marko Šoštarić Željka Zgorelec Dinko Babić Ivana Šestak Ivica Kisić Milan Mesić Aleksandra Perčin 《Water, air, and soil pollution》2017,228(6):218
We present a study on the radioactivity of selected Croatian agricultural soils that vary considerably with respect to geological background; physical, chemical, and biological characteristics; soil type; land use; and soil management. Our investigation is focused on the main naturally occurring radionuclides (40K, 238U, 226Ra, 232Th, 235U) and 137Cs as the most threatening long-lived anthropogenic radionuclide. We find that the radioactivity level is not influenced by the application of different soil amendments, at least in moderate quantities, and that no effect of soil management can be detected as well. In contrast, geological and location-specific properties influence radionuclide content in soil, especially regarding the naturally occurring ones. Moreover, physical and chemical soil properties such as texture and soil adsorption complex, respectively, seem to be the main factors regarding fixation of 137Cs in soil. Calculated dose rates for external exposure to the gamma radiation originating from soil have been found to be generally low, except for two locations where they are higher but not at a level that would lead to health problems for workers on the field. 相似文献
44.
V. B. Il’in 《Eurasian Soil Science》2007,40(9):993-999
Data on the bulk contents of heavy metals in polluted soils are not quite suitable to judge the ecological situation in an agrocenosis. According to the results of model experiments with artificial contamination of soil, the flux of zinc and lead from the starting point (from a medium loamy leached chernozem) to the final point (wheat grains) sharply decreases. It is possible to obtain an ecologically pure (uncontaminated) grain yield even on a strongly contaminated soil due to the buffering capacity of the latter and due to the self-protective capacity of agricultural crops. The ecological potential of the soil-crop system is formed mostly at the expense of the buffering capacity of soil to heavy metals; the barrier function of plants is less significant. It is argued that the existing ecological standards based on the total contents of heavy metals in soil are of little use for predicting the quality of crops. 相似文献
45.
Changes in soil nutrient content and bacterial community after 12 years of organic amendment application to a vineyard 下载免费PDF全文
M. E. Calleja‐Cervantes A. J. Fernández‐González I. Irigoyen J. F. Cibriáin‐Sabalza N. Toro P. M. Aparicio‐Tejo M. Fernández‐López 《European Journal of Soil Science》2015,66(4):802-812
An interesting alternative to landfills for disposing of organic residues is their addition to soil as composted organic residues. There is little information available about the long‐term benefits following prolonged periods of application. After 12 years of annual incorporation of organic amendments to the soil of a vineyard, three soil characteristics were analysed: mineral content, bacterial community and soil greenhouse gas (GHG) emissions. The organic amendments were (i) a pelletized organic compost (PEL) made from plant, animal and sewage sludge residues, (ii) a compost made from the organic fraction of municipal solid waste (OF‐MSW) and (iii) a stabilized sheep manure compost (SMC). Mineral fertilizer (NPK) and an unaltered control treatment were also included. Our results showed that long‐term application of treated residues as compost changed soil nutrient content, bacterial community and gas emission rates. For instance, SMC increased nutrients and soil organic matter (OM) throughout the experiment. There was a change in bacterial community structure, with an increase in the phylum Proteobacteria observed for all four treated soils, and an increase in the phylum Bacteroidetes for PEL, OF‐MSW and SMC treatments. Among the organically‐amended soils, the amount of Adhaeribacter increased by a factor of 2.5 times more than the control, which reported a total of 2.0% of the bacterial community compared with 5.6% for PEL, 5.2% for OF‐MSW and 5.0% for SMC. Adhaeribacter may be a genus that specializes in the degradation of residues in the different composts. The SMC treatment had the largest Chao1 estimator and was the most biodiverse of all treatments. These changes in bacterial community structure did not correlate with the observed GHG fluxes from the sampling day. The application of amendments did not affect N2O fluxes. However, the application of treatments slightly reduced the capacity for CH4 sequestration by soil with respect to the untreated soils. Compost is an effective method to increase soil fertility. Soil GHG emissions should be further evaluated. 相似文献
46.
I. R. Il’in 《Eurasian Soil Science》2006,39(2):168-175
The total content of air entrapped, adsorbed, dissolved, and occurring as bubbles in soil water is termed “bound soil air.” The content of free soil air is determined from the difference between the total and bound soil air. Data on the content of free and bound air in different-sized aggregates of calcareous coarse silty-clayey meadow alluvial soil in the Dnestr River floodplain are presented. The effect of density, aeration, and sand and straw addition on the content of the free and bound air in soil aggregates was shown. A classification of aggregates based on their density and the content of the free, bound, and total soil air was proposed. 相似文献
47.
Some Physical Properties of Linseed 总被引:1,自引:0,他引:1
48.
Computer-based aids have been used extensively to support surveys of threatened plants in Southern Africa. The surveys have shown that by far the highest concentration of threatened plants occurs in the relatively small area of the Cape Floristic Kingdom, a region with many local endemics that are easily put in hazard by impacts such as agriculture, invasive exotics and over-frequent fires. Of the estimated 20 000 vascular plants in Southern Africa, 2373 appear to be critically rare, threatened or recently extinct. Sixty-eight per cent of the plants in hazard occur in the Cape Floristic Kingdom. Obstacles to conservation, particularly a lack of nature reserves in critical areas, are discussed. 相似文献
49.
CO_2浓度、氮素和水分对春小麦碳素固定的影响 总被引:1,自引:0,他引:1
试验设350μmolmol-1和700μmolmol-12种CO2浓度水平,湿润、干旱2种水分处理和施N0、50、100、150和200mgkg-15个水平。结果表明,CO2浓度增加,春小麦地上部碳固定量和碳固定总量均增加,但与氮肥施用水平有关。在中氮和高氮时,CO2浓度增高,地上部碳固定量和碳固定总量明显增加,而不施氮肥和低氮时,增加则不明显。不同水分处理地上部碳固定量和碳固定总量也没有明显差别,这表明,CO2浓度升高对氮素和水分胁迫及对春小麦碳固定并没有补偿作用。 相似文献
50.