ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

The reasons for the inefficiency of traditional deep-ploughing and subsoiling methods are investigated. Compressibilities are compared on two soil samples, with and without tubular holes, which are hit axially with compressing force. It is shown that axially arranged holes decrease the compressibility, as compared with reference samples with equal initial void ratios.

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Flooding with wastewaters over a period of 80 years has led to a fairly strong concentration of nitrogen, phosphorus, copper, and zinc in a sandy Cambisol of glacial origin in comparison with that of a forest soil of the same type. Nevertheless, we registered a loss of iron and manganese. The 2-year examination of the water, redox, and nutrient dynamics showed that hardly any filtering of iron and manganese nutrients is taking place anymore.

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

In a stand ofFagus silvaticain the Solling highlands, Federal Republic of Germany, we followed the effect of acid precipitation on chemical soil state and the ion fluxes in the ecosystem between 1966 and 1979. As indicated by increasing aluminum concentration in the soil solution and an increase in organic matter storage in the forest floor, for example, the soil shifted during the measuring period from one state toward another one. During this transition, the acid precipitation has induced soil internal H+ion production, partly by accumulation of organic matter poor in nitrogen, and partly by a probable change in the type of nitrogen nutrition. Two-thirds of the H+ion buffering is due to the dissolution of polymeric hydroxoaluminum, resulting in the formation of solid AlOHSO4and the leaching of Al ions. There are indications that the Al concentration in soil solution reaches toxic levels for the stand. The findings may have serious consequences for forestry in central Europe.

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

We describe a soil that, in view of its sesquioxidic and smeary subsoil, could be related to Orthods, Andepts, or Ochrepts morphologically, but not genetically, as an albic horizon and pyroclastic material are lacking, and sesquioxides are accumulated absolutely. Its properties can be understood only by relating it to adjacent soils. From this experience we conclude that, in general, a rational soil classification should rely on pairs of diagnostic horizons that may even be parts of different soils in a catena.

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

In a field experiment on a Udalf soil formed from loess, we studied nitrate and water uptake of spring wheat as a function of soil depth and of time. Before the wheat was sown, 40 kilograms of nitrogen per hectare, tagged with 20 percent nitrogen-15, was applied three times. Nitrate concentration in the soil solution, soil water content, and soil water suction were determined as a function of soil depth and time by means of suction probes, a neutron meter, and tensiometers, respectively.From these data, total vertical water flowut, capillary water flowvc, water flow through the rootsvrlabeled fertilizer and total nitrate content in the soil, and apparent mass flow of nitrate to the roots were computed. This was compared with N uptake of the crop at four harvests taken at the first node stage, anthesis, milk stage, and maturity. Total N uptake was 85, 134, 164, and 197 kg/ha at the respective harvests, of which 81, 71, 57, and 50 percent, respectively, were derived from the labeled fertilizer N. Uptake of labeled fertilizer N was practically complete at the second harvest at anthesis. Up to the first harvest, about 50 percent of the total uptake could be accounted for by apparent mass flow. This percentage dropped to about 30 at maturity. Seventy-six percent of the total N uptake by mass flow and 62 percent of the total water uptake came from the arable layer (0 to 30 cm). These values are comparatively high because quantity and distribution of rainfall did not require the plants to utilize the reserves of the subsoil to a large extent. The favorable water regime and relatively low nitrate concentrations were also responsible for the comparatively low contribution of mass flow to N supply.

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

To obtain general information on the quantities of mineral nutrients in the microbial biomass of soils, we determined the carbon content of the microbial cells of 29 soils. Carbon data were converted to nutrient values using C to N, C to P, C to K, and C to Ca ratios established by measuring (1) the average C to mineral content of pure cultures of 24 species of soil microorganisms and (2) the relative contributions of bacterial and fungal cell populations to the microbial biomass of 17 soils. The biomass in 26 agricultural soils contained between 0.27 and 4.8 percent of the total soil C (&OV0335; ≅ 2.5 percent) and between 0.50 and 15.3 percent of the total soil N (&OV0335; ≅ 5.0 percent). The average quantities of N, P, K, and Ca in the microflora of the soils (upper 12.5 cm) were about 108, 83, 70, and 11 kg ha−1, respectively. In theL+F+Hlayers of three forest soils, between 0.52 and 0.91 percent of the total C and 0.16 and 0.22 percent of the total N were in the microbial biomass.

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Concentrations of trace elements and macroelements in rainfall, canopy drip, runoff, and soil solution have been determined each week at four free-drained and three hydromorphic sites at an altitude of 1000–1300 meters above sea level in the very humid, cool Black Forest. Among these elements, the turnover of beryllium, cadmium, copper and lead are discussed in detail. Beryllium had the lowest input and the highest output of these four elements. It was primarily mobilized in the mineral topsoil, and only a small amount was readsorbed by humic acids or subsoil or taken up by plants. Lead concentrations were highest in precipitation, but only about 5 percent of the input appeared in the output. Cadmium, Cu, and Pb were all adsorbed by the humus and iron oxide accumulation horizons of podzols andOckererde.Copper was adsorbed in all soils except podzols, and fixation of Cu was especially obvious in theOckererde.Cadmium was not highly adsorbed in mineral soil. The recent increase in atmospheric input resulted in an enrichment and rise of turnover for Cd, Cu, and Pb throughout the watershed.

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

In a closed system column experiment, 0.005MCaCl2solutions were percolated through two different soils, with a thin layer of freshly ground biotite on top of the column. The potassium release from the biotite was influenced by the clay mineralogy of the soils. For a loess soil containing interstratified illite-smectite, typical for loess deposits in southern Germany, the rate of K release was significantly higher than that for a clay soil derived from Amaltheen claystone with illite and some vermiculite in its clay fraction. For both soils, K buffering capacity, as well as K fixing capacity, decreased during the contact with biotite, this tendency being more pronounced in the loess soil. Equilibrium K-Ca-activity ratios increased with time, but were permanently higher in the clay soil than in the loess soil. In the loess soil, lithogenic smectite was transformed into illite in all clay subfractions. Vermiculite into illite transformation is important only in the coarse clay. The illites formed by these reactions have lower K contents than detrital illites.

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID