摘要:

Recent work has shown that several phosphorodiamides and phosphorotriamides are potent inhibitors of soil urease activity and have potential value for retarding hydrolysis of fertilizer urea in soil. The effects of nine of these compounds on nitrification, denitrification, and mineralization of organic nitrogen in soil were studied by determining the influence of different amounts of each compound on (1) the amounts of (nitrate + nitrite)‐N produced when soils were incubated aerobically after treatment with ammonium sulfate, (2) the amounts of nitrate‐N lost and the amounts of (nitrite + N2O + NO + N2)‐N produced when soils were incubated anaerobically after treatment with potassium nitrate, and (3) the amounts of inorganic N produced when soils were incubated aerobically after treatment with alanine. The compounds studied were phenylphosphorodiamidate,N‐(diamino‐phosphinyl)‐cyclohexylamine,N‐benzyl‐N‐methyl phosphoric triamide, trichloroethyl phosphorodiamidate, diethyl phosphoric triamide, dimethyl phosphoric triamide,N‐butyl phosphorothioic triamide,N‐fluoro‐N‐(diaminophosphinyl)benzamide, andN‐phenylphosphoric triamide. The data obtained showed that only trichloroethyl phosphorodiamidate had a significant inhibitory effect on nitrification when applied at the rate of 5 or 10 μg g‐1soil and that only trichloroethyl phosphorodiamidate andN‐butyl phosphorothioic triamide had an appreciable inhibitory effect when applied at the rate of 50 or 100 μg g‐1soil. None of the phosphoroamides studied inhibited denitrification of nitrate or mineralization of organic nitrogen when applied at the rate of 10 or 50 μg g‐1soil.

ISSN:0010-3624    

DOI:10.1080/00103628609367719

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Landfilling of ash from waste‐to‐energy conversion plants poses a potential problem because some ashes contain excessive concentrations of Cd and Pb according to the Extraction Procedure test (EP toxicity test) developed by the Environmental Protection Agency (EPA). Current EPA limits to delineate hazardous materials are 1.0 and 5.0 μg/mL of Cd and Pb, respectively, in the 0.5Macetic acid extract. Since incinerator residues from several facilities have been reported to exceed these levels, a study was initiated whereby ash was combined with different amendments in an attempt to reduce Cd and Pb solubility below EPA limits and to render the ash acceptable for landfilling. Amendments most effective in reducing Pb solubility and extractability by the EP test were: CaO; commercial calcitic lime—CaCO3; limestone scrubber sludge (LSS) from a coal‐fired steam plant; fluidized bed waste (FBW) from a coal‐fired steam plant; acidic NH4H2PO4and basic K2HPO4; and elemental S. Cadmium solubility was reduced only by CaO and the phosphate sources.

ISSN:0010-3624    

DOI:10.1080/00103628609367720

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

An improved method is described for the extraction of14C from biological samples, based on the wet oxidation techniques of Snyder and Trofymow6. Evolved14CO2is trapped in a 2M NaOH solution, and subsequently mixed in a scintillation cocktail for ß counting. Recovery of14C is consistent between batches, with an average recovery of 97.2% over fifteen standards. The technique described does not involve large capital expenditure and is relatively rapid.

ISSN:0010-3624    

DOI:10.1080/00103628609367721

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Crop nutrition under different tillage systems continues to be an issue. Corn (Zea maysL.) growth and nutrient (N, P, K, Ca, Mg) uptake were monitored for two years under either no‐tillage or conventional (moldboard plow plus disc) tillage management. Two rates of applied N (84, 168 kg N ha‐1) were imposed as well. The crop was planted in mid‐May, and sampled about 60 days after planting and at crop maturity. Grain yields were generally increased by the higher N application rate and by tillage reduction. Phosphorus, calcium, and magnesium uptake were generally unaffected by treatment. Total nitrogen recovery by the crop was lowered by no‐tillage soil management at the 84 kg N ha‐1application rate, but was equal across tillage treatments at the 168 kg N ha‐1rate. Potassium acquisition by the crop was strongly related to the surface stratification of K in the no‐till soil environment.

ISSN:0010-3624    

DOI:10.1080/00103628609367722

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Molybdenum concentrations were determined in plant tissue digests and soil extracts by direct‐current plasma optical emission spectrometry (DCP) and compared to molybdenum analysis with nitrous oxide/acetylene flame atomic absorption spectrometry (AAS). Regression analysis of the DCP results on the AAS results indicated a highly significant relationship (r2=0.97) with a slope of 1.01 and a y‐axis intercept of ‐0.40. The slope of the regression equation was not significantly different than 1.0 and the y‐axis intercept was not significantly different than zero. DCP results were enhanced at low Mo concentrations as compared to AAS results when high levels of the Ca and Mg were present in the sample matrix.

ISSN:0010-3624    

DOI:10.1080/00103628609367723

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Beaufils’ Diagnosis and Recommendation Integrated System (DRIS) was used to diagnose nutrient balance through foliar analysis on hybrid poplar clone 1–45/51. The norms for N, P, K, Ca and Mg were evaluated and tested for increased diameter growth through fertilizer treatments in the field.

ISSN:0010-3624    

DOI:10.1080/00103628609367724

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

For soil acidity assessment purposes, the relationship of either percent Al saturation or exchangeable Al to water pH is often misleading for tropical soils. Published data from studies using Ultisols and Oxisols were used to determine whether relationships between Al saturation or exchangeable Al and pH in 1M KCl and pHo are better criteria to assess soil acidity for these variable charge soils. For Ultisols, a highly significant negative relationship (R2=0.76**) was found between Al saturation and pH in 1M KCl. For Oxisols, soil acidity assessment appears to be better expressed in terms of actual exchangeable Al rather than Al saturation per se. Exchangeable Al correlated best with pHo (R2= 0.78**). From a practical standpoint, Oxisols with pHo values higher than 4.0 should not contain exchangeable Al which could be detrimental to plant growth. For Ultisols, a threshold pH value in 1M KCl higher than 4.0 should indicate an Al saturation less than 15%. The above relationships appear to take into account the effect of the electrolyte concentration and the nature of the soil charge system in assessing soil acidity in variable charge soils.

ISSN:0010-3624    

DOI:10.1080/00103628609367725

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103628609367718

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor