摘要:

SUMMARYSince the concentration of free radicals in humic subtances increases at high pH the use of basic solutions for13C NMR spectroscopy may cause broadening and loss of aromatic signals, with distortion of intensity distributions. No such effects were found in13C spectra of soil humic and fulvic acid, an aquatic fulvic acid, and two phenolic polymers run in aqueous solutions at different pH values, and in dimethylsulphoxide. With increasing pH, the peak in the carboxyl region shifted in a manner consistent with greater dissociation of carboxyl and phenolic groups, and also certain features in the aliphatic and carboxyl regions were enhanced under some solution conditions. Elevated solution temperature (70°C) caused only slight improvement in the resolution of some lines. Chemical shifts were determined for some known phenolic and benzenecarboxylic acid compounds in DMSO and NaOD. The range for phenolic carbons extended to 173 ppm in NaOD, while some aromatic carbons occurred around 105 ppm, in the same region as anomeric carbons. Thus, even under quantitative acquisition conditions, relative areas may be used only to estimate proportions of different types of carbons and functional groups

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1987.tb02164.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARYAmmonia volatilization from granular urea applied at 10gNm−2to pasture was investigated using an enclosure method. Misting 0, 4 or 16 mm of water on to the soil at field capacity within 3 h of urea application resulted in total NH3losses of 2.81, 0.92 and 0.18 g N m−2respectively. Further delaying the watering reduced this effect until at 48 h, volatilization was lowered from 3.33 to only 3.09gNm−2with 16mm of water. Hydrolysis and NH3loss were rapid. Similar trends occurred at a lower initial soil moisture content.On air‐dry soil (0.06 g H2O/g soil), hydrolysis was slow (73 ± 14% of the urea remained after 30 days) and volatilization, while gradual, accounted for 33% of applied urea‐N after 30 days. Addition of 16 mm of water 48 and 96 h after urea application was followed by a period of rapid hydrolysis and volatilization, resulting in a total loss of 2.59 and 2.40gNm−2respectively. Repeated addition of 2mm of water produced bursts of hydrolysis and NH3loss until completion of hydrolysis when additional water had no effect. A total loss after 30 days of 3.94 g N m−2occurred in this

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1987.tb02165.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARYTwo field experiments commencing in winter (December) and spring (April) were conducted to determine the fate of nitrogen (N) in cattle slurry following application to grassland. In each experiment three methods of application were used: surface application, and injection ± the nitrification inhibitor, nitrapyrin. Slurry was applied at 80t ha−1, (≡248 kg total N ha−1in the winter experiment, and 262 kg N ha−1in the spring experiment). From slurry applied to the surface, total losses of N through NH3volatilization, measured using a system of wind tunnels, were 77 and 53 kg N ha−1respectively for the winter and spring experiments. Injection reduced the total NH3volatilization loss to ∼2 kg N ha−1. Following surface application, loss by denitrification, measured using an adaptation of the acetylene‐inhibition technique, was 30 and 5 kg N ha−1for the two experiments. Larger denitrification losses were observed for the injected treatments; in the winter experiment the loss from the injected slurry without nitrapyrin was 53 kgN ha−1, and with nitrapyrin 23 kgN ha−1. Total denitrification losses for the corresponding injected treatments in the spring experiment were 18 and 14 kg N ha−1. Apparent recoveries of N in grass herbage in both experiments broadly reflected the differences between treatmen

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1987.tb02166.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARYThe formation of CH3ONO in 11 soils treated with HNO2or NaNO2in a closed system, was studied by measuring the concentration in the gas space above the soil and by absorbing CH3ONO in HI. The gaseous concentration of CH3ONO increased and then decreased following additions of HNO2or NaNO2, and the production of CH3ONO increased with increasing concentrations of HNO2or NaNO2added to soils.The amounts of CH3ONO trapped in HI were 13.5 to 20.4 times higher than those determined by integrating under the net production curves. The evolved CH3ONO amounted to 0.4 to 3.5% of added NO2−, and 4.2 to 50% of the gaseous forms of N absorbed by acidic KMnO4solution. The CH3ONO evolved from soils was positively correlated with the methoxy content of the soils, and inversely related to soil pH, with negligible amounts being evolved from alkaline soils. The results show that CH3ONO is a product of NO2−decomposition in soils, and indicate that small concentrations of the gas may be produced in N–fertilized soils in which NO2−accu

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1987.tb02167.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

SUMMARYThe significance of exchangeable cations in the release of phosphorus by sequential extraction with water was evaluated in 11 acid (pH 5.0–6.3) New Zealand soils contrasting in P status and P retention. The release of P from Na‐saturated soil exceeded that from the original Ca‐dominated soils by up to four‐fold. Possible explanations for the larger P release in the Na system include: (i) desorption of P induced by increased surface negative potential associated with the exchange of Na for Ca/Mg, and/or (ii) accelerated dissolution of Ca phosphate compounds or complexes resulting from the creation of a sink for Ca.The potential of a series of anion‐ and cation‐exchange resin systems (AER and CER, respectively) as sinks for labile soil P was also examined. For all soils studied, P extracted by AER‐HCO3

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1987.tb02168.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Beek, K. J., Burrough, P. A.&Mccormack, D. E. (eds)Quantified Land Evaluation Procedures.Brady, N. C. (ed.)Advances in Agronomy, Volume 40.Bruehl, G. W.Soilborne Plant Pathogens.Dokuchaevinstitute ofSoilScience.Classification and Diagnostics of Soils of the USSR.Dunsmore, J. R.KHARDEP; Rural Development in the Hills of Nepal.Fairchild, D. M.Ground Water Quality and Agricultural Practices.Fitzpatrick, E. A.An Introduction to Soil Science.Follett, R. F. (ed.)Soil Fertility and Organic Matter as Critical Components of Production Systems.Greenhalgh, R.&Roberts, T. R. (eds)Pesticide Science and Biotechnology.Hallsworth, E. G.Anatomy, Physiology and Psychology of Erosion.Lof, P.Soils of the World.Methods of Soil Analysis.Klute, A. (ed.).Physical and Mineralogical Methods.Page, A. L., Miller, R. H.&Keeney, D. R. (eds)Chemical and Microbiological Properties.Morgan, R. P. C.Soil Erosion and Conservation.Newman, A. C. D. (ed.).Chemistry of Clays and Clay Minerals.Runge, E. C. A.,et al.(eds)Utilization, Treatment, and Disposal of Waste on Land.Tabatabai, M. A. (ed.)Sulfur in Agriculture.Tate, R. L.,Soil Organic Matter; Biological and Ecological Effects.Tate, R. L. (ed.)Microbial Autecology; a Method for Environmental Studies.Vaughan, D.&Malcolm, R. E. (eds)Soil Organic Matter and Biological Activity.West, S. H. (ed.)Physiological‐Pathological Interactions Affecting Seed Deterioration.White, R. E.Introduction to the Principles and Practice of Soil Science.Wilcox, J. R. (ed.)Soybeans: Improvement, Production and Uses.Wilson, M. J. (ed.)A Handbook of Determinative Methods in Clay Mineralogy.Wolfe, M. S.&Caten, C. E. (eds)Populations of Plant Pathogens; their Dynamics and Genetic

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1987.tb02169.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY