摘要:

AbstractSince large amounts of nitrogen may be lost by leaching during the winter period, investigations have been carried out to find suitable crops for catching nitrogen during the autumn. The plant species phacelia, common sunflower and italian ryegrass were sown at three times during the late summer. The soil was analysed for mineral nitrogen at the end of November just before incorporation of the catch crops and in the middle of April the following year.The dry matter production and the uptake of nitrogen decreased as the establishment was postponed and the growth period thereby decreased. When sown in the middle of July or at the beginning of August phacelia and italian ryegrass accumulated 150 kg N per ha in the above ground plant parts.The content of soil mineral nitrogen in November was reduced by growing catch crops during the autumn. The content of soil mineral nitrogen increased as the growth period of the catch crops decreased. The content of mineral nitrogen in the upper 50 cm soil layer in April was, irrespective of plant species, increased by catch crops.When no crop was grown the difference between the content of soil mineral nitrogen measured before and after the winter period indicated a net loss of 144 kg of N per ha in 0–100 cm soil depth. When italian ryegrass was sown in the middle of July the previous year the content of soil mineral nitrogen found in April was 59 kg per ha higher compared to the content found in Novembe

ISSN:0044-3263    

DOI:10.1002/jpln.19921550112

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractMit steigenden DOC‐Gehalt sind Mehrbefunde bei der photometrischen Bestimmung von Sulfat und Chlorid zu beobachten, die sich durch eine Probenvorbereitung mit Festphasenextraktion (reversed phase‐Material) zur Entfernung von Huminstoffen zwar vermindern, aber nicht vollständig beseitigen lassen. Das verwendete Verfahren zur photometrischen Nitratbestimmung wird durch den DOC hingegen nicht ges

ISSN:0044-3263    

DOI:10.1002/jpln.19921550113

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractCasts of the lumbricid earthworm speciesE. fetidawere investigated by means of chemical analyses and13C NMR spectroscopy and compared to the beech litter used as food. The casts are characterized by slightly reduced C‐to‐N ratios, higher ash contents and lower polysaccharide and lignin concentrations in comparison with the litter material. These differences between casts and litter are very small, ranging from 1 to 7%, and are not supported by any statistical evidence. In addition, NMR and Py‐FIMS data complete the picture ofE. fetidacasts as almost exclusively physically altered (i.e. comminuted) plant res

ISSN:0044-3263    

DOI:10.1002/jpln.19921550114

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractA criterion is proposed for assessing ranges of validity of equilibrium isotherms for phosphate sorption by soils. This criterion is based on the geometrical features commonly exhibited by such isotherms and is analogous to the one that was first formulated byAharoniandUngarishin connection with the kinetics of chemisorption reactions. Its use with equilibrium isotherms is illustrated with three widely used expressions for the representation of phosphate sorption by soils but it would also be expected to be useful in connection with sorption of other solutes by soils as well as by other adsorbents.

ISSN:0044-3263    

DOI:10.1002/jpln.19921550115

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

ISSN:0044-3263    

DOI:10.1002/jpln.19921550118

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

ISSN:0044-3263    

DOI:10.1002/jpln.19921550119

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

ISSN:0044-3263    

DOI:10.1002/jpln.19921550101

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY