ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1988.tb00727.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract.Soil water samples from five horizons in a stagnopodzol were collected regularly over a five‐year period in a Sitka spruce plantation at Beddgelert Forest, North Wales. Samples were analysed for nitrate‐N and ammonium‐N. After felling, inorganic‐N concentrations increased markedly in the C horizon, generally decreased in the surface horizons and showed little change in the E and Bs horizons. Fluxes through the C horizon increased after felling from 10 to 70 kg N ha‐1a‐1, the latter being equivalent to leaching losses in intensive lowland agricultural systems. Trends in concentration and flux were attributed to seasonal temperature and rainfall variations.Nitrate‐N dominated the dissolved inorganic‐N, especially in the lower horizons. Nitrification was obviously active, despite the acid soil. Nitrate leaching losses occurred, even beneath the standing crop. On felling, cessation of nitrogen uptake allowed substantially more nitrate to be leached as no alternative sink was immedi

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1988.tb00728.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract.In a field experiment over two years, broad beans (Vicia faba), cabbage (Brassica oleraceavar.capitata), leeks (Allium porrum) and red beet (Beta vulgarisvar.esculenta) were grown on a sandy clay loam soil in which a range of bulk densities and penetration resistances had been established by (1) thorough loosening to 0.9 m by trenching, (2) artificially compacting with tractor wheelings or (3) leaving unloosened.Loosening the soil substantially increased, and compacting it decreased, yields of all four crops. The mean penetration resistance of the subsoil at field capacity correlated negatively with dry matter production. The relationship was broadly similar for all crops and years, showing a decrease in dry matter production of about 1 t ha‐1per 0.5 MPa increase in resistance over the range examine

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1988.tb00729.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract. A combination of crop photography and crop radiance (near‐infrared and red) values are used to measure ground cover establishment (leaf area). The high correlation between the green leaf area and near‐infrared/red ratio (NIR/R) can provide a non‐destructive method for monitoring crop growth. Using this relationship the effects of pre‐ and post‐emergence herbicide treatments (Metazachlor) on winter oilseed rape were studied. It is shown that pre‐emergence spraying reduces germination and autumn and spring growth rates. One management aspect of pre‐emergence spraying is the delay in achieving ground cover. For marginal crops on soils with a high risk of erosion critical ground cover may be delayed by as much

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1988.tb00730.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract.Plots of spring barley, winter wheat and winter barley were sheltered with netting in a coastal area of North‐East England. Crop height, yield components and grain yield were measured and compared with unsheltered crops receiving the same agronomic treatments. Plant height, ears m‐2, 1000 grain weight and grain yield were increased by shelter in seasons with windy, dry weather during the tillering and stem extension phases. Negligible response was found in a wet season. One experiment suggests that greater applications of nitrogen fertilizer can counteract the effects of expos

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1988.tb00731.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract.The soil of a restored opencast site in Northumberland is described and compared with the surrounding undisturbed soil. The most serious change in the soil was increased bulk density at the surface of the subsoil (0.3 m depth). Only a small overall reduction in pore space occurred, at the expense of continuous macropores. More of the pore space in the restored soil occurred as fine fissures as opposed to biotic channels, and the restored soil was weaker because of subsoiling and a loss of stability in microstructures. These changes are discussed in relation to root exploration, water movement and land management.

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1988.tb00732.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY