ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1992.tb00911.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.Seasonal variation in the aggregate stability of chalk downland soils on the South Downs, East Sussex, UK, was studied using two measures of aggregate stability: water stable aggregation by wet sieving and dispersibility by a turbidimetric determination. Aggregate stability and organic carbon content were assessed on a monthly basis at 20 sites over a 19‐month period.Results indicated considerable variation in water stable aggregation over the time period studied but little variation in dispersibility. There were differences between sites mainly reflecting differences in organic carbon content. Soils with more organic carbon showed less seasonal variation in aggregate stability than soils with small amounts of organic carbon. This suggests that in less organic soils organic materials, mainly microbial in origin, play an important role in forming stable aggregates, though their effect is transien

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1992.tb00912.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.The quantitative effects of different cultivation practices and wheelings on the generation of runoff and soil loss on the South Downs were assessed experimentally with a small drip‐type rainfall simulator and rainfall intensities of 42.5 and 23.3 mm/h. Runoff volumes generated by different cultivation practices and between wheeled and non‐wheeled areas were significantly different. Amounts of soil lost from different cultivation treatments and from wheelings were less consistent. Less runoff and erosion occurred from shallow cultivated land than from conventionally ploughed and cultivated land. Runoff is further increased by rolling ploughed land after drilling and along tramlines compressed by wheelings. Under high intensity rainfall, considerable runoff can be generated from stubble, especially from wheeled ar

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1992.tb00913.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.Results from over seven years of monitoring of erosion rates on bare arable loamy sand soils at the Hilton experimental site, Shropshire, UK, are reported. On bare plots, rates are very variable; erosion during one summer convectional storm exceeded that recorded during six individual years of plot measurement. Exposure of erodible arable soils to convectional storms puts them at risk of excessive erosion. Plot erosion rates were frequently high, with rates up to 67.4 t/ha occurring during an individual storm. Rates were influenced by rainfall erosivity, slope steepness and soil organic content. Mean soil organic content on the bare plots decreased over five years by 0.08%/yr.

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1992.tb00914.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.Water erosion was recorded between mid‐October and mid‐December 1989 in 31 out of 73 erosion‐susceptible arable fields being monitored in England and Wales. Most fields were drilled to winter cereals. Tramlines and wheelings were the factors most commonly linked with initiation of erosion, particularly where runoff was concentrated on valley floors or headlands. Lack of crop cover (<15%) was also an important factor at a number of sites; 25–30% ground cover was generally sufficient to protect the soils from erosion. Erosion was initiated by rainfall events of 15 mm or more in a 24 h period, with a maximum intensity greater than 4 mm/h. A large erosion event in south‐west England was associated with 33 mm of rainfall in 4.25 h, with a maximum intensity o

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1992.tb00915.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.The data from the national project to monitor water erosion has mostly been treated in an aggregate form, because in many of the monitored transects in any year too few fields were eroded for the data to be split into its component parts. However, in crop year 1983 erosion affected enough fields in two localities with contrasting soils for their data to be compared. Rainfall patterns in the two localities were similar. The transects covered a sandland area in Nottinghamshire and an area of clayland in and on the margins of Bedfordshire. Compared with the clayland, rilling of the sandland was widespread, related to the greater range of crops grown there, and more severe. On clayland, rills were mainly confined to valley floors, and slopes flanking these valleys generally had lower gradients than those on the sandland. On sandland, slopes were steeper in eroded fields drilled to winter cereals than they were in fields planted to potatoes or sugarbeet. Such field‐ based studies hint at the complex interactions of rain falling on a cropped field. Erosional thresholds are not static. The areas of fields affected by erosion and deposition were mostly very small. This helps us understand why the farmer often considers erosion unimportan

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1992.tb00916.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract.Soil erosion occurs with sufficient frequency and severity on arable land in the UK to warrant erosion control measures. The main justification is to decrease the off‐farm damages resulting from sedimentation and pollution. The grassing of valley floors, the creation of riparian buffer zones and the use of winter cover crops are recommended as suitable measures. These have additional benefits in terms of wildlife habitats and decrease of nitrate leaching. Financial incentives targeted at farmers in erosion‐sensitive areas are proposed as the main method of implementat

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1992.tb00917.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Book review in this ArticleFarming, Fertilizers and the Nitrate Problem By T.M. Addiscott, A.P. Whitmore and D.S. Powlson.Land Husbandry By N. Hudson.

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1992.tb00918.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY