摘要:

Abstract.Agricultural soil erosion is serious in developed and developing countries alike. Soil runoff can diminish long‐term land productivity and accompanying sedimentation of waterways contributes to flooding and substantially reduces both water quality and the useful life of reservoirs and irrigation works. To design effective erosion control policies, planners need to be able to evaluate conservation efforts by fanners. The research reported here develops comparative measures of conservation effectiveness using the management factors of the Universal Soil Loss Equation. These factors measure the effectiveness of farmers' existing conservation practices and can help policymakers identify the regions and types of farms which are not using effective erosion control measures, enabling them to direct scarce personnel and funds to areas where they are most neede

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1985.tb00968.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.An example is given of urban fringe farming from Freetown, Sierra Leone, where immigrants practise intensive cultivation in an environmentally marginal situation. Great reliance is placed on farming experience, generally gained from rural areas, before migration to Freetown. Two main problems result; declining soil fertility and increased erosion hazards. Lack of government recognition of these farmers means that indigenous, innovative solutions to overcome these problems are being formulated.

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1985.tb00969.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.Soil and crop responses to traffic with vehicles having an axle load of 10 tonnes were studied in 9 field experiments. The clay content of the soils ranged from 6 to 85%. The traffic resulted in increased soil bulk density and strength to a depth of 50 cm. Compaction effects persisted below plough depth 7–8 years after traffic. Crop response was negative and increased with clay content of the soil and with traffic intensity and decreased with time. The results indicate that maximum axle loads on arable fields should be less than 10 tonnes, especially on clay soil

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1985.tb00970.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.Losses of soil and fertilizer nitrogen by leaching and denitritication from a clay soil in southern England have been measured over four years. Nitrate losses in drainage water from direct‐drilled land averaged 20–30 kg N ha ‘a’ with wide seasonal variation. Ploughing and conventional cultivations increased this loss. Denitritication from direct‐drilled land averaged 5–10 kg N ha ‘a’ with wide seasonal variation. Ploughing and drainage both diminished denitritication losses but cultivation had the greater effect. These nitrogen losses occurred mainly in autumn and spring.Nitrogen losses, in drainage water or by denitritication after spring fertilizer applications, were related to the rainfall in the 28 days following top dressing. Approximately 40 mm rain was needed to cause a loss of 10% of the nitrogen applied but in practice losses were

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1985.tb00971.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.Sugarcane yields in the Herbert Valley in North Queensland have been declining over the past 15 years. Better yields are obtained where crops are grown on previously unused land. Soils under cane are more compacted, more acid, contain less organic matter and are lower in cation exchange capacity and exchangeable cations. These differences reflect soil degradation caused by intensive cultivation.Contributing factors to the degradation of soils include soil compaction and structural breakdown occurring during harvest and cultivation operations, losses of organic matter due to burning of crop residues and acidification of soils due to large applications of nitrogen fertilizers.Soil management practices should aim to increase soil organic matter levels, provide a more favourable biological environment, reduce physical damage to soils during harvesting and cultivation, reduce soil acidity and improve the effectiveness of fertilizing practices.

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1985.tb00972.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.After satisfactory results during the mid‐1970s, winter cereal yields and profitability were disappointing during 1979–81 on a Buckinghamshire farm with Ragdale series stagnogley soil. Poor soil physical conditions were diagnosed and then improved by soil loosening and mole drainage. Other inputs and management remained intensive but essentially constant. Three‐year average winter wheat and barley yields rose from 5.6 and 4.9 t ha for 1979–81 to 7.4 and 6.8 t ha respectively for 1982–84. A large part of this increase could be attributed to improved soil management. The observations were made as a farm case study and not as a replicated field trial. They may nevertheless be of interest to others and of national relevance as similar soils occupy some 30% of the cereal area i

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1985.tb00973.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.Information on rainfall erosivity, soil erodibility and land capability is combined to produce a map of England and Wales showing areas with a risk of soil erosion at rates above the soil loss tolerance level. About 20 500 km2or 37% of the arable area is at risk. Given the shallow soils and current rates of erosion, sustained use of this area for cereal, sugar beet and vegetable production beyond the first quarter of the next century is threatened. A further 4000 km2is at risk in non‐arable areas, mainly associated with blanket peat in the uplands and with coastal sand dune

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1985.tb00974.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.Effects on soil physical properties in a trial which compared establishing an apple orchard on grassed and cultivated soil and of maintaining soil with or without a vegetative cover post‐planting are discussed. On a fine sandy loam soil (Fyfield series) prone to erosion, bulk density, water filled porosity and soil erosion, measured at intervals after the establishment year, were all unaffected by the use of grass. Infiltration rate was much higher on grassed than on herbicide treated soil as was the apparent ability to accept heavy rainfal

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1985.tb00975.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract.A new method of measuring susceptibility to poaching is described, based on the concept that poaching is caused by a progressive loss of soil strength during repeated treading in wet weather. Susceptibility was measured by the rate of loss of strength in response to concurrent treading and irrigation at standard rates. The pressures exerted on the ground by a walking dairy cow were simulated by a purpose‐built penetrometer, whilst water was applied via a network of plastic pipes fitted with syringe needles. Measurements were performed on four pasture soils having a range of clay contents and compared in relation to a mechanism proposed for the process. The results show susceptibility to be a property not wholly determined by the clay content of the soil, but suggest that it is influenced by bulk density and the strength of the sward, which will van, according to weather and pasture managemen

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1985.tb00976.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1985.tb00977.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY