摘要:

Abstract.A land evaluation at farm level was made for a toposequence of three New York soils, using the FAO framework and the LEACHN simulation model. The land utilization type (LUT) was continuous corn, using three varieties with different growing periods. Ten experts identified the same land qualities but three different types of land characteristics, as derived from soil survey data, field observations and simulation modelling. Differences could be explained by the backgrounds of the experts. A land evaluation procedure according to framework criteria using decision trees rather than matching tables was more accessible and transparent. Simulation of the soil‐water regime provided quantitative data for all land qualities considered, and this procedure was preferred to qualitative estimates based on poorly defined procedures. When some land qualities cannot be characterized by simulation, however, a mix of qualitative and quantitative decision tree branches may be considered. The standard scheme of land evaluation, which is scale independent, provides irrelevant results at farm level because farmers’ questions are different from those of regional planners who are well served by the traditional land evaluation procedure. For the farmer, development of decision support systems should be focused on optimal management decisi

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1993.tb00942.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Abstract.The impact of cattle trampling on the porosity of a representative soil (Typic Natraquoll) of the flooding Pampa of Argentina was studied from 1984 to 1987. Water content, total porosity (TP), macroporosity (>30 μm) and mean weight diameter of water‐stable aggregates (MWD) were determined in undisturbed topsoil samples taken from adjacent continuously grazed (1.0 animal unit/ha/yr) and ungrazed (since 1976) areas. It was expected that trampling would decrease macroporosity when the soil was ponded, and that the damaged macropores would regenerate during the subsequent soil drying. This was only partly verified. The soil varied in TP from 58 to 64% in the ungrazed area, and from 53 to 78% in the grazed area. This variation resulted mainly from shrink‐swell processes. Trampling decreased soil macroporosity (mainly>60 μm) from 8 to 5% and decreased MWD from 5.35 to 4.58 mm under dry soil conditions. The damaged soil pores regenerated and aggregate stability recovered during the subsequent period of surface water ponding, when soil swelling increased macropores in the grazed area but not in the ungrazed area. There was no evidence of poaching damage in this

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1993.tb00943.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Abstract.Preferential flow paths (PFP) are important in water and solute movement through soils, especially in regions where vertical water movements predominate, such as the flooding Pampa (Argentina). The impact of grazing on PFP and its interactions with other properties were studied in three soils with natric horizons in the flooding Pampa using an iodide colouring technique. In the soil with a mollic horizon (Typic Natraquoll), % PFP was decreased by trampling but was later restored by shrink‐swell. In the Typic Natraqualf, the most alkaline of the studied soils, % PFP was very small under both grazed and ungrazed conditions. In a coarser textured soil (Mollic Natraqualf) trampling did not affect % PFP. The % PFP of the Ah horizons increased with increasing organic carbon and sand contents and decreased as clay content, pH and sodium adsorption ratio (SAR) increased. The Bt horizons had small % PFPs and were not affected by cattle tramplin

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1993.tb00944.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Abstract.Field trials measured the benefits of using soil in the reclamation of colliery spoil. Increasing the thickness of the soil cover increased grass yield, particularly on a site with potentially acidic spoil materials. Mixing soil with the underlying spoil increased yield slightly compared to using the same amount of soil as a cover. From these and earlier results, we conclude that: the use of soil as a cover is essential on sites with acidic, or potentially acidic, spoil; to be effective in the short‐term, the thickness of soil can be as little as 15 cm; the use of soil on sites with non‐acidic spoil is beneficial in terms of physical conditions, such as improved water‐holding capacity and better root penetration; the benefits of incorporating the soil on such sites are probably insufficient to justify the additional effort inv

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1993.tb00945.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Abstract.Runoff and soil loss were measured using simulated rainfall at nine shrubland sites on gypsiferous soils in the Ebro Valley. The sites represented diverse physiographical situations, including three soil types, three slopes and different percentages of rock outcrop and vegetation cover. Soil type, slope and vegetation cover significantly affected runoff and soil losses. An average of 40% of the simulated rainfall (48 mm/h) appeared as runoff and amounts were positively correlated with soil losses. The greatest runoff and soil losses were from plots with the steepest slopes. Rock outcrops decreased soil losses.

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1993.tb00946.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Book Reviewed in this article:Soils and the Environment By Alan Wild.Nitrate. Processes, Patterns and Management Edited by T.P. Hurt, A.L. Heathwaite and S.T. Trudgill.Urban Soil and Landscape Design By P.J. Craul.Bullock, P.&Gregory, P. J. 1991.Soils in the urban environment.

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1993.tb00948.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY