摘要:

The organisation and funding of research and development work in soil science in the United Kingdom are described. The customer/contractor system of financing research and development in agriculture has been introduced and the changes resulting from this are discussed. Some examples of the fields of work undertaken by the different groups are included.

ISSN:0038-075X    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

There exist mathematical models to determine the optimum depth and spacing of field drains from measurements of hydraulic conductivity, or indirect estimates of this. The results are reasonably useful as long as the hydraulic conductivity exceeds perhaps. 1–2 m/day. For heavier, less permeable soils, it is necessary either to use very cheap “pipes” (mole drains) at the calculated spacing or normal pipes at wider spacing after increasing the hydraulic conductivity by subsoiling.

ISSN:0038-075X    

出版商:OVID    

年代:1975

数据来源: OVID

ISSN:0038-075X    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

Recent ideas and findings on the mechanisms and products of weathering of felspars, micas, and ferromagnesian minerals are reviewed, with illustrations from mineralogica1studies on residual soil profiles where unambiguous mineral transformations have been directly observed and from experimental work in the laboratory.

ISSN:0038-075X    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

An appraisal of research on soil polysaccharides and phosphate esters of carbohydrates.

ISSN:0038-075X    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

The distribution of microorganisms on and around roots, and their effects on higher plants, are discussed. Bacterial effects on plant nutrition are uncertain, and direct effects seem likely to be small. Mycorrhizal fungi can improve plant nutrition greatly, usually by increasing phosphate supply, and the mechanisms are now fairly well understood.

ISSN:0038-075X    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

This paper discusses adsorption reactions between orthophosphate ions and calcium carbonate and the hydrous oxides, and relationships between the soluble and labile phosphate in soils.

ISSN:0038-075X    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

Recent developments in herbicides and machinery for drilling and cultivation require a reassessment of tillage requirements in terms of soil physical conditions, since these may determine to what extent current or new systems of reduced or zero tillage can be more widely adopted. Soil and climate conditions frequently interact in Britain to give obviously unfavourable soil conditions particularly where heavy machinery is in use. A review of the physical conditions of field soils under different tillage systems shows that reduced or zero tillage cannot yet be recommended for the more demanding crops and less well drained soils.

ISSN:0038-075X    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

A review of soil microstructure with particular reference to microscopy and the mechanical behaviour of soil.

ISSN:0038-075X    

出版商:OVID    

年代:1975

数据来源: OVID

摘要:

Day-to-day judgments in soil systematics that are usually made intuitively can now be made automatically and consistently using numerical methods. Nevertheless, intuition is still required to choose suitable methods. This paper recommends those that can be represented geometrically, and describes them as means of examining a character space in which each soil specimen, profile, or site is represented by a point. The estimation of likeness, classification, ordination, allocation, and the optimisation of classifications are discussed in turn.

ISSN:0038-075X    

出版商:OVID    

年代:1975

数据来源: OVID