ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1956.tb00875.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1956.tb00876.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1956.tb00877.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY

摘要:

SummaryThe effect of four wheat rotations on soil organic carbon and nitrogen in two long‐term experiments at Chapman and Wongan Hills Research Stations is discussed. The experiments compare continuous wheat, fallow‐wheat, fallowwheat‐pasture, and fallow‐wheat‐z years lupins.On the assumption that adjacent uncultivated soils were comparable in carbon and nitrogen to the original virgin soils, the four‐course rotation is at each site the only one which maintained soil nitrogen at levels approaching those of the virgin soils. The two‐ and three‐course rotations, including in each case a year of fallow, by contrast, produced serious losses in both carbon and nitrogen at both localities, but particularly at Chapman. The soil‐nitrogen data support the hypothesis of Shier and Cullinane (1948) that these levels are influencing wheat yield and the flour quality of the grain.The data emphasize, also, the very low nitrogen and carbon contents of these soils both in the virgin condition and after zz years of a four‐course rotation in which half of each +year period was occupied by a leguminous crop.It is concluded that much longer periods under legumes are necessary if the carbon and nitrogen levels of these soils are to approach those typical of known highly fert

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1956.tb00878.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY

摘要:

SummaryThe effect of four wheat rotations on the water stability of the aggregates, organic carbon, porosity relations, and depth of penetration of a penetrometer at Chapman and Wongan Hills Research Stations is discussed. These rotations compare continuous wheat, fallow‐wheat, fallow‐wheat‐pasture, and fallow wheat‐z years lupins. The soils are coarse‐textured.Significant correlations were obtained between several measurements of structure. These include organic carbon and aggregation, organic carbon, and capillary porosity. Non‐capillary porosity is correlated with penetrometer readings.No such relation was found with total porosity. Wetting and drying of the soil and the action of growing plant roots are considered the two main factors contributing to the physical condition of the soil, and fallowing is considered to be the principal agent causing loss of structure.Water‐stable aggregates were demonstrated in the lateritic sandplain soils from Wongan Hills. These soils have been usually regarded as structureless. Variations in the content of coarse sand considerably obscured the results from

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1956.tb00879.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY

摘要:

SummaryA method is described for measuring the mean value of soil/implement friction over a given depth in the field. The results of experiments using this technique indicate that the simple laws of friction are applicable to soil/metal interfaces, provided that allowance is made for the existence of an adhesive component which is independent of the applied normal load.

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1956.tb00880.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1956.tb00881.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1956.tb00882.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1956.tb00883.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY

ISSN:0022-4588    

DOI:10.1111/j.1365-2389.1956.tb00884.x

出版商:Blackwell Publishing Ltd    

年代:1956

数据来源: WILEY