ABSTRACT This paper is a short communication about methods used in the analysis of biophysical da... more ABSTRACT This paper is a short communication about methods used in the analysis of biophysical data from the scoping stage of a soil fertility management survey in Papua New Guinea conducted in September–October 2005 (Australian Centre for International Agricultural Research project SMCN/2005/043). The goal of this communication is to describe and promote the good practice of statistics in application to biophysical surveys. A step-by-step analysis is presented of the difference in sweetpotato yield between newly established gardens and gardens that have been cultivated for a long period. We comment on the strengths and limitations of statistical techniques used in the analysis, and also relate the techniques to the corresponding software procedures (R15, Minitab Inc., Chicago). Although we refer to various general methods, the analysis presented is specific to one particular survey. This paper may be useful for agricultural researchers as a case study of the data analysis of field surveys in research or extension projects
The effect of soil puddling on soil physical properties of 3 different textured soils (clay, loam... more The effect of soil puddling on soil physical properties of 3 different textured soils (clay, loam, and silty loam) and growth of rice (Oryza sativa) on these soils was investigated under glasshouse conditions. Puddling intensity was expressed as the ratio of soil volume subjected to the puddling implement and the total soil volume in the puddled layer, thus integrating the effects of speed and time of the puddling operation. This parameter was well related to soil dispersion, bulk density, and saturated hydraulic conductivity. However, following prolonged periods of submerged conditions during rice growth, saturated hydraulic conductivity decreased with a decrease in soil dispersion, in contrast to an expected reduction in saturated hydraulic conductivity with increased dispersion. There was indication that continuous waterlogging reduced the effect of soil puddling, in particular on heavy-textured soils.
Rainfall, vegetation characteristics and soil hydraulic properties influence deep drainage patter... more Rainfall, vegetation characteristics and soil hydraulic properties influence deep drainage patterns in agricultural landscapes, but more information is required on the variability of their interactions with site conditions. Therefore, the objective of the study was to investigate the impact of the interactions of soil permeability, vegetation rooting depth and growth duration on drainage in 3 sites in northern New South
The effect of repeated wetting and drying and the degrees of drying on structure regeneration of ... more The effect of repeated wetting and drying and the degrees of drying on structure regeneration of puddled soil were studied on two soils, e.g., a grey clay and a sandy loam soil. Degrees of drying were arranged by sun drying at different periods, e.g., 2-4 days, 5-8 days and 9-12 days drying, which were corresponding to pF 2.12.5, 3.1-3.8 and 4.6-6.0 respectively. Five wetting/drying cycles were conducted during this experiment. Measurements on the effect of different degrees of puddling showed that the two soils responded quite similar towards partially drying. An increased in the degree of drying resulted in faster improvement of soil structure.. Drying the puddled soil to its air dry water content is very effective in the process of structural regeneration. But this study also showed that the regeneration of puddled soil is possible by partial drying.
... Australian Industrial Publishers, Adelaide, Australia. Freeman BM and Smart RE 1976 A root ob... more ... Australian Industrial Publishers, Adelaide, Australia. Freeman BM and Smart RE 1976 A root observation laboratory for studies with grapevines. Am. ... Heilman MD and Gonzalez CL 1973 Effect of narrow trenching in Harlingen clay soil on plant growth, rooting depth and salinity. ...
ABSTRACT This paper is a short communication about methods used in the analysis of biophysical da... more ABSTRACT This paper is a short communication about methods used in the analysis of biophysical data from the scoping stage of a soil fertility management survey in Papua New Guinea conducted in September–October 2005 (Australian Centre for International Agricultural Research project SMCN/2005/043). The goal of this communication is to describe and promote the good practice of statistics in application to biophysical surveys. A step-by-step analysis is presented of the difference in sweetpotato yield between newly established gardens and gardens that have been cultivated for a long period. We comment on the strengths and limitations of statistical techniques used in the analysis, and also relate the techniques to the corresponding software procedures (R15, Minitab Inc., Chicago). Although we refer to various general methods, the analysis presented is specific to one particular survey. This paper may be useful for agricultural researchers as a case study of the data analysis of field surveys in research or extension projects
The effect of soil puddling on soil physical properties of 3 different textured soils (clay, loam... more The effect of soil puddling on soil physical properties of 3 different textured soils (clay, loam, and silty loam) and growth of rice (Oryza sativa) on these soils was investigated under glasshouse conditions. Puddling intensity was expressed as the ratio of soil volume subjected to the puddling implement and the total soil volume in the puddled layer, thus integrating the effects of speed and time of the puddling operation. This parameter was well related to soil dispersion, bulk density, and saturated hydraulic conductivity. However, following prolonged periods of submerged conditions during rice growth, saturated hydraulic conductivity decreased with a decrease in soil dispersion, in contrast to an expected reduction in saturated hydraulic conductivity with increased dispersion. There was indication that continuous waterlogging reduced the effect of soil puddling, in particular on heavy-textured soils.
Rainfall, vegetation characteristics and soil hydraulic properties influence deep drainage patter... more Rainfall, vegetation characteristics and soil hydraulic properties influence deep drainage patterns in agricultural landscapes, but more information is required on the variability of their interactions with site conditions. Therefore, the objective of the study was to investigate the impact of the interactions of soil permeability, vegetation rooting depth and growth duration on drainage in 3 sites in northern New South
The effect of repeated wetting and drying and the degrees of drying on structure regeneration of ... more The effect of repeated wetting and drying and the degrees of drying on structure regeneration of puddled soil were studied on two soils, e.g., a grey clay and a sandy loam soil. Degrees of drying were arranged by sun drying at different periods, e.g., 2-4 days, 5-8 days and 9-12 days drying, which were corresponding to pF 2.12.5, 3.1-3.8 and 4.6-6.0 respectively. Five wetting/drying cycles were conducted during this experiment. Measurements on the effect of different degrees of puddling showed that the two soils responded quite similar towards partially drying. An increased in the degree of drying resulted in faster improvement of soil structure.. Drying the puddled soil to its air dry water content is very effective in the process of structural regeneration. But this study also showed that the regeneration of puddled soil is possible by partial drying.
... Australian Industrial Publishers, Adelaide, Australia. Freeman BM and Smart RE 1976 A root ob... more ... Australian Industrial Publishers, Adelaide, Australia. Freeman BM and Smart RE 1976 A root observation laboratory for studies with grapevines. Am. ... Heilman MD and Gonzalez CL 1973 Effect of narrow trenching in Harlingen clay soil on plant growth, rooting depth and salinity. ...
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