The apparatus is a board 220 cm x 18 cm on the face of which thin rods 50 cm in length are placed at 10-cm intervals at right angles to the long edge. The board is supported vertically by legs and adjusted until its long edge is parallel to the soil surface. When released the rods slide down to touch the soil and their position is measured on a scale on the board. These data permit the determination of surface roughness of soil. Roughness after plowing generally increased with increasing clay content, and deep plowing increased roughness on a light soil. Roughness in spring depended mainly on roughness after autumn plowing. (Abstract retrieved from CAB Abstracts by CABI’s permission)
Moisture content at pF 2 decreases at high bulk densities when areation under wet conditions is top poor for plant growth, and increases if the soil contains a considerable amount of aggregates
Aggregates were collected from the arable layer at eight sites in the IJsselmeer polders. The compositions of the soils were determined, and measurements were made of porosities, tensile strengths and water stabilities of undisturbed aggregates. Porosity was negatively correlated with the age of the soils since reclamation. Tensile strength of dry aggregates and water stability were both positively correlated with the clay content. The soils had extremely high values of friability. Tensile strength was negatively correlated with porosity. Porosity had no clear influence on water stability. (Abstract retrieved from CAB Abstracts by CABI’s permission)
A method is described for measuring the height of the soil surface at different times relative to level marks under the ploughed layer. These heights can be used to calculate pore space immediately after plowing from its value determined before plowing & the plowing depth. The height of the surface soil is measured with a relief meter which is shown in a photograph. It consists of a vertical scale 10 cm high, divided into cm & fitted in an aluminium frame. In front of the scale 20 needles are placed 10 cm apart & held in position by a spring-mounted bar. If the bar is pushed in, the needles slide down until they touch the soil surface. Experiments show that spring cultivations compact the soil; frost raises the height of the surface soil, but has little effect on surface roughness. (Abstract retrieved from CAB Abstracts by CABI’s permission)
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