Over de invloed van grondbewerking op het transport van warmte, lucht en water in de grond

The influences were calculated physically of tillage on the temperature of soil and air near the surface, on the composition of the air in the soil and on infiltration capacity for water. The calculations were compared with experimental data obtained in different parts of the world.

Unworked soil was considered to be homogeneous while worked soil consisted of 2 or 3 layers with different volume fractions of solid material; the lowest layer had the properties of uncultivated soil.

The physical aspects of tillage for plant growth involved aeration of a compact soil by increasing the volume fraction of air-filled pores and improving the permeability of the soil and a rather small influence on its temperature. Tilling caused more extreme temperatures of the aerial part of the plant and of the seed, if the depth of working was more than about twice the depth of sowing, and less extreme temperatures of the root zone.

Deep tillage was sometimes not desirable, as in a region with dry cold winters if winter crops are grown and in a dry hot region, because of the increased oxidation of organic matter. In a temperate climate it may be favourable for both winter and summer crops.