Diunduh dari: Ĥ Perubahan air dalam tanah = Input air – Kehilangan air This is commonly done with the aid of a water balance equation, which compares for a given period of time, incoming water in the rooted soil with outgoing water and quantifies the difference between the two as a change in the soil moisture amount stored. A crop growth simulation model must therefore keep track of the soil moisture potential to determine when and to what degree a crop is exposed to water stress. The consequence is evident: this stomatal closure interferes with CO2 intake and reduces assimilation and dry matter production consequently. Above or below this level the plant senses stress it reacts by actively curbing its daily water consumption through partial or complete closure of the stomata. An optimum range exists within which the plant takes up water freely. In hydrology, the potential is usually used and is expressed as energy unit per weight of soil water, with the dimension of length (van Bakel, 1981). This suction known as the soil moisture potential or 'matrix suction', can be measured. The tenacity with which the soil retains its water is equalled by the suction which roots must exert to be able to take up soil moisture. If soil moisture uptake by the roots is not replenished, the soil will dry out to such an extent that the plants wilt and - ultimately- die. The daily turnover can be considerable: transpiration from 0.4 cm of water from a crop surface on a clear sunny day corresponds with a water loss from the root zone of than kg ha-1 d-1. Most water that plants take up from the soil is again lost to the atmosphere by transpiration through the same openings. ģ SOIL WATER BALANCE Plant production involves CO2 intake through stomatal openings in the epidermis. (Source: LANDY / DUNSTE) Diunduh dari: …. When the excess has drained away the amount of water retained in the soil is termed its field capacity, when some of its pore spaces are still free of water. Water in excess of hygroscopic and capillary water is termed gravitational water, which is of a transitory nature because it flows away under the influence of gravity. Since it is held against the force of gravity it is permanently available for plant growth and it is this type of soil water which contains plant nutrients in solution.
Water forming thicker films and occupying the smaller pore spaces is termed capillary water.
Ada tiga macam bentuk lengas tanah: Water adhering in thin films by molecular attraction to the surface of soil particles and not available for plants is termed hygroscopic water.
Salah satu faktor yang sangat penting dalam proses pedologis dan pertumbuhan tanaman. Priyono dan Soemarno psl-ppsub nopember 2012Ģ LENGAS TANAH Definisi: Air yang disimpan dalam tanah.
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