Diagnosis and Improvement of Saline and Alkali Soils

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U.S. Government Printing Office, 1954 - Alkali lands - 160 pages

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Page 155 - The moisture content of soil in the field 2 or 3 days after a thorough wetting of the soil profile by rain or irrigation water.
Page 69 - ... (3) concentration of boron or other elements that may be toxic; and ( 4 ) under some conditions, the bicarbonate concentration as related to the concentration of calcium plus magnesium.
Page 5 - As long as excess salts are present, the appearance and properties of these soils are generally similar to those of saline soils. Under conditions of excess salts, the pH readings are seldom higher than 8.5 and the particles remain flocculated.
Page 76 - In the classification of irrigation waters, it is assumed that the water will be used under average conditions with respect to soil texture, infiltration rate, drainage, quantity of water used, climate, and salt tolerance of crop. Large deviations from the average for one or more of these variables may make it unsafe to use what, under average conditions, would be a good water ; or may make it safe to use what, under average conditions, would be a water of doubtful quality.
Page 155 - A soil containing sufficient exchangeable sodium to interfere with the growth of most crop plants and containing appreciable quantities of soluble salts.
Page 141 - S0 4 (2.4) until the galvanometer shows no deflection. If a shunt is used, reverse the switch, thus eliminating it from the circuit and permitting the galvanometer to function at its greatest sensitivity. Again adjust to balance with either dilute acid or alkali. The galvanometer should be steady, showing at most only a slow drift. This is the initial point of the titration. Bring the shunt into the circuit by reversing the DPDT switch or open the SPST switch if the shunt is omitted. Add 5 0.1...
Page 37 - It has been defined as the fraction of the irrigation water that must be leached out of the bottom of the root zone...
Page 155 - Leaching Requirement — The fraction of water entering the soil that must pass through the root zone in order to prevent soil salinity from exceeding a specific value which would adversely affect plant growth or crop yield.
Page 39 - At this time, also, water may be more plentiful and the water table and drainage conditions more favorable than during the regular irrigation season. Unless drainage is adequate, attempts at leaching may not be successful, because leaching requires the free passage of water through and away from the root zone. Where drainage is inadequate, water applied for leaching may cause the water table to rise so that soluble salts can quickly return to the root zone.
Page 71 - In general, water having an electrical conductivity below 750 micromhos per centimeter is satisfactory for irrigation insofar as salt content is concerned, although salt-sensitive crops may be adversely affected by irrigation water having an electrical conductivity in the range of 250 to 750 micromhos per centimeter.

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