An Experimental Study Of Salinity Impacts On Summer Corn Growth, Nitrogen Uptake And Soil Hydraulic Properties

The main purpose of this paper is to investigate salinity effect on plant growth, N uptake and soil permeability with greenhouse and laboratary experiments.(1) The experiment of investigating the salinity effect on crop growth was conducted in the greenhouse. Summer corn was growing in pots with diameter of 35 cm and height 30cm, and the perlite was used as culture medium. Five treatments with three replicates were set, each of them corresponded to a salinity level with addtional NaCl of 10mmol/L, 20mmol/L, 40mmol/L, 60mmol/L and one control in the irrigated culture solutions respectively. The leaf area (LA) decreases significantly when the salinity concentration was up to 60mmol/L at 25 days after emergence, and there is no significant difference in LA among the four salinity treatments but the LA of the salinity treatment is lower than the treatment with salinity control at 35 days after emergence. No significant difference in LA was dected among the five treatments from 50 days to 101 days after emergence. Plant height, dry matter accumulation in root, stem and leaf show no big difference among the five treatments during the whole growing period. The root length in the treatment of 60mmoI/L is much lower the other four at 65 days after emergence. N accumulation in plant can be qualified with a quadratic function of time.(2)The second experiment was conducted with soil column. Sixteen treatments with three replicates for each were taken. The simulating saline water was made by adding NaCl and CaCl2 into the deionized water with SAR range from 0 to 15 (mmol/L)1/2 and salinity range from 2 to 100 mmol/L. After one season and five seasons irrigation, the coloum was saturated and the leached with saline water and then followed by a leaching of deionized water. After one season irrigation and then leaching by saline water with SAR value from 0 to 15(mmol/L)-2, the hydraulic conductivity(HC) of the soil column decreases first to a lowest value and then increases with salinity concentration, while the HC for the treatment with SAR equals to 30(mmol/L)-2 increases with the increasing of the concentration. At the same SAR value, HC is a quadratic function of salinity concentration. After five seasons' irrigation, HC decreases with the increasing of the concentration, meanwhile HC shows no big difference among the treatments with concentration equal to or higher than 10 mmol/L at the same SAR value, but the HC value of these treatments is higher than that with concentration of 2mmol/L, and the relationship between HC and salinity concentration can be quantified with an exponent function. When the leachate was replaced by deionized water, the HC in the one season irrigation treatment shows no difference with the value leached with saline water. When SAR value is in the range of 0 to 15(mmol/L)-2, soil infiltration property is not signicantly affected by lower salinity levels with concentration from 2 to l0mmol/L, while the significan reduction on the soil permeability happens at higher salinity levels with concentration of 50 and l00mmol/L. At higher SAR level of 30(mmol/L)1/2, there is no significant effect on HC only at very low salinity with Concentration eqwuals to 2mmol/L, while significant reduction on soil permeability was found at salinity concentration form 10 to l00mmol/L. HC first decreases to a lowest value and then increases with the increasing of SAR, then increased with the increase of SAR when leached with either saline water or deionized water.