Tiny soil particles lodge in the soil pores, sealing the soil surface. Tilth also suffers and crusts hard enough to stop seed germination may form. In many cases, sodic soils also show a poorly drained columnar subsoil structure. The effect of sodium is most extreme on fine-textured soils and least extreme on coarse soils. Crop plants may take up enough sodium to injure plant tissues.
Crops vary in the tolerance to sodium.
For the most sensitive crops, like citrus fruits, the nutritional effects of sodium are more important than its effects on structure. For sodium-tolerant crops, poor growth results mainly from soil conditions. In the biological process of degrading the inert salt binding compounds, there are other benefits to the soil. Under these conditions, the soil takes on a completely different soil structure. Soils that contain high salt ion concentrates exhibit characteristics of being compacted with a hardpan, hard to plow with a thick, hard crusting and clodding which causes the grower serious problems in getting a stand up.