The effects of salinization on irrigated land are as follows:

It decreases crop production: Salinization increases the salt content in the soil, which makes it difficult for plants to absorb water and essential nutrients. This, in turn, reduces crop yields.

It makes some soils impermeable: Excess salt in the soil can cause soil particles to bind together, making the soil impermeable to water. This can lead to waterlogging and other problems.

It lowers the water table: Salinization can reduce the amount of available water by lowering the water table. This makes it more difficult for plants to access water, leading to reduced crop yields.

It fills the air spaces in the soil with water: Salinization can lead to the accumulation of excess water in the soil, which can fill the air spaces in the soil that are needed for root respiration. This can lead to reduced plant growth and other problems.

Therefore, the correct statement is "It makes some soils impermeable."