Excess salts in the soil can have a negative impact on plant growth and productivity. When there are high levels of salts in the soil, it can lead to osmotic stress on plants, inhibiting their ability to take up water and nutrients. This can result in reduced water storage efficiency in the soil, as the excess salts can prevent water from being effectively absorbed and stored by the soil.

Explanation:

1. Osmotic Stress on Plants:
- Excess salts in the soil create a high salt concentration in the soil solution.
- This high salt concentration creates an osmotic imbalance between the soil solution and the plant's root system.
- As a result, water movement from the soil into the plant's roots is hindered, leading to water stress in the plant.

2. Reduced Water Storage Efficiency:
- When there are high levels of salts in the soil, the excess salts can bind to soil particles and reduce the soil's ability to retain water.
- This means that the soil's water storage capacity is reduced, as the excess salts prevent the soil from effectively holding onto water.
- As a result, the soil may have a lower water storage efficiency, meaning it cannot retain as much water as it would without the presence of excess salts.

3. Impact on Plant Growth:
- When plants are exposed to high salt concentrations in the soil, they can experience reduced growth and productivity.
- The osmotic stress caused by the excess salts can inhibit the plants' ability to take up water, leading to water deficiency and stunted growth.
- Additionally, the high salt concentration can also directly damage plant cells and tissues, further impairing plant growth and development.

4. Importance of High Water Storage Efficiency:
- High water storage efficiency in the soil is crucial for plant growth and productivity, especially in areas with limited water availability.
- When the soil has a high water storage efficiency, it can effectively retain and hold onto water, making it available for plant uptake.
- This ensures that plants have access to an adequate water supply, even during periods of low rainfall or drought.
- By having a high water storage efficiency, the soil can provide plants with a continuous supply of water, promoting their growth and overall health.

Therefore, the presence of excess salts in the soil requires high water storage efficiency to compensate for the reduced water availability caused by high salt concentrations. This allows plants to access the water they need for proper growth and development, even in salt-affected soils.