The elements like sulphur and calcium are a part of the structural component of the cell and hence are not easily realsed
in ncert
in transport in plants chapter sulphur is under mobile element
where as in mineral nutrition chapter sulphur is under immobile element
undoubtedly sulphur is immobile element because there are no perfect reasons to prove sulphur as A mobile element

Sulphur is a nutrient essential for plant growth and development. Its availability to plants depends on its mobility in the soil. The mobility of sulphur in the soil is influenced by various factors such as soil pH, texture, organic matter content, and microbial activity.

Mobile Element

In NCERT BIO 1ST YEAR pg.no190 (3rd para), it is mentioned that sulphur is a mobile element. This means that it can easily move within the soil and from the soil to plant roots. Sulphur in the soil can be in different forms such as sulphates, elemental sulphur, and organic sulphur. Sulphates are the most common form of sulphur in the soil, and they are highly mobile. They can easily move with soil water and get absorbed by plant roots.

Immobile Element

In PG.no.198 last para, it is mentioned that sulphur is an immobile element. This means that once sulphur is absorbed by plants, it cannot be easily transported within the plant. Sulphur is essential for the formation of proteins, enzymes, and chlorophyll in plants. Hence, plants have developed mechanisms to efficiently utilize sulphur. They can store sulphur in their tissues, and they have a mechanism to recycle it.

Conclusion

In conclusion, the mobility of sulphur in the soil and its availability to plants depend on various factors. Sulphur is a mobile element in the soil, but once it is absorbed by plants, it becomes immobile. Hence, it is essential for plants to have a continuous supply of sulphur to meet their growth and developmental needs. Farmers can ensure sulphur availability to their crops by adding sulphur-containing fertilizers to the soil.