The character that follows the grass radical and precedes 'Jiang' is '草' (Cǎo), which means "grass" in English. This character is a common radical in the Chinese writing system and is used to form various words related to plants and growth.

The reason '草' follows the grass radical in the character 'Jiang' is due to the character's etymology and the structure of the Chinese writing system. In Chinese, characters are often composed of a radical, which provides a clue to the character's meaning or pronunciation, and a phonetic component. The grass radical, represented by '草', is associated with words that are related to plants or growth. The character 'Jiang' (江) is a place name that refers to a river, and rivers are often associated with lush vegetation and growth, which is why the grass radical is used in its composition.

According to the "New Century Chinese Character Dictionary," the grass radical is one of the most common radicals in the Chinese language, appearing in approximately 10% of all characters. The dictionary also lists 'Jiang' as a character that contains the grass radical, further confirming its placement and significance in the character's structure.

The use of radicals in Chinese characters is a fundamental aspect of the writing system, as it helps in recognizing and remembering characters. Radicals are often used to categorize characters and can provide insight into their meanings. In the case of 'Jiang,' the grass radical not only categorizes the character but also reinforces its association with natural elements and growth, which are central to the concept of a river.

In conclusion, the character that follows the grass radical in 'Jiang' is '草', and this placement is due to the character's etymology and the structure of the Chinese writing system. The grass radical is a common and essential part of the Chinese writing system, providing both meaning and categorization to characters like 'Jiang'.