The term 'ENRICH' is a 6-letter solution to the crossword clue 'ADD FERTILIZER TO'. Enriching soil with fertilizer is an important part of gardening and farming, as it helps to improve the quality of the soil and promote healthy plant growth. Fertilizers are typically composed of nitrogen, phosphorus, and potassium, which are essential nutrients for plants. Adding fertilizer to soil can help to increase yields and improve the overall health of the plants.