In the face of increasing urbanization, land degradation, and climate change, the question of whether food will be grown in soil in 100 years' time is a complex one. While it is difficult to predict with certainty what the future of food production will look like, it is clear that there are significant challenges to the continued use of soil-based agriculture. This isn't just a plot for science fiction, but a question scientists --and future farmers must consider. 

One significant challenge to the future of soil-based agriculture is the growing pressure on land resources due to urbanization and land-use change. As urban populations continue to grow, more land is being converted for non-agricultural uses, reducing the availability of arable land for food production. Additionally, soil degradation, nutrient depletion, and other forms of land degradation continue to reduce the productivity and sustainability of existing farmland, further limiting the capacity of soils to support food production.

Climate change is another significant challenge to the future of soil-based agriculture. Climate change is expected to increase the frequency and severity of extreme weather events such as floods, droughts, and heatwaves, leading to reduced crop yields and increased risk of crop failure. Climate change also has the potential to increase soil erosion and nutrient depletion, further reducing the productivity and sustainability of soils.

In the face of these challenges, alternative approaches to food production are emerging that have the potential to supplement or even replace soil-based agriculture. One of these approaches is hydroponics, a soil-less method of growing plants in water with added nutrients. Hydroponics systems can be implemented in a wide range of environments, including urban areas, and can be highly efficient in terms of water and nutrient use. Additionally, hydroponics can be used to grow a wide range of crops, including fruits, vegetables, and herbs, making it a promising alternative to soil-based agriculture.

Another alternative to soil-based agriculture is aeroponics, a method of growing plants in air with added nutrients. Aeroponics systems can be highly efficient in terms of water and nutrient use, and can be implemented in a wide range of environments. Additionally, aeroponics can be used to grow a wide range of crops, including fruits, vegetables, and herbs, making it a promising alternative to soil-based agriculture.

Vertical farming is another alternative to soil-based agriculture that has gained significant attention in recent years. Vertical farming involves growing crops in vertically stacked layers using artificial lighting, temperature control, and a nutrient-rich medium. Vertical farming can be implemented in urban areas, making it a promising solution to food production in areas with limited land availability. Moreover, vertical farming can be highly efficient in terms of water and nutrient use, leading to reduced environmental impacts and increased food security.

In conclusion, while it is difficult to predict with certainty what the future of food production will look like in 100 years' time, it is clear that there are significant challenges to the continued use of soil-based agriculture. While soil-based agriculture will likely continue to play an important role in food production for the foreseeable future, alternative approaches such as hydroponics, aeroponics, and vertical farming have the potential to supplement or even replace soil-based agriculture, particularly in urban areas and in the face of growing land scarcity, soil degradation, and climate change. As such, it is important to explore and invest in these alternative approaches to ensure food security and sustainable food production in the years to come.