Welcome in China! As a geographer, I carry some interest in agriculture, the über form of interaction between the physical earth and us, human beings. Today's pearl shows the magnificent Chinese rice terraces. Steep hillsides are rebuild to staircases, irrigated intensely, providing the well-being of millions Chinese people. The terraces hold the water and protect the crop for severe erosion.
Other tropical agriculture systems may chose to subject themselves to the rules of mother nature. For example, the infamous 'slash & burn' system is based on the natural fertility of untouched forests and farmers adapt by burning the forest down and exploiting the remaining soil. Depending on the fertility, water capacity, ... of the soil they encounter, they chose their crop, the density etc. Once the soil is depleted they burn the next forested patch and again they adapt their crop types, husbandry and habit to the state of the cleared soil. For water and solar energy, they completely rely on the local climatic conditions.
An irrigation system such as these rice paddies operates by another principle. They adapt their environment to their culture of rice cropping. Rice requires a lot of water. The fields which are available, are on steep slopes with absolutely no water storage and besides, they are very erosive. Not a problem for our new Chinese friends and they built their terraces, solving both the water capacity and the erosion problem. The water which they use comes from uphill where it takes up solutes and nutrients which they could deliver to field downwards. Moreover, some algae living in the steady water fix nitrogen which the rice crops gladly absorb. The stagnation of the water, further, influence some chemical processes, providing even more nutrients for the rice crops. Finally, the farmers also use different other land use types and cattle to foresee additional manure, mineral fertilizer etc to keep the system going for ages. In a few words: it just works.
Despite being one of my favorite agricultural system (as a geographer, you have some a favorite thing in a lot of categories), it's also a pretty impressive and colorful picture. Side note: the different colors probably are the result of different stages in the growing cycle or cultivating cycle.
