In order to get a good harvest people need to fertilize soil and then, when your future harvest sprouts you shall care about protecting it from harmful insects and diseases. Nowadays as far as I know people use small planes, which pulverize fertilizes and insecticides. I think about a little bit different way to do that. To pulverize everything not upon the earth, but upon the rain clouds, which are above the fields. It will make this process more natural. In cities it would be possible to enrich rain clouds with iodine for example, because the shortage of this element in organisms can lead to serious problems with health. Or with something else, which may be usesful for people and nature.