Book Excerpt: on when its efficiency in crop production may behighest. South China has a rainfall of some 80 inches with little ofit during the winter, while in our southern states the rainfall isnearer 60 inches with less than one-half of it between June andSeptember. Along a line drawn from Lake Superior through centralTexas the yearly precipitation is about 30 inches but only 16 inchesof this falls during the months May to September; while in theShantung...