On the other hand, farmers In the irrigated lands use even a larger quantity of fresh water for agrlculture. In fact so far, the largest quantity of fresh wa ter that man invests in is for irrlgation of agrlculture. About 80 percent of t he world s fresh water is used for grow-ing rice and wheat on irrigated lands. In the United States, it takes an average 6,500 liters of water to produce food for one person per day (Parfit, 1996a); in the Asian tropics, it takes an aver age of 8 million liters of fresh water to grow one hectare of rice. Irriga-tion contlnues to cause agricultural growth, but new sources of fresh water are inc reas-ingly expensive to exploit. In Table 2, the rate of irrigated arable land in some countries of the Asla-Pacific region increased rapidly since 1970, brin ging the total irrigated areas to about 65.7 million hectares (or 41.3%) of the total 159 million hectares of arable lands.