All the 12 counties in Yulin prefecture of Shaanxi province are poor and severely eroded in the Yellow river basin .Since the new China founded

there has been 378000 ha of irrigated land

soil-saving dam land and terraced land(called“three lands”for short)constructed

which consists of 60% of the total farmland .A regression coefficient of 43.9 of field cropyield to“three lands” area has been drawn by regression analysis

that means the yield of the total farmland increased by 43.9 kg/ha with an increment of each 10000 ha of“three lands”.For the 35 years

“three lands” increased by 906 500 ton of food

and the relevant coefficient is 0.9955

being doubly marked and positively interrelated .Percapita food of villagers was 444 kg in 1996

increased by 1.95 times comparing to that of 150.5 kg in 1949.The sandy area of northern Yulin holds a great potentialin developing irrigated land and food production

and 134000 ha of land can be opened up for well-irrigated farmland.It is predicted that the total food production can reach 1870000 ton

and there will be 521kg food percapita by 2010.