Lao Zhang in order to experiment with the effect of a brand of fertilizer, the rice fields divided into east, west two pieces, in the east of the plot fertilization, the west of the plot does not fertilize. After the rice harvest, the eastern plot yields 700 kg per acre, and the western plot yields 400 kg per acre. 
The same variety of rice is planted in the East and West
 the fertilizer of this product can effectively increase production.