Mexican soldiers discovered the biggest marijuana plantation ever found in Mexican history, in the state of Baja California, about 150 miles (250km) south of the U.S. border Tuesday.

Soldiers patrolling the area found 300 acres (120 hectares) of pot plants being tended by dozens of men, said General Alfonso Duarte. Since the discovery of the second biggest marijuana fields at a ranch in Chihuahua state in 1984, it is four times larger.

The country's colossal plantation was shielded by a black screen and had a sophisticated system of piped-in irrigation to support the plants.

According to the Mexican Defense Ministry the crop would yield about 120 metric tons which is worth an estimated $160 million.

Although it is unknown which drug cartel owned the plantation, the Catholic bishop of Saltillo, in the northern border state of Coahuila, said drug cartels are recruiting children and paying them to act as watch guards.

Mexico is in drug wars with drug gangs. The United Nations figures reveal that Mexico is ranked number one producer of marijuana, with the U.S. a close second.

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