Constant negative pressure differentia irrigation device

The utility model discloses a constant negative pressure differentia irrigation device, which comprises one or more absorption and seepage heads, wherein, the upper part of the absorption and seepage head is connected with an air collection chamber having the upper opening sealed by a seal plug through a connecting pipe; the sidewall of the air collection chamber is communicated with a water duct. The utility model is characterized in that: the other end of the water duct is inserted into a water level regulator being lower than the absorption and seepage heads; the sidewall of the upper part of the water level regulator is provided with an overflow pipe, and a water overflow measuring cylinder is arranged below the overflow pipe; the upper part of the water level regulator is corresponding to the height of the overflow pipe and has one sidewall communicated with a water pipe having a water-stopping device; the other end of the water pipe is communicated upwards with a water feeder provided with measuring scales; in addition, the upper part of the water feeder is provided with a water-stopping device connected with a pressurizing water pipe. The utility model has the advantages of automatic supply of constant negative pressure water for soil to make soil maintain constant humidity suitable for crop growth as well as multifunction and extensive application.