Wetting patterns and water distributions in cultivation media under drip irrigation

• The infiltration and distribution of water in two cultivation media are examined.
• The wetting body is shaped like a rotating projectile.
• The maximum horizontal migration radius occurs at 3–6 cm below the medium surface.
• The smaller irrigation flow is more suitable for irrigation in the test substrates.
• Models were used to express the migration distance and the size of wetting body.

The infiltration and distribution of water in two kinds of cultivation media are examined under different conditions of drip irrigation in terms of flow, volume, and initial medium water content and the models were used to express the horizontal migration distance and the vertical migration distance, and express the size of the wetting body indirectly. The results show that in different media, the wetting body is shaped like a rotating projectile, whose maximum horizontal infiltration radius occurs at 3–6 cm below the medium surface. Under drip irrigation of the same volume, the volume of the medium wetting body declines while the horizontal and vertical migration rates of the medium wetting front both rise with increasing irrigation flow; additionally, there are declines in medium water content, and water content increment at the same position. Under drip irrigation of the same duration, increasing irrigation flow leads to increases in the volume of the medium wetting body, horizontal and vertical migration rates of the medium wetting front, surface medium water content, and the medium wetting range. Under drip irrigation at the same flow, there are increases in the width and depth of the medium wetting body, declines in the migration rate of the medium wetting front, and horizontal rises in the progressively decreasing rate of medium water content as the irrigation volume increases. Under drip irrigation of the same duration, the horizontal migration rate of the medium wetting front rises while the vertical migration rate of the medium wetting front declines with increasing initial medium water content; correspondingly, medium wetting body tends to flatten gradually as a whole, and the increment of medium water content at the same position is diminished.