METHOD AND APPARATUS FOR AUTOMATIC CONTROLLING OF DROP IRRIGATION Russian patent published in 2003 - IPC

FIELD: agriculture. SUBSTANCE: method involves measuring moisture content of substrate under control in planting vessels by pulling isolated wire used as moisture content sensor through root layers; assigning and completing drop irrigation procedure, when substrate soil moisture content around isolated wire reaches lower and upper boundary, simultaneously in all planting vessels of greenhouse parts; experimentally averaging substrate moisture content in planting vessels on area under control and, accordingly, length of isolated wire and calculating by formula where n is number of planting vessels; G is root-mean-square deviation of moisture content in planting vessel; G_xg is permissible error of root-mean-square deviation of moisture content in planting vessel. Apparatus adapted for mounting on area under control has moisture content sensor, generator, current meter, and transformer. Moisture content sensor is made of flexible isolated wires having sealed ends and divided in their mid portions into two bundles, one of bundles being connected to first terminal and other bundle being connected to second terminal of secondary winding. Primary winding is connected to generator through current meter, whose output is connected to threshold unit. The latter has comparator connected with its second input to predetermined moisture content setting potentiometer and with its output to time relay and actuating mechanism of irrigation unit. Third winding is connected to feedback circuit for stabilizing of voltage amplitude. Moisture content sensor-wire is pulled on area under control through root layers in planting vessel. Transformation coefficient between generator and moisture content sensor is determined on the basis of number of planting vessels on area under control and calculated by formula where K_n is transformation coefficient for planting vessels on area under control; K_i is transformation coefficient for one planting vessel on area under control; n is number of planting vessels on area under control. EFFECT: increased efficiency by providing automatic controlling of irrigating substrate with nutritive solution in planting vessel depending on demand by vegetable crop plants in greenhouse. 1 dwg, 2 tbl