Microdrip Irrigation of Field Crops

Abstract

Microdrip irrigation supplies water at a rate close to that of plant water uptake. It is thus expected to improve yields and reduce water losses from drainage below the root zone. To test this assumption, four drip irrigation treatments were applied on corn (Zea mays L.) at Bet Dagan, Israel: (i) daily irrigation with 2 L h−1 emitters (2‐D); (ii) twice‐weekly irrigation with 2 L h−1 emitters (2‐TW); (iii) weekly irrigation with 2 L h−1 emitters (2‐W); (iv) daily microdrip irrigation with 0.25 L h−1 emitters (0.25‐D). Total irrigation was similar for all treatments. Soil water content depth distribution was monitored by the neutron scattering method. Total water uptake (sap flow, SF) was measured using the heat pulse method for two consecutive periods of 2 wk. Relative drying of the 0.60‐ to 0.90‐m soil layer was observed only in the microdrip treatment. These might indicate different root structure or water uptake patterns because of the low application rate. Highest estimated drainage fluxes were obtained for the 2‐D treatment and lowest for the 0.25‐D treatment, especially at the end of the growing period. The SF/ETp ratio was the steadiest for the 0.25‐D treatment. The relationship of canopy conductance to vapor pressure difference for 0.25‐D was not different from those of 2‐D and 2‐TW. Lower conductance values were obtained for 2‐W at the end of the irrigation cycle. Daily irrigation led to the highest yield, while weekly irrigation led to the lowest. The results indicate that microdrip irrigation might improve yields and reduce water losses from drainage below the root zone.