Evapotranspiration from citrus trees growing in sandy soil under drip irrigation with saline water  

作　　者：杨胜利 Shin-ichi Takeuchi Tomohisa Yano Yoshinobu Kitamura 

机构地区：[1]Arid Land Research Center, Tottori University, 1390 Hamaska, Tottori 680-0001, Japan [2]Faculty of Engineering, Kyushu Kyouritsu University, Kitakyushu 807-8585, Japan [3]Faculty of Agriculture, Tottori University, Tottori 680-8553, Japan

出　　处：《Science China Earth Sciences》2002年第z1期41-46,共6页中国科学（地球科学英文版）

摘　　要：An experiment on evapotranspiration from citrus trees under irrigation with saline waterwas carried out for 4 months. Two lysimeters planted with a citrus tree in the green house wereused. One lysimeter was irrigated with saline water (NaCl and CaCl2 of 2000 mg/L equivalence,EC = 3.8 dS/m, SAR = 5.9) and the other was irrigated with freshwater using drip irrigation. Theapplied irrigation water was 1.2 times that of the evapotranspiration on the previous day.Evapotranspiration was calculated as the change in lysimeter weight recorded every 30 minutes.The lysimeters were filled with soil with 95.8% sand. The results of the experiment were as follows.(i) The evapotranspiration from citrus tree was reduced after irrigation with saline water. Theevapotranspiration returns to normal after leaching. However it takes months to exhaust the saltfrom the tree. ( ii ) To estimate the impact of irrigation with saline water on the evapotranspirationfrom citrus trees, the reduction coefficient due to salt stress (Ks) was used in this experiment.Evapotranspiration under irrigation with saline water (ETs) can be calculated from evapotranspira-tion under irrigation with freshwater (ET) by the equation ETs = Ks× ET. Ks can be expressed as afunction of ECsw. (iii) The critical soil-water electrical conductivity (ECsw) is 9.5 dS/m, beyondwhich adverse effects on evapotranspiration begin to appear. If ECsw can be controlled at below9.5 dS/m, saline water can be safely used for irrigation.An experiment on evapotranspiration from citrus trees under irrigation with saline water was carried out for 4 months. Two lysimeters planted with a citrus tree in the green house were used. One lysimeter was irrigated with saline water (NaCl and CaCl_2 of 2000 mg/L equivalence, EC = 3.8 dS/m, SAR = 5.9) and the other was irrigated with freshwater using drip irrigation. The applied irrigation water was 1.2 times that of the evapotranspiration on the previous day. Evapotranspiration was calculated as the change in lysimeter weight recorded every 30 minutes. The lysimeters were filled with soil with 95.8% sand. The results of the experiment were as follows. (i) The evapotranspiration from citrus tree was reduced after irrigation with saline water. The evapotranspiration returns to normal after leaching. However it takes months to exhaust the salt from the tree. (ii) To estimate the impact of irrigation with saline water on the evapotranspiration from citrus trees, the reduction coefficient due to salt stress (K_s) was used in this experiment. Evapotranspiration under irrigation with saline water (ET_s) can be calculated from evapotranspira- tion under irrigation with freshwater (ET) by the equation ET_s=K_s×ET. K_s can be expressed as a function of EC_(sw). (iii) The critical soil-water electrical conductivity (EC_(sw)) is 9.5 dS/m, beyond which adverse effects on evapotranspiration begin to appear. If EC_(sw) can be controlled at below 9.5 dS/m, saline water can be safely used for irrigation.

关 键 词：lysimeter  DRIP irrigation  SALINE water  reduction coefficient DUE to salt stress  evapotranspiration. 

分 类 号：S152[农业科学—土壤学]