| Xinjiang is located in the northwest of China and the climate is dry. We choose three cotton fieldswhich were different to study.Firstly,to analyse the soil water,soil salinity and groundwater table of thosecotton fields in Growth period and Non-growth period.Secondly, to selecte the most suitable irrigationsystem, spring and winter irrigation quantity in different salinity cotton fields in growth period andnon-growth period.Then based on the studies of indoor and outdoor,using software of Hydruss.1D tosimulate the change of soil moisture in light salinity cotton field. In this way,we could provide our studyabilities of irrigation technologys for the further development in cotton field.The main research results and conclusions are as follows:(1) In different salinity cotton fields, formulating rational irrigation system was particularly importantfor the moderate and the heavy salinity cotton field in the non-growth period.(2) When the total quantity of irrigation (300m3/mu) was certain for growth period, the light and themoderate salinity cotton field was suitable for the medium frequency irrigation system (30m3/mu,7d/time,10times) and the heavy salinity cotton was suitable for high-frequency irrigation system (25m3/mu,5d/time,12times).(3) It was showed that after the spring irrigation the germination rate was easily fluctuated by the saltcontent. As a result, the spring irrigation quantity should be strictly controlled.(4) The use of winter or spring irrigation to controll and leach the salt was very necessary. When soiltexture of the0-80cm was silt loam and the water table was from the depth of0.75to3.5meters, theclimatic conditions similar to the southern Xinjiang and the water quantity conditions were allowed, Winterirrigation was better than the spring irrigation system.So we would better to use winter irrigation system.(5) For the spring irrigation, when the drainage conditions were the same, the smallest springirrigation quantity (150m3/mu) should be used to the light salinity cotton field. The medium springirrigation (200m3/mu) was suitable for the moderate salinity cotton field, because it met the requirement ofdesalination stabilit in the depth of0-60cm, secured germination rate and kept the cotton’s sustainable usein the depth of60-120cm.While in a certain range,the heavy salinity cotton field was suitable for thebiggest spring irrigation quantity (250m3/mu) for it’s requirment of higher desalination rate.(6) The numerical simulation results of HYDRUS.1D showed that the simulation results was better inthe light salinity cotton field and the model would have an important forecasts and guidance role in thefuture for the water movement law in cotton fields. |
