A Relationship Between Soil Salinity and Soil Temperature and Volumetric Soil Moisture Content during Irrigation Under Furrow and Drip Irrigated Onion Fields.

Water scarcity accompanied by salinity build up is a major challenge faced by the farmers of arid areas. Flushing the sufficient salts out of the root zone with large amount of good quality water is a temporary solution as salts can again accumulate at the bottom boundary of the root zone with the upward movement of water from water table. Continuous monitoring of soil salinity is time consuming and expensive as it requires expensive instrumentation. Thus, the objective of the research was to develop a relationship between soil salinity, soil temperature and volumetric soil moisture content because soil temperature and soil water content are easier to measure as compared with soil salinity. This study was conducted in two onion fields under drip and furrow irrigation systems in Mesilla Valley of Las Cruces. Monthly soil samples were collected at six depths from two fields. A total of sixteen Time domain reflectometry (TDR) sensors (CS 640) coupled with soil temperature sensors (CS107), eight in each field were installed at 5-, 20- and 50- cm depth. The coefficient of determination between volumetric soil moisture content and bulk soil electrical conductivity for furrow irrigated field at 20 cm depth was 0.69 to 0.83 for winter and summer, respectively. A higher coefficient of determination of 0.78 was found during summer as compared with 0.63 during winter in furrow irrigated field. The increase in soil salinity from winter to summer was higher in the furrow than in the drip irrigated field. The measurement of coefficient of determination between soil salinity, soil temperature and volumetric soil moisture content under drip irrigation system are currently underway and results will be presented during the conference.