Using Landmapper to Monitor Soil Salinity and Mitigate its Effects on Rice Production at US Gulf Coast

Most of the soils along US Gulf Coast are naturally slightly saline and some are waterlogged during much of the growing season. Naturally, those areas are used for rice production rotated with cattle grazing or hay growing. Soil salinity of those areas varies spatially and temporarily due to drought, hurricane-pushed sea water surges, micro-elevation within fields, variability of salinity levels in irrigation water. Monitoring soil and water salinity with conventional techniques of collecting soil samples by farmer and sending them to outside lab is costly and time-consuming. Such approach fails to provide timely advice to the farmer regarding crop selection pre-planting and mitigation inputs during the growing season. Several rice farms affected by Katrina and Ike hurricanes were monitored in 2006-2011 utilizing field soil EC meter, LandMapper ERM-02, consumer-grade GPS, and other common equipment available to a farmer. On six test fields EC values were recorded with LandMapper directly in the field at 30 locations in less than 45 min. EC on those fields varied from 5 mS/m to 106 mS/m on surface; and from 19 mS/m to 400 mS/m in deeper layer. Thus, advice on soil salinity levels and possible ways of its mitigation was given to the farmer directly at the field. Pre-planting and within-season advices included selection of salt-tolerant rice hybrids, adjusting fertilizer rates, scheduling additional field flushes and monitoring irrigation water salinity with small, low-cost EC meters. A few farmers have reported higher yields from such closely monitored fields despite worse than optimal salinity levels in soil.