2017 ASHS Annual Conference

Managing water resources in times of drought is essential for crop production and managing tree stress in arid and semi-arid environments. Management practices such as groundcovers, mulch, and water conserving irrigation practices can be used to not only conserve water but help maintain and promote tree health and the growth of deeper root systems. Citrus in southern Texas are particularly vulnerable to drought because of periodic droughts and shallow feeder root systems adapted to the predominantly used flood irrigation method. This traditional flood irrigation method allows for large amounts of water to be lost through evaporation or infiltration past the effective feeder root zone that leads to non-optimal tree water use efficiency. Furthermore, water conservation practices have been difficult to implement in south Texas because water is inexpensive and the cost of switching to water-saving irrigation methods such as drip or microjet sprinkler irrigation systems is prohibitive. This led to the development of a new orchard planting design using raised beds adapted to a flood irrigation management system between bed rows. Raised bed plantings in tandem with the use of plastic mesh groundcovers has been found to increase soil moisture retention further in the soil profile, increase soil temperatures, and provide a better soil environment for root development. To analyze the impact these management practices have on root development, distribution and turnover, soil cores were taken and in-growth cores were installed in March 2016. Root area, fibrous root length density, fine roots, coarse roots, and root diameter were analyzed at the 0-15cm depth and 15-45cm depth to determine if distribution further down in the soil profile was promoted by groundcovers and raised beds. Results have shown that trees grown on raised beds with the groundcover have higher root area, and fibrous root length density which corresponds to higher aboveground biomass. Furthermore, roots of trees grown on raised beds with groundcovers have more roots in the lower 15-45cm depth than trees in the other treatments.