2011 Annual Report
1a.Objectives (from AD-416)
To determine the impact of treated municipal waste water and other waste waters on soil physical and chemical properties and plant response (biomass, marketable yield and growth/appearance (turfgrass) and compare this response to that of degraded low organic natural waters.
1b.Approach (from AD-416)
To conduct laboratory and field research as needed to evaluate the use of treated municipal waste waters and other waste waters for irrigation of crops and turfgrass. This will include measurement of soil physical properties and plant growth and yield characteristics.
We have made excellent progress on the characterization of soil infiltration as related to use of municipal waste water for irrigation. Knowledge of the effect of using degraded waters on water infiltration into soil and other related properties is critical to sustained use of such waters for irrigation and essential to meeting NP 211 research goals. We completed the long-term (180 d) outdoor study of the impact of tertiary treated waste water on soil infiltration into Arlington sandy loam. Our treatments were waste water from Carlsbad CA and a prepared water of the same composition (but without the high dissolved organic matter content). Based on these stock waters we generated treatments at different pH and sodium adsorption ratios, using a total of 36 soil containers. As expected, increasing pH and increasing sodicity resulted in decreased infiltration, even with small additions of sodium. In all instances the actual waste water had a lower infiltration rate than the prepared water of the same concentration. This result is interpreted as the adverse effect of elevated dissolved organic carbon on infiltration. The differences were consistent for all treatments, indicating that there was limited interaction between the effects of dissolved organic matter and the other two variables, sodicity and pH on infiltration. Growers and landscape managers now have new information that enables them to evaluate the additional potential infiltration losses associated with irrigating with treated waste waters. Extension specialists and growers can also make informed decisions about the need for soil or water amendments, depending on water composition.
This research will contribute to develop new guidelines related to the use of treated municipal waste waters for irrigation, helping meet NP211 program and project Objective 1, Develop new knowledge and guidelines related to salinity and ion concentrations for the sustained use of degraded waters for irrigation.
The results from this research project is referenced in the main in-house associated project. Research plans and progress were monitored through frequent on-site visits and telephone conversations.