Dissolved Organic Carbon, Total Carbon and Nitrogen in Pomegranate Cultivation Under Drip Irrigation Systems.

In the past six years, pomegranate (POM) cultivation has become a popular commercial crop in San Joaquin Valley, California. The rising demand for this permanent crop is primarily due to POM juice high nutritional and antioxidants properties. In addition, it has been found POM trees are drought tolerant that can thrives on a wide range of soils. However, the establishment of not well managed permanent crops in California Valley soils can increase the actual deficit of water and reduce water quality by increasing soil salinity. For that reason, in 2010, a three years POM project was proposed at San Joaquin Valley Agricultural Science Center (SJVASC), trying to determine POM water requirements under different drip irrigation systems [surface (DI) and subsurface (SDI)] and minimize leaching losses of nitrogen and carbon. In March 2011, prior to starting DI &SDI treatments, samples were collected from 8 depth increments (0-6, 6-12,12-18,18-24,24-30,30-36,36-42,and 42-48 in) to provide initial quantitative and qualitative information on stored soil carbon (C) and nitrogen (N) and dissolved organic carbon (DOC). Collected soil samples were dried, ground and analyzed for dissolved organic carbon (DOC), total carbon (TC) and nitrogen (TN). Preliminary results from year one shows higher DOC was found under DI for the first 30 in. However, at deeper depth (> 30 in), higher DOC was found under SDI system. While for TC, higher TC was found under SDI for 0-12 and 30-48 in soil depth. However, there was no consistent response for TC under DI. In addition, higher TN was found at 0-6 in under SDI and 18-30 in soil depth under DI system. This research is ongoing and additional data will be collected this year to clarify soil TC, TN and DOC in POM cultivations.