Rebecca Tirado-Corbala, WMRU, USDA-ARS, Parlier, CA, Dong Wang, Water Management Research Unit, USDA-ARS, Parlier, CA and Jim Ayars, USDA-ARS, Parlier, CA
In the past seven 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, a POM project was proposed at San Joaquin Valley Agricultural Science Center (SJVASC), trying to determine POM water requirements and nitrogen (N) injection rates efficiency [50, 100 and 150 %] under different drip irrigation systems [surface (DI) and subsurface (SDI)] and minimize leaching losses of nitrogen and carbon in mature POM. In 2012, all N was automatically applied by continuous injection of N-pHURIC (46 lb/ac) for all the treatments and additionally as AN-20 for N-2 (and N-3 treatments, starting on May 12 through August 18, 2012. In December 2012, samples were collected from 8 depth increments (0-6, 6-12,12-18,18-24,24-30,30-36,36-48,and 48-60 inches) to provide quantitative and qualitative information on stored soil carbon (TC), nitrogen (TN) and dissolved organic carbon (DOC). Collected soil samples were dried, ground and analyzed for DOC, TC and TN. This research is ongoing and additional data will be collected this year to clarify soil TC, TN and DOC in POM cultivations under different N fertigation and drip irrigation systems.