Carbon and nitrogen dynamics affected by drip irrigation methods and fertilization practices in a pomegranate orchard

Authors: TIRADO-CORBALA, REBECCA - University Of Puerto Rico; Gao, Suduan; Ayars, James; Wang, Dong; PHENE, CLAUDE - Consultant; PHENE, REBECCA - Kearney Agricultural Center

Submitted to: Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/10/2019
Publication Date: 12/12/2019
Citation: Tirado-Corbala, R., Gao, S., Ayars, J.E., Wang, D., Phene, C., Phene, R. 2019. Carbon and nitrogen dynamics affected by drip irrigation methods and fertilization practices in a pomegranate orchard. Horticulturae. 5(4):77. https://doi.org/10.3390/horticulturae5040077.
DOI: https://doi.org/10.3390/horticulturae5040077

Interpretive Summary: Soil carbon and nitrogen dynamics can partially reflect soil health status or how agricultural practices impact the sustainability of an agronomic production system. This research investigated the effect of high frequency drip irrigation and different levels of nitrogen application on total or soluble carbon and nitrogen concentration changes in soil and leaf tissues as well as total N uptake in fruits in a 1.4 ha pomegranate orchard in the San Joaquin Valley of California. Results clearly show the advantage of using subsurface drip in comparison with surface drip irrigation in total N uptake with different patterns of soil C and N distribution. This research concluded the proper amount of N needed for a 4–6 year old pomegranate orchard is in the range of 166–263 kg/ha, and demonstrated that the high frequency subsurface drip irrigation can lead to higher N use efficiency and minimized leaching loss while increasing water use efficiency. The results are applicable to other orchards in the same region or other regions with similar irrigated agriculture.

Technical Abstract: Information is limited on carbon (C) and nitrogen (N) dynamics under different irrigation management practices in pomegranate orchards, but such information is needed to develop sustainable production systems. The objective of this research was to determine the effect of high frequency drip irrigation and different levels of applied nitrogen on C and N distribution in soil, and N uptake in pomegranate fruit and tree tissues. A pomegranate (Punica granatum, L var. Wonderful) orchard was established in 2010. The main treatments were surface drip (DI) and subsurface drip (SDI) irrigation and sub-treatments were three N application rates (50, 100, and 150% of current practice denoted as N1, N2, and N3, respectively). Soil and leaf total C (TC) and N (TN), soil dissolved organic carbon (DOC), soil nitrate (NO3-), and total N uptake in fruits were determined for two or three years between 2012 and 2015. The DI had higher concentrations of TN, TC, NO3-, and DOC in the upper soil depths (up to 75 cm) compared with SDI irrigation in subsurface soil (below 30 cm depth). The N3 treatment resulted in much higher concentration of TN, TC, NO3-, and DOC in both DI and SDI. Neither DI or SDI at N1 and N2 levels elevated TN and NO3- concentrations at 105-120 cm soil depth suggesting reduced leaching risk using high frequency irrigation. Significantly higher N uptake in fruits was determined from SDI than DI in 2014 and 2015 and also in N2 and N3 compared with N1 in 2013 and 2014. All data indicate that application at the N2 rate (166–263 kg/ha) provided sufficient N for a 4-6 year old pomegranate orchard and high frequency SDI is a promising technology for achieving higher N use efficiency and minimizing leaching loss.