Alternative fertilization practices lead to improvements in yield-scaled global warming potential in almond orchards

Authors: NICHOLS, PATRICK - University Of California, Davis; DABACH, SHARON - University Of California, Davis; ABU-NAJM, MAJDI - University Of California, Davis; BROWN, PATRICK - University Of California, Davis; CAMARILLO, REBEKAH - University Of California, Davis; SMART, DAVID - University Of California, Davis; Steenwerth, Kerri

Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/12/2023
Publication Date: 3/1/2024
Citation: Nichols, P.K., DaBach, S., Abu-Najm, M., Brown, P., Camarillo, R., Smart, D.R., Steenwerth, K.L. 2024. Alternative fertilization practices lead to improvements in yield-scaled global warming potential in almond orchards. Agriculture, Ecosystems and Environment. 362. Article 108857. https://doi.org/10.1016/j.agee.2023.108857.
DOI: https://doi.org/10.1016/j.agee.2023.108857

Interpretive Summary: The sustainability of agricultural practices is of paramount importance in mitigating climate change. This study investigates the impact of alternative fertilization practices on the yield-scaled global warming potential (YS-GWP) in almond orchards. That frequent applications of fertilizer at low concentrations demonstrated 52% to 78% decrease in GWP per unit of almond yield compared to two of the more standard fertilizer practices in the almond industry. We demonstrate that adopting alternative fertilization practices can effectively mitigate the environmental footprint of almond orchards while maintaining crop yields. These practices offer viable options for almond growers to reduce greenhouse gas emissions, enhance sustainability, and contribute to climate change mitigation.

Technical Abstract: The sustainability of agricultural practices is of paramount importance in mitigating climate change. This study investigates the impact of alternative fertilization practices on the yield-scaled global warming potential (YS-GWP) in almond orchards. Almond production is a contributor to greenhouse gas emissions, primarily due to nitrogen-based mineral fertilizers. This research aims to identify strategies that reduce the environmental footprint of almond cultivation while maintaining yield. Field experiments were conducted in an almond orchard using three alternative fertigation practices: Advance Grower Practice (AGP), Pump and Fertilize (P&F), and High Frequency Low Concentration (HFLC). AGP followed the current practice producers generally use to meet annual N demand for almond tree growth; P&F is a reduction in applied N rate in response to measured N concentrations in the groundwater so that the added N and groundwater N reach the same total N applied; HFLC is a practice of applying smaller N rates per individual event, with use of a greater number of fertigation events to reach similar total annual N load as other treatments. The results revealed that both P&F and HFLC reduced the YS-GWP compared to the AGP. The HFLC fertigation demonstrated 52% to 78% decrease in GWP per unit of almond yield compared to AGP, while P&F showed 48% to 58% decrease over AGP. These reductions were attributed to the reduced nitrous oxide emissions associated with P&F and HFLC. We demonstrate that adopting alternative fertilization practices can effectively mitigate the environmental footprint of almond orchards while maintaining crop yields. These practices offer viable options for almond growers to reduce greenhouse gas emissions, enhance sustainability, and contribute to climate change mitigation.