# Spinach yield and quality response to elevated soil carbon dioxide

## TL;DR

Elevated soil CO2 from carbon capture projects harms spinach growth and reduces overall nutritional yield, despite increasing some nutrients like vitamin C and cellulose.

## Contribution

This study quantifies the impact of soil CO2 leakage on spinach growth and nutritional quality, revealing both harmful and unexpected beneficial effects.

## Key findings

- Prolonged soil CO2 exposure reduced spinach leaf area, fresh weight, and root weight by over 90%.
- Vitamin C, vitamin E, and cellulose concentrations increased significantly, while oxalate decreased.
- Total nutrient yield per plant declined due to severe biomass reduction despite enriched nutrient concentrations.

## Abstract

With the widespread implementation of carbon capture and storage (CCS) projects, assessing the associated environmental risks has become increasingly important, particularly concerning crop responses to soil carbon dioxide (CO2) leakage. While previous studies have examined plant responses to soil CO2 stress, the implications for crop nutritional quality remain poorly characterized.

A pot experiment was conducted in Shunyi, Beijing, during autumn 2023 to quantify the effects of CO2 leakage from CCS on the nutritional indicators of leafy vegetables. The experiment included four replicates per treatment, consisting of a control group (CK) and a CO2 leakage treatment group (1500 g·m-2·d-1, G1500). Spinach yield and quality were assessed under elevated soil CO2 conditions, with emphasis on vitamin C, vitamin E, cellulose, and oxalate content.

Prolonged exposure to high soil CO2 concentrations severely inhibited spinach growth, reducing leaf area, aboveground fresh weight, and root weight by 92.76%, 93.46%, and 95.83%, respectively. Chlorophyll b decreased by 35.48%, indicating impaired photosynthesis. Conversely, concentrations of vitamin C, vitamin E, and cellulose increased by 185.47%, 131.45%, and 315.03%, respectively, while oxalate content decreased by 43.08%. However, the severe biomass reduction led to an overall decline in total nutrient yield per plant.

These findings demonstrate that soil CO2 leakage markedly inhibits growth and reduces total nutrient yield in leafy crops, despite the relative enrichment of certain nutritional components. The results highlight critical challenges to agricultural productivity and food quality in regions affected by CO2 leakage from CCS.

Diagram illustrating spinach yield and quality response to elevated soil carbon dioxide. It includes an experimental setup, phenotypic and biomass indicators showing decreased growth metrics, and quality indicators with increased levels of vitamin C, vitamin E, cellulose, and oxalate. Planting and injection times are noted, with control and CO2 treatment groups compared.