Seasonal variation in soil CO2 emission and leaf gas exchange of well‐managed commercial Citrus sinensis (L.) orchards

Abstract

Purpose To investigate whether soil clay content, cultivar and seasonal variation have any effect on soil CO2 emission rates and leaf CO2 assimilation rates in a drip-irrigated commercial Citrus sinensis orchard. Methods The study was carried out in the field as a randomised complete block design in a 2 × 2 factorial consisting of two soil types and two citrus cultivars on a drip-irrigated commercial Citrus sinensis orchards with 2-week interval measurements of soil CO2 emission and leaf gas exchanges for a year. Results Soil clay content did not influence plant CO2 assimilation rates and soil CO2 emission rates in irrigated citrus. However, seasonal variation significantly influenced both processes. Soil CO2 emission rates were highest in summer and were more than double the rates observed in winter while leaf CO2 assimilation rates were highest in autumn and four times higher than the winter season rates. Mean seasonal soil CO2 emission rates were strongly influenced by mean minimum seasonal temperatures while leaf CO2 assimilation rates only showed a relatively weak relationship with mean maximum seasonal temperatures. Conclusions Soil clay content did not influence soil CO2 emission and assimilation rates in drip irrigated citrus suggesting a non-significant effect of clay content for soils subjected to similar management practices. Citrus CO2 assimilation rate peaks in the autumn while soil CO2 emission rates peak in summer. A snapshot analysis of CO2 sequestration rates suggests that irrigated citrus orchards are net sinks of CO2 in summer, autumn and winter season.

Management options influence seasonal CO2 soil emissions in Mediterranean olive ecosystems

“…The decline of the R s detected at irrigated and rainfed sites during Phase II, despite soil temperature increasing (Fig. 1, 2) is consistent with reports on other perennial ecosystems including olive, peach and citrus (Almagro et al, 2009;Montanaro et al, 2012;Munjonji et al, 2021). However, the underlying mechanisms would differ between sites (see below the "Bimodal effect" paragraph).…”

Understanding the Impact of the Intercropping System on Carbon Dioxide (CO2) Emissions and Soil Carbon Stocks in Limpopo Province, South Africa

“…Tese fndings suggest that seasonal environmental conditions especially temperature and precipitations had an impact on CO 2 emissions. Te fuctuations and seasonal variations were also reported by other authors [16,17]. planting two crop species on the same plot of land reduces CO 2 emissions compared to planting only one species as a result of the interaction between intercropping populations [20].…”

“…High rainfall in 2020/21 and the minimum temperature of more than 10 °C resulted in higher CO 2 emission rates. Warmer summer temperatures, according to Munjonji et al [16], are the driving factors in the soil releasing more cumulatively CO 2 . Tese fndings suggest that seasonal environmental conditions especially temperature and precipitations had an impact on CO 2 emissions.…”

Reduction in Greenhouse Gas Emission from Seedless Lime Cultivation Using Organic Fertilizer in a Province in Vietnam Mekong Delta Region

“…When nutrient inputs were balanced, irrigation practices (furrow and deficit irrigation), plant growth regulator application, nitrification inhibitor fertilizer application, and bio-fertilizer application improved fruit yield [53][54][55][56][57]. The current irrigation methods in the SL orchards are sprinkler and overflowing; the change to better practice would help save energy and decrease N 2 O emission [29,58]. The application of each or a combination of recommended practices under Vietnamese Mekong Delta SL orchard fruticulture conditions must be further studied.…”