Soil Organic Carbon Restoration through Organic Farming in Citrus Plantations

In the NOVASOIL project blog, we would like to share with you ground-breaking research that promises to light the way for farmers who are sceptical about sustainable production methods and techniques. These practices, which are vital for the future of our planet, offer not only an environmentally friendly alternative, but also a cost-effective long-term solution for the agricultural industry. Backed by robust scientific data and success stories, this research underlines the urgency and feasibility of adopting more environmentally friendly approaches to agriculture. We are embarking on a journey towards sustainability and invite the farming community to join us in this essential paradigm shift, where efficiency and environmental responsibility go hand in hand to ensure a greener and more prosperous future for all.

Before starting, it is only fair to mention the authors of this research, such as A. Novara and Gristina (University of Palermo), Pulido (University of Extremadura), Rodrigo-Comino (University of Malaga), Di Prima (University of Lyon), Smith (University of Aberdeen), Giménez-Morera and Terol (Universitat Politècnica de València), Salesa (University of Valencia) and Keestra (University of Newcastle).

This research proposes to demystify the prejudices against organic farming and organic practices and demonstrate their value not only for the environment, but also for the economy and long-term sustainability of farms. 

Study area 

It is essential to begin this section by highlighting the location of this research, which is characterised by its physico-chemical and socio-economic peculiarities. Accordingly, the research was carried out at the Alcoleja Experimental Station, located in the Cànyoles river basin (eastern Spain). This site is characterised by a Mediterranean climate, sandy-clay soils and the practice of organic farming since 1995. 

Experiments were carried out on a 1 ha plot of orange trees (Naveline variety), with a focus on sustainable water management in the face of over-exploitation of water resources. This context prepares us to evaluate the impact of organic farming on soil organic carbon recovery, highlighting the environmental values inherent in this transition towards more sustainable agricultural practices.

Analysis

To understand how we measure the impact of organic farming on the soil, let’s imagine that we store carbon like a coin in an underground ‘piggy bank’. Over time, we calculate how much carbon has been saved each year by comparing the amount at the start and end of the study, and convert this into CO2 to better understand its impact on climate change. 

And to verify the data, we use a statistical test that allows us to compare before and after to see if the changes are significant, proving that our farming practices are helping to ‘fill’ this carbon sink in the soil.

Results of the research

The results of the research showed promising data. The soil organic carbon stock increased significantly after 21 years of organic farming, with an increase of 115.56% in the 0-31 cm depth, from 4.5 g kg^-1 in 1995 to 9.7 g kg^-1 in 2016. In the top layer (0-1 cm), the increase in organic carbon content was even more remarkable, with an increase of 368.64%, from 11.8 g kg^-1 in 1995 to 55.3 g kg^-1 in 2016. This remarkable increase in the top layer is mainly due to increased carbon inputs from litter, pruning residues, manure and spontaneous vegetation. 

Over a 21-year period, organic farming sequestered 16.5 tonnes of carbon per hectare in the soil, equivalent to an annual enhancement rate of 0.78 tonnes of carbon per hectare. This finding is consistent with other studies of more sustainable farming practices, suggesting that organic farming consistently delivers environmental benefits.

In total, 61 tonnes of CO2 per hectare were sequestered and converted into carbon safely stored in the soil, making a significant contribution to climate change mitigation. This effect became apparent after the first 5 years of conversion to organic farming practices, highlighting the importance of allowing sufficient time to observe the full benefits of these practices. Thus, the transition to organic farming not only benefits soil health and crop yields, but also plays a crucial role in protecting the environment.

Conclusions

Research at L’Alcoleja shows that organic farming not only increases soil organic matter and sequesters atmospheric carbon, but also promotes healthy soils, floral and faunal diversity and landscape complexity. The practice improves natural soil fertility, biodiversity and ecosystem services, contributing to more sustainable systems in environmental, energy and economic terms. It also improves the nutritional quality of produce, promotes clean water and has environmental effects similar to those of land abandonment, improving water retention and the recovery of soils affected by fires.

Farmers concerned about the economic viability of organic farming can be reassured by the results of L’Alcoleja’s research. The study shows that in addition to the environmental benefits, organic farming can be economically sustainable. It increases soil fertility and biodiversity, which in the long term improves crop quality and can reduce the need for expensive chemical inputs. In addition, organic products are often sold at a premium, offsetting the initial transition costs. This holistic approach not only protects the environment but can also strengthen farm economics, demystifying the belief that sustainability and profitability are mutually exclusive.