In recent years soil degradation and desertification has become a prevalent issue threatening agricultural productivity, and attempting to solve it in a way that is accessible in the developing world is incredibly important. That is why we need to look at case studies throughout the world that show how certain communities are able to overcome these issues in a sustainable manner, and what they do that can be transferred to others that are struggling. In this article we will be looking at chinampas, an ancient Mesoamerican agricultural system that has sustained civilisations for centuries around certain river networks in Mexico. These man-made, rectangular-shaped fields are built around canal systems – and have been a beacon for sustainable agriculture. In recent years, the use of biochar in chinampas has emerged as promising inspiration for other areas of the world that are looking to integrate biochar into their agriculture.
Chinampas, often referred to as "floating gardens," were originally developed by the ancient Aztecs in what is now Mexico City. These ingenious agricultural systems use a combination of activated biochar, aquatic plants, and water management to create highly productive and sustainable fields. The canals that crisscross the chinampas serve as natural nutrient reservoirs, while the rich, fertile soil is maintained through careful management and rotation of crops.
Despite their historical success, modern chinampas have faced challenges such as soil erosion, loss of soil fertility, and changing weather patterns due to climate change - which have threatened their productivity. Additionally, the use of chemical fertilisers and pesticides can lead to eutrophication within the canal networks due to run-off, which means that workarounds need to be made in order to accommodate – such as the introduction of biochar into the soil.
Biochar has been used for millennia in South America – and for good reason. It has emerged as a sustainable replacement for modern chemical fertilisers and can oftentimes be more versatile due to its localised production and ability to be applied around more novel irrigation systems (like the previously mentioned canals). When incorporated into the soil, biochar can enhance fertility, improve water retention, and (most importantly for us) sequester carbon. These benefits make biochar an ideal candidate for addressing the challenges faced by chinampa farmers.
Biochar's porous structure provides a habitat for beneficial microorganisms and fungi, fostering nutrient cycling and enhancing soil fertility. In chinampas, where soil degradation is a growing concern, biochar can rejuvenate the soil, promoting healthier plant growth and higher crop yields.
One of the key features of chinampas is their intricate canal system. Biochar's ability to retain moisture can help maintain optimal water levels within the fields, reducing the risk of both drought and flooding due to it drastically reducing run-off and increasing lead-time before water reaches the river. This improved water management is crucial for sustaining chinampas in a changing climate and can be used elsewhere in other regions of the world that have ‘rainy’ and ‘dry’ seasons – keeping crops and fields safe throughout the year.
Biochar not only benefits chinampa agriculture but also contributes to carbon sequestration. By locking carbon in the soil for 100+ years, biochar helps mitigate climate change. In chinampas, this carbon sequestration can help offset the carbon emissions associated with farming activities. Chinampas are a particularly important example to look at when attempting to maximise carbon sequestration, as it uses much more biochar per square metre of field due to its application deeper into the soil – and therefore is able to be a more effective carbon sink.
The use of biochar in chinampas in Mexico represents a harmonious blend of ancient wisdom and modern innovation - by revitalising these historical agricultural systems and transferring the applicable technologies to other areas of the world we can ensure the continued productivity and resilience of global agriculture in the face of contemporary challenges. As we strive to build a more sustainable future, biochar offers a glimpse into how ancient practices can be adapted and enhanced to meet the needs of the present and future generations.
