It's all about soil

Today, it's all about soil and its role in helping us fight climate change. In my previous posts, I have addressed the misfortunes today's agricultural soil faces due to the use of fertilisers in modern farming. Before chemical fertilisers come into play, healthy soil is packed with microorganisms, retaining nutrients and moisture to grow plants. Healthy topsoil organic matter sucks up atmospheric nitrogen, converting it to ammonia and nitrates that is consumed by the plants. This biological cycle breaks down as soon as soil is treated with synthetic fertilisers, leading to topsoil loss and the release of carbon dioxide, a major greenhouse gas causing global climate change. So how do we stop this disastrous cycle?

Michael Pollan (author, journalist and professor of journalism at UC Berkeley Graduate School of Journalism) and Debbie Barker suggest that there is a way to make the soil work in favour of climate change mitigation.

(Source: https://www.washingtonpost.com)

But firstly, with the help of Pollan and Barker, let us take a closer look at what exactly has happened to our soil across the globe. Their article in the Washington Post explains: the industrialization of farming has allowed farmers to grow more crops more quickly. But modern techniques have also wreaked havoc on the earth, water and atmosphere. Intense plowing, for example, has introduced more oxygen into the soil, boosting the microbes that convert organic matter into carbon dioxide. The quest to wring every last dollar out of fields has put pressure on farmers to rely on chemical fertilisers. This often leaves fields more bare between growing seasons, allowing carbon to escape into the air. Scientists estimate that cultivated soil has lost 50 to 70 percent of its carbon, speeding up climate change.' Industrialised farming is also having a detrimental effect on water security, especially in places that are already experiencing acute water scarcity. The chemical treatment and extensive plowing of soil causes the ground to absorb water less efficiently. Any water that the soil cannot absorb becomes runoff, taking some of the chemicals and fertilisers with it to the nearest water body. This contaminates rivers, lakes and seas while putting human water supply sources at risk.

This all starts to sound very apocalyptic (as talking about climate change tends to do from time to time) but Pollan and Barker do suggest there is something we can do. It's called 'cover crops'. To all the farmers out there, try this! Cover crops (beans, rye and oats for example) are planted in between vegetable rows, keeping as much of the crop field covered and using up as much photosynthesis potential as possible. Cover crops also help to keep nitrogen and other nutrients in the soil, making it a favourable environment for the 'main crops' to grow without needing fertiliser treatment. Additionally, cover crops can be grown throughout the year to ensure the field never sits empty, leaving the soil exposed and wasting photosynthesis potential.

In reality, growing cover crops may be more difficult than it sounds. Pollan and Barker explain that current federal policy in the United States ensures that farmers do not waste their time growing crops they cannot sell, limiting growing season for cover crops. In order to allow carbon friendly farming, these policies need a revisit.

(Source: https://broadforkfarm.files.wordpress.com)

In addition to the cover crop strategy, a switch towards organic fertilisers instead of synthetic nitrogen ones should be encouraged. Research at UC Berkeley shows that 'applying a single layer of compost, less than an inch thick, to rangelands stimulates a burst of microbial and plant growth that sequesters dramatic amounts of carbon in the soil - more than 1.5 tons per acre.' All these practices fit into a lifecycle of a sustainable, organic and self-sustaining farm. Cattle are used to graze the fields, cattle manure is used to fertilise the crops and fields, plant growth increases due to manure fertilisation and the process starts again. In the meantime, cattle are fed with organic grass rather than corn, leaving out the industrialised, fossil-fuel intensive corn production from the equation. Sounds too good to be true?

Unfortunately, it probably is, for the moment. At a global level at least. As world leaders gather in Paris over the next week to address the global action plan on climate change, food production and food related climate change does not seem to be on the list of priorities. Transport and energy sectors will likely to take the front seat at the conference. However, I do hope that when the next climate change conference comes along, agriculture induced climate change will have a central seat at the table. In the mean time, change will have to come from local and government level. It seems to me that changes that can be done in the agriculture sector to slow down climate change are just too good to miss out on. But hey, that's just me.

Until next time,

Laura