Bokashi v Compost
Soil, the new fossil fuel
Agriculture in the UK has been under increasing scrutiny after being labeled one of the main contributors to Greenhouse gas (GHG) emissions in recent times. The building pressure to reverse global warming on Governments worldwide has lead to the introduction of ambitious targets which will be followed by new legislation.
ELMs replaces the Common Agricultural Policy (CAP) and will focus on public money for public goods. This means further payments will revolve around public goods such as managing landscapes, protecting water courses and reducing emissions. The emphasis on protecting the environment has refocused the minds of farmers and has seen a return to more traditional farming methods, similar to those seen pre-1950s and the agricultural revolution.
The last agricultural revolution, ironically named The Green Revolution, came after the second world war, however the real Green Revolution is happening now. This time record breaking yields, crop genetics and increased fertiliser / pesticide use will be replaced with record breaking efficiencies, the regeneration of lost top soil and the rebuilding of organic matter and carbon in soils.
The world in which we live has finite resources. Take coal for example. Thousands of years ago microbes couldn’t digest lignin, meaning fallen trees scattered the Earth’s surface. These fallen trees piled higher and were slowly compressed under the weight of yet more trees, creating what we now refer to as coal, a fossil fuel. The evolution of lignin digesting microbes lead to the breakdown of complex organic compounds to more useable, simpler ones meaning no more coal but instead, soil.
Soil became the new fossil fuel and is, by far, the greatest thing mother nature ever gave us. Every single living organisms exists because of soil and if maintained it can sustain life indefinitely. There is the same amount of Carbon elements today as there was 1000 years ago, even 1,000,000 years ago. The amount of carbon hasn’t changed but where that carbon is stored, has. It is thought that somewhere between 50 and 70% of carbon stored in the soil has been release by modern farming practices. Despite this soil continues to store three times more carbon than what can be found in the atmosphere and four times more than in living organisms.
The recycling of energy throughout the soil, plant, animal, manure cycle is the what sustains life on this planet and without it, life would look very different. The understanding of this cycle and the increasing knowledge of soil science is showing us that agriculture can feed the world but also that regenerative practices are sustainable and profitable.
When you consider that 1kg of humus can hold 4kgs of water and 1kg of humus contains approximately 50% carbon by weight. Increasing humus in soils by 1% would mean an increased water holding capacity of 160,000 litres/ha and a very rough approximate of 40,000kgs/ha of carbon stored. This addresses everything ELMs sets out to achieve. Less flooding, less CO2 in the atmosphere, healthy ecosystems and plenty of nutritious food.
If looking after soil and creating humus is the answer then Bokashi is the solution. To support this Agriton Netherlands commissioned a three year trial comparing Bokashi to traditional composting. The trial highlighted a number of positive effects with the results promising enough to extend the trial for another four years.
What is Bokashi? “Fermented organic matter”.
Decomposition is the chemical breakdown of organic matter into its constituents by the action of bacteria and other organisms. In other words it is the return of nutrients broken down by microbes to provide food for the next living organisms. There are a number of different ways in which organic matter can be decomposed (see table 1).
Composting has received a lot of press lately, largely good, but a simple Google search highlights the large quantities of misleading advice and misinformation. This misinformation is usually down to personal bias or a less than full understanding of the decomposition process.
Agriton believe Fermentative decomposition provides the greatest returns with minimal environmental impact compared to the generally accepted industry standard, aerobic composting. The trial looked at which method provided the best decomposed material to be used as a soil improver for the regeneration of humus.
After three years the data showed that Bokashi increased the organic matter in soil by 0.6 and 0.5% over the control and composting respectively. This increase in organic matter resulted in more Carbon, Nitrogen, Potassium, Phosphorus, Magnesium and Sulphur stored in the soil. It increased average yields over the three years and saw less disease and lodging of crops. The results after three years were significant enough to extend the trial to demonstrate the longer term benefits of using Bokashi compared to aerobic composting.
Of particular concern were the losses from aerobic composting. Of the 13,400kgs of starting material only 5,070 kgs remained after composting and of the 8,330kgs total weight lost 630.9kgs was pure Carbon, or 2,313.3kgs of CO2. Comparatively Bokashi lost 31.8kgs of Carbon or 116.6kgs CO2.
The additional material retained during Bokashi fermentation means more organic matter, more carbon and basically more food for the soil. This means more humus, more nutritious crops, less flooding, less atmospheric CO2 and a healthier ecosystem which is exactly what ELMs is hoping to achieve.
Bokashi (Zymogenic fermentation) vs Composting (Aerobic decomposers) - The differences between aerobic decomposition and fermentative are described in table 1.
Over the three years 20 test sites were allocated a specific application. The applications would be the same each year (see table 2). As Bokashi and composting are two very different methods of decomposition the most accurate comparison is made using the starting weights to determine application rates. During the composting process over 60% of the total weight (see Table 3) is lost, which means the end product has a different ratio of minerals. To apply the same quantity of decomposed material would not be a fair comparison therefore starting material was used as a guide.
At the end of each year wheat yields and quality were recorded (see tables 4 and 5) along with disease presence and lodging (see table 6). It was noted that the yields decreased year on year for a number of reasons with the main two being a lack of crop rotation and below recommended N applications with the 50% fertiliser application. The results showed a positive response to Bokashi application and surprisingly Composting didn’t fair as well as the Control when considering yield.
When comparing the yields from Bokashi and Composting the results were largely unsurprising, especially when you consider the retention of nutrients from the Bokashi decomposition method. To lose over 60% of the starting weight, as with composting, and the loss of Nitrogen, Carbon and MJ of energy (Feed innovation Services BV, 2013) is noticeable when comparing yields. An effective soil improver, however, needs more than just a yield response, especially if rebuilding humus in the long term is desired.
Higher soil organic matter levels cause greater soil nitrogen retention, greater microbial biodiversity, and promote the presence and growth of mycorrhizal fungi that penetrate the roots of crops and facilitate the movement of plant nutrients from the soil into the crop plants resulting in better crop growth and yields (Pimentel et al., 2005) After the three years soil samples were taken and analysis results compared.
Conclusion:
The trial data clearly shows a positive response to applications of Bokashi compared to both the control and compost after the three years. Final conclusions will be made after the full 7 year trial is complete but early data favours Bokashi.
What we can determine from the three years so far is:
Improvements were evident in both crop quantity and quality although small.
Soil analysis results showed significant increases in N, P, K and Mg levels.
Soil Organic Matter was noticeably higher, 0.6% higher than the control and 0.5% higher than compost.
It is also worth mentioning that trial work carried out by Feed Innovation Services in 2013 compared the direct CO2 emissions from the production of Compost and Bokashi. Table 14 shows the differences and give a per tonne CO2 footprint.
Full trial results are available on this link: http://tinyurl.com/Bokashi-as-a-soil-improver