We have cultivated 2 varieties of rice for the last 4 years – a white rice variety and a red rice variety. The reason for choosing 2 varieties is to bring diversity to our plates. For my entire childhood and corporate career, I had never had red or black rice. So, when we started in the food cultivation journey, it was obvious that we wanted to cultivate colourful varieties.
As you might know, Tamil Nadu is one of the few places in the country which receives a majority of its rainfall in the months of October to December during the retreating monsoon. So, the major rice crop is cultivated during this period. We started the rice nursery 20 days back in the first week of November and we will be ready to transplant in another 4-5 days.
For the white rice variety, we have chosen Kichili Samba for the third year in a row now because it has yielded decent productivity. For the red rice, we have failed growing Kuruvai varieties in our land during this Samba season – the yields were very poor, maybe because they weren’t meant to be cultivated during this season. So, we have chosen a red rice variety historically cultivated during Samba season : Kothamalli Samba. More about this red rice variety and others in a later post.
The conventional way to ensure nitrogen availability for the rice crop is to feed urea to the soil. One of the key ingredients needed for manufacturing urea is Hydrogen (for Ammonia production). Hydrogen is produced industrially in a process called Steam Methane Reforming, of which Carbon Dioxide is a major byproduct. Carbon Dioxide is a major greenhouse gas and conventional agriculture’s dependence on urea contributes significantly to climate change.
Among the methods that organic farmers such as your’s truly apply to ensure high nitrogen in soil are green manuring and applying compost.
Green Manuring
Green manuring is a technique which uses fast growing leguminous species to add carbon to the soil and fix nitrogen in the soil via rhizobium growing in their root nodules. Over a long period, this ensures that the soil acts as a carbon sink.
Our green manure crop of sunhemp and hyacinth beans that we planted in October-mid have started flowering – this is the perfect stage to plough it in because it maximizes the nitrogen availability during transplanting of rice. The higher nitrogen availability ensures that the rice saplings have enough strength to tide over the transplant shock.
Compost application
Composting as an activity itself is a net producer of greenhouse gases. But when the entire lifecycle of the process of production and application on land is considered, the process has a capability to be net zero, if done right. Thermopholic composting via a balanced C/N ratio and continuous aeration ensures that the pile doesn’t produce high amounts of green house gases.
If there isn’t sufficient aeration within the compost or the Carbon:Nitrogen ratio is much lesser than 30:1, the pile will be under anaerobic conditions and higher methane and nitrous oxide will be produced. Methane (CH4) and Nitrous Oxide (N2O) are more potent greenhouse gases than Carbon Dioxide (CO2), in the short term at least.
Other techniques to ensure aeration of compost piles is to let chicken turn the piles or introduce earthworms to the pile (vermicompost).
The native bacterial and fungal populations of the compost flourish in the soil and their necromass adds to the carbon in the soil more than the carbon simply added via compost. The power of compounding is realised when bacteria & fungi multiply in the soil helping to break down the green manure; thereby making the nutrients assimilable and available to the crop.
Conclusion
Organic Farming techniques such as these ensure that we are investing in the possibility of a climate friendly future. They are more expensive right now because not enough government policies are not aligned in that direction. With time, with enough civil society buying organic produce and supporting organic farmers, i am sure government administration and politicians will start acting for a brighter future. š
Regards,
Sudhakar