Explainer: How Green Manure Can Help Degraded Farmlands Sustain Themselves

The traditional agricultural practice of green leaves manure involves creating manure and fertiliser from natural, homegrown plants as sources of various nutrients for soil

by Manjunatha G

Jun 19, 2023

A rotavator crushes a row of plants to create manure. Photo by Revanna Siddappa, Prarambha

Soil fertility, i.e. the soil’s ability to support plant growth and optimise yield, depends on myriad factors. Soil is a habitat – to be a nurturing one, its biological, physical and chemical properties must all be favourable. This includes water retention capacity and moisture levels, organic carbon, and nutrients like nitrogen, phosphorus and potash. Maintaining the right balance of all these factors can take a lot of time and money – so much so, that the cost of manure and fertilisers alone has made agricultural practices unfeasible for many. Some farmers are solving this issue by going back to their roots, and reviving the traditional practice of green leaves manure: manure and fertiliser created from natural, homegrown sources of nutrients instead of chemical fertilisers. One farmer – Prabhakar B from Thondahalli village (near Nangali Lake) in Karnataka’s Kolar district – has been gracious enough to explain his technique to WELL Labs, helping us to spread it to our test sites in Raichur and Koppal that face soil degradation. Now, these villages have succeeded in making their own green leaves manure, adding it to their soil in early June.

Plants grown for green leaves manure being observed in Malakasamudra village. Photo by Vishwanath Koppal

Read more | Soil Workshop in Raichur In Mukkanal village, Raichur, this was a joint effort: while farmers provided the land, labour and rotavator, WELL Labs provided the right mix of seeds after much searching, checking with government sources and private providers, and doing germination tests. Nine varieties of seeds were finally procured from private buyers in the same and neighbouring districts. We had originally planned to test the process of 50 acres of farmland, but succeeded in starting the attempt on 32 acres in Raichur and three acres in Koppal. We worked with 23 farmers on this project, of whom over half (13) work on rainfed land. As we wait to observe the results, here is a breakdown of our process so far.

Understanding the recipe

Green manure is essentially the organic matter obtained from green leaves, stems, and roots of plants. It can be created within 45 days – making it feasible even for farms with shorter cropping cycles – and from natural materials at low cost. Karnataka has one of the highest chemical fertiliser consumption rates in the country, at around 71 kgs per hectare in recent years – depending only on these fertilisers can be expensive for a farmer, so green leaves manure makes a cost-effective partial add-on, not a complete substitute. Here, we look into two cases of farmers who have practised this technique for years, making green manure from scratch on the very land it is meant to sustain – one in Karnataka and the other in Telangana.

Prabhakar, from Karnataka’s Kolar district who we mentioned earlier, uses a different mix of seeds than Anumula Ramreddy, of Muthagudem village in Telangana’s Khammam district. But both follow broadly the same procedure, dedicating their farms to the process for 45 days. They deliberate on which plants to use for their manure, then till their soil and sow the seeds. After 45 days, when these crops are at the flowering stage, they use a rotavator to crush the green plants into manure and mix it in with the soil.

Measurements are key for good manure

For Prabhakar, who sows 30 kgs of seeds, the amount of manure yielded depends on which seeds he sowed and how tall the plants could grow in 45 days. If the plants grow half a foot, they amount to three tonnes; at one foot, the yield is seven tonnes; and if their growth is 1.5 feet before crushing, he gets 10 tonnes of green manure to give back to his soil. The seeds he sows for this are usually three kinds of monocots (like pearl millets, sorghum and maize), three kinds of dicots (like cowpeas, chickpeas and green gram) and three kinds of oilseeds. On the other hand, Anumula Ramreddy explains on his YouTube channel how his green manure is made from different proportions of dhaincha seed, sunn hemp seeds (janumu vithanalu), cow pea (bobbarlu), horse gram (ulavalu), pearl millet (sajjalu), broad beans (anumulu), hyacinth beans, coriander seeds (dhaniyalu), sesame seeds (nuvvulu), and fenugreek seeds (menthulu).

Amount of green leaf manure Prabhakar can make when his plants reach heights of 0.5 feet, 1 foot and 1.5 feet

Along similar lines at our site in Raichur, we sowed 30 kgs of seeds. We had decided on a combination of four types: three monocots, three dicots, three oil seeds and a mix of dill seeds including coriander and fenugreek.

After 45 days of growing, then harvesting and crushing, these seeds yielded a total of four to five tonnes of green leaves manure per acre, distributed across lands of varying degradation levels. In Koppal, we managed to create five tonnes of manure for the same input.

Weighing the pros and cons

For Prabhakar and Anumula, the total green manuring cost is less than ₹5,000 per acre, while depending entirely on chemical fertilisers would have cost anywhere between ₹10,000 and ₹15,000 per acre. This difference in cost not only breaks a vicious cycle of expenses, but also promotes self-sufficiency with farmers making green manure in their own time, as per their needs and schedules, instead of having to wait for affordable fertilisers in the market.

It also puts a stopper on another domino effect that is caused by chemical inputs like urea, whose need for dilution through irrigation often surpasses the moisture needs of the actual crop. Crops need adequate but not too much irrigation – they need moisture and organic matter that can hold moisture. On the other hand, it is chemical fertilisers that need irrigation to dilute their effects. Over-irrigation can pull salty content from the ground to the surface; canal irrigation can sometimes lead to high salinity for this reason. This might worsen the fertility of the land. Green manure can bypass this phenomenon entirely. The manure also stays longer in the soil, yielding benefits throughout the year, as compared to market fertilisers whose benefits are absorbed within the first few days.

Farmers uproot plants to be crushed for manure in Raichur. Photo by Revanna Siddappa.

Access to seeds for manure is an issue

Appealing as these benefits are, not all farmers have the means to make their own green leaves manure. Access to seeds is an issue – not all farms yield crops that are rich in seed, so they often have to be bought at market cost. In the pilot sites, WELL Labs had to procure most of the seeds from private sellers and shops, including some from neighbouring districts. Government agencies dedicated to providing support to farmers, often do not have all seeds types needed for GLM, since they serve a different purpose – their stocks of specific seeds are meant to aid harvest and income-generating yields.

For farmers like Prabhakar, who do have access to their own seeds (Prabhakar’s mother is a seed saviour we briefly wrote about before), the next challenge is protecting the growing plants from livestock. He recalls how, once, his neighbours left their cattle on the plot for grazing right when it was in good growth – ‘because they didn’t understand what I needed these plants for’. So now, Prabhakar notes the last 15 days of plant growth as the time to stay most alert for cattle. Community sensitisation would make this stage easier, ensuring success of such interventions. The farmers in Raichur and Koppal have gone through all these steps, in an effort to prevent and arrest years of soil degradation. Come the first harvest, we will measure certain indicators to track improvement in the harvest itself (like crop height and density of growth), as well as in soil health (such as yield per acre, biomass produced per acre to mulch back into the soil, input requirement per acre and soil organic carbon). Improvement in some of these indicators over the last few months, will inform us about the effectiveness of this process.

A farmer uses a rotavator to uproot and crush a row of plants. Photo by Revanna Siddappa, Prarambha

Acknowledgements

The author began this work when he was with the Centre for Social and Environmental Innovation at the Ashoka Trust for Research in Ecology and the Environment (CSEI-ATREE). WELL Labs is now taking it forward in collaboration with ATREE. Edited by Meghna Majumdar and Kaavya Kumar If you would like to collaborate with us outside of this project or position, write to us. We would love to hear from you. Follow us and stay updated about our work: