• K S Gopal and Aneesh Mohan

Designs that build on interdependence: Connecting water, soil and microbes through SWAR technology

Despite increasing water scarcity in India, initiatives and policies have remained limited to water conservation and availability. Agriculture consumes a significant portion of water resources, and it is imperative to invest in innovations that can focus on efficient water use instead of increased irrigation measures. Turns out, the answer literally lies under our feet. Changing the focus of interventions that go a long way in transforming farming practices and ensuring a healthy ecosystem.


India as a country has been struggling with the groundwater depleting beyond rechargeable limits. 20% of the blocks of India have been critically exploited for groundwater, with more than 3/4th of it being overexploited, beyond natural rechargeable capacity.


When drip irrigation was introduced in the agricultural mainstream, it was hailed as ‘State-of-the-Art’ technology that shifted the focus to water conservation. In the simulated test, drip could save upto 70% of water, compared to flood irrigation. For many years, and even today, Drip Irrigation continues to carry the reputation of a one-stop solution to saving water. What remains largely undiscussed are the caveats of this system.


In drip irrigation, the water falls on the surface, resulting in a lot of evaporation loss, which in peak summers is very likely death sentence for horticulture crops and fruit trees. Hence, in 2011,Centre for Environment Concerns (CEC), an NGO in Hyderabad and National Rural Employment Guarantee Mission (NREGM) together with farmers, dissected the issue which, initially seemed to be that of water availability. Women in Andhra Pradesh had to walk miles to fetch water for household use and irrigation. Understanding this, water-trolleys for women were created with the idea that instead of head-loading 20L of water, they could more efficiently just push 200L. While this reduced the drudgery significantly, the core issue of water-shortage remained unsolved.

Tribal woman in Mahaboobnagar district in Telangana installing SWAR for backyard vegetable cultivation (2017)

During that time, NREGM’s number one priority was water conservation. However, it was realised, that to solve the farmers’ problems, the conversation needs to be shifted from water conservation to water efficiency.

“How do we ensure efficient uptake of the available water by plants?”

Moving From ‘Water on field’ to ‘Moisture at roots’

Beeragowda of Kadur in Karnataka installs SWAR on his pomegranate plants in 2019

CEC sat down with farmers once again to build a solution and clay pots emerged as a potential answer. Clay pots, however, came with their own set of problems. Foremost being, there is no uniformity in size or material between batches, and there is breakage. Neither can water diffusing through the pots be increased or decreased. Such a scenario is okay when one is concerned with long-term growth (like in case of forestry trees). However, when it comes to yield (like in case of horticulture and fruit trees), water scarcity can be detrimental to the plant’s health.


This led NREGM, and later CEC, through multiple iterations, to formulate the criteria and architecture of low water “ideal irrigation” to cultivate fruit, flower, forestry, and vegetables in groundwater scarce areas and for farmers with drip systems, thus, innovating ‘System of Water for Agriculture Rejuvenation’ (SWAR). It is the first-of-its-kind “moisture at plant root zone irrigation technology” requiring 50% less water compared to scientists' recommendations in drip systems. It consists of a low-cost buried plastic moisture diffuser that comes as an add-on to drip laterals with a special dripper from where water is sent via a micro-tube into a box containing granular cut size quartz. Using design software and field testing - the ideal box size, shape, and height that release water slowly and to maximize moisture spread – was calculated. Short-runs on vegetables convince the farmers, once they see the results themselves.


Moving from ‘Water in soil’ to ‘Microbes in soil’

Water does not work autonomously; it works in conjunction with the soil. The soil’s ability to absorb and retain moisture is important, therefore soil health becomes important and roots (Mycorrhizae) are significant players in this. CEC studied traditional Indian farm soil rejuvenation practices across multiple states and engaged scientists, microbiologists and farmers to learn various approaches. This helped them develop ‘Living Compost’ as a microbe inoculate. It is locally made using available soil microorganisms. It is a “produce it yourself” multiplier of soil organisms that takes four weeks to prepare. It is an upgrade of farmyard manure coupled with select other ingredients, added for microbe bio-diversity such as soil under a banyan tree and seeding of Navadanya (multiple diverse native grains covering multiple traits) to foster Mycorrhizae.


However, often farmers give exclusive importance to only water and despite a drip, they over-irrigate the fields by 65-70%. It was realised, drip irrigation functions on field capacity to wilting point, (i.e., water that remains in the soil, and the point at which the water becomes insufficient for a plant to recover from wilting). The logic works effectively with chemical applications as these happen through water (e.g., Urea, NPK, etc), but it is extremely poor in accounting for the biology of the soil.


Measuring root zone moisture to plan irrigation using portable sensor in Chetna Organic Demonstration Farm in Odisha (2018)

Hence, 12-inch portable root-zone moisture metres were installed with sensors that are linked by Wi-Fi to regularly provide soil moisture status to the farmers. With measurable readings, farmers feel confident with the irrigation quantity and over-watering is avoided.


Moving from ‘Water for Chemicals’ to ‘Biological inputs’

Decades of sole focus on crop yields using artificial inputs, at the expense of soil health has resulted in multiple interconnected problems, the inability of eroded soils to store water being one of them. However, this is also an opportune time for farmers to build a mezzanine for a fundamental shift from ‘chemical to biological’, especially with climate change, water scarcity, heat waves and consumers wanting healthy food. The shift’s payback time is 1-3 years. CEC is confident that investing in soil health and efficient moisture provision will reduce the need for external nutrients by at least 30%, with a minimum of 10% increase in yield.


Growth and plant health difference after 40 days of SWAR (40% less water) with drip on tuber rose flowers in Yavatmal district of Maharashtra (2017)

In the transition period, chemicals could be used sparingly with simultaneous practices to increase the biological activity of the soil. Care should be taken that the chemicals being applied do not kill the soil microbes.


The foundation to successful farming and conservation of productive natural resources is by changing our irrigation architecture. It must foster a dynamically rich natural ecosystem of bio-diverse living organisms that maximize water storage, soil aeration with efficient suction of moisture by the roots along soil micro-nutrients.


The 5Ms of farming summarise the success as –

Moisture at the root zone that reduces water usage.
Measured moisture to optimise as per plant need.
Microbes to improve soil health and efficient use of water by the plant.
Mycorrhizae for the root zone for effective nutrient uptake.
Moisture adequacy data at the root zone to plan and be confident of irrigation adequacy crucial for bridging the gap that exists between what the scientists recommend and the practice of farmers.

All of these maximize water savings and plant-produce, soil health and is basis for changing the approach to irrigation. Both SWAR and Living Compost sufficiently impact and build the 5Ms. Further studies and feedback from farmers would help in building better iterations of the products.


 

K S Gopal is the Director of Centre for Environment Concerns in Hyderabad, Telangana. He can be contacted at cecgopal@yahoo.com.

Aneesh Mohan is a Research Assistant at SFI project at IRMA.


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