Guwahati: Rice is a staple for billions, and India, as the world’s second-largest producer, faces mounting pressure to sustain high yields. However, excessive reliance on chemical fertilisers depletes soil quality over time, leading to a potential 38% decline in yield. This has prompted researchers to explore alternative fertilisation methods that balance productivity with environmental sustainability.
Researchers from Mizoram University and Manipur University found that substituting 50% of chemical fertilisers with phumdi compost led to a 33.6% increase in grain yield—the highest among all tested treatments. The study, published in Scientific Reports, offers a sustainable solution to declining soil health caused by long-term chemical fertiliser use. The experiment was conducted at the Rice Research Station, Wangbal, which was set up under the Department of Agriculture, Manipur.
For better yields, rice needs three essential nutrients: nitrogen (N), phosphorus (P), and potassium (K). Although organic fertilisers have many advantages over chemical fertilisers, their sole application might not meet the essential nutrient requirement of crops due to their slow nutrient-release pattern.
The integrated use of chemical and organic fertilisers resulted in a significant increase in the growth, yield, and macronutrient content of rice. While applying compost, total nitrogen content or the percentage of mineralisable nitrogen should be considered for the proper efficiency of compost use. The judicious use of chemical and organic fertilisers could achieve sustainability by improving the environment, productivity, and economic state of the region.
Researchers associated with the study emphasised the need to explore the potential of locally made organic fertilisers, which are easily available, affordable for farmers, and environmentally friendly. The large-scale accumulation of phumdi, a heterogeneous mass of soil and aquatic floating plants in Loktak Lake (a Ramsar site in Manipur, Northeast India), causes the shallowing of the lake’s depth.
Few studies have been conducted on estimating the possibility of converting phumdi into compost, but those that have indicate that compost made from phumdi contains more nutrients compared to other types of composts. Consequently, private entrepreneurs have started producing compost from phumdi on a small scale. India generates a considerable amount of solid waste daily, amounting to 170,339 tons per day, yet lacks a proper management plan.
However, composting of the organic component, particularly from municipal solid waste, has been undertaken by non-governmental organisations on a small scale.
The study focused on the effectiveness of integrating organic composts with chemical fertilisers. Researchers tested three types of compost: municipal solid waste compost (MSWC), which is made from decomposed organic household waste; vermicompost (VC), derived from decomposed rice straw and cow manure with the help of earthworms; and phumdi compost (PC), made from floating vegetation collected from Loktak Lake in Manipur.
The field experiment was conducted over two growing seasons at the Rice Research Station in Wangbal, Manipur. Researchers tested eight different fertiliser treatments, including 100% chemical fertilisers, 100% composts, and a 50-50 mix of composts with chemical fertilisers.
The most promising result came from the combination of phumdi compost and chemical fertiliser (PC + CF), which increased grain yield by 33.6% and straw yield by 26.21% compared to chemical fertilisers alone. The combination of vermicompost and chemical fertiliser also improved grain yield by 13.16%, while municipal solid waste compost with chemical fertiliser saw a 5% increase.
Since phumdi compost is locally made, it can be easily made available to farmers. Additionally, converting phumdi into compost helps manage the eutrophication rate of Loktak Lake.
The study attributes these benefits to the rich composition of phumdi, which consists of decomposed aquatic plants such as Leersia hexandra, Azolla pinnata, Polygonum orientale, and Hydrilla verticillata. These plants break down into nutrient-rich organic matter, improving soil structure and microbial activity.
Additionally, compared to vermicompost and municipal solid waste compost, phumdi compost exhibited higher nitrogen and potassium content, which are essential for rice growth.
“The 50% substitution of chemical fertiliser with composts recorded more grain yield compared to conventional chemical fertiliser treatment in the cultivation of the present rice variety. The co-application of phumdi compost with chemical fertiliser was able to produce maximum grain yield.
The present study would recommend the utilisation of locally available composts as a substitution for 50% chemical fertiliser, especially phumdi compost and vermicompost, as they were able to produce 5% more grain yield compared to the sole application of chemical fertiliser,” the study says.
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