Agricultural residue management in India: Unlocking economic potential

Introduction

India is seventh largest country with 3.287 million square kilometers of land area over the world. With 139.35 million hectares (Mha) of land used for agriculture, or roughly 42.4% of our nation's total land area, India is one of the world's most significant producers of agricultural goods. Agriculture plays a vital role in the Indian economy, contributing over 25% of the gross domestic product and providing livelihood to about 70% of the country's population (Raihan et al., 2024 and Nagar et al., 2024) [29,22] . Since independence, the nation has seen a 25% increase in cropping intensity. As per Meena et al., (2020) [12] Indian agriculture sector produces wide range of crops, including rice, wheat, oilseeds, sugarcane, fiber and cotton, generating a large volume of agricultural waste as illustrated in fig. 1. Agricultural waste called as residues and byproducts from farming activities. These include crop residues (straw, husks, stalks), animal waste, agro-industrial waste, and unutilized portions of plants (Hoang et al., 2024a) [13] . According to estimates, India produces 500-550 million tons of crop remnants annually (Abdullah et al., 2021 and Kataki et al., 2023a) [16] . This is a huge amount of agricultural waste. Sixty-six percent of total production has been used for a range of purposes, including as household firewood, industrial fuel, livestock feed, and roofing for rural homes. A total of 89 Mt of wheat, 56 Mt of sugarcane, 47 Mt of cotton, 43 Mt of rice, and 23 Mt of vegetables and fruits are wasted, making up 34% of the entire output (Athwal et al., 2023) [3] . Most of this waste (about 65-75%) is burned in open fields as illustrated in fig. 2. Farmers frequently burn agricultural waste as it is an easiest way of disposal, effective form of weed and pest management, as well as low-cost method for field preparation for next crop (Porichha et al., 2021) [28] and there is a dramatic fall in the incidence, after menopause due to cessation of clinical ovarian. Burning crop residues contributes significantly to global warming through the emission of greenhouse gases (GHGs) and increases health hazards by releasing particulate matter (PM) and smog. It results in a lack of essential elements such organic carbon, nitrogen, phosphorus, potassium, and sulfur as well as loss of biodiversity and soil fertility. Air pollutants such as CO 2 , CO, NH3, NOx, SOx, non-methane hydrocarbons (NMHCs), volatile organic compounds (VOCs), and semi-volatile organic compounds (SVOCs) are also released throughout the process (Parmod et al., 2015) [26] . One tonne of stubble, for instance, loses more than 1 kilogram of sulfur, 25 kg of potassium, 2.3 kg of phosphorus and 5.5 kg of nitrogen, all of which are essential for healthy soil. Additionally, it drastically reduces soil nutrient levels, which has a detrimental effect on agricultural productivity. Make it shorter. Burning paddy straw destroys vital bacterial and fungal populations and raises soil temperatures to 33.8-42.2 ºC (Gupta et al., 2004). Crops become more susceptible to harm as a result of this approach, which damages the organic matter and microorganisms in the soil, decreasing beneficial pests and boosting harmful ones. There is also a reduction in the topsoil's capacity to dissolve minerals (Kumar et al., 2015) [22] . Burning agricultural residue is a common practice in many locations, particularly in India's Indo-Gangetic plains.

Burning one ton of chaff produces 199 kg of ash, more than 1 kg of sulfur dioxide, 60 kg of carbon monoxide, and 1460 kg of carbon dioxide and 3 kg of particulate matter in air and reduction in the soil's 5.5 kg of nitrogen (N), 2.3 kg of phosphorous (P), 25 kg of potassium (K), 1.2 kg of sulfur (S), and all organic carbon (ministry of agriculture and NPMCR).

Additionally, this could be a source of dangerous greenhouse gases (GHGs), as well as other significant invisible gases and aerosols that are chemically and radiatively significant. Burning agricultural leftovers produces heat that raises the soil's temperature, killing off helpful soil microbes and lowering the amount of N and C in the topmost layer of soil (Kadian et al., 2024) [15] . Agro-industries have gradually come to realize that valorization of biomass leftovers is not only helpful from an environmental standpoint but can also help to prevent economic losses or even improve the net value of firms. (Singh et al., 2022). Crop residue, which makes up the majority of agricultural harvests, contains a significant quantity of carbon and other nutrients like nitrogen (N), phosphorous (P), potassium (K), sulfur (S), etc., are a great supplier of soil nutrients (Kumar et al., 2023) [19] . As per estimates, India generates more than 500 million tons of agricultural waste each year, of which only about half is used successfully (Singh & Prabha, 2018) [31] . A significant amount of the residual garbage is either burned in the open, producing air pollution, or wasted, resulting in environmental damage and the loss of potentially valuable resources. Proper management and disposal of crop waste remain significant concerns. This review paper addresses numerous technical breakthroughs and crop residue management tactics, including mechanised management systems, in-situ incorporation, nanotechnology, biogas production, biochar preparation, bioethanol production, and the use of decomposers. These technologies provide promising alternatives for reducing the environmental impact of residue burning while also improving soil health and encouraging renewable energy. The paper also explores policy frameworks, community engagement, and collaboration as essential components for the successful implementation of sustainable practices.

Economic Advantages of Sustainable Agricultural Waste Practices in India

The economic worth of agricultural residues is projected to be more than $32 billion every year. However, about 60% of this wastes is in use at the moment, and the rest is either incinerated or thrown away, which causes serious ecological and health related issues (Baruah et al., 2024) [5] . There are, however, great possibilities for businesses in making value added products such as biogas, organic fertilizers, bio-degradable plastics, and biofuels out of agricultural waste (A. Kumar et al., 2021) [18] . It also minimizes the expensive use of chemical fertilizers when farmers create fertilizer or feedstock out of waste. Also, bioconversion of agrowastes provides bioenergy which increases alternative energy sources and minimizes fossil fuel utilization in remote areas feeding their energy upsurge. In the countryside, the growth of industries that manage waste-a full process starting from collection, treatment, and recycling-may provide employment opportunities whilst enhancing environmental conservation and economic development.

Approaches to mitigate the issue

In order to handle residues effectively, a bioeconomy strategy must modify traditional methods (Fig 3). During this shift, approaches that improve agricultural ecosystem sustainability must be implemented (Jordan et al., 2007) [14] . Crop leftovers have traditionally been employed for a variety of purposes, including roof thatching, bedding, animal feed, cooking fuel, and packing (Lohan et al., 2018). Considering the current situation and the abundance of crop wastes, it is necessary to find alternate applications for them. In-situ management Using in-site approaches such as crop residues or Zero-till conservation agriculture is very eco-friendly and sustainable (Marjanovic, 2018 and Badarinath et al., 2006) [23] . Leaving crop residues on the land after harvest nourishes the soil, allows top soils to develop and provides organic nutrients due to decay. Decomposition of raw materials such as residues enriches the soil with organic material, aids in the development of top soil and provides essential nutrients such as nitrogen, phosphorus and sulphur. This allows reducing the risk of nitrogen outflow and the need for artificial fertilizers by controlling runoff and soil loss (Liu et al 2023) [20] . Additionally, it is sustainable to produce biochar from crop wastes. [17] .

Composting

In India, composting is not a novel idea. [27] . ). Yet, many South Asian landowners find the expenses of owning and running these devices to be exorbitant. Consequently, to promote its use, it is essential to lower rental rates, subsidize fuels, and increase the number of machines available.

Machinery

Bioenergy

The potential for producing clean energy from agricultural waste in the area was emphasized by Kashif et al. (2020). This covers the manufacturing of alternative fuels, biogas, and bioethanol (Kumar and Singh, 2021) [18] . Furthermore, rice straw granules and charcoal briquettes have the potential to replace coal in power stations.

Bio-decomposers

It is necessary to provide bio-decomposer solutions with microbes that promote and improve in-situ composting of crop remains accessible and reasonably priced (Srinivasan and Abirami, 2020). For instance, farmers in India can purchase a crop-waste decomposer for around ₹20 per solution, which has the capacity to break down over ten thousand tons of crop residue within a month after spraying (Wangchuk, 2019).

Biochar

One of the environmentally beneficial ways of dealing with crop residue is to prepare biochar, which improves crop productivity and boosts soil fertility and retains carbon. Biochar was made by slowly pyrolyzing rice husk at 650 °C and maize stover at 550 °C. A decline in CO2 emissions was observed along with a boost in many soil parameters when compared to biochar and unpyrolyzed rice husks in various soil types used for agriculture (Khare et al., 2020) [17] . Various methods were used to produce biochar, including pyrolysis, carbonization, hydrothermal, gasification and torrefaction. The kind of waste leftover and its chemical makeup dictate the properties of the synthesized biochar, and the time frame and temperature of the pyrolysis setup affect the biochar's excellence (Vijayaraghavan et al., 2019) [34] . Allesina et al., estimated 130 kilogram of biochar can be produced annually from a one-hectare cotton crop. Instead of residue burning, using raw mulch and processed biochar in the field increased soil yield capacity (36%-64%) in the tested areas of South Asia (Dey et al., 2020) [8] .

Nanotechnology

Nanotechnology presents enhanced opportunities for value addition to agricultural waste in a short span of time and, therefore, excludes the use of toxic chemicals which would otherwise cause various environmental and health problems. A greener nanomaterials (NM) synthesis using plant extracts from agricultural wastes has been gaining interests lately. These nanoparticles (NPs) have specific applications researched in detail for use as antibacterial agents, in water purification, decolouration of industrial dyes, and many others (Nath et al., 2023) [23] . In order to synthesize nanomaterials from agricultural waste, both top-down and bottom-up methods are essential. The top-down approach reduces bulk material to nanoscale particles through chemical or mechanical energy. Conversely, the bottomup approach forms nanoparticles from individual atoms or molecules by adjusting factors like pressure, temperature, or using chemical substances (González-González et al., 2022b) [10] . Using palm pods, Dawwam et al., (2022) [7] produced bionanocomposites that prevent the spread of Salmonella, E. Coli, Listeria monocytogenes, and Staphylococcus aureus. The bionanocomposite was made by extracting cellulose nanocrystals, which were then utilized to synthesize zinc oxide. Because these nanoparticles prevented the production of exotoxins and growth of microbes, they also had an impact on the expression of genes linked to pathogenicity. Utilising rice husk waste, Unglaube et al. (2021) [33] synthesized carbon-based and silver-containing silica composites. The nanomaterial had exceptional efficacy in combating virulent yeast C. albicans, A. baumannii, E. fecium, S. aureus, K. pneumoniae, E. coli and P. aeruginosa.

Government Policies and Initiatives

One major issue that the government is still battling with is minimizing or controlling the agricultural waste, crop postharvest management particularly. The efforts and actions of the state and central government in this respect has been challenged in the courts several times. In this respect, both the state and central government have actively taken steps to control crop residues. Several approaches for efficient management of crop residue have been advocated and are elucidated.

National Bioenergy Programme

National Bioenergy Programme, launched by Minister of New and Renewable Energy(MNRE), seeks to utilize agricultural waste for energy. The period of the project is from FY 2021-22 till 2025-26 and various sub-schemes are included such as Waste to Energy Programme, Biomass Programme, Biogas Programme, etc (Vikaspedia 2024). Theses make possible putting up biogas, BioCNG, and power plants along with production of briquettes and pellets for power generation. The basic aim is reducing waste, producing clean energy and enhancement of natural ecology. The Indian government recently ordered the National Thermal Power Generation (NTPC) to produce 10% of the country's electricity using coal and agricultural residue briquettes. The farmers benefited from this, as it cost only Rs. 5500 per metric tons of agricultural leftover (Singh & Prabha, 2018) [31] . These appealing methods are currently inactive but can be successfully applied by farmers.

Only a few projects pertaining to bio-composting are supervised by the Indian government.

Subsidies and Financial Support

The government consider a multitude of subsidies and incentives in order to persuade the farmers in fully adopting the effectively useful measures of waste management, such as funding of the

Environment laws

Strict regulations have been implemented in India in recent years to minimize pollution and protect biodiversity. Some common laws are-The Environment Protection Act (EPA) 1986, the National Environmental Tribunal Act of 1995 (as amended in 2010), the National Environment Appellate Authority Act of 1997 (Gathala et al., 2011) [9] . The National Policy for Management of Crop Residue (NPMCR) 2014 by the Ministry of Agriculture and Farmers' Welfare (Govt. of India) with the primary objectives of tackling agricultural residue management. This promotes the use of advanced machinery; is supportive of industrial solutions, training of farmers, providing of funds and even promulgating relevant laws. This in turn makes it possible to achieve an effective and sustainable crop residue management that is advantageous to both the farmers and the ecosystem (NPMCR).

Case Studies and Success Stories

• Regions such as Punjab, Haryana, and Uttar Pradesh have made a lot of progress in the management of crop residues by Technologies like Happy Seeder machines and Super Straw Management System are already in place (Sen et al., 2024) [30] . Such measures in addition to encouraging the use of crop residues in other forms like bioenergy, composting or as fodder for livestock assist the farmers in minimizing the burning of residues while enhancing soil health (Porichha et al., 2021) [28] . • In the state of Tamil Nadu, the implementing composting practices has seen farmers with the intent of organic fertilizers into agricultural wields and that of to marketing. The campaign implemented by the government on the community organic waste management has enlightened many on the need to reduce landfill usage and improve soils (Balasubramanian et al., 2021) [4] . • Strengthen Policy Implementation: Due to the fact that accomplishing policy objectives without effective policy enforcement cannot be considered a success, other educational campaigns are necessary to educate the farmers on sustainable waste management. Provisions from the state like subsidies, training, awareness campaigns may assist the farmers in abandoning the traditional practice of burning and embracing cleaner options • Sustainable agriculture practices: It is important to encourage the use of agriculture which produces less waste and utilizes more of the nutriens. Practices such as zero tillage, crop rotation and organic agriculture will help to limit residue burning and enhance soil health as well.

Conclusions

The research underscores the substantial effects of agricultural residue combustion on air quality, soil integrity, and human well-being in India. The ongoing directly combustion of agricultural leftovers, mainly wheat and rice, results in elevated concentrations of particulate matter, CO, NO2, SO2, CO2 and O3 in the environment. In addition to significantly affecting human health by degrading air quality, this practice causes considerable soil nutrient loss, therefore reduces yields from agriculture. Approaches like in situ incorporation, biofuel, nanotechnology, composting, bio-decomposers and biochar are some management techniques and Happy Seeder and Zero Till Seed Drill mechanised advancements have been put forward and brought into practice to tackle these issues. Furthermore, there are more proactive measures that can be taken by government agencies, such as encouragement for need-based assistance, and other options aimed at preventing residue burning, than resorting to strict enforcement of the law. Lastly, the article addresses the ecological and geographical consequences of burning agroresidues in the open air and, more optimistically, offers alternative management practices. Should these techniques be widely implemented, they would assist in alleviating many environmental concerns currently discussed, and would be beneficial to the global agricultural market.

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