Nutrient expert®-rice: A tool for increasing crop yields, farm profit and improves yields while balancing fertilizers use

Introduction

Rice (Oryza sativa L.) constitutes the backbone of food security in India, serving as the primary source of dietary calories for more than half of the population (FAO, 2023; Government of India, 2022) [14] . India consistently ranks as the world's second-largest rice producer, cultivating the crop over approximately 44-45 million ha with an annual production exceeding 130 million tonnes (FAOSTAT, 2023; Ministry of Agriculture and Farmers Welfare, 2023) [14,24] . According to the Ministry of Agriculture and Farmers Welfare (2024), Kharif rice production during the 2022-23 crop year alone was estimated at about 110.5 million tonnes, underscoring the central role of rice in the national agrarian economy. Despite this substantial output and sustained growth in total production, national average rice productivity remains modest, at approximately 3.0-3.2 t ha⁻¹, and falls considerably short of attainable yields achieved under optimized agronomic and nutrient management practices. This disparity highlights the persistence of significant yield gaps across Indian rice systems (Cassman et al., 2003; Dobermann et al., 2004) [5,9,10,11] . With limited scope for horizontal expansion of cultivated land, future increases in rice production must therefore be driven primarily by improvements in productivity and resource-use efficiency. As emphasized by Cassman et al., (2003) [5] , "meeting future food demand will require producing more grain per unit of land, water, and nutrient input, while minimizing adverse environmental impacts." India's fertilizer economy has mirrored this expansion in rice cultivation. With an increasing reliance on mineral fertilizers over past decades, India has solidified its position as the second-largest consumer of fertilizer nutrients globally, accounting for nearly 15% of total global consumption (PIB, 2025). Government data indicates that during the 2023-24 fiscal year, total fertilizer consumption in India reached a record 601 Lakh Metric Tonnes (LMT), a substantial portion of which was utilized for cereal crops, particularly rice (Department of Fertilizers, 2024) [8] . These statistics demonstrate the massive scale of nutrient inputs but also highlight systemic imbalances. Nitrogen (N) is predominantly applied at rates far exceeding those of phosphorus (P) and potassium (K), disrupting the optimal 4:2:1 nutrient ratio recommended for Indian soils. As highlighted by the Indian Council of Agricultural Research (ICAR), "policies which encourage the use of only one type of fertilizer, particularly N alone, can lead to a decline in productivity and reduction in response to nitrogen," thereby threatening long-term soil health and sustainability (Tiwari et al., 2023) [38] . Mineral fertilizers, particularly nitrogen (N), phosphorus (P), and potassium (K), have played a central role in enhancing rice productivity in India. [12] highlighted that "yield and nitrogen-use efficiency in rice are maximized only when nitrogen supply is closely matched with crop demand in both time and quantity."

In reality, nutrient management decisions by farmers are predominantly guided by experience, perceptions of yield response, and access to fertilizers, rather than by scientific assessment of soil nutrient supply and crop requirement. Consequently, nutrient inputs are rarely balanced and are often driven more by resource availability than by agronomic principles. Pampolino et al., (2012) [25] reported that fertilizer practices in Asian rice systems are "highly [9,10,11] . noted that "field-to-field variability in soil nutrient availability is the norm rather than the exception in intensive rice-based systems. [17] , SSNM "provides a systematic approach to adjusting fertilizer application to match spatial and temporal variability in crop nutrient demand. [25] emphasized that Nutrient Expert® offers "a practical and scalable means of implementing SSNM, enabling farmers to achieve higher yields, improved nutrient-use efficiency, and greater profitability compared with conventional fertilizer practices."

Given the widespread reliance on blanket fertilizer recommendations, rising fertilizer costs, and the urgent need to enhance fertilizer-use efficiency in rice systems, systematic evaluation of Nutrient Expert®-Rice under farmers' field conditions is essential. Therefore, the present study was undertaken to test the hypothesis that site-specific fertilizer recommendations generated through Nutrient Expert®-Rice can enhance rice yield and farm profitability while balancing fertilizer use, in comparison with conventional farmer practices and recommended blanket fertilizer doses.

Methodology

Nutrient Expert® (NE) Among ICT-based decision support tools, Nutrient Expert® (NE) has emerged as a practical delivery mechanism of SSNM principles for cereals such as rice, wheat, and maize (Satyanarayana et al., 2012) [34] . NE is a computer-based decision support system (DSS) that provides rapid, field-specific fertilizer recommendations for N, P, and K, with or without soil test data (Qureshi et al., 2016) [28] . The tool estimates attainable yield and nutrient requirements based on farmer-provided information on soil type, crop management, residue use, previous yields, climate, and resource availability (Pampolino et al., 2012; Dutta et al., 2014) [13,25] . [18,19,20,40,41] . NE also promotes the integrated use of mineral fertilizers and organic amendments for long-term soil fertility and sustainability (Sapkota et al., 2014, 2021; Parihar et al., 2017) [26,32] . Nutrient Expert®-Rice (NE-Rice) is a decision-support tool designed to improve crop productivity, profitability, and fertilizer use efficiency while ensuring balanced nutrient supply for rice farmers. Developed by the International Plant Nutrition Institute (IPNI) and a network of partners, NE-Rice is the rice-centric component of the broader Nutrient Expert® initiative, which encompasses maize and wheat versions. The tool's objective is to recommend nutrient management practices that increase crop yields and farm profitability while minimizing production costs and providing good estimates of nutrient balances, recovery efficiencies, and associated emissions. NE-Rice incorporates locationspecific information on rice production such as variety, soil texture, climate data, growing season, and agricultural prices to produce crop-and location-specific fertilizer recommendations under standard management practices (Chivenge et al., 2022) [6] . NE-Rice generates timely, directly applicable, and realistic recommendations within a simple framework. The tool targets water-scarce situations and locations where fertilizer use is low and climatic and agronomic conditions support crop intensification. It operates based on verifiable agronomic data and does not favour specific products or technologies, thereby enabling a wide range of stakeholders to deploy it without technical or organisational barriers (Ali et al., 2018) [2] . We compared three nutrient management strategies (farmer's fertilizer practice-FP, government recommendation -GR, and Nutrient Expert®-NE-based recommendation), in many farm field/experimental field trials. We used the Nutrient Expert®-Rice tool, for the rice using data from those trials. [3] .

 Eastern Terai, Nepal

On-farm trials in Jhapa and Morang districts using the variety Sambha Mansuli Sub-1 demonstrated that NEbased SSNM increased grain yield by 0.8-1.2 t ha⁻¹ over FFP and government recommendations, along with improved nutrient use efficiency and reduced yield variability (Amgain et al., 2021; Timsina et al., 2014) [3,37] .  Indo-Gangetic Plains (IGP), India

A large dataset comprising 1,594 paired on-farm trials across Punjab, Haryana, and Bihar showed that NEbased SSNM increased rice and wheat yields by 4-8% while reducing nitrogen input by 15-35% and lowering greenhouse gas emissions compared with farmers' practices (Sapkota et al., 2021) [32] .

 Bihar, India

Field experiments on calcareous soils at RPCAU, Pusa, using rice variety RAU 1476-4-1 revealed that NEbased SSNM significantly improved grain yield, yield attributes, and nutrient uptake compared with RDF and FFP, confirming the suitability of NE under alkaline and nutrient-imbalanced soils (Singh et al., 2019) [35] .

 Chitwan, Nepal

Comparative evaluation of a hybrid (Arize Tej Gold) and an improved variety (Radha-4) showed that NEbased SSNM and LCC-guided N combined with NEbased P and K enhanced tillering, grains per panicle, grain yield, and benefit-cost ratio compared with conventional fertilizer practices (Acharya et al., 2022) [1] .  New Delhi, India

Under zero-till Direct-Seeded Rice (DSR) at ICAR-IARI, NE combined with LCC-based nitrogen management improved grain yield, nutrient and water use efficiency, and profitability while reducing N₂O emissions compared with RDF and state recommendations (Sadhukhan et al., 2023) [31] .

 Chhattisgarh, India

Experiments on Vertisols at Raipur demonstrated that NE-based SSNM produced the highest tiller density, panicle number, grain yield, and straw yield, outperforming RDF and nutrient omission treatments, thereby emphasizing the importance of balanced nutrient supply in heavy clay soils (Mannade et al., 2017) [21] .  Pantnagar, India

Long-term evaluations under a rice-wheat cropping system on silty loam Mollisols showed that NE-based SSNM consistently increased grain yield, yield attributes, nutrient use efficiency, and profitability compared with RDF and farmers' practices, with performance comparable to or better than STCR-based recommendations (Qureshi et al., 2016) [28] . [3] Sapkota et al., (2021) [32] Singh et al., (2019) [35] Acharya et al., (2022) [1]: Sadhukhan et al., (2023) [31] Mannade et al., (2020): Qureshi et al., (2016) [28] The [31,32] . These consistent yield advantages across contrasting agro-ecologies validate NE as a robust and scalable decision-support tool for improving rice productivity under diverse production environments. The superior yield performance of NE-based SSNM can be attributed to its field-specific estimation of attainable yield and nutrient demand, which corrects chronic nutrient imbalances common under FFP and blanket recommendations.

Results and Discussion 1. Grain yield response of rice to nutrient expert®-based ssnm across locations

Farmers' practices are often characterized by excess nitrogen and inadequate potassium application, while GR/RDF approaches fail to capture spatial variability in soil nutrient supply (Dobermann and Witt, 2004; Buresh et al., 2010) [4,9,10,11] . By synchronizing nutrient supply with crop demand at critical growth stages, NE improves nutrient uptake efficiency and yield realization (Pampolino et al., 2012; Majumdar et al., 2014) [19,25] . [3]: singh et al., (2019) [35] mannade et al., (2020) Improvements in grain yield under NE-based SSNM were consistently supported by enhanced yield-attributing characters, confirming that yield gains were physiologically and structurally driven rather than incidental (Table 2 [1,35] . Compared with FFP, NE-based SSNM increased tillers (350-400 m⁻² vs. 260-300 m⁻²) and panicles (310-350 m⁻² vs. 230-260 m⁻²), indicating improved early vegetative vigor and productive tiller survival (Mannade et al., 2017; Qureshi et al., 2016; Amgain et al., 2021) [3,21,28] . Similarly, grains per panicle (125-135) and 1000-grain weight (26-27 g) were highest under NE-based SSNM, reflecting better spikelet fertility and grain filling (Singh et al., 2019; Acharya et al., 2022) [1,35] . These improvements arise from balanced nitrogen and potassium nutrition during reproductive stages, which enhances assimilate production and translocation to grains (Dobermann et al., 1998; Feng et al., 2007) [9,10,11] . In contrast, FFP and GR/RDF treatments showed comparatively lower yield components, largely due to asynchronous nutrient supply particularly early nitrogen stress and late-season potassium deficiency. Numerous studies have shown that potassium plays a critical role in carbohydrate transport, enzyme activation, and grain filling in rice, and its omission limits yield even under adequate nitrogen supply (Sridhara, 2008; Buresh et al., 2010) [4,36] . Thus, the superior yield attributes under NE-based SSNM provide a mechanistic explanation for the observed yield advantages.

Yield-attributing characters as determinants of yield improvement

Economic performance and profitability of nutrient expert®-rice

The economic analysis across locations clearly indicates that NE-based SSNM substantially improves farm profitability compared with FFP, GR, and RDF (Table 3 [3,21,28,35] . Net returns under FFP ranged from USD 700 to 1100 ha⁻¹, whereas NEbased SSNM consistently achieved higher returns (USD 1100-1450 ha⁻¹), as reported across Nepal and India [21,35] . Importantly, the profitability gains under NE were driven primarily by yield enhancement and improved fertilizer efficiency rather than increased input costs (Qureshi et al., 2016; Mandal et al., 2016) [20,28] . In several cases, NE-based recommendations reduced nitrogen input while increasing potassium application, leading to higher yield per unit of fertilizer applied (Mannade et al., 2017; Singh et al., 2019) [21, 35] . This finding supports earlier reports that SSNM-based approaches improve profitability by optimizing nutrient allocation rather than intensifying fertilizer use (Mandal et al., 2016; Jat et al., 2018) [18,20] . In the Indo-Gangetic Plains (IGP), where detailed cost data were expressed as percentage gains, NE-based SSNM increased net returns by 8-12% over FFP, demonstrating that even modest yield improvements translate into meaningful income gains under large-scale cereal systems (Sapkota et al., 2021) [32] . [3]: Sapkota et al., (2021) [32] Singh et al., (2019) [35] Acharya et al., (2022) [1]: Sadhukhan et al., (2023) [31] Mannade et al., (2020): Qureshi et al., (2016) [28] [3]: Sapkota et al., (2021) [32] Singh et al., (2019) [35] Acharya et al., (2022) [1]: Sadhukhan et al., (2023) [31] Mannade et al., (2020): Qureshi et al., (2016) [28] The benefit-Cost (B:C) ratio followed trends similar to net returns ( [1,21,35] [21,28,35] [20,28] . Partial adoption of precision approaches (e.g., GR or RDF) improved B: C ratios compared with FFP, but these gains were consistently lower than those achieved under full NEbased SSNM (Budhathoki et al., 2018; Acharya et al., 2022) [1] . This highlights that balanced and complete implementation of SSNM principles is necessary to maximize economic benefits (Satyanarayana et al., 2012; Majumdar et al., 2014) [19,34] . [3]: Sapkota et al., (2021) [32] Singh et al., (2019) [35] Acharya et al., (2022) [1] Sadhukhan et al., (2023) [31] Mannade et al., (2020): Qureshi et al., (2016) [28] One of the most significant outcomes of NE-based SSNM is its ability to optimize fertilizer input while enhancing productivity (Table 5). Compared with FFP, NE-based SSNM reduced nitrogen application by 15-35%, while maintaining or increasing grain yield. At the same time, phosphorus application was adjusted downward where soil supply was sufficient, and potassium application was increased to correct long-term nutrient mining. This rebalancing of nutrient inputs resulted in higher agronomic efficiency of nitrogen and improved overall nutrient use efficiency. These findings align with earlier reports that SSNM can reduce nitrogen input by up to 30% without yield loss by improving synchronization between nutrient supply and crop demand (Wang et al., 2007; Dobermann et al., 2004) [9,10,11] . [31,32] . Thus, NE-based SSNM aligns strongly with the principles of climate-smart and sustainable intensification

Benefit-cost ratio and economic efficiency

Optimization of fertilizer use and nutrient use efficiency

Environmental implications and sustainability

Conclusion

Nutrient Expert®-based Site-Specific Nutrient Management (NE-SSNM) provides a scientifically robust and practical alternative to farmers' fertilizer practices and blanket government recommendations in rice systems. Across diverse agro-ecological regions, NE consistently improved grain yield, farm profitability, and nutrient use efficiency while promoting balanced fertilization. Yield gains were achieved through better synchronization of nutrient supply with crop demand, particularly optimized nitrogen splitting at critical growth stages, enabling higher productivity with more efficient fertilizer use. Unlike static recommendations, NE adjusts fertilizer rates according to field-specific conditions, correcting nutrient imbalances-especially chronic potassium under-application-and enhancing sustainable nutrient management. Importantly, increased economic returns were driven by improved input optimization rather than excessive fertilizer application, making NE both feasible and cost-effective for smallholder farmers. Wider adoption of NE-SSNM can help close yield gaps, enhance food security, and support sustainable intensification of rice and rice-wheat systems in South Asia and similar agro-ecologies worldwide.

Future line of work

Future research should emphasize multi-location and multiseason validation of Nutrient Expert®-based SSNM across diverse soils, climates, rice varieties, and cropping systems to enhance its robustness and regional calibration. Longterm experiments are required to assess impacts on soil health, nutrient balances, and overall system sustainability. Integration of NE with soil testing, sensor-based tools (e.g., LCC, SPAD, remote sensing), weather advisories, and digital mobile platforms can further improve precision and farmer accessibility. Expanding recommendations to include secondary and micronutrients, stress-prone environments (drought, salinity, direct-seeded rice), and integrated use of organic amendments will strengthen its comprehensiveness. Additionally, socio-economic adoption studies, extension strategies, and supportive policy frameworks are essential to accelerate large-scale implementation and promote sustainable intensification of rice-based production systems.

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