Long-term nutrient inputs and soil quality dynamics in vertisol-dominated rice–wheat systems

Introduction

Soil quality reflects the integrated influence of natural-resource management on key soil properties that determine crop productivity and long-term sustainability. Soil is a dynamic, living medium that performs multiple essential functions within terrestrial ecosystems. Beyond supporting plant growth, soil properties also buffer and modulate the formation and breakdown of hazardous compounds. Evaluations of soil quality provide a robust framework for assessing the sustainability of agricultural and land-management systems. Soils exhibit varying quality levels, underpinned by enduring intrinsic properties shaped by pedogenic factors and modified by management practices (Larson & Pierce). Soil quality has declined due to contamination by organic and inorganic chemicals, altering its chemical, physical, and biological properties. The Green Revolution markedly boosted food-grain production in the Indo-Gangetic Plain through sustained chemical-fertilizer use, yet it also fostered secondary and micronutrient deficiencies arising from limited application of organic manures. Concerns persist that soil health may deteriorate with prolonged fertilizer use, particularly under continuous cropping with imbalanced nutrient applications (N or NP) in the absence of organic manures, which has lowered crop productivity. Overall, the sustainability of cropping systems is challenged by these nutrient imbalances and their impacts on soil properties and plant performance (Tiwari et al., 2002) [37] . The quality of soil emerges from the integrated effects of cropping-system components, such as crop rotation and tillage, together with fertility management that incorporates inorganic fertilizers and organic manures (Purakayastha et al., 2008) [30] . Prolonged continuous cultivation has led to a reduction in soil organic matter, accompanied by deterioration of general soil physical quality (Bhattacharyya et al., 2007) [3] . Enduring improvements in soil quality require sustaining SOM above a specified threshold for extended durations (Aune et al., 1997) [1] . Without organic amendments, the sustained productivity of intensive cropping systems is compromised despite NPK fertilizer inputs (Yaduwanshi, 2003) [41] . Integrating organic manures, however, strengthens soil physical and biological health and thereby improves soil fertility and crop performance (Mandal et al., 2003) [22] . The addition of organic matter elevates soil organic carbon, an important proxy for soil quality and a predictor of crop yields (Lal, 2003) [20] . Organic manures play a significant role in sustaining productivity, acting as nutrient sources and altering soil physical properties, while also improving the efficiency of applied nutrients (Sahadevareddy and Aruna). Organic manures enhance soil biological quality by increasing microbial abundance and delivering growthpromoting compounds. In parallel, improvements in soil physical properties occur as soil organic carbon content rises, reflecting direct and indirect effects of elevated organic matter on soil structure and function (Haynes and Naidu 1998) [16] . SOC content shows a positive response to organic waste inputs (manures and compost) relative to equivalent inorganic fertilization (Gregorich et al., 2001). Generic fertilizer recommendations can cause nutrient losses through leaching, volatilization, and runoff, contributing to environmental degradation and reduced sustainability of crops. In contrast, location-specific, yield-based nutrient recommendations offer the potential to harness the genetic potential of a variety at a given site, enabling more efficient use of soil resources. The conjunctive use of manures with chemical fertilizers raises soil organic carbon and helps narrow the gap between potential and actual yields, a benefit that is substantial in practice (Tolanur and Badanur, 2003) [38] . Yield stagnation or decline has been observed across multiple cropping systems nationwide, driven by nutrient depletion, deterioration of soil structure, imbalanced nutrient use, soil acidification, and insufficient integration of manures and fertilizers. The risk to soil quality intensifies under intensive cropping systems, particularly in rice-wheat rotations, which are among the most affected systems in India. Rice (Oryza sativa L.) is one of the world's most important cereals, contributing roughly 60% of global staple-food production. India ranks second in rice production, with approximately 110. 15 Prolonged mining of soil nutrients and concurrent losses from erosion and other factors threaten future crop production and soil health if unchecked. Continuous cropping without attention to nutritional needs degrades soil fertility. The application of manures and fertilizers alters soil chemical, physical, and biological properties, with implications for system sustainability. Maintaining soil quality at an optimal level is complex, given the interactions among soil, climate, human practices, and crops. There is an urgent need to adopt integrated soil and crop-management practices to curb soil degradation and sustain soil quality. Long-term fertilizer experiments provide valuable insights into crop productivity and soil-quality trajectories under different management scenarios. Long-term fertilizer experiments (LTFE) provide a key framework for understanding sustainability, capturing the complex interactions among plants, soils, climate, and management practices and their effects on crop productivity. LTFE enable monitoring of sustained changes in yields and nutrient balances and help identify the drivers of these dynamics. There is growing emphasis on integrating organic manures and efficiently utilizing available renewable cropresidue nutrients alongside inorganic fertilizers to maintain soil health and sustain crop production over the long term. This crop-specific approach provides a scientific basis for balanced fertilization, aligning fertilizer nutrients with soil nutrients. The focused-performance concept harmonizes fertilizing the crop with fertilizing the soil, promoting integrated nutrient management tailored to each crop.

Material and Methods

Study Area

Geographically, Raipur lies near the center of Chhattisgarh, at approximately 21°16′ N latitude and 81°60′ E longitude, with an elevation of about 289.56 meters above mean sea level. The research farm, located along NH 6 in the eastern part of Raipur, is near 20°04′ N latitude and 81°39′ E longitude, at an altitude of 293 meters above mean sea level.

Soil Characteristics

The experimental soil, locally known as Kanhar, is a fine montmorillonitic, hyperthermic Udic chromustert within the Vertisol order, identified as the Arang II series. It is typically deep, with clay content exceeding 44.8 percent, and ranges from dark brown to black in color. The soil pH is neutral to alkaline, reflecting lime presence.

Treatment Details

The study was conducted at the Research Farm of IGKV Raipur (Chhattisgarh). It used a Vertisol soil and the cropping system involved rice (Oryza sativa) and wheat (Triticum aestivum), using the MTU1010 rice variety and the GW-366 wheat variety. Experimental plots covered 16 square meters each, arranged with a row-to-plant spacing of 5 m by 8.5 m. The experiment employed five treatments, replicated four times, following a randomized block design (RBD).

Soil Sample Collection, Processing and Analysis

Soil samples were collected from the 0-15 cm layer prior to rice transplanting and again after wheat harvest from all experimental plots. These samples served to assess soilquality parameters. A portion of the collected soil was airdried, ground, and passed through a 2 mm sieve. The remaining material was analyzed for a range of physical and chemical soil parameters. The bulk density of soil was determined by the core method. The particle density of the soil sample was measured of the oven-dry mass per unit volume of soil solids only. To determine the particle density by Pycnometer is the most common method. The clay fraction, silt fraction and the sand fraction were determined using the pipette method as described by Piper (1966) [43] . Water holding capacity was determined as per the method is given by Piper (1950) [28] . The infiltration rate was determined in the field by using the double ring infiltrometer. Soil pH was determined by glass electrode pH meter in 1:2.5 soil-water suspensions given by piper (1966) [43] . The electrical conductivity of the supernatant liquid was estimated by conductivity meter as given by Black (1965) [4] . Soil Organic carbon was determined by Walkley and Black's rapid titration method (1934). The available nitrogen in the soil was estimated by using alkaline KMnO 4 method as given by Subbiah and Asija (1965) [34] . The available Phosphorous in soil was estimated by using 0.5M NaHCO 3 as determined by Olsen's et al (1954). Available soil potassium was estimated by Flame Photometer after extraction by 1 N ammonium acetate method of Hanway and Heidel, 1952 [13] . Cation exchange capacity was measured by leaching with neutral 1 N ammonium acetate (1N NH 4 OAc).method given by Chapman, 1965. The micronutrients Zn, Cu, Mn, and Fe were extracted by using 0.005M DTPA, 0.01M calcium chloride dehydrate and 0.1M triethanol amine buffered at 7.3 pH (Lindsay and Novell, 1978) [21] .

Results and Discussion

3.1 Bulk density and Particle density of soil Table 3.1 represented bulk density ranging from 1.32 to 1.45 Mg m -3 and particle density from 2.35 to 2.39 Mg m -3 across treatments; long-term fertilizer management did not produce a significant alteration in either density. Among treatments, the lowest bulk density occurred with the FYMinclusive mix (YT 6/2.5 t ha -1 + FYM, designated as T 5 ), followed by the T 3 (YT 5/2 t ha -1 ), T 2 (GRD), and T 4 (YT 6/2.5 t ha -1 ) treatments, with the highest density observed in the control (T 1 ). Incorporation of FYM with inorganic fertilizers reduced bulk density, consistent with findings reported by Hati et al. (2007) [15] , Bhattacharya et al. ( 2007) [3] , and Hati et al. ( 2006) [14] . In contrast, particle density remained essentially unchanged by organic or inorganic amendments, reflecting its status as an intrinsic soil property; Ram et al. and Schjonning et al. (1994) [33] reported similar stability in particle density under comparable treatments.

Porosity and infiltration rate

Soil porosity was assessed in relation to long-term fertilizer and organic-matter management, with porosity ranging from 38.57% to 44.75% across treatments. Treatments incorporating organic amendments, particularly farmyard manure (FYM) alongside inorganic nutrients, produced the highest porosity values, followed by other organic-inorganic combinations; the control exhibited the lowest porosity. Overall, total porosity increased with the inclusion of organic matter and varying fertilizer regimes, an effect attributable to higher organic matter content, improved soil aggregation, and shifts in pore-size distribution. Similar patterns have been reported in previous studies (Hati et al., 2007; Reddy et al) [15] . Table 3.2 shows that infiltration rates ranging from 0.38 to 0.67 mm h -1 . The highest infiltration was observed in the FYM-inclusive treatment (T 5: 6/2.5 t ha -1 + FYM), significantly exceeding all other treatments, while the control (T 1 ) showed the lowest rate. Treatments with inorganic-plus-organic combinations such as T 4 (6/2.5 t ha -1 ) and T 3 (5/2 t ha -1 ) were statistically comparable to T 2 (GRD). The superior infiltration in T 5 is attributed to reduced bulk density and enhanced soil porosity following FYM-inorganic fertilizer co-application. The tendency for infiltration to rise with combined organic and inorganic inputs aligns with findings reported by Sarkar et al. (2003) [32] and Bhattacharya et al. (2007) [3] .

Water holding capacity

Table 4.3 shows that water holding capacity (WHC) was significantly influenced by higher fertilizer rates and exceeded the control. WHC varied from 34.98% to 41.92% during the kharif season and from 34.88% to 41.57% during the rabi season. The greatest WHC was observed with the FYM-inclusive treatment (T 5: 6/2.5 t ha -1 + FYM), followed by T 4 (6 t/2.5 ha -1 ), T 3 (5 t/2 ha -1 ), and T 2 (GRD), with all these surpassing the control at pre-rice and post-wheat sampling. Incorporating FYM before the preceding crop further enhanced soil WHC. The highest WHC values were achieved under balanced fertilizer applications and integrated nutrient management practices. Soils with organic inputs generally exhibited higher WHC than control or fallow soils, in line with findings reported by Bandyopadhyay et al. ( 2007) [15] . Similar trends were reported by Rasool et al. (2008) [31] . [27] , Verma et al. ( 2012) [39] , Pothare et al. ( 2007) [29] , and Dwivedi et al. ( 2007), who reported little or no consistent influence of long-term fertilization on soil pH and EC under varied management regimes.

Cation Exchange Capacity

Table 3.5 shows soil Cation Exchange Capacity (CEC) ranged from 38.88 to 41.95 cmol(+) kg -1 , with differences among treatments that were not statistically significant. The highest CEC occurred with the FYM-inclusive treatment (T 5: 6/2.5 t ha -1 + FYM), followed by T 4 (6 t/2.5 ha -1 ), T 3 (5 t/2 ha -1 ), while the control (T 1 ) registered the lowest CEC.

Higher CEC with FYM is attributed to increased organic matter, which enhances exchange sites. The observed rise in CEC under the combined organic-inorganic nutrient regimens aligns with findings from Bellakki et al. (1998) [2] and is supported by Brar et al. (2015) [5] , Chouhan et al.

(2017) [8] , Sharma et al. (2012) [39] , and Rezig et al, who reported elevated CEC with organic amendments or integrated nutrient management.

Soil Organic Carbon

Table 3.6 shows that soil organic carbon (SOC) increased significantly with the application of inorganic fertilizer alone or in combination with farmyard manure (FYM). No seasonal differences in SOC were detected. Across treatments, SOC ranged from 0.28% to 0.60% before rice transplanting and from 0.27% to 0.62% after wheat harvest. The highest SOC was observed with the FYM-inclusive treatment (T5: 6/2.5 t ha -1 + FYM), while the control (T 1 ) recorded the lowest. Treatments combining inorganic fertilizer with organic amendments (e.g., T 4 , T 3 , and T 2 ) were statistically comparable. Increases in SOC under longterm FYM fertilization are attributed to direct input of organic matter, improved root growth, and greater residue return. Inorganic fertilizer alone also raised SOC relative to the unfertilized control, likely due to enhanced biomass inputs from crops. The observed SOC gains with balanced fertilizer-plus-organic-manure regimens align with findings by Hati et al. (2007) [15] and are corroborated by Kaur et al.

(2005) [18] , Yadav et al. (2017) [40] , and Datta et al. (2018) [9] . 3.7 shows the status of available macronutrients (N, P, K) in soil, expressed as kg ha-1, with no pronounced difference between the pre-rice and postwheat sampling, though treatment effects varied. The FYMinclusive regime (T 5: 6/2.5 t ha -1 + FYM) yielded the highest macronutrient availability, followed by T 4 (6 t/2.5 ha -1 ), T 3 (5 t/2 ha -1 ), and T 2 (GRD); all were significantly higher than the control (T 1 ). The observed increases across treatments reflect adequate macronutrient inputs and consistent nutrient supply, which influenced soil nutrient pools for both crops. Continuous application of inorganic fertilizers with FYM enhanced soil macronutrient content relative to unfertilized controls. The findings align with prior reports: long-term chemical fertilizer use with manure elevates N, and phosphorus availability increases with combined phosphorus fertilization and FYM; similar patterns have been reported by Kundu (2016) [19] , Kachot et al. (2001) [17] , Yeshpal et al. (2017) [42] , Mishra et al. (2008) [24] , Thakur et al. (2011) [36] , Sharma et al. (2008) [24] , Sharma et al. (2017) [42] , Tadesse et al. (2013) [35] , Meena et al.

(2019) [23] , Munehwar et al, Singh et al. ( 2015) [5] .

Micronutrients

Table 3.8 presents micronutrient (Fe, Mn, Cu, Zn) status in ppm, showing higher micronutrient levels before rice transplanting than after wheat harvest. Among treatments, micronutrient concentrations were highest under the FYMinclusive regime (T5: 6/2.5 t ha -1 + FYM) with the rice/wheat yield targets, followed by the control (T 1 ); other treatments did not differ significantly. Overall, treatment effects on soil micronutrients were not pronounced, likely because no micronutrient inputs were applied given apparent sufficiency in the experimental fields. Consequently, soil micronutrient status remained largely unchanged between pre-rice and post-wheat sampling under the long-term fertilizer and cropping-system regime. Trends reported here are consistent with Swarup et al. (2008) [30] , Gowda et al. (2017) [11] , and Choudhary et al. (2018) [7] .

Conclusions

This study demonstrates that long-term integrated management of organic and inorganic nutrients markedly influences soil physical, chemical, and biological properties, as well as crop productivity in acid soils. Incorporating organic amendments such as farmyard manure (FYM) with inorganic fertilizers consistently improved soil quality indicators, including soil pH stabilization, increased soil organic carbon, higher cation exchange capacity, and enhanced porosity and water holding capacity, which in turn supported higher or more stable yields under rice-wheat rotations. Biochar and crop residues varied in their effects depending on residue type, carbon content, and application rate, but generally contributed to soil structure, nutrient dynamics, and resilience against acidity-related constraints. Across sites (Palampur and Ranchi), residue-and FYMbased strategies showed potential to mitigate acidity effects, improve nutrient availability (N, P, K, and micronutrients), and reduce reliance on mineral NPK inputs when integrated thoughtfully. However, feasibility concerns remain for large-scale FYM application due to resource constraints, underlining the need for locally appropriate, sustainable management options that leverage available organic resources and residue management. The findings support a move toward integrated nutrient management (INM) that balances crop yield goals with soil health and environmental sustainability, particularly in intensely cropped, acidic soils common in parts of India. Further work should refine optimal residue types, carbon-equivalent dosing, and sitespecific INM frameworks, and assess long-term environmental and economic implications.

Acknowledgement

AcknowledgementsThe authors gratefully acknowledge the facilities and support provided by Indira Gandhi Krishi Vishwavidyalaya (IGKV), Raipur. We thank the Department of Soil Science and Agricultural Chemistry for enabling long-term field trials and for access to experimental plots and data management. Special thanks are due to the field staff and technicians at IGKV, Raipur, for their meticulous assistance in plot preparation, sample collection, and routine laboratory analyses. We also acknowledge the contributions of colleagues in the lab.

References

1. Aune JB, Lal R. Agricultural productivity in the tropics and critical limits of properties of Oxisols, Ultisols, and Alfisols. Trop Agric (Trinidad). 1997;74:96-103.
2. Bellakki MA, Badanur VP, Setty RA. Effect of longterm integrated nutrient management on some important properties of a Vertisol. J Indian Soc Soil Sci. 1998;46(2):176-180.
3. Bhattacharyya R, Chandra S, Singh RD, Kundu S, Srivastva AK, Gupta HS. Long-term farmyard manure application effects on properties of a silty clay loam soil under irrigated wheat-soybean rotation. Soil Tillage Res. 2007;94(2):386-396.
4. Black CA. Methods of Soil Analysis. Madison (WI): American Society of Agronomy; 1965.
5. Brar BS, Singh J, Singh G, Kaur G. Effects of longterm application of inorganic and organic fertilizers on soil organic carbon and physical properties in maizewheat rotation. Agronomy. 2015;5:220-238.
6. Chapman HD. Cation-exchange capacity. In: Black CA, editor. Methods of Soil Analysis. Agronomy Monograph 9. Madison (WI): American Society of Agronomy; 1965. p. 891-901.
7. Choudhary M, Panday SC, Meena VS, Singh S, Yadav RP, Mahanta D, Pattanayak A. Long-term effects of organic manure and inorganic fertilization on sustainability and chemical soil quality indicators of soybean-wheat cropping system in the Indian midHimalayas. Agric Ecosyst Environ. 2018;257:38-46.
8. Chouhan B, Kumar RH, Suryawanshi S. Assessment of chemical properties of a Vertisol under long-term fertilizer experiment in soybean-wheat cropping system. Int J Chem Stud. 2017;5(6):2107-2111.
9. Datta A, Mandal B, Badole S, Majumder SP, Padhan D, Basak N, Narkhede WN. Interrelationship of biomass yield, carbon input, aggregation, carbon pools and its sequestration in Vertisols under long-term sorghumwheat cropping system in semi-arid tropics. Soil Tillage Res. 2018;184:164-175.
10. Dwivedi AK, Singh M, Kauraw DL, Wanjari RH, Chauhan SS. Impact of fertilizer and manure use for three decades on crop productivity and soil quality under soybean-wheat system on a Vertisol in central India. Bhopal: Indian Institute of Soil Science (ICAR); 2007. p. 224-235.
11. Gowda RC, Veeranagappa P, Gayathri B, Hanumanthappa DC, Singh M. Long-term application of fertilizers on chemical and biological properties of an Alfisol. J Appl Nat Sci. 2017;9(4):1970-1974.
12. Gregorich EG, Drury CF, Baldock JA. Changes in soil carbon under long-term maize monoculture and legume-based rotation. Can J Soil Sci. 2001;81(1):2131.
13. Hanway JJ, Heidel H. Soil analysis methods as used in Iowa State College Testing Laboratory. Bull 57. Ames (IA): Iowa State College; 1952. p. 1-131.
14. Hati KM, Mandal KG, Misra AK, Ghosh PK, Bandyopadhyay KK. Effect of inorganic fertilizer and farmyard manure on soil physical properties and wateruse efficiency of soybean in Vertisols of central India. Bioresour Technol. 2006;97(16):2182-2188.
15. Hati KM, Swarup A, Dwivedi AK, Misra AK, Bandyopadhyay KK. Changes in soil physical properties and organic carbon status of a Vertisol after 28 years of continuous cropping and manuring. Agric Ecosyst Environ. 2007;119(1-2):127-134.
16. Haynes RJ, Naidu R. Influence of lime, fertilizer and manure applications on soil organic matter and physical conditions: a review. Nutr Cycl Agroecosyst. 1998;51(2):123-137.
17. Kachot NA, Malavia DD, Solanki RM, Sagarka BK. Integrated nutrient management in rainy-season groundnut (Arachis hypogaea). Indian J Agron. 2001;46(3):516-522.
18. Kaur K, Kapoor KK, Gupta AP. Impact of organic manures with and without mineral fertilizers on soil properties under tropical conditions. J Plant Nutr Soil Sci. 2005;168(1):117-122.
19. Kundu DK, Mazumdar SP, Ghosh D, Saha AR, Majumdar B, Ghorai AK, Behera MS. Long-term effects of fertilizer and manure on soil quality in juterice-wheat system. J Appl Nat Sci. 2016;8(4):17931800.
20. Lal R. Soil erosion and the global carbon budget. Environ Int. 2003;29(4):437-450.
21. Lindsay WL, Norvell WA. Development of DTPA soil test for zinc, iron, manganese and copper. Soil Sci Soc Am J. 1978;42:421-428.
22. Mandal UK, Singh O, Victor US, Sharma KL. Green manuring: effect on soil properties and crop growth under rice-wheat system. Eur J Agron. 2003;19:225237.
23. Meena BP, Biswas AK, Singh M, Chaudhary RS, Singh AB, Das H, Patra AK. Long-term sustaining crop productivity and soil health in maize-chickpea system through integrated nutrient management in Vertisols. Field Crops Res. 2019;232:62-76.
24. Mishra B, Sharma A, Singh SK, Prasad J, Singh BP. Influence of continuous amendments on soil microbial biomass in an Alfisol. J Indian Soc Soil Sci. 2008;56(1):71-75.
25. Muneshwar S, Wanjari RH. Potassium response and requirement in crops grown in Vertisols. Indian J Fertilisers. 2012;8(3):26-32.
26. Olsen SR, Dean LA. Phosphorus. In: Black CA, editor. Methods of Soil Analysis. Agronomy Monograph 9. Madison (WI): American Society of Agronomy; 1965. p. 1035-1049.
27. Parvathi E, Venkaiah K, Munaswamy V, Naidu MVS, Giridhara Krishna T, Prasad TNVKV. Long-term effect of manure and fertilizers on properties of an Alfisol. Int J Agric Sci. 2013;3(4):500-505.
28. Piper CS. Soil and Plant Analysis. Adelaide: University of Adelaide; 1950.
29. Pothare S, Rathod PK, Ravankar HN, Patil YG, Yewale AC, Pothare D. Effect of long-term fertilization in Vertisols on soil properties and sorghum-wheat yield. Asian J Soil Sci. 2007;2(1):74-78.
30. Purakayastha TJ, Rudrappa L, Singh D, Swarup A, Bhadraray S. Long-term impact of fertilizers on soil organic carbon pools in maize-wheat-cowpea system. Geoderma. 2008;144(1-2):370-378.
31. Rasool R, Kukal SS, Hira GS. Soil organic carbon and physical properties under long-term FYM and inorganic fertilizers in maize-wheat system. Soil Tillage Res. 2008;101(1-2):31-36.
32. Sarkar S, Singh SR, Singh RP. Effect of organic and inorganic fertilizers on soil physical condition and productivity of rice-lentil sequence. J Agric Sci. 2003;140(4):419-425.
33. Schjonning P, Christensen BT, Carstensen B. Physical and chemical properties of a sandy loam receiving manure or fertilizer for 90 years. Eur J Soil Sci. 1994;45(3):257-268.
34. Subbiah V, Asija GL. A rapid procedure for estimation of available nitrogen in soil. Curr Sci. 1956;25:259-260.
35. Tadesse T, Dechassa N, Bayu W, Gebeyehu S. Effects of farmyard manure and inorganic fertilizer on soil physico-chemical properties in rain-fed rice ecosystem. Am J Plant Sci. 2013;4(2):309-316.
36. Thakur R, Sawarkar SD, Vaishya UK, Singh M. Impact of continuous use of fertilizers and manure on soil properties under soybean-wheat system of a Vertisol. J Indian Soc Soil Sci. 2011;59:74-81.
37. Tiwari A, Dwivedi AK, Dikshit PR. Long-term influence of fertilization on soil fertility and productivity of soybean-wheat system in a Vertisol. J Indian Soc Soil Sci. 2002;50:472-475.
38. Tolanur ST, Badanur VP. Integrated use of organic manure and fertilizer nitrogen in sorghum-chickpea system of a Vertisol. J Indian Soc Soil Sci. 2003;51:4144.
39. Verma G, Sharma RP, Sharma SP, Subehia SK, Shambhavi S. Changes in soil fertility of maize-wheat system due to long-term fertilizers in an Alfisol. Plant Soil Environ. 2012;58(12):529-533.
40. Yadav RK, Purakayastha TJ, Khan MA, Kaushik SC. Long-term impact of manuring on organic carbon in Inceptisol under potato-based systems. Sci Total Environ. 2017;609:1535-1543.
41. Yaduwanshi NPS. Substitution of inorganic fertilizers by organic manures in rice-wheat rotation on reclaimed soil in India. J Agric Sci. 2003;140:161-168.
42. Yeshpal S, Duhan BS, Sharma NL. Physico-chemical properties of soil influenced by NPK, FYM and sulphur in mustard-moong sequence. Int J Curr Microbiol Appl Sci. 2017;6(12):4187-4195.
43. Piper J. Diffusion of hydrogen in copper-palladium alloys. Journal of Applied Physics. 1966 Feb 1;37(2):715-21.