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EFFECT OF COATED NITROGENOUS
FERTILIZERS ON CARBON FRACTIONS IN
RICE BASED CROPPING SYSTEM
Prof. P. K. Mani and Somadrita ...
 Rice followed by wheat is a dominant cropping sequence under
a range of management regimes in the Indo-Gangetic Plains o...
Nitrogen is a major nutrient for crop production, yield
increase. But its loss from soil through denitrification,
volatil...
Objectives of the Experiment
 Assessment of yield in rice based cropping systems, viz,.
Rice-Rice, Rice-Wheat and Rice- p...
Detailed background information for the experimental site
at D-Block Farm. Kalyani
Geographical location Latitude-22057′36...
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43 45 47 49 51 1 3 5 7 9 11 13 15 ...
Design of the Experiments and Treatments
 The experiments were simple 2 factor strip plot design
Horizontal strip contai...
T1 N0PK
T2 100% NPK (NCU)
T3 75% N(NCU) +PK+ 25% N (Organics)
T4 100% NPK (PSCU)
T5 75% NPK (PSCU) + 25% N (Organics)
Vert...
Physico-chemical
properties
Analytical techniques applied
1. Soil pH Soil pH was measured with the help of pH meter
contai...
Chemical properties Analytical methods applied
7. Oxidisable organic carbon Soil oxidizable organic carbon (SOC) was deter...
Yield (t/ha) of Summer rice, Wheat and Potato grown in Rabi
season at Kalyani farm during 2017- 2018
Summer rice (C1) Whea...
Effect of treatments on distribution of pH and EC under different cropping systems
Cropping
Systems Treatments
pH EC
Depth...
Table- Distribution of available nitrogen (N), phosphorus (P) and potassium (K)
under different controlled release urea tr...
Table : Distribution of available nitrogen (N), phosphorus (P) and potassium (K)
under different controlled release urea t...
Table : Distribution of available nitrogen (N), phosphorus (P) and potassium (K)
under different controlled release urea t...
Table: Distribution of soil bulk density (BD), Oxidizable Organic Carbon (WBC),
organic C fractions (F1, F2, F3 and F4), t...
Table : Distribution of bulk density (BD), Walkley and Balk carbon (WBC), total organic
carbon (TOC) and TOC stock under d...
Table: Distribution of bulk density (BD), Walkley Black Carbon (WBC), total organic
carbon (TOC) and TOC stock under diffe...
Distribution of Bulk density (BD), Walkley and Balk Carbon (WBC), total
organic carbon (TOC) and TOC stock under different...
Table : Distribution of Carbon fractions (g kg-1) under different controlled
release urea treatment in Rice-Rice cropping ...
Table: Distribution of Carbon fractions (g kg-1) under different controlled release
urea treatment in Rice-Wheat cropping ...
Distribution of Carbon fractions (g kg-1) under different controlled release urea treatment in
Rice-Potato cropping system...
Active Pool, Passive Pool and Lability Index under different controlled release urea
treatment in Rice-Rice cropping syste...
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%ofTOC
AP PP
Effect of trea...
Table : Active Pool, Passive Pool and Lability Index under different
controlled release urea treatment in Rice-Wheat cropp...
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T1 T2 T3 T4 T5 T1 T2 T3 T4 T5 T1 T2 T3 T4 T5
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Fig: Effect of...
Table: Active Pool, Passive Pool and Lability Index under different controlled
release urea treatment in Rice-Potato cropp...
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Fig: Effect...
Table: Correlation among different soil C fractions under Rice-
Rice cropping system
BD AvN F1 F2 F3 F4 WBC TOC
TOC
stock
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Table: Correlation among different soil C fractions under Rice-
Wheat cropping system
BD AvN F1 F2 F3 F4 WBC TOC
TOC
stock...
Table: Correlation among different soil C fractions under Rice-Potato
cropping system
BD AvN F1 F2 F3 F4 WBC TOC
TOC
stock...
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Comparing with the initial TOC stock (in 2015) highest C build-
up was observed under Rice-Rice systems followed by Rice-...
Higher positive correlation of F4 with TOC and TOC stocks
better stability and long turnover time of C under Rice-Rice an...
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EFFECT OF COATED NITROGENOUS FERTILIZERS ON CARBON FRACTIONS IN RICE BASED CROPPING SYSTEM

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Studied on various carbon pools as influenced by the use of coated nitrogenous fertilizer along with 25% substitution by Organics like FYM and VC.

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EFFECT OF COATED NITROGENOUS FERTILIZERS ON CARBON FRACTIONS IN RICE BASED CROPPING SYSTEM

  1. 1. EFFECT OF COATED NITROGENOUS FERTILIZERS ON CARBON FRACTIONS IN RICE BASED CROPPING SYSTEM Prof. P. K. Mani and Somadrita Sen pabitramani@gmail.com Dept of Agricultural Chemistry and Soil Science Bidhan Chandra Krishi Viswavidyalaya Mohanpur, Nadia,West Bengal, India
  2. 2.  Rice followed by wheat is a dominant cropping sequence under a range of management regimes in the Indo-Gangetic Plains of South Asia  But the cereal based systems in Indo-Gangetic plains (rice- wheat and rice-rice) are facing several second generation problems like, reduction in profitability, declining soil organic matter and increasing multiple deficiencies of major nutrients (N, P, K, and S) and micronutrients (Zn, Fe, and Mn) due to their overmining from soils ( Adhikari et al.,1999; Yadav et al., 2000; Ladha et al., 2000; Tiwari, 2002)  Diversification of rice-rice cropping system with other food crops like potato, oilseeds is necessary for obtaining higher yield and return, maintenance of soil health, protection of environment and meeting up daily requirement of human and livestock (Samui et al., 2004; Ray et al., 2009).
  3. 3. Nitrogen is a major nutrient for crop production, yield increase. But its loss from soil through denitrification, volatilization is a major problem now-a-days. Liegel and Walsh (1976) showed frequent potato yield depressions with fast-release N fertilizers, mainly due to N leaching.  Many new types of fertilizers and placement methods have been developed to increase nutrient use efficiency, such as slow- release urea, urease inhibitors, urea super granules, neem cake, N deep-placement etc.  Distribution of carbon fractions within soil is very important which depends on crop management practices, fertilizer management etc.
  4. 4. Objectives of the Experiment  Assessment of yield in rice based cropping systems, viz,. Rice-Rice, Rice-Wheat and Rice- potato cropping systems.  To find the role of organic additions ( FYM, Vermicompost etc.) on carbon fractions.  To find out the interaction effect of coated nitrogenous fertilizer with organics on various soil Carbon fractions.
  5. 5. Detailed background information for the experimental site at D-Block Farm. Kalyani Geographical location Latitude-22057′36″'N, Longitude- 88024'36''E Altitude – 10.0 m (MSL Year of start Rabi 2017-2018 Climate Sub-humid Rainfall 1323.7 mm Mean annual temp.(0C) Max. 31.5 and Min. 20.8 Relative humidity (%) Max. 93.1 and Min 62.4 Soil Inceptisol, Texture –clayey Agro-ecosystem Irrigated Design of experiment Strip Plot Design, with three replications Plot size 5.0 m X 4.0 m
  6. 6. 0.0 5.0 10.0 15.0 20.0 25.0 30.0 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0 43 45 47 49 51 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 Rainfall(mm) Meteorolgical observations (Weekly) during the crop growth period of D Block Farm, KalyaniHumidity(%),Temperature(0 C)andSunshine(hrs) Week (during November, 2017 to October, 2018) Rainfall Max. Temp Min. temp. Max. Humid. Min. Humid. Sunshine Meteorological observations (weekly basis) during crop growth period at D block farm, Kalyani
  7. 7. Design of the Experiments and Treatments  The experiments were simple 2 factor strip plot design Horizontal strip contained three different rice based cropping systems. Vertical strip contained five nutrient management practices as sub plot. Horizontal Strips (Main plot): Rice based cropping systems: (C) C1 = Rice - rice C2 = Rice - wheat C3 = Rice – Potato
  8. 8. T1 N0PK T2 100% NPK (NCU) T3 75% N(NCU) +PK+ 25% N (Organics) T4 100% NPK (PSCU) T5 75% NPK (PSCU) + 25% N (Organics) Vertical Strips (Sub-plot): Nutrient Management Practices (T)
  9. 9. Physico-chemical properties Analytical techniques applied 1. Soil pH Soil pH was measured with the help of pH meter containing glass and calomel electrodes (Page et al., 1982). 2.Electrical conductivity (EC) Electrical methods of these samples were determined by conductivity meter with of principle of Wheatstone bridge 3. Available nitrogen Amount of available nitrogen was determined by using alkaline permanganate method which was proposed by Subbiah and Asija (1956). 4.Available phosphorus available phosphorus was determined by Olsen method 5. Available potassium Available potassium of soil samples were determined with neutral normal ammonium acetate and determined on a Flame Photometer (Merwin and Peech 1951). 6 Bulk density Bulk density was determined by following the method of Blake and Hartge(1986)
  10. 10. Chemical properties Analytical methods applied 7. Oxidisable organic carbon Soil oxidizable organic carbon (SOC) was determined by the Walkley and Black’s titration method (1934). 8. Total organic carbon(TOC) This method was discovered by Tiessen and Moir, 1993. 9. soil organic carbons of different oxidisability The concentration of organic carbon was determined by using three types of acid aquous solutions which divided the whole total organic carbon into four fractions depending on oxidizability Fraction 1(very labile):organic carbon oxidisable under 12(N) H2SO4 Fraction 2(labile): organic carbon that is available in between 12(N) and 18(N) H2SO4 Fraction 3(less labile): organic carbon that is available in between 18(N) H2SO4 and 24(N) H2SO4 Fraction 4 (recalcitrant):difference in organic carbon that is available in between total organic carbon and 24 (N) H2SO4
  11. 11. Yield (t/ha) of Summer rice, Wheat and Potato grown in Rabi season at Kalyani farm during 2017- 2018 Summer rice (C1) Wheat (C2) Potato (C3) Treatments Grain Straw AEN Grain Straw AEN Tuber Haulm AEN T1 2.78 3.15 0.0 1.28 1.48 0.0 6.34 0.9 0.0 T2 4.77 5.95 16.6 3.50 3.95 14.5 15.28 2.4 44.9 T3 5.13 6.35 19.6 3.88 4.23 17.1 16.30 2.6 50.0 T4 5.72 7.13 24.5 2.98 3.37 11.1 13.67 2.3 36.9 T5 5.13 6.07 19.6 2.75 3.08 9.5 15.04 2.4 43.7 LSD (0.05) 0.42 0.74 0.46 0.53 1.17 0.48
  12. 12. Effect of treatments on distribution of pH and EC under different cropping systems Cropping Systems Treatments pH EC Depths (cm) 0-15 15-30 30-45 0-15 15-30 30-45 Rice-Rice T1 8.07aC 8.21aB 8.27aA 0.22 0.24 0.23 T2 8.04aC 8.20aB 8.26aA 0.24 0.23 0.22 T3 7.97bC 8.08bB 8.20bA 0.24 0.22 0.24 T4 8.04aB 8.21aA 8.20bA 0.26 0.25 0.23 T5 7.95bA 8.11bA 8.14cA 0.23 0.22 0.21 LSD (0.05) T =0.035 D =0.028 T x D =0.093 T =NS D =NS T x D = NS Rice-Wheat T1 7.85a 7.91a 8.34a 0.30B 0.33A 0.30B T2 7.70b 7.65c 8.31a 0.23A 0.23B 0.28A T3 7.66b 7.80b 8.22b 0.23A 0.22B 0.25A T4 7.87a 7.90a 8.28ab 0.23A 0.23B 0.23A T5 7.68b 7.88ab 8.22b 0.23A 0.21B 0.23A LSD (0.05) T =0.082 D =NS T x D =0.200 T =NS D =0.012 T x D =NS Rice-Potato T1 7.66bC 8.17aB 8.42abA 0.40 0.32 0.30 T2 7.80aC 8.11bB 8.43aA 0.32 0.33 0.30 T3 7.60cC 7.88cB 8.38bcA 0.25 0.32 0.20 T4 7.76aC 8.10bB 8.42abA 0.40 0.30 0.30 T5 7.65bC 7.87cB 8.35cA 0.25 0.22 0.20 LSD (0.05) T =0.048 D =0.040 T x D =0.157 T =NS D =NS T x D =NS
  13. 13. Table- Distribution of available nitrogen (N), phosphorus (P) and potassium (K) under different controlled release urea treatment in Rice-Rice cropping system Available N Available P Available K Treatments Depths (cm) 0-15 15-30 30-45 0-15 15-30 30-45 0-15 15-30 30-45 T1 120.42cA 35.41bB 29.36bB 62.55c 57.76c 51.51b 267.26c A 117.56cB 87.01bC T2 146.95bA 39.88abB 38.97abB 65.34b 58.74bc A 55.30a 287.46b A 147.43aB 78.41cC T3 155.13ab A 43.14abB 42.10aB 70.59a 61.51a 56.12a 293.31a A 148.80aB 87.02bC T4 167.21aA 48.50aB 47.00aB 65.84b 58.16c 54.63a 291.05a A 147.90aB 79.69cC T5 163.50aA 47.23aB 42.40aB 71.23a 60.44ab 55.48a 291.10a A 142.22bB 91.22aC LSD (0.05) T =12.619 D =6.292 T x D =8.032 T =1.976 D =NS T x D =2.175 T =3.104 D =1.778 T x D =6.799
  14. 14. Table : Distribution of available nitrogen (N), phosphorus (P) and potassium (K) under different controlled release urea treatment in Rice Wheat cropping system Available N Available P Available K Treatment s Depths (cm) 0-15 15-30 30-45 0-15 15-30 30-45 0-15 15-30 30-45 T1 114.15cA 41.69cB 27.60bC 64.29cA 58.53eB 50.49cC 290.06c A 122.96dB 85.75bC T2 137.64bA 55.67bB 36.21abC 74.35bA 62.88cB 52.58abC 304.70b A 138.13bB 82.65cC T3 140.48abA 60.71abB 36.50abC 78.755a A 67.58b B 53.43aC 312.15a A 143.19aB 92.16aC T4 149.31aA 65.60aB 38.80aC 74.70bA 60.56d B 51.91bC 302.91b A 130.28cB 81.72cC T5 145.93abA 63.65abB 37.40aC 79.91aA 69.44aB 52.42abC 312.39a A 139.16bB 91.97aC LSD (0.05) T =9.532 D =8.491 T x D =9.529 T =1.357 D =1.512 T x D =2.668 T =2.121 D =5.539 T x D =6.067
  15. 15. Table : Distribution of available nitrogen (N), phosphorus (P) and potassium (K) under different controlled release urea treatment in Rice-Potato cropping system Available N Available P Available K Treatment s Depths (cm) 0-15 15-30 30-45 0-15 15-30 30-45 0-15 15-30 30-45 T1 110.83cA 41.46bB 28.13aC 62.23cA 55.23b B 49.54aC 318.81e A 146.30d B 97.28cC T2 125.90bA 49.15bB 36.30aC 71.27bA 56.69a bB 50.45aC 337.30c A 155.13c B 102.55b C T3 132.61abA 57.75abB 37.87aC 79.61aA 58.36a B 52.21aC 345.54b A 165.41a B 105.55a C T4 144.27aA 63.18aB 40.87aC 70.62bA 54.04b B 50.48aC 333.15d A 148.43d B 94.67dC T5 134.87abA 57.73abB 38.60aC 78.50aA 59.02a B 49.98aC 353.95a A 159.43b B 97.95cC LSD (0.05) T =13.030 D =7.716 T x D =15.501 T =2.910 D =1.280 T x D =3.336 T =2.463 D =3.482 T x D =12.306
  16. 16. Table: Distribution of soil bulk density (BD), Oxidizable Organic Carbon (WBC), organic C fractions (F1, F2, F3 and F4), total organic C (TOC), TOC stock and Lability Index of initial soil Soil Parameters Depths (cm) LSD (0.05)0-15 15-30 30-45 BD (Mg m-3) 1.46c 1.53b 1.59a 0.026 WBC (g kg-1) 6.42a 5.49b 4.41c 0.340 F1 (g kg-1) 2.62a 2.64a 1.88b 0.383 F2 (g kg-1) 2.19a 1.78b 0.92c 0.320 F3 (g kg-1) 1.58a 1.02b 1.49a 0.366 F4 (g kg-1) 2.76a 2.75a 1.34b 0.296 TOC (g kg-1) 9.15a 8.19b 5.63c 0.393 TOC Stock (Mg ha-1) 20.09a 18.84b 13.46c 1.027 Labilty Index 1.51c 1.53b 1.59a 0.010
  17. 17. Table : Distribution of bulk density (BD), Walkley and Balk carbon (WBC), total organic carbon (TOC) and TOC stock under different controlled release urea treatment in Rice- Rice system BD (Mg m-3) WBC (g kg-1) TOC (g kg-1) TOC Stock Treat ments Depths (cm) 0-15 15-30 30-45 0-15 15-30 30-45 0-15 15-30 30-45 0-15 15-30 30-45 T1 1.49abA 1.63aA 1.65aA 6.42eA 6.41eA 4.33cB 9.16eA 8.35eB 5.58cC 20.42eA 20.42dA 13.83cB T2 1.51aA 1.54bA 1.54bA 8.46bA 8.38dA 4.47cB 10.91dA 10.8dB 6.53bC 24.66dA 24.87cA 15.09bB T3 1.49abA 1.47cA 1.48cA 8.69bB 9.03bA 4.88ab C 11.78cA 11.49cB 6.66bC 26.29cA 25.30bcB 14.74bC T4 1.55aA 1.43cA 1.48cA 8.75bA 8.77cA 5.05ab B 12.66bA 12.02bB 6.64bC 29.42aA 25.84bB 14.78bC T5 1.47bA 1.47cA 1.49cA 9.13aB 9.38aA 5.36aC 13.11aA 12.82aB 7.52aC 28.84bA 28.22aB 16.81aC LSD (0.05) T =0.043 D =NS T x D =0.058 T =0.327 D =0.137 T x D =0.790 T =0.207 D =0.105 T x D =0.237 T = 0.735 D = 0.611 T x D = 1.049
  18. 18. Table: Distribution of bulk density (BD), Walkley Black Carbon (WBC), total organic carbon (TOC) and TOC stock under different controlled release urea treatment in Rice- Wheat cropping system BD (Mg m-3) WBC (g kg-1) TOC (g kg-1) TOC Stock Treatm ents Depths (cm) 0-15 15-30 30-45 0-15 15-30 30-45 0-15 15-30 30-45 0-15 15-30 30-45 T1 1.59aA 1.60aA 1.63aA 6.87cA 6.81dA 4.13bcB 9.07dA 9.01dA 5.85bB 21.59dA 21.62cA 14.27bB T2 1.52bA 1.52bA 1.53bA 8.16bA 8.16cA 4.03cB 10.93cA 10.46cB 5.82bC 24.96cA 23.78bB 13.40bC T3 1.47cA 1.45cA 1.47cdA 8.39aB 8.97aA 4.26aC 11.64bA 10.74bB 6.09aC 25.60bA 23.43bB 13.43bC T4 1.45cdA 1.47cA 1.49cA 8.15bB 8.62bA 4.19abC 11.73bA 10.74bB 6.02aC 25.58bA 23.73bB 13.47aC T5 1.44dA 1.46cA 1.46dA 8.35aB 9.01aA 4.29aC 12.19aA 11.40aB 6.15aC 26.28aA 24.95aB 13.50bC LSD (0.05) T =0.022 D =NS T x D =0.046 T =0.115 D =0.109 T x D =0.415 T =0.164 D =0.147 T x D =0.301 T = 0.470 D = 0.288 T x D = 1.027
  19. 19. Distribution of Bulk density (BD), Walkley and Balk Carbon (WBC), total organic carbon (TOC) and TOC stock under different controlled release urea treatment in Rice-Potato cropping system BD (Mg m-3) WBC (g kg-1) TOC (g kg-1) TOC Stock Treatment s Depths (cm) 0-15 15-30 30-45 0-15 15-30 30-45 0-15 15-30 30-45 0-15 15-30 30-45 T1 1.48aC 1.56aB 1.61aA 6.33dA 5.58cB 3.3bC 8.59bA 7.98bB 4.47cC 19.04bA 18.62aA 10.82bB T2 1.46abC 1.51bB 1.54bA 7.31cA 5.78bB 3.7aC 9.16aA 8.39bB 5.15bcC 20.11abA 18.98aB 11.93bC T3 1.45bB 1.43dC 1.48cA 7.67abA 5.81bB 3.42bC 9.43aA 8.84aB 5.34bC 20.57abA 18.98aB 11.85bC T4 1.47abB 1.47cB 1.49cA 7.59bA 5.87bB 3.65aC 9.22aA 8.91aA 5.28bB 20.33abA 19.63aA 11.80bB T5 1.46abA 1.42dB 1.45dA 7.79aA 6.01aB 3.72aC 9.69aA 9.09aB 6.44aC 21.24aA 19.40aB 14.01aC LSD (0.05) T =0.020 D =0.101 T x D =0.039 T =0.123 D =0.260 T x D =0.940 T =0.967 D =0.431 T x D =1.098 T = 1.589 D = 0.930 T x D = 2.468
  20. 20. Table : Distribution of Carbon fractions (g kg-1) under different controlled release urea treatment in Rice-Rice cropping system Carbon fractions (g kg-1) F1 F2 F3 F4 Trea tme nts Depths (cm) 0-15 15-30 30-45 0-15 15-30 30-45 0-15 15-30 30-45 0-15 15-30 30-45 T1 2.29dA 2.83cA 1.77aA 2.07cA 1.22bB 0.89ab C 2.06cA 2.36c A 1.67bA 2.74bA 1.94cB 1.25cC T2 2.69cA 3.51cA 1.96aA 2.78aA 1.56aA 1.13aC 2.99aA 3.31b A 1.38bA 2.45bc A 2.42bA 2.06aB T3 2.94bA 4.39aA 1.92aA 2.88aA 0.75cC 1.04aB 2.87aA 3.89a A 1.92bc A 3.09bA 2.46bB 1.78aC T4 3.62aA 4.53aA 2.00aA 2.65bA 1.11bA 0.99aA B 2.48bA 3.13b A 2.06aA 3.91aA 3.25aB 1.59ab C T5 3.58aA 3.87bA 1.9aA 2.67abA 1.66aB 1.08aC 2.88aA 3.85a A 2.38aA 3.98aA 3.44aB 2.16aC LSD 0.05 T =0.189 D =NS T x D =0.677 T =0.207 D =0.182 T x D =0.577 T =0.376 D =NS T x D =0.907 T =0.447 D =0.051 T x D =0.833 Higher recalcitrant portion than other fractions in surface soil.
  21. 21. Table: Distribution of Carbon fractions (g kg-1) under different controlled release urea treatment in Rice-Wheat cropping system Carbon fractions (g kg-1) F1 F2 F3 F4 Treatmen ts Depths (cm) 0-15 15-30 30-45 0-15 15-30 30-45 0-15 15-30 30-45 0-15 15-30 30-45 T1 2.18dB 2.98bA 1.62aC 1.57dA 1.36aA 1.05aA 3.12aA 2.47bA 1.46aA 2.20dA 2.20aA 1.72aA T2 3.50aA 3.44aA 1.56aB 2.09cA 0.85aA 1.27aA 2.57bA 3.87aA 1.20aA 2.77cA 2.30aB 1.79aC T3 2.86cB 3.38aA 1.74aC 2.96abA 1.73aA 1.16aA 2.57bA 3.86aA 1.36aA 3.25bA 1.77aC 1.83aB C T4 3.14bB 3.38aA 1.88aC 2.71bA 1.32aA 0.98aA 2.30bA 3.92aA 1.33aA 3.58abA 2.12aB 1.83aC T5 2.73eB 3.34aA 1.67aC 3.36aA 1.70aA 1.17aA 2.26bA 3.97aA 1.45aA 3.84aA 2.39aB 1.86aC LSD (0.05) T =0.198 D =0.143 T x D =0.271 T =0.512 D =NS T x D =NS T =0.500 D =NS T x D =NS T =0.425 D =0.220 T x D =0.867
  22. 22. Distribution of Carbon fractions (g kg-1) under different controlled release urea treatment in Rice-Potato cropping system Carbon fractions (g kg-1) F1 F2 F3 F4 Treatment s Depths (cm) 0-15 15-30 30-45 0-15 15-30 30-45 0-15 15-30 30-45 0-15 15-30 30-45 T1 3.81c 3.11a 1.96a 1.19bA 0.99aA 0.35aA 1.33a A 1.48aA 0.99aA 2.26aA 2.40aA 1.17aA T2 4.17b 3.28a 2.39a 1.90aA 1.07aA 0.31aA 1.24a A 1.43aA 1.00aA 1.85aA 2.61aA 1.45aA T3 5.68a 3.32a 2.38a 0.74bA 1.13aA 0.17aA 1.25a A 1.36aA 0.87aA 1.76aA 3.03aA 1.92aA T4 5.89a 3.14a 2.26a 0.65cA 1.07aA 0.30aA 1.05a A 1.66aA 1.09aA 1.63aA 3.04aA 1.63aA T5 5.64a 3.25a 2.24a 1.08bA 1.30aA 0.34aA 1.07a A 1.46aA 1.14aA 1.90aA 3.08aA 2.72aA LSD (0.05) T =0.295 D =0.292 T x D =0.493 T =0.502 D =NS T x D =NS T =NS D =NS T x D =NS T =NS D =NS T x D =NS More amount of very labile fraction of carbon irrespective of all treatments
  23. 23. Active Pool, Passive Pool and Lability Index under different controlled release urea treatment in Rice-Rice cropping system Treatments Active Pool Passive Pool Lability Index Depths (cm) 0-15 15-30 30-45 0-15 15-30 30-45 0-15 15-30 30-45 T1 4.36dA 4.05cB 2.66cC 4.8eA 4.30dB 2.92dC 1.43b 1.59a 1.57a T2 5.47cA 5.07bB 3.09aC 5.44dB 5.73cA 3.44cC 1.52a 1.57a 1.46b T3 5.82bA 5.14bB 2.96bC 5.96cB 6.35bA 3.7bC 1.48ab 1.62a 1.47b T4 6.27aA 5.64aB 2.99ab C 6.39bA 6.38bA 3.65bB 1.47ab 1.58a 1.51ab T5 6.25aA 5.53aB 2.98ab C 6.86aB 7.29aA 4.54aC 1.45ab 1.46b 1.36c LSD (0.05) T =0.118 D =0.190 T x D =0.242 T =0.181 D =0.230 T x D =0.374 T =0.078 D =NS T x D =NS
  24. 24. 0 10 20 30 40 50 60 70 T1 T2 T3 T4 T5 T1 T2 T3 T4 T5 T1 T2 T3 T4 T5 0- 15 cm 15-30 cm 30-45 cm %ofTOC AP PP Effect of treatments on active pool (AP) and passive pool (PP) as percentage of TOC under Rice- Rice cropping system
  25. 25. Table : Active Pool, Passive Pool and Lability Index under different controlled release urea treatment in Rice-Wheat cropping system Treatments Active Pool Passive Pool Lability Index Depths (cm) 0-15 15-30 30-45 0-15 15-30 30-45 0-15 15-30 30-45 T1 3.75c 4.34b 2.67a 5.32c 4.67d 3.18a 1.41c 1.57b 1.44b T2 5.59b 4.29b 2.83a 5.34c 6.17b 2.99b 1.58a 1.52d 1.45ab T3 5.82ab 5.11a 2.9a 5.82b 5.63c 3.19a 1.47b 1.63a 1.46ab T4 5.85ab 4.70ab 2.86a 5.88b 6.04b 3.16a 1.46b 1.56bc 1.48a T5 6.09a 5.04a 2.84a 6.1a 6.36a 3.31a 1.41c 1.53cd 1.43b LSD (0.05) T =0.460 D =NS T x D =1.044 T =0.151 D =NS T x D =1.405 T =0.036 D =NS T x D =NS
  26. 26. 0 10 20 30 40 50 60 70 T1 T2 T3 T4 T5 T1 T2 T3 T4 T5 T1 T2 T3 T4 T5 0- 15 cm 15-30 cm 30-45 cm %ofTOC AP PP Fig: Effect of treatments on active pool (AP) and passive pool (PP) as percentage of TOC under Rice-Wheat cropping system
  27. 27. Table: Active Pool, Passive Pool and Lability Index under different controlled release urea treatment in Rice-Potato cropping system Treatments Active Pool Passive Pool Lability Index Depths (cm) 0-15 15-30 30-45 0-15 15-30 30-45 0-15 15-30 30-45 T1 4.40c 4.1b 4.21a 3.59 3.88 3.26 1.62 1.60 1.77 T2 6.07b 4.35ab 4.4a 3.09 4.04 3.75 1.92 1.60 1.70 T3 6.42ab 4.45ab 4.25a 3.01 4.39 4.09 2.10 1.54 1.65 T4 6.54a 4.21ab 4.36a 2.68 4.7 3.92 2.17 1.48 1.67 T5 6.72a 4.55a 4.18a 2.97 4.54 4.26 2.08 1.52 1.62 LSD (0.05) T =0.446 D =NS T x D =0.901 T =NS D =NS T x D =1.202 T =NS D =NS T x D =0.264 In case of Potato, highest amount amount of lability index was at surface soil.
  28. 28. 0 10 20 30 40 50 60 70 80 T1 T2 T3 T4 T5 T1 T2 T3 T4 T5 T1 T2 T3 T4 T5 0- 15 cm 15-30 cm 30-45 cm %ofTOC AP PP Fig: Effect of treatments on active pool (AP) and passive pool (PP) as percentage of TOC under Rice-Potato cropping system
  29. 29. Table: Correlation among different soil C fractions under Rice- Rice cropping system BD AvN F1 F2 F3 F4 WBC TOC TOC stock BD 1 AvN -0.169 1 F1 -0.320* 0.165 1 F2 -0.143 0.909** 0.122 1 F3 -0.380** 0.119 0.747** 0.165 1 F4 -0.409** 0.621** 0.642** 0.635** 0.356* 1 WBC -0.375* 0.501** 0.858** 0.535** 0.854** 0.726** 1 TOC -0.411** 0.573** 0.842** 0.603** 0.745** 0.863** 0.974** 1 TOC stock -0.273 0.585** 0.832** 0.619** 0.721** 0.845** 0.966** 0.988** 1 * Correlation is significant at the 0.05 level (2-tailed). ** Correlation is significant at the 0.01 level (2-tailed) n = 45
  30. 30. Table: Correlation among different soil C fractions under Rice- Wheat cropping system BD AvN F1 F2 F3 F4 WBC TOC TOC stock BD 1 AvN -0.330* 1 F1 -0.300* 0.458** 1 F2 -0.345* 0.751** 0.293 1 F3 -0.194 0.219 0.768** -0.101 1 F4 -0.354* 0.849** 0.420** 0.811** 0.075 1 WBC -0.369* 0.616** 0.928** 0.483** 0.800** 0.547** 1 TOC -0.402** 0.745** 0.876** 0.626** 0.673** 0.732** 0.971** 1 TOC stock -0.274 0.732** 0.882** 0.598** 0.681** 0.711** 0.966** 0.990** 1 * Correlation is significant at the 0.05 level (2-tailed). ** Correlation is significant at the 0.01 level (2-tailed) n = 45
  31. 31. Table: Correlation among different soil C fractions under Rice-Potato cropping system BD AvN F1 F2 F3 F4 WBC TOC TOC stock BD 1 AvN -0.403** 1 F1 -0.397** 0.915** 1 F2 -0.329* 0.362* 0.256 1 F3 -0.024 -0.007 0.126 -0.212 1 F4 -0.332* -0.113 -0.141 0.253 -0.395** 1 WBC -0.427** 0.818** 0.896** 0.471** 0.402** -0.167 1 TOC -0.581** 0.700** 0.756** 0.579** 0.157 0.396** 0.839** 1 TOC stock -0.490** 0.695** 0.757** 0.572** 0.166 0.381** 0.841** 0.994** 1 ** Correlation is significant at the 0.01 level (2-tailed). * Correlation is significant at the 0.05 level (2-tailed) n = 45
  32. 32. e d c b a c b b b a c bc abc ab a 0 10 20 30 40 50 60 70 80 T1 T2 T3 T4 T5 T1 T2 T3 T4 T5 T1 T2 T3 T4 T5 Rice-Rice Rice-Wheat Rice Potato TOCstockupto45cmdepth (Mgha-1) Fig: Effect of different treatments on TOC Stock (Mg ha-1) upto 45 cm depths under different cropping systems
  33. 33. 0 10 20 30 40 50 60 70 80 90 100 T1 T2 T3 T4 T5 T1 T2 T3 T4 T5 T1 T2 T3 T4 T5 Rice-Rice Rice-Wheat Rice-Potato %0fTOC(upto45cm) F1 F2 F3 F4 Fig: Effects of treatments on distribution of soil organic C fractions of different lability (as % of TOC upto 45 cm depth) under three different cropping systems
  34. 34. 4.40 23.36 26.66 33.75 41.02 9.75 18.66 19.23 19.87 23.60 -7.43 -2.56 -1.86 -1.18 4.42 -30.00 -20.00 -10.00 0.00 10.00 20.00 30.00 40.00 50.00 T1 T2 T3 T4 T5 T1 T2 T3 T4 T5 T1 T2 T3 T4 T5 Rice-Rice Rice-Wheat Rice-Potato PercentchangeinTOCStock Fig: Effect of different treatments on percent changes in TOC Stocks as compared to the initial values under different cropping systems
  35. 35. Comparing with the initial TOC stock (in 2015) highest C build- up was observed under Rice-Rice systems followed by Rice- Wheat system while negative change was observed under Rice potato system except T5. Among the treatments T5 [75% N through PSCU and 25 % through Organic Manure (FYM/Vermicompost)] found best for attaining considerable yield along with maintenance of soil sustainability by improving soil C to a considerable extent. Allocation of higher proportion OC into passive pools helped to achieve higherTOC stocks under treatment with organics (T3 and T5) over mineral fertilization and the phenomenon was pronounced under Rice-Rice system while higher proportion of Active pool and higher Lability Index (LI) under Rice-Potato system leading to loss of C.
  36. 36. Higher positive correlation of F4 with TOC and TOC stocks better stability and long turnover time of C under Rice-Rice and Rice-Wheat system while Rice-Potato system exhibited highest positive relation between F1 and TOC and its stock indicating more susceptibility of C towards oxidation and mineralization loss. Among different cropping systems rice-rice system contained lowest amount of total available P and K, while rice-wheat and rice-potato system contained higher amount of P and K respectively. As depth increases N, P, and K also reduced irrespective of the treatments. It was also found that heavy utilization of fertilizer in potato field reduced the pH of soil, as compare to rice and wheat cultivated soil. The pH of the soil system increases with depth irrespective of the cropping system and treatments used. Similar trend was also found in case of EC measurement.

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