Land Use Changes on Soil Carbon Dynamics, Stocks in Eastern

Himalayas, India

BrajendraICAR- Indian Institute of Rice Research, Hyderabad, India

Co-AuthorsDhermesh Verma1, B.P. Bhatt2, Ranjan Bhattacharyya4 and Lehar Jyoti5

1Head: ICT, Remote Sensing & GIS, AgriNet Solutions, India. verma.dharmesh@gmail.com2Director, ICAR Research Complex for Eastern Region, Patna, Bihar, Indiadrbpbhatt.icar@yahoo.com4Sr. Scientist, CESCRA, Nuclear Research Laboratory Building, Indian Agricultural Research Institute, Pusa, New Delhi, 110 012, India ranjan_vpkas@yahoo.com5ICAR Research Complex for NEH Region, Umiam, Meghalaya, India

What is there lying below the ground?

Soil sampling sites in Eastern Himalayas, India

We went to the land of the highlanders (at 5000 ft above msl) did diagnostic survey, collected soil

samples.

Soil Sampling Sites

Soil Sampling Sites

- In the Eastern Himalayas, India, shifting cultivation has caused severe environmental degradation.

Agroforestry interventions-The specific objective was to study the impacts of different AFS on the selected SOM fractions (MBC, POM-C and SOC) in the surface soil layer and their relationships with other soil parameters after five years of land management practices in an acidic soil of the Eastern sub-Himalayas.-Hedge species have also been found suitable for soil conservation and sustainable crop production in rain-fed agriculture.

Growth performance of different hedgerow species

Hedgerow species Survival (%)

Plant densityper ha

Plant height(m)

Collar diameter

(cm) Cajanus cajanCrotolaria tetragonaDesmodium rensoniiFlemingia macrophyllaIndigofera tinctoriaTephrosia candida

75.080.060.080.070.080.0

1,86,2071,63,1202,63,1582,80,3032,66,1922,48,062

1.79±0.049

1.61±0.332

1.28±0.108

1.17±0.123

1.55±0.046

1.05±0.253

2.23±0.25

3.80±0.75

2.50±0.67

1.61±0.40

2.73±0.33

1.53±0.25

Production of pruned biomass (q/ha- FW basis)

Hedge species Component-wise biomass Total biomass Leaves Branch Main axis

C. cajanC. tetragonaD. rensoniiF. macrophyllaI. tinctoriaT. candida

19.54 57.44 13.28 16.16 42.47 38.26

31.95 63.82 17.03 5.8025.0 26.9

37.93 74.23 40.34 25.08 52.6843.41

89.42 195.49 70.65 47.04

120.15 108.57

- Proper land use and management practices can lead to increased SOC and improved soil quality that can mitigate atmospheric CO2 rise .

- Appropriate agroforestry systems (AFS) have the potential to decrease soil erosion, augment N build-up, maintain soil organic matter (SOM) and promote efficient nutrient cycling, where trees are incorporated widely with crops

Pigeon pea cultivation on fallow landThese 9 sets included six hedge species (Cajanus cajan, Crotolaria tetragona, Desmodium rensonii, Flemingia macrophylla, Indigofera tinctoria and Tephrosia candida); one multipurpose tree (Himalayan Alder; Alnus nepalensis); one fruit tree (Guava; Psidium guajava cv. Allahabad safeda) and one control (without a tree). - Significantly higher soil microbial biomass carbon (MBC) content was

observed for the plots under hedgerow based and Alder based AFS over the control plots.

- For all land use systems (except for the control plots), SOC contents in the 10-20 cm depth was significantly higher than in the 0-10 and 20-30 cm soil layers, indicating the importance of the middle layer for SOC sequestration.

Influence of hedge species on physico-chemical properties of the soil,

irrespective of soil depths

Name of the hedge

pH

(1:2.5)

Org. C

(%)

Available nutrient (kg/ha)

Exch. cations [c mol (p+)

kg‑1] N P K Ca Mg

F. macrophyllaD. rensoniiI. tinctoniaT. candidaC. tetragonaC. cajanControl

4.674.344.544.664.564.304.57

1.711.722.332.322.281.2971.69

256.05

205.66

209.97

175.45

216.6222.5200.9

7

9.2913.7813.6513.1614.1611.1610.97

129.2146.5155.0

5143.8159.4154.4149.5

1.621.632.633.432.131.561.5

7.375.567.426.562.683.753.75

Effects of various agroforestry systems on mean (± SD) soil organic carbon concentration and content in the Indian sub-

Himalayas

Farming system/soil depth

Total SOC (g kg-1) Soil bulk density (Mg m-3)

Total SOC content (Mg ha-1)

1. Hedge based AFS0-10 cm 24.8 ± 3.6B 0.98 ± 0.03B 24.30B10-20 cm 28.9 ± 3.9A 1.02 ± 0.03AB 29.48A20-30 cm 24.1 ± 3.2B 1.05 ± 0.03A 25.31BMean 25.9 ± 3.6 a 1.00 ± 0.03 a

25.9 a2. Alder based AFS0-10 cm 24.1 ± 3.2B 0.93 ± 0.02B 22.41B10-20 cm 24.4 ± 3.5B 0.95 ± 0.02AB 23.18B20-30 cm 27.9 ± 3.6A 0.98 ± 0.02A 27.34AMean 25.4 ± 3.4ª 0.95 ± 0.02b 24.13 a3. Guava based AFS0-10 cm 18.4 ± 2.3ª 1.01 ± 0.01B 18.54ª10-20 cm 15.7 ± 2.0B 1.02 ± 0.01B 16.01B20-30 cm 13.3 ± 2.1C 1.06 ± 0.01A 14.10CMean 15.8 ± 2.2b 1.03 ± 0.01a 16.24 b4. Control (without a tree)0-10 cm 16.3 ± 1.9A 0.99±0.02B 16.14B10-20 cm 14.7 ± 1.9B 1.01±0.02B 14.85B20-30 cm 16.8 ± 2.0A 1.07±0.02A 17.98AMean 16.0 ± 1.9c 1.02±0.02a 16.32 b

Effect of various agroforesty systems on mean (± SD) total N and particulate organic matter-carbon contents in the Indian sub-

Himalayas

AFS system/Soil depth (cm)

POM-C (g kg-1) Total N (g kg-1) C/N Ratio POM-C/SOC POM-C Stock (Mg/ha)

1. Hedge based AFS0-10 8.5 ± 1.2B 2.0 ± 0.1A 12.4 ± 1.2B 0.34 ± 0.02A 8.33C

10-20 11.3 ± 1.4A 1.9 ± 0.1A 15.2 ± 1.5A 0.39 ± 0.02A 11.3ª20-30 8.9 ± 1.0B 1.8 ±0.1A 13.4 ± 1.2B 0.37 ± 0.02A 9.35BMean 9.2 ± 1.2 a 1.9 ± 0.1 a 13.7 ± 1.3 b 0.36 a 9.66 a

2. Alder based AFS0-10 9.2 ± 0.8B 1.7 ± 0.1B 14.2 ± 0.4A 0.38 ± 0.01A 8.56B

10-20 10.4 ± 0.9ª 1.8 ± 0.2B 13.5 ± 0.4A 0.43 ± 0.01A 9.88A20-30 8.8 ± 0.8B 2.1 ± 0.2A 13.3 ± 0.4A 0.31 ± 0.01B 8.62BMean 8.6 ± 0.8 a 1.9 ± 0.2 a 13.6 ± 0.4 b 0.34 a 9.02 a

3. Guava based AFS0-10 4.2 ± 0.6B 1.1 ± 0.1 A 16.7 ± 0.6A 0.23 ± 0.04B 4.24B

10-20 4.8 ± 0.5A 0.9 ± 0.1B 17.5 ± 0.5A 0.30 ± 0.04A 4.90A20-30 3.9 ± 0.4B 0.8 ± 0.1B 16.6 ± 0.6A 0.30 ± 0.04A 4.13BMean 4.6 ± 0.5 b 0.9 ± 0.1 b 17.0 ± 0.5 a 0.29 b 4.42 c

4. Control (without a tree)0-10 4.0 ± 0.5B 1.9 ± 0.1A 8.5 ± 0.8B 0.25 ± 0.01B 3.96C

10-20 5.6 ± 0.6AB 1.5 ± 0.1B 9.8 ± 0.9A 0.38 ± 0.01A 5.66B20-30 6.1 ± 0.7A 1.6 ± 0.1B 10.4 ± 0.9A 0.37 ± 0.01A 6.53AMean 4.9 ± 0.6b 0.17±0.01 a 9.5 ± 0.9 c 0.31 ± 0.01 b 5.38 b

The particulate organic matter–C (POM-C) content closely followed similar trend to SOC content in different soil depths and

land use systems.

- Relationship between MBC (mg kg-1) and SOC (g kg-1) in AFS

MBC = 79.40 x SOC + 118.4 (1)

- Relationship between POM-C (g kg-1) and SOC (g kg-1) in AFSPOM-C = 0.415 x SOC - 0.147 (2)

- Relationship between MBN (mg kg-1) and MBC (mg kg-1) in AFSMBN = 0.038 x MBC - 0.52 (3)

- The regression relationship obtained for SOC to POM-C, MBC to SOC, MBN to MBC for all data were highly significant (P <0.01).

- Biomass production by Crotolaria tetragona was highest. On average, hedges accumulated 59.68, 11.95 and 28.31 kg ha-1 yr-1 of N, P and K, respectively.

- Maize cultivation in IIFS along with guava and other tree species. This conclusively proved that different AFS systems have significant role in SOC retention.

- As hedge and Alder based AFS had significantly higher SOC stock, POM-C and MBC than the Guava based AFS and the control plots, the former management practices are recommended for better soil carbon retention (and thus for mitigation of global warming) in the Indian sub-Himalayas.

This is one of the rare studies that evaluated rate of soil carbon retention by different agroforestry systems in the Indian Himalayas.