Increasing Land Degradation

Girish Chander, Suhas P Wani and Team/ Asia Regional Planning Meeting/ ICRISAT-Patancheru/04 May 2016)

Widespread global land degradation !

• Land degradation - a temporary or permanent decline in the productive capacity of the land, or its potential for environmental management.

• 2 billion ha (22.5%) out of 8.7 billion ha degraded; support ~1.5 billion people

• Cost of land degradation – 300 billion USD per annum

• Causes - Water & wind erosion, nutrient and or soil organic C depletion, waterlogging, compaction, salinization, acidification, pollution.

• Soil chemical degradation like nutrient-loss accounts for >40% of cropland degradation.

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Agricultural Land PermanentPasture

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Total Land Degraded Land

[38%][18%][21%]

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AgriculturalLand -Africa

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Africa

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Africa

Million ha

Non-Degraded Land Degraded Land

[38%]

[19%]

[27%]

[31%]

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[65%]

A global perspective A regional perspective

Land degradation in ‘Drylands’

• Drylands (arid, semi-arid, sub-humid) - 40% of world total land

• 47% of rainfed cropland degraded

• People affected – 40% of world population living in Drylands; ~1400 million (42% of region population) in Asia; ~270 million (41%) in Africa

Drylands in the world

Land Degradation & Implications

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Observed Yield Gap between Farmers’ Yield and Achievable Yields

Long-term experiment at ICRISAT: Large untapped potential

Provisioning services• Food, fibre, fuel supply• Productivity losses due to land degradation in

drylands = US$13 billion to $28 billion year-1

Regulating services• Climate regulation (CO2, CH4, N2O emissions)• Water quality (Filtering, buffering substances)• Water supply (Infiltration, drainage)

Supporting services• Primary production (medium for root growth)• Nutrient cycling (transformation of organic

materials, retention/release of nutrients)

Cultural services• Landscape diversity

Nutrient mining or imbalances

• Globally, chemical soil degradation mainly soil nutrient loss accounts for more than 40 percent of cropland degradation.

• Infertile soils a major contributor to the yield gap.

• Bhoochetana, watersheds findings on soil health mapping based management – 20%-70% yield increase, 3 – 14 : 1 B:C ratios for farmers.

State% deficiency w.r.t. available nutrients in India

N* P K S B Zn

Karnataka 52 41 23 52 62 55

Andhra Pradesh 76 38 12 79 85 69

Madhya Pradesh 22 74 1 74 79 66

Rajasthan 38 45 15 71 56 46

Tamil Nadu 57 51 24 71 89 61

Jharkhand (Gumla) 33 23 27 100 93 73

Jharkhand (Saraikela) 45 80 58 69 98 71

*Deduced from % low levels of soil organic carbon;

Organic C,Karnataka

• Currently stresses in the nitrogen cycle, climate change are beyond safe operating ‘planetary boundaries’.

Land management & N use efficiency

NUpE (Nitrogen uptake efficiency) = Total plant N uptake/N supply[N-supply means sum of N applied as fertilizer and total N uptake in control]

NUtE (N utilization efficiency) = Grain yield/Total plant N uptake;NUE (N use efficiency) = Grain yield/N supply;NHI (N harvest index) = N in grain/Total N uptake

TreatmentNUpE NUtE NUE NHI

(kg kg-1) (kg kg-1) (kg kg-1) (%)

NP 0.37 80.7 30.1 67NP+SBZn-(every yr) 0.46 78.5 36 61NP+50%SBZn-(every yr) 0.51 92.5 47.3 66NP+SBZn-(once in 2 yr) 0.47 84.4 39.7 69NP+50%SBZn-(once in2 yr) 0.42 80.8 34.1 67LSD (5%) 0.11 17.4 8.85 11

Soil need based management at ICRISAT, Patancheru, Maize crop, rainy season 2010

Watershed catchment management

Year Rainfall Runoff Soil loss(mm) (mm) (t ha

-1)

Untreated Treated Untreated Treated

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2000 1161 118 65 4.17 1.46

2001 612 31 22 1.48 0.512002 464 13 Nil 0.18 Nil

2003 689 76 44 3.2 1.12004 667 126 39 3.53 0.532005 899 107 66 2.82 1.22006 715 110 75 2.47 1.562007 841 115 82 4.5 2.09

2008 1387 281 187 8.94 4.5Mean 802 99.3 72.5 3.48 1.62

ICRISAT, Patancheru

Mean ~800 220 91 6.64 1.60

• 114 M ha degraded lands in India – water erosion & Vegetaldegradation with water erosion major factor

• Watershed management is one of the most trusted and eco-friendlyapproaches to managing soil and rainwater resources

• Reduced soil loss

Soil & Carbon-cycle

Biota600 Pg C

Atmosphere750 Pg C

Soil (to 2-m depth)

2500 Pg C (billion tons)

100 Pg Yr-1

100 Pg Yr-1

Respiration

Photosynthesis

• Climate change - more people and larger areas of land in drylands to be affected• A global loss of 70 to 90 billion tons C through land misuse and soil degradation• 2.1 billion t C year-1 global potential of C-sequestration in soil• 10% increase in soil organic C pool in world soils over the 21st century implies a

drawdown of about 110 ppm of atmospheric CO2

Depleted soil organic C

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Soil org C in pilots in AP

Low levels of soil organic C – major stumbling block for enhancing productivity and livelihoods

Soil Management & C-Sequestration

Additional 7.3 t C ha-1 (335 kg C ha-1 yr-1) sequestered under IM over 24-year period

CaCO3 content of IM decreased from 6.2 % under FM system to 5.7 %

C inputs increased with continuous cropping and soil test-based balanced fertilizers application and when legumes were included

Properties System Soil depth (cm)

0 to 60 60 to 120

Organic C (t C ha-1)Improved 27.4 19.4Traditional 21.4 18.1

Long term study at ICRISAT

An increase of 1 ton of soil carbon pool of degraded cropland soils may increase crop yield by 200 to 400 kg ha-1 for maize, 20 to 70 kg ha-1 for wheat, 20 to 30 kg ha-1 for soybean, 5 to 10 kg ha-1 for cowpeas, 10 to 50 kg ha-1 for rice, 50 to 60 kg ha-1 for millets and 20 to 30 kg ha-1 for beans.

An increase in the soil organic C pool within the root zone by 1 t C ha-1 year-1

can enhance food production in developing countries by 30 to 50 Mt year-1.

Management for Soil Health

Properties System Soil depth (cm)

0 to 60 60 to 120

Microbial biomass C (kg C ha-1)Improved 2676 2137Traditional 1462 1088

Organic C (t C ha-1)Improved 27.4 19.4Traditional 21.4 18.1

Microbial biomass N (kg N ha-1)Improved 86.4 39.2

Traditional 42.1 25.8

Total N (kg N ha-1)Improved 2684 1928

Traditional 2276 1884

Olsen-P (kg P ha-1)Improved 6.1 1.6

Traditional 1.5 1

Soil microbial biomass C serves as a surrogate for soil quality

Soil microbial biomass C responds more rapidly than soil organic C to changes in management

Higher (10.3 vs. 6.4%) biomass C as a proportion of soil organic C (up to 120 cm soil depth) under improved management

Biomass N comprised about 2.6% of total soil N in the improved system, whereas in the traditional system it constituted only 1.6%.

Long term study at ICRISAT

• Best entry point activity for harnessing low hanging fruits – Bhoochetana(Karnataka, AP), watersheds - >7 million ha; 5million families.

• Use of microbial consortia and earthworms for enriched composts forsoil C-building and to cut cost of chemical fertilizers

• Cultivating post-rainy fallows – Jharkhand example of cultivatingchickpea (KAK-2; JG-11) (1520-1340 kg ha-1 yield)

• Cultivating rainy fallows – MP example of cultivating soybean (1400-2500kg ha-1 yield)

• For exploiting varietal potential – Rajasthan case: 40% increase with varbut 140% with var+BN

• Shifting to high value agriculture – Karnataka case, 2011: Rs 20000-50000 additional returns with BN

• Enhancing rainwater use efficiency – soybean in MP, 2010: 1.48-3.45 kgmm-1 ha-1 improved to 2.07-4.38 under INM.

• Resilience-building - Benefits of balanced fertilization particularlymicronutrients observed in 3 succeeding seasons in crop yields

• Soil Test-Based Fertilization for Nutrition and Produce Quality

Scaling-out/up land rejuvenation in drylands

Conclusions & Way Forward

• Minimize further degradation of soils and restore the productivity of soilsthat are already degraded in regions where people are most vulnerable

• Stabilize global stores of soil organic carbon and soil organisms

• Stabilize or reduce global use of nitrogen and phosphorus fertilizer, whileincreasing fertilizer use in regions of nutrient deficiency

• Improve our knowledge about the state and trend of soil conditions

o “Soils are the foundation of food production and food security, supplying plants withnutrients, water, and support for their roots.

o Soils function as Earth’s largest water filter and storage tank;

o Soils contain more carbon than all above-ground vegetation & atmosphere, henceregulating emissions of carbon dioxide and other greenhouse gases;

o Soils host a tremendous diversity of organisms of key importance to ecosystem processes.”

Thank you!

ICRISAT is a member of the CGIAR Consortium