Crop residue management for

sustaining soil productivity and

environment health

Yadvinder Singh

PAU and CIMMYT

Production of crop residues in India-500 mt, Punjab -51 mt

Rice 34%

Crop Residues

• Residue production, although unavoidable, involves a major input of resources in the form of nutrients water, fuel, labour and time

•• 25% of N & P, 50% of S, 7525% of N & P, 50% of S, 75--85% of 85% of

K and 50K and 50--80% of micronutrients 80% of micronutrients

removed by the rice and wheat removed by the rice and wheat

crops are retained in strawcrops are retained in straw

Crop residues production and N content in million tons in Punjab

Item Rice Wheat Total

Total residues 22.0 20.5 42.5

Residue burnt 18.7 5.1 24.9

Total N in residues (mt) 0.11 (.09)

0.09 (.02)

0.20

(0.11)

Total N consumption mt)

1.4

(values in parenthesis(values in parenthesis--N lost during burning)N lost during burning)

Management options for crop residuesManagement options for crop residues

•• Burning (Partial/complete)Burning (Partial/complete)

•• InIn--situ recycling as stubble mulchsitu recycling as stubble mulch

•• Mulching material for crops other than Mulching material for crops other than rice/wheatrice/wheat

•• IncorporationIncorporation

•• CompostingComposting

•• Animal feedAnimal feed

•• Bio fuelBio fuel

•• ElectricityElectricity

•• Gasification of residuesGasification of residues

•• Building materialBuilding material

•• PaperPaper

Fuel

0%

Burnt

81%

Incorporation

11%

Composting

1%

Sold

2%

Fodder

5%

Present status of rice straw management Present status of rice straw management

in Punjabin Punjab

Burning of crop residues

About 140 Mt of residues are burned in field in India primarily to clear the field from straw and stubble after the harvest of the preceding crop.

• Unavailability of labour, high cost in removing the residues, interference with tillage and seeding operations, short interval between harvest and sowing of next crop, especially in the IGP are some of the reasons of burning crop residues in field.

• It is easy & cheapest way to remove large amount of residues as the primarily tool of convenience in field preparation & seeding.

• Burning is perceived to improve weed, insects & disease control but has no direct agronomic benefits.

Burning of crop residues

2) emission of greenhouse gases (GHGs) such as carbon dioxide, carbon mono oxide, methane and nitrous oxide causing global warming;

3) loss of plant nutrients such as N, P, K and S;

4) adverse impacts on soil properties and

5) wastage of valuable C and energy rich residues.

6) Accidental deaths

Burning of crop residues is unacceptable as it leads to:1) release of soot particles and smoke causing human health problems such as asthma or other respiratory problems,

OnOn--farm straw managementfarm straw management

•• Incorporation by using mould board plough, discs Incorporation by using mould board plough, discs

and rotavatorand rotavator

•• Surface retention as mulch using newly developed Surface retention as mulch using newly developed

machine called Happy Seedermachine called Happy Seeder

•• Collection, storage and use as surface mulch in Collection, storage and use as surface mulch in

other cropsother crops

•• Crop residues help in nutrient cycling, improve Crop residues help in nutrient cycling, improve organic matter, physical, chemical and biological organic matter, physical, chemical and biological properties of soil, and air quality. properties of soil, and air quality.

•• However, improvements in soil properties often do However, improvements in soil properties often do not flow to yield on short not flow to yield on short --term basis.term basis.

•• Phtytoxicity/pestsPhtytoxicity/pests

Straw incorporation (most difficult)

• The incorporation of rice residue before wheat planting is challenging for farmers because of the short interval between rice harvest and wheat planting.

• The incorporation of crop residue with high C–to–N ratio into soil typically results in microbial N immobilization and a temporary decrease in plant-available N. Maximum rate of N immobilization: 25-35 mg N per g of carbon (10-14 kg/t of rice straw)

• Incorporation or surface placement of crop residues may cause phytotoxicity and pest build up.

• We must examine each situation (soil, climate and crop rotation) on its merit for evaluating the effect of straw management on crop yields.

• The incorporation of paddy straw involves use of straw chopper followed by rotavator and allowing residue to decompose for 15-20 days and involves additional cost of Rs. 2500/ha.

Effect of management of rice straw in wheat and Effect of management of rice straw in wheat and

wheat straw in rice on mean (11 yrs) crop yields wheat straw in rice on mean (11 yrs) crop yields

(t ha(t ha--11) in RWS (Beri et al., 1995)) in RWS (Beri et al., 1995)

CropCrop RemovedRemoved BurnedBurned Incorp.Incorp.

RiceRice 5.505.50 5.655.65 4.634.63

WheatWheat 4.144.14 4.264.26 3.873.87

Factors affecting crop residue Factors affecting crop residue

decompositiondecomposition

A. Crop residue factors A. Crop residue factors

•• Composition (N, C:N ratio, cellulose, hemicellulose, Composition (N, C:N ratio, cellulose, hemicellulose, lignin, polyphenol), particle size, age of materiallignin, polyphenol), particle size, age of material

B. Soil and climatic factors B. Soil and climatic factors

•• pH, texture, available nutrients, moisture, pH, texture, available nutrients, moisture, temperature, aeration, microbial activity, rainfalltemperature, aeration, microbial activity, rainfall

C. Management factors C. Management factors

•• Loading rate, method and mode of application, time Loading rate, method and mode of application, time and frequency of application, irrigation, cropping and frequency of application, irrigation, cropping system, fertilization, (starter N) manure, microbial system, fertilization, (starter N) manure, microbial inoculation, earthworm populationinoculation, earthworm population

Effect of time of incorporation on Kinetics of Effect of time of incorporation on Kinetics of

in situ rice straw decomposition (Yadvinderin situ rice straw decomposition (Yadvinder--

Singh et al., 2004)Singh et al., 2004)

Effect of preEffect of pre--decomposition of rice straw decomposition of rice straw

on N immobilization (Y.S. et al., 2004b)on N immobilization (Y.S. et al., 2004b)

Effect of rice straw management on yield Effect of rice straw management on yield

(t/ha) and recovery efficiency of N (%) in RW (t/ha) and recovery efficiency of N (%) in RW

rotation , mean for 8 yrs (Yrotation , mean for 8 yrs (Y--Singh et al., 2004)Singh et al., 2004)

TreatmentTreatment Wheat yieldWheat yield REN(%)REN(%)

RemovedRemoved 4.94 b4.94 b 52 bc52 bc

BurnedBurned 5.10 ab5.10 ab 56 ab56 ab

Incorp. Incorp. --10DBS10DBS 4.95 b4.95 b 53 bc 53 bc

Incorp. Incorp. --20DBS20DBS 5.22 ab5.22 ab 53 bc 53 bc

Incorp. Incorp. --20DBS 20DBS

+25% N+25% N4.96 b4.96 b 49c49c

Incorp. Incorp. --40DBS40DBS 5.17 ab5.17 ab 54 ab 54 ab

Field after uniform distribution of rice straw and wheat

sown with Happy Seeder

Rice residue decomposition during wheat season as a function of time as affected by method of placement

(A). Sandy loam

y = 106.01e-0.0788x

R2 = 0.956

y = 135.69e-0.2373x

R2 = 0.989

0

20

40

60

80

100

120

0 20 40 60 80 100 120 140

Days after placement

% w

eig

ht

rem

ain

ing

Surface placement Subsurface placement

(B). Silt loam

y = 100.49e-0.0777x

R2 = 0.941

y = 123.41e-0.2097x

R2 = 0.940

0

20

40

60

80

100

120

0 20 40 60 80 100 120 140

Days after placement

% w

eig

ht

rem

ain

ing

Surface placement Subsurface placement

Release of N from rice residue at three wheat growth stages on sandy loam (mean for two yrs)-Residue load, 8t/ha

Growth

Stage

Residue

placement

Residue

decomposition

Nitrogen

released

Amount

(t/ha)

% of

initial

Amount

(kg/ha)

% of

initial

Maximum

tillering

Surface 1.4 17.2 -8∗∗∗∗ -

Buried 2.7 33.8 6 14.6

Boot stage Surface 2.1 26.5 -8 -

Buried 4.0 49.9 12 29.2

Maturity Surface 4.2 51.7 -7 -

Buried 6.5 81.2 28 64.6

Effect of straw management in wheat on the grain yield (t ha-1) of following rice

Treatment 2008

(After one

year)

2009

(After two

years)

Experiment 1 (Sandy loam)

No Mulch 7.10 6.51

With mulch 7.37 (3.8%) 7.27* (11.7%)

Experiment 2 (Silt loam)

No Mulch 7.65 7.40

With mulch 7.92 (3.5% ) 8.01* (8.2%)

FERTILIZER N MANAGEMENT GUIDELINES FOR ZT

WHEAT- literature survey

• The efficiency and N losses associated with the application method have a major impact on the success of nutrients in the CA systems.

• When possible, place N below the soil surface (about 5 cm beside and/or below the seed row) to minimize immobilization and volatilization.

• Apply urea before irrigation/rain. • Apply more N the first few years after conversion to NT due to tie-up and volatilization loss of N , especially with surface broadcasting of urea on fine-to medium-textured soils.

• Seed row N should not exceed 30-35 kg/ha as urea.• Factors that influence how much fertilizer can be safely applied with the seed include: row spacing, width of seed row, soil texture, moisture, organic matter, fertilizer placement, seed furrow opener, source, and crop.

Effect of straw management on urea hydrolysis and NH3 volatilization losses

Treatment Days for complete urea hydrolysis

% applied N loss in 16 days

- Straw 12 23.0

+ Straw 6 56.4

Effect of straw and urea placement on 15N recovery (%) by barley (Malhi et al., 1989)

Strawmanagement

Grain yield (t/ha) 15 N recovery (%)

UreaIncorp.

Ureabanded

UreaIncorp.

Ureabanded

No straw 3.44 3.46 49 54

Straw incorp. 2.81 3.27 42 53

Effect of method & time of N application on yield & NUE of wheat under straw mulch (3 yrs’ mean)

Treatment (D-drill at sowing-

1st irrig.-2nd irrig.) B-broadcast

Grain yield

(t/ha)

Apparent N

recovery (%)

No N control 2.49 -

25D+35B–60–0 4.42 45.0

25D+35B -30- 30 4.29 44.1

25D+65B-0– 30 4.17 41.9

25D+95B - 0– 0 4.02 39.1

25D - 48 – 48 4.79 56.7

25D+35PSI-60-0 4.37 47.8

25D+35PSI–30-30 4.36 49.4

25D+65PSI-0-30 4.36 45.3

25D+95PSI-0-0 4.40 45.4

Effect of high doses of fertilizer N applied at sowing using modified furrow

openers on wheat yield

Treatment (% of 120 kg N/ha as urea)

Furrow opener Grain yield (t/ha)

50% unmodified 4.79a ± 0.26

modified 4.80a ± 0.18

80% unmodified 3.76b ± 0.19

modified 4.92a ± 0.18

20% unmodified 5.10a ± 0.24

Unmodified- seed and fertilizer in the same row; Modified- fertilizer placed in between two rows

Use of straw mulch in other crops

• Greater advantage in summer crops Mentha, turmeric, sunflower, spring maize, sugarcane, potato, chillies, maize/sorghum fodder

• Reduction in evaporation losses, moderating soil temperature

• Increasing soil N mineralization thereby economizing use of fertilizer N,

• Magnitude of yield gain 5-30%, saving in 7-40 cm of irrigation water

Effect of rice straw mulch on the red chillies yield (t/ha). Averaged for three

years (Sekhon et al., 2008)

Straw

mulch

N rate (kg/ha) Mean

45 75 105

No

mulch

13.3 14.9 15.8 15.1

Straw

mulch

16.0 17.3 17.9 17.5

Burning of wheat straw during 2012

Effect of wheat straw management practices Effect of wheat straw management practices

on mean yield (t/ha) and REN (%) in RWS on mean yield (t/ha) and REN (%) in RWS

(1988(1988--2001)2001)

TreatmentTreatment Rice yieldRice yield Recovery Recovery

efficiencyefficiencyWheat Wheat

yieldyield

WS WS

RemovedRemoved5.74a5.74a 38 ab38 ab 4.41 ab4.41 ab

GMGM 5.70 a5.70 a 39 a39 a 4.41 ab4.41 ab

WS Incrop.WS Incrop. 5.37b5.37b 32 b32 b 4.32 b4.32 b

WS Incorp. WS Incorp.

+GM+GM5.76a5.76a 42 a42 a 4.44 a4.44 a

Wheat straw management left after Wheat straw management left after

using straw combine (1using straw combine (1--2 t/ha) 2 t/ha)

Treatment Mean rice yield (t/ha)

Complete removal 7.6a

WS incorporated at field preparation

7.6a

WS incorporated at 2 WBT 7.5a

WS incorporated at 4 WAT 7.5a

Direct seeding of mungbean (67% N to rice)

7.6a

Tillage and Residue Management in wheat on permanent raised beds (PB) in Mexico. Lemon-Ortega et al. (2001)

Treatment Grain yield (t/ha)(mean for 6 yrs )

Conven.till beds- straw incorp. 5.55a

PB- straw burned 5.59a

PB- straw removed 5.55a

PB- straw incorp. 5.89b

Effect of tillage and rice straw mulch on wheat yield (t/ha) in rice-wheat system

Rice

Treatments

Wheat treatments

CT ZT-SR ZT-SM (HS)

2010-11

CT-DSR 4.88 3.57 4.79

ZT-DSR 4.91 3.51 4.82

PTR 4.81 4.04 4.85

Mean 4.87 3.71 4.82

2011-12

CT-DSR 5.22 4.48 5.54

ZT-DSR 5.58 3.60 5.35

PTR 5.15 4.92 5.65

Mean 5.32 4.33 5.51

Effects of mulching in rice on water Effects of mulching in rice on water

consumption , yield and WUE in riceconsumption , yield and WUE in rice--rice rice

system (Jiangsystem (Jiang--tao et al., 2006)tao et al., 2006)

Treatment

Irrigat-ionm3/ha

ET m3/ha

Seepage(m3/ha)

Yield (t/ha)

WUE kg/m3

PTR -F 19950a 7990a 13560a 6.81a 0.311b

NF 8230b 5080b 4750b 4.72b 0.462b

NF + Mulch

6030c 3050c 4680b 6.49a 0.810a

Crop residues as animal feedCrop residues as animal feed

•• Straws are a poor livestock feed, and rice straw is no exceptionStraws are a poor livestock feed, and rice straw is no exception. .

•• Straws contain only 3 to 5% crude protein. For good growth on stStraws contain only 3 to 5% crude protein. For good growth on straw raw

diets, a level of 8 to 10% protein is needed for young stock; thdiets, a level of 8 to 10% protein is needed for young stock; this also is also

improves consumption and thus increases energy intake.improves consumption and thus increases energy intake.

•• Rice straw differs from other straws in having a higher content Rice straw differs from other straws in having a higher content of of

silica (12silica (12––16 vs. 316 vs. 3––5%) and a lower content of lignin (65%) and a lower content of lignin (6––7 vs. 107 vs. 10––

12%). Whereas in all other straws lignin is the chief cause of l12%). Whereas in all other straws lignin is the chief cause of low ow

digestibility, in rice straw it is silica. digestibility, in rice straw it is silica. Rice straw in the western IGP Rice straw in the western IGP

contains more silica compared the straw from the other reasons (contains more silica compared the straw from the other reasons (need need

data??). data??).

•• Rice straw stems are more digestible than leaves because their Rice straw stems are more digestible than leaves because their silica silica

content is lower; therefore the paddy crop should be cut as closcontent is lower; therefore the paddy crop should be cut as close to e to

the ground as possible if the straw is to be fed to livestock. the ground as possible if the straw is to be fed to livestock.

•• Protein supplements increase intake, while the alkali treatment Protein supplements increase intake, while the alkali treatment of of

straws increases digestibility and usually voluntary intake as wstraws increases digestibility and usually voluntary intake as well. ell.

Composting of residues for manure

• The residues can be composted by using it as animal bedding and then heaping in dung pit. Each kg of straw absorbs about 2-3 kg of urine from the animal shed.

• Can also be composted by alternative methods on the farm itself.

• The residues of rice from one hectare give about 3.2 tons of manure as rich in nutrients as FYM.

• Valued added compost can contain 1.5% N, 2.3% P2O5 and 2.5% K2O

Bioethanol Production from Rice Straw

• Using rice straw as lignocellulosic biomass to produce bioethanol would appear to be a promising and ambitious goal to both manage this agricultural waste and to produce environmentally friendly biofuel.

• Technical difficulties, however, associated with the conversion of lignocellulose into simple, fermentable sugars, have hampered the massive development of rice-straw-derived bioethanol.

• Recent technical advances in straw pre-treatment, hydrolysis and fermentation may, however, overcome these limitations and facilitate a dramatic turnover in biofuels production in the near future.

• Agnienergy Corporation Ltd. Has already established pilot plant in Mohali & likely to start commercial production of ethanol. Working on utilization of liquid and solid wastes.

• Total potential can never be more than 10% of the total residues proudced

Biomethanation and Biochar

• Biomass such as rice straw can be converted to biogas, a mixture of carbon dioxide and methane and used as fuel. It is reported that biogas of 300 m3 t-1 of rice straw can be obtained. The process yields good quality of gas with 55-60% of methane and the spent slurry can be used as manure. This process promises a method to utilize crop residues in a non-destructive way to extract high quality fuel gas and produce manure to be recycled in soil. (Economics???)

• Biochar is a high carbon material produced from the slow pyrolysis (heating in the absence of O2) of biomass. Can be used as soil amendment to store C , reduce GHG emissions and increase nutrient use efficiency. (Economics??, Data??)

Effect of crop residue management on soil properties after11 yr of RWS at Ludhiana ( Beri et al., 1995)

Property Removed Burned Incorporated

Total N (mg/kg) 1140 1236 1343

Total p (mg/kg) 420 390 612

Total K (%) 1.54 1.71 1.81

Olsen-P (mg/kg) 17.2 14.4 20.5

NH4OAc-K (mg/kg) 45 58 62

Dehydrogenase activity

33 36 52

Phosphatase activity

135 125 175

Effect of rice residue recycling in wheat on soil fertility after two yrs ( 2008-09)

Soil

property

Silt loam Sandy loam

- straw +straw - straw +straw

Organic

carbon

(g/kg)

5.3 5.8* 3.9 4.5*

Olsen-P

(kg/ha)

5.3 6.8* 17.1 18.6

NH4OAc-K

(kg/ha)

159 173* 95 105*

Effect of crop residue management on soil physical properties (NSW, Australia)

Property Incorp. Burn

Organic carbon (%) 0.8 0.55

WSA (%) 15 8

Bulk density (Mg/m3) 1.3 1.6

Hydraulic

conductivity

(mm/h)

50 15

Sub soil strength (kPa) under

different tillage optionsLocation Time (yrs) of Roto

Seeder in useCT HS N Total

no. offields3 2 1

GurusarKaunke

3220 2887 - 2241 1522 120 24

Sangrur 3579 3160 2548 2274 2090 135 27

Mean 3400 3024 2548 2258 1806 255 51

Roto-seeder is a rotavator with attachment of seed-cum fertilizer box on the top.

Wheat Productivity and Soil compaction under

different tillage systems (BR Kamobj, CSISA Hub, Karnal)

Wheat canopy temperature during

third week of March, 2010 (n=76)

10

15

20

25

30

35

18-Oct-03 26-Oct-03 03-Nov-03 11-Nov-03 19-Nov-03

Temperature (oC)

Mulch

Bare

Max.

Min. Bare

Bare

Mulch

Mulch

Effect of residue management on soil temperature (5 cm)

Sidhu et al. 2007

8

7

Sowing-Flowering,

113

Sowing-Flowering,

103

Sowing-Maturity, 154

Sowing-Maturity, 148

0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300

Mulch

Non-mulch

Germination Sowing-Flowering Sowing-Maturity

Sowing Date- 13/11/2008

Effect of Straw mulch on Wheat Phenology

Cummulative Es (mm) 2007-08

0

20

40

60

80

100

120

140

160

180

4/11/2007 4/12/2007 3/01/2008 2/02/2008 3/03/2008 2/04/2008 2/05/2008

Soil E

vapora

tion (m

m)

Mulch Ep Non-mevp

Soil evaporation undermulch and no mulch during wheat

Effect of mulching on soil water Effect of mulching on soil water

content prior to irrigation to wheatcontent prior to irrigation to wheat

0

20

40

60

4 6 8 10 12 14

Gravimetric water content (%)

De

pth

(c

m)

no mulch

mulch

Prior to 1st irrigation

0

20

40

60

4 6 8 10 12 14

Gravimetric water content (%)

De

pth

(c

m)

no mulch

mulch

Prior to 2nd irrigation

Effect of irrigation and rice straw mulch (4 t/ha)on grain yield and WUE (kg grain/ha/cm) in wheat (Hari Ram, personal communication)

Irrigation level (Number)

Grain yield (t/ha) Water use efficiency

No mulch + Mulch No Mulch + Mulch

2 4.3 5.2 133 162

3 5.0 6.0 130 158

4 5.2 6.4 106 139

5 5.6 6.4 103 118

Lsd (0.05)= Yield-0.31; WUE-3.2

Challenges with residue management

• Disease, insect or weed problems and difficulties in proper seed, fertilizer and pesticide placement.

• Nutrient management is more complex with crop residue management because of higher residue levels and reduced options with regard to method and timing of nutrient applications.

• No-till in particular can complicate manure application and may also contribute to nutrient stratification within soil profile from repeated surface applications without any mechanical incorporation.

• Limiting factor in adoption of residue management systems for some farmers include additional management skill requirements , apprehension of lower crop yields and/or economic returns, negative attitudes or perceptions, and institutional constraints.

Research needs for efficient residue

management

• Reliable data on yields and chemical composition of both above- and below-ground crop residues are needed in order to interpret soil OM dynamics and nutrient cycling.

• Better quantification of mineralization-immobilization , decomposition rates , ammonia volatilization and leaching losses will be useful. Use of labelled residues for generating better information.

• Evaluation and breeding of rice cultivators with more root biomass.

• Si content in rice straw under different soil and water management situations needs investigation.

• Further improvement in the machinery used for planting, fertilizer drilling, and pesticide application.

Research Agenda

-Developing complete package of practices (fertilizer, irrigation, weed control, pest management, etc.) of CA for each agro-ecological region.

Establishment of long-term expts. at different sites & soil types. Long term studies will provide useful database for simulation modelling and economic analysis. Many changes in soil quality become apparent after several years (10 yrs or more).

-Investigate largely unexplained benefits that arise from residue recycling, such as microbiological, BNF, pest suppression, etc.-Multidisciplinary approaches are needed to problems (genotypes, machinery, insects, diseases, weeds, phytotoxicity, soil physical, chemical& biological properties, and economics) associated with residue management

Policy needs for efficient residue management

• Monitoring and discouraging burning of crop residues through incentive and punishment.

• Supplying machineries on subsidized rates and providing soft loans. Subsidies have been an important component in helping

make the technology affordable during the awareness raising phase.

• Promoting custom hiring systems for agricultural implements.

• Establishing self-help groups and encouraging unemployed youth to take up custom hiring of CA machineries as profession.

• Medium farmers have the opportunity to supplement their farm income by the purchase of Happy Seeder for use on their own and neighbouring farmers. At current hire rates, this business model will provide reasonable returns on the investment, but operators need to be aware of the risks involved.

• Capacity building through training