Recycling of crop residues for improved soil nutrient€¦ · • Retention of crop residues on the...
Transcript of Recycling of crop residues for improved soil nutrient€¦ · • Retention of crop residues on the...
Recycling of crop residues for
improved soil nutrient status
and farm income
Dr BASUDEV BEHERA
PROFESSOR & HEAD
DEPARTMENT OF AGRONOMY
CA, OUAT, BHUBANESWAR
05.02.2018
Crop residues• Crop residues are parts of the plants left
in the field after crops have been harvested and threshed.
• In India there are 500-550 million tones (Mt) of crop residues are produces annually
• Gadde et al. (2009) estimated that the • Gadde et al. (2009) estimated that the burning of rice straw contributed 0.05% of the total amount of greenhouse gas (GHG’s) emissions in India, which not only lead to loss of huge biomass, i.e. organic carbon, plant nutrients, but also cause adverse effect on soil properties as well as soil flora and fauna.
Crop residue – Types
a) Crop wastes of cereals, pulses,
oilseeds(Rice, wheat, jowar, bajra,
greengram, blackgram, cowpea,
pigeonpea, groundnut, linseed,
other crops)other crops)
b) Stalks of maize, cotton, jute,
tapioca leaves etc)
c) Other wastes – rice husk, saw
dust, tea waste
Crop residue availability-
Globally
Globally, the total crop residue
production is estimated at 3.8 billion
tons per year(Lal, 2005).
• 74% from cereals• 74% from cereals
• 8% from legumes
• 3% from oil crops
• 10% from sugar crops
• 5% from tubers
Crop residue potential in
India
The Ministry of New and Renewable Energy (MNRE, 2009), Govt. of India has estimated that about 500 Mt of crop residues are generated every year.
1. Cereals - 352 Mt
year.
1. Cereals - 352 Mt
2. Fibres - 66 Mt
3. Oilseeds - 29 Mt
4. Pulses - 13 Mt
5. Sugarcane - 12 Mt
Cereals - cereal crops (rice, wheat, maize, millets) contribute 70%. Rice crop alone contributes 34% to the crop residues. Wheat ranks second with 22% of the crop residues
Fibres - Fibre crops contribute 13% to the crop residues generated from all crops. Among fibres, cotton generates maximum (53 Mt) with 11% of crop maximum (53 Mt) with 11% of crop residues. Coconut ranks second among fibre crops with generation of 12 Mt of residues.
Sugarcane - Sugarcane residues comprising of tops and leaves, generate 12 Mt, i.e., 2% of the crop residues in India.
State Crop
residues
generation,
(MNRE,
2009)
Crop
Residues
surplus(MNR
E, 2009)
Crop
residues
burnt (based
on IPCC
coefficients)
Crop surplus
residues
burnt
(Pathak
et al. 2010)
HP 2.85 1.03 0.20 0.41
J & K 1.59 0.28 0.35 0.89
Jharkhand 3.61 0.89 1.11 1.10Jharkhand 3.61 0.89 1.11 1.10
Karnatak 33.94 8.98 3.05 5.66
Kerala 9.74 5.07 0.40 0.22
MP 33.18 10.22 3.74 1.91
Maharashtra 46.45 14.67 7.82 7.41
Manipur 0.*0 0.11 0.14 0.07
Meghalaya 0.51 .09. 0.10 0.05
Nagaland 0.49 0.09 0.11 0.08
Odisha 20.07 3.68 2.61 1.34
Punjab 50.75 24.83 9.84 19.62
Rajasthan 29.32 8.52 3.84 1.78
Sikkim 0.15 0.02 0.01 0.01
Tamilnadu 19.93 7.05 3.62 4.08Tamilnadu 19.93 7.05 3.62 4.08
Tripura 0.04 0.02 0.22 0.11
Uttarakhand 2.86 0.63 0.58 0.78
UIttar
Pradesh
59.97 13.53 13.34 21.92
West Bengal 35.93 4.29 10.82 4.96
India 501.76 140.84 91.25 92.81
Fate of crop residues
Left on the soil surface - Eaten by
roaming cattle or allowed for grazing
of cattle by farmer itself
Multi-purpose uses in household
• Removed from the field and
transported to houses to serve for
multi-purpose uses in the
household as thatching material
and fuel. and fuel.
Crop residues as compost
For preparing compost, crop residues are used as animal bedding and then heaped in dung pits. In the animal shed each kilogram of straw absorbs about 2-3 kg of urine, which enriches it with N. The residues of rice crop from one hectare land, on composting give about 3 tons of manure as rice crop from one hectare land, on composting give about 3 tons of manure as rich in nutrients as farmyard manure (FYM). The rice straw compost can be fortified with P using indigenous source of low grade rock phosphate to make it value added compost with 1.5 % N, 2.3 % P2O5 and 2.5 % K2O (Sidhu and Beri 2005)
Mushroom cultivationUse of residues in mushroom production
represents a valuable conversion of inedible crop residues into valuable food, which despite their high moisture content has two to three times as much protein as common vegetables and an amino acid composition similar to that of milk or meat. of milk or meat.
Wheat and rice straws are excellent substrates for the cultivation of Agaricus bisporus (white button mushroom) and Volvariella volvacea(straw mushroom), two of the four most commonly grown fungi.
Crop residues as bio-fuelBiofuel is an important strategy to reduce
dependence on fossil fuel.
Conversion of ligno-cellulosic biomass into alcohol is of immense importance, as ethanol can either be blended with gasoline as a fuel extender and octane enhancing agent or used as a neat fuel enhancing agent or used as a neat fuel in internal combustion engines.
Theoretical estimates of ethanol production from different feedstock (corn grain, rice straw, wheat straw, bagasse and saw dust) vary from 382 to 471 l t-1 of dry matter.
Crop residues as biocharBiochar is a fine-grained charcoal
having high carbon material produced through slow pyrolysis(heating in the absence of oxygen) of biomass. It can potentially play a major role in the long-term storage of carbon in soil.
Biochar converted from plant Biochar converted from plant biomass contains a unique recalcitrant form of carbon that is resistant to microbial degradation, therefore can be used as a carbon sequester, when applied to soil
Crop residues as livestock feed
• Cultivation of forage crops in
tropical developing countries has
been limited due to inadequate
technical support, such as non technical support, such as non
availability of quqlity forage
seeds/planting materials. Small
farmers in rural areas depend on
crop residues to feed livestock.
Crop residue as surface mulch• Residue retention on the surface of soil seems to be a
better option for conservation of soil and avoiding water losses by evaporation.
• It also reduces the weed seed germination and helps in building of soil microbial populations results in increasing soil organic carbon- a direct indicator of soil health.
• Zero-till wheat has been adopted in the rice wheat • Zero-till wheat has been adopted in the rice wheat system in the northwest IGP with positive impacts on wheat yield, profitability and resource use efficiency.. New advance generation seed drill is evolved for this purpose.
• The Happy seeder works well for direct drilling in standing as well as loose residues provided the residues are spread uniformly.
Burnt prior to tillage or land
preparation
• A large portion of the residues is burnt on-farm primarily to clear the field for sowing of the succeeding crop.
The problem of on-farm burning of • The problem of on-farm burning of crop residues is intensifying in recent years due to shortage of human labour, high cost of removing the crop residues by conventional methods and use of combines for harvesting of crops.
• The residues of rice, wheat,
cotton, maize, millet, sugarcane,
jute, rapeseed-mustard and
groundnut are typically burnt on-
farm across different states of the
country. country.
• The problem is more severe in the
irrigated agriculture, particularly in
the mechanized rice-wheat system
of the northwest India.
Crop residue BurntThe farmer is not only cleaning his field, but also
'cleaning his pockets' by burning the potential
fertility of his soil.
Effect of crop residues on
soil properties
Incorporation of crop residues into
soil or retention on the surface soil or retention on the surface
has several positive influences on
physical, chemical and biological
properties of soil.
Year Burnt Incorporate
d
CD(P=0.05) Increase
in yield
1993-94 4.27 4.36 0.27 0.09
1994-95 4.38 4.50 0.28 0.12
1995-96 4.09 4.29 NS 0.20
19896-97 4.85 4.78 NS -
Wheat yield as influenced by rice residue management(Sidhu and Beri)
** Wheat sown late, * Rice straw incorporated 203 weeks before wheat sowing
19896-97 4.85 4.78 NS -
1997-98 4.85 5.21 NS 0.36
1998-99 4.25 4.37 NS 0.12
1999-2000 4.55 5.71 NS 0.16
2000-2001 4.73 4.87 0.12 0.14
2001-02 4.01 5.97 NS -
2002-03 4.70 4.20 0.12 0.50
2003-04** 4.10 3.90 0.30 -
Physical Chemical Biological
Soil erosion Soil organic
matter content
and quality
Carbon and
nutrients in
microbial biomass
Soil aggregation Nutrient status
and availability
Microbial activity
Soil parameters
and availability
Soil bulk density Soil pH Microbial diversity
Soil hydraulic
properties
Cation Exchange
Capacity
Meso and macro
fauna population
and activitiesSoil WHC
Soil moisture and
temperature
Soil erosion• Leaving substantial amounts of
crop residues evenly distributed over the soil surface reduces wind and water erosions, and reduces surface sediment and water runoff.runoff.
• Crop residues act as physical buffer and protect soil from the direct impacts of rain and wind leading to reduced runoff and erosion.
• Retention of crop residues on the
soil surface slows the runoff by
acting as tiny dams, reduces
surface crust formation and
enhances infiltration.
• The channels (macro pores)
created by earthworms and old
• The channels (macro pores)
created by earthworms and old
plant roots, when left intact with
no-till, improve infiltration to help
reduce or eliminate runoff.
Soil aggregation
• Addition of organic matter to the
soil favours formation of
aggregates. Structural stability
increases due to addition of increases due to addition of
straw. Better aggregate size
distribution occurs due to a
reduction in soil disturbance.
Tillage and weed management for maize
(Zea mays L.) in rice-maize cropping
system(Modak and Behera, 2014)
Main plot treatments (Tillage
methods)methods)
CT : Conventional tillage
MT : Minimum tillage
ZT : Zero tillage + Glyphosate
(Glyphosate @ 1 kg/ha)
Treatme
ntpH
EC
(dS/m)
OC
(%)
BD
(g/cc)
Macro-
aggregate
s % (>250
µm)
Micro-
aggregate
s %
(53 -250
µm)
Tillage Methods (CT,MT,ZT)
Soil physical properties is influenced
by tillage method
CT 6.21 0.52 0.692 1.48360.27
18.23
MT 6.16 0.51 0.696 1.47566.49
17.76
ZT 6.13 0.46 0.788 1.44370.88
11.90
SE(m) ± 0.03 0.01 0.004 0.013 0.96 0.53
CD(P=0.0
5)NS 0.02 0.017 NS 3.78 2.07
CV 2.02 4.48 2.565 3.663 6.20 14.03
Soil bulk density
• Incorporation of straw with FYM
reduces the bulk density of soil
and increases the porosity of the
soils.soils.
Soil hydraulic properties
Crop residues increase hydraulic
conductivity by improving soil
structure, microspores and
aggregate stability. aggregate stability.
Soil water holding capacity
• Residue incorporation raises
organic matter content of the soil.
Leading to improvement in water
holding capacity of the soil.holding capacity of the soil.
Soil temperature
• Mulching with plant residues
raised the minimum soil
temperature in winter due to
reduction in upward heat flux reduction in upward heat flux
from soil and decrease soil
temperature during summer due
to shading effect.
Soil moisture
• Presence of crop reduces
evaporation rate due to increase
in amount of residues on the soil
surface and helps in retaining surface and helps in retaining
moisture in the soil.
Crop Nutrient
N P K
Rice 0.61 0.09 1.15
Wheat 0.48 0.07 0.98
Nutrient content in crop residues
Wheat 0.48 0.07 0.98
Maize 0.58 0.09 1.25
Jowar 0.52 0.12 1.21
Bajra 0.45 0.07 0.95
Barley 0.52 0.08 1.25
Sugarcane 0.45. 0.08 1.20
Potato 0.52 0.09 0.85
Soil organic matter content
and quality
Continuous addition of crop residue
increases organic matter status
of soil. crop residues
favourcarbon sequestration in favourcarbon sequestration in
soils.
Nutrient status and availability
• Soil OM acts as reservoir for
essential plant nutrients, prevents
leaching of elements, required for
growth and increases CEC.growth and increases CEC.
Soil property Crop residue management
Burned Removed Incorporated
Total P (mg
kg -1)
390 420 612
Total K(mg
kg -1)
17.1 15.4 18.1
Effect CRM on soil fertility in 11 years
of rice – wheat system(Beri et al, 1995)
kg -1)
Olsen’s P(mg
kg -1)
14.4 17.2 20.5
Available
K(mg kg -1)
58 45 52
Available
S(mg kg -1)
34 55 61
Soil pH
The crop residues play an
important role in amelioration of
soil acidity through the release of
hydroxyls especially during the hydroxyls especially during the
decomposition of residues with
higher C:N, and soil alkalinity
through application of residues
from lower C:N crops, including
legumes, oilseeds and pulses.CEC
CEC
• Soil OM as reservoir for essential
plant nutrients, prevents leaching
of elements, required for growth.
Addition of residues increases Addition of residues increases
CEC.
Carbon and nutrients in
microbial biomass
Increased microbial biomass can
enhance nutrient availability in
soil as well as act as sink and
source of plant nutrients.source of plant nutrients.
Microbial activity
• Crop residues provide energy for
growth & activities of microbes &
substrates for microbial biomass.
• Crop residues enhance activities • Crop residues enhance activities
of enzymes such as urease,
dehydrogenase and alkaline
phosphatase.
Treatment
Microbial population
Bacteria
CFU/ml
(X×105)
Actinomy
cetes
CFU/ml
(X×104)
Fung
us
CFU/
ml
(X×103)
MBC
(µg
C/g
soil)
Soil Microbial Biomass Carbon (MBC)
and microbial population
3)
Tillage Methods (CT,MT,ZT)
CT Conventional tillage 72.0 217.5 42.7 278.3
MT Minimum Tillage 78.0 228.6 47.8 289.3
ZTZero tillage +
Glyphosate
96.0 248.6 55.9314.0
SE(m) ± 2.5 3.3 2.9 5.6
CD(P=0.05) 9.8 12.9 11.5 21.9
CV 12.9 6.0 25.4 8.1
Treatment
CO2 evolution (mg
CO2/100 g soil/day)
Dehydrogenated
activity
(μg TPF/g soil/day)
30
DAS
60
DAS
Maturi
ty
30
DAS
60
DAS
Maturi
ty
CO2 evolution and dehydrogenated activity is influenced by
tillage methods
DAS DAS ty DAS DAS ty
Tillage Methods (CT,MT,ZT)
CTConventional
tillage
12.5
015.44 11.95
11.7
18.96 7.60
MTMinimum
Tillage
14.2
318.15 14.25
13.1
210.62 8.44
ZTZero tillage +
Glyphosate
20.8
323.58 19.13
15.2
713.14 10.47
SE(m) ± 0.35 0.40 0.25 0.25 0.19 0.17
CD(P=0.05) 1.39 1.58 0.96 0.98 0.73 0.68
Soil Control(Soi
l)
FYM Wheat/rice
straw
Bajra/Maize
stalk
0.5%
C
2.0%C 0.5% C 2.0%
C
0.5% C 2.0%
C
Bacterial population((10 8/g soil)
Alluvia 32.08 74.83 141.18 92.12 197.7
Microbial population in differentially treated
during organic matter decomposition
(Gaur et al., 1984), NRRI, Cuttack
Alluvia
l
32.08 74.83 141.18 92.12 197.7
6
Actnomycetes population((10 6/g soil)
3.22 9.74 16.08 8.77 13.24
Fungal population((10 4/g soil)
27.15 39.00 48.23 75.54 134.1
5
Crop residue decomposition and
management
• There is great variability in C : N
ratio of the CRs which determine
the rate of decomposition and
release of nutrients.
Materials with high or wide C: N • Materials with high or wide C: N
ratio like rice straw, wheat straw,
rice husk and sugarcane bagasse
decompose slowly.
• Materials with narrow C: N ratio like residues of leguminous crops decompose faster.
• Addition of N in form of fertilizer or cakes to N poor materials accelerates decomposition and can be compared well with N rich materials. materials.
• The decomposition of FYM is slow and steady.
• The order of decomposition ie cakes > legumes > cereal + cakes > cereal> FYM.
CRM in rice-wheat cropping
systemIn areas where mechanical
harvesting is practiced, a large
quantity of crop residues are left in
the field, which can be recycled
for nutrient supply. for nutrient supply.
About 25% of N and P, 50% of S,
and 75% of K( uptake by cereal
crops are retained in crop
residues, making them valuable
nutrient sources.
• Both rice and wheat are exhaustive
feeders, and the double cropping
system is heavily depleting the soil
of its nutrient content.
• A rice-wheat sequence that yields 7
t/ha of rice and 4 t/ha of wheat
removes more than 300 kg N, 30 kg removes more than 300 kg N, 30 kg
P, and 300 kg K/ha from the soil.
• Traditionally, wheat and rice straw
were removed from the fields for
use as cattle feed and for other
purposes in South Asia.
• Recently, with the advent of mechanized harvesting, farmers have been burning in situ large quantities of crop residues left in the field.
• As crop residues interfere with tillage and seeding operations for the next crop, farmers often prefer to burn the residue in situ, causing loss of nutrients and organic matter in the of nutrients and organic matter in the soil.
• Unlike removal or burning, incorporation of straw builds up soil organic matter, soil N, and increases the total and available P and K contents of the soil.
• The major disadvantage of incorporation of cereal straw is the immobilization of inorganic N and its adverse effect due to N deficiency.
• Incorporation of cereal crop residues immediately before sowing /transplanting into wheat or rice significantly lowers crop yields. significantly lowers crop yields.
• Due to straw incorporation, wheat yield (mean of 10 years) decreases from 0.54 t/ha to 0.08 t/ha with the application of 60 kg N/ha and 180 kg N/ha, respectively.
• Residue characteristics and soil and management factors affect residue decomposition in the soil.
• Under optimum temperature and moisture conditions, N immobilization can last from four to six weeks.
• Adverse effects of wheat straw incorporation can be averted by
• Adverse effects of wheat straw incorporation can be averted by incorporating both green manure (having narrow C:N ratio) and cereal straw (having wide C:N ratio) into the soil before rice transplanting.
Legume crop residues and
green manures• In northwestern India, short-duration
legumes (e.g., mungbean and cowpea) can be grown in the fallow period after wheat harvest.
• In the rice-wheat system, incorporation of mungbean residue incorporation of mungbean residue after picking pods, significantly increases rice yield and saves 60 kg N/ha.
• The advantages of incorporation of legume crop residues and green manuring to rice are similar.
• Green manures are a valuable potential source of N and organic matter.
• Green manure crops (e.g., Sesbaniasp.) can be used in rice-based cropping systems.
• A 45- to 60-day-old green manure crop can generally accumulate
• A 45- to 60-day-old green manure crop can generally accumulate about 100 kg N/ha, which corresponds to the amount of mineral fertilizer N applied to crops.
• Sometimes green manure crops accumulate more than 200 kg N/ha.
• Integrated use of green manure and chemical fertilizer can save 50-75% of N fertilizers in rice.
• Green manuring also increases the availability of several other plant nutrients through its favourable effect on chemical, physical, and biological properties of soil. properties of soil.
• In Bangladesh, N supplied by Sesbania green manure was effective for rice grown in coarse-textured soils but its residual effect on the following crop of wheat was negligible.
Rice straw management
practices
• Incorporation of rice straw before wheat planting compared to wheat straw before rice planting is difficult due to low temperatures and the short interval between rice harvest and wheat planting.short interval between rice harvest and wheat planting.
• Farmers use different straw management practices: burning, removal, or incorporation.
• Rice and wheat yields under these practices are generally similar.
• In few studies, wheat yields were lower during the first one to three years of rice straw incorporation 30 days prior to wheat planting, but in later years, straw incorporation did not affect wheat yields adversely.
• In contrast, rice straw incorporation gave significantly higher wheat yields of 3.51 t/ha compared to 2.91 t/ha with gave significantly higher wheat yields of 3.51 t/ha compared to 2.91 t/ha with straw removal in Pakistan.
• Incorporation of rice straw three weeks before wheat sowing significantly increased wheat yields on clay loam but not on sandy loam soil.
• About 10-20% of N supplied through organic materials having high C:N ratio such as rice straw and stubble is assimilated by the rice crop, 10-20% is lost through various pathways, and 60-80% is immobilized in the soil. immobilized in the soil.
• Addition of 10 t/ha rice straw at 4 -5 weeks before transplanting rice is equivalent to the basal application of 40 kg N/ha through urea.
• Proper fertilizer management practices can reduce N-immobilization due to incorporation of crop residues into the soil.
• These practices include appropriate method, time, and rate of fertilizer-N application.
• The following options can reduce the • The following options can reduce the adverse effects of N immobilization:
1. Place N-fertilizer below the surface soil layer which is enriched with carbon after incorporation of crop residue.
2. Apply N-fertilizer at a higher dose than the recommended dose.
Effect of starter dose of N on
CRM
When cereal straw is added in soil, growth of crop declines. This is attributed to several factors. Added straw fixes N during early stages of decomposition of soluble carbohydrates resulting in N deficiency to the subsequent crop. soluble carbohydrates resulting in N deficiency to the subsequent crop. Inorganic N should be added to promote decomposition of straw in time. Added N enhances the rate of decomposition measured in terms of CO2 production and loss of total C from soil.
• Application of 15 to 20 kg N/ha as starter dose with straw incorporation increases yields of wheat and rice compared to either burning of straw or its incorporation in the soil.
• At recommended fertilizer-N level, rice straw incorporation reduces rice yields than urea alone.
• Therefore, a higher dose of urea-N application with rice straw incorporation is application with rice straw incorporation is necessary to get good yields.
• The beneficial effect of straw incorporation before rice planting does not carry over to the succeeding wheat crop.
• Application of 30 kg extra N/ha than the recommended fertilizer dose, increases rice yields only slightly.
Beneficial effects of wheat
crop residues• During a 10-year (1984 to 1994) long-term
field experiment conducted in India, comparisons were made between the application of wheat crop residues versus inorganic fertilizers on rice and wheat.
• In the first year, inorganic fertilizer-treated plots of rice and wheat yielded treated plots of rice and wheat yielded the highest.
• However, in the second and third year, yield from the treatment with combined application of wheat straw and inorganic fertilizer was similar to that with inorganic fertilizer alone
• Beyond fourth year, plots treated with a combination of wheat straw and inorganic fertilizer outyieldedall other treatments.
• Another long-term study (1988 to 2000) conducted in Punjab, India showed that wheat straw could be showed that wheat straw could be combined with green manure with no adverse effect on rice yield.
• Yield and N-use efficiency in rice, however, were reduced with wheat straw incorporation.
• Results from the All India
Coordinated Agronomic Research
Project showed the beneficial effects
of wheat crop residues when
applied as a substitute for chemical
fertilizer needs of rice in the rice-
wheat cropping system. wheat cropping system.
• In another study, incorporation of
wheat straw (10 t/ha) saved 50% of
the recommended fertilizer dose (60
kg N + 13.1 kg P + 25 kg K/ha) and
helped achieve higher yield of rice.
Adverse effectsImpact of crop residues on pestsIncorporation of crop residues inconservation agriculture has direct andindirect effects on pests.
Crop residues directly affect egg layingof beetles and cutworms. Lower soiltemperature and higher soil moisturetemperature and higher soil moisturecontent under crop residues would alsoaffect pest infestation.
Indirectly, residues change the typeand density of weeds, which in turninfluence insects and natural enemies.Crop residues generally increasediversity of useful arthropods and helpin reducing pest pressure.
• The surface residues may ensure survival of a number of insects, both harmful and beneficial. Reduced tillage systems particularly under staggered planting system of crops in monoculture, may contain higher levels of pest inoculums than the conventional system.
• Further, the decomposition of crop residues along with several inter-related residues along with several inter-related factors like climate, crop geometry, irrigation and fertilization, cultural practices and pesticides may affect the survival of insects in crop residues.
• The decomposition of residues brings out a chemical change in soil which may affect the host reaction to pests.
• The decomposition of plant residues may produce phytotoxic substances, particularly during early stages of decomposition. The effects could be severe in reduced tillage systems which incorporate huge amount of crop residues into the soil and an extra application of N is made to hasten decomposition of these residues. A change in weed ecology is expected to influence the survival of is expected to influence the survival of several of those insects which tend to develop on weeds, particularly during the fallow period. Since the zero/reduced tillage system reduces the fallow period among crops, it may result in altered incidence of certain insects.