Effect of Chemical composition of plant residues on Nitrogen mineralization in

soil

Presented By:Vikram Singh

MSc. Agri.

MAJOR GUIDE :Dr. J.N. NariyaProfessordept. of agril chem and soil scienceJAU ,Amerali

MINOR GUIDE: DR. P.K. ChovatiaAsso. ProfessorDept. of agronomy JAU Junagadh

Introduction Nitrogen mineralization is the process by which organic N is

converted to plant available inorganic forms .Most of the nitrogen (N) in the environment is in forms that are unavailable for plant uptake .

Use of plant residues as organic nutrient source is relatively simple for the farmers compared to the application of manure. Incorporating plant residues into agricultural soils can sustain organic carbon content, improve soil physical properties, enhance biological activities and increase nutrient availability

In the short-term, incorporation of plant residues provides the energy and nutrients for microbial growth and activity, acts as a driving force for the mineralization–immobilization processes in the soil and is a source of nitrogen (N) for plants .In the long-term, incorporation of crop residues is important for the maintenance of organic carbon (C) and N stocks in the nutrient pool of arable soils .The N availability from these residues depends on the amount of N mineralized or immobilized during decomposition.

Residue:Whatever remains after something else has been taken, separated, removed, or designated; remnant; remainder.

Plant residue:Defined as the vegetative plant(crop/trees) material left on a ground after its harvesting, prunning or processesing or grazzing.Ex: stalks, stems, leaves, roots, and weeds.

Crop residue:Residues which left after harvesting of crop or during training and pruunning in horticultural crops and remainder after their prossesing.

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DAS,2011

Crop residues

Field residues Process residues

Types of crop residues

Stalks and Stubble Leaves, and Seed pods.

Husks, Seeds, Bagasse and Roots.

Composition of Plant Materials

6BRADY N.C. AND WEIL

R.C.2012

Chemical composition of plant residues:

Plant residues /material may be classified underthree major chemical groups:Polysaccharides:these arelarge group of carbon compounds, and made

upof simple monosaccharides units like glucose etc. cellulose and hemicelluloseare most important polysaccharides and they accumulate in plants tissues. They form the sekelton of plant tissues.

Lignins: these arecomplex carbon compounds. They are found in woody tissue.it is binding material and covers the cell walls and fibro-vascular bundles.

Protiens :they are nitrogenous substances, it`s predominant in cell protoplasm. Simple forms of protien is amino acids.

Other composition: plant residues also contains t\fats,oils, waxes,sterols,fatty acids,aldehyde ,alcohol ,phenol,alkoids enzymes, hormones, pigment and vitaminsetc.

Decomposition Rates of Crop residuesRapid

Very slow

Sugars and Starch and simple protiens

Crude proteins

Hemicellulose

CelluloseFats, Waxes and Oils

Lignin's and phenolic compounds

8BRADY AND WEIL,2012

Nitrogen

Nitrogen is most important primary nutrient which is required in large quantity for plant growth.

Most widely distributed element in nature.

Preferred as nitrate (NO3-) and ammonical (NH4

+) Nitrogen by plants.

Nitrogen makes up 78 % of our airThe largest single source of Nitrogen is in Atmosphere.

N N

Very small amount of soil nitrogen is available to plants.Total nitrogen in furrow slice(0-15 cm) soils generally varies from 0.02 to 0.44 per cent by wieght.

Role of Nitrogen

An essential constituent of proteins and is present in many compounds of great physiological importance in plant metabolism

Is an integral part of chlorophyll.

Imparts vigorous vegetative growth and dark green colour to plants.

Governs utilization of potassium, phosphorus and other elements.

Facts about nitrogen

Forms of Soil Nitrogen:

Nitrogen in soil exists in two major forms

1)Organic

2)Inorganic (mineral)

Sources of Nitrogen :

• Fertilizers• Organic manures• Plant residues• Bio-fertilizers• Green manure• Rain water and Bacterial nitrogen fixation

Soil Nitrogen

Organic Inorganic

Hydrolysable-N Non-hydrolysable-NNH4-N NO3-N NO2-N

Hydrolysable-N Aminosugar

Amino Acid

Acid soluble humin

FixedNH4

+Insoluble humin

Different forms of soil-Nitrogen

Transformation of Nitrogen in soils

Various pathways:

Mineralization

Immobilization

Fixation

Losses of N(volatisationvolatisation)

•Nitrogen in crop residue become available after mineralization •Available nitrogen includes NH4

+ , NO3- , and NO2

-

Mineralization Process by which nitrogen in organic compounds is

converted to inorganic ammonium and nitrate ions

carried out by micro-organisms.

Organic NR-NH2

(Amine) NH4

+

(Ammonium) NO2

-

(Nitrite) NO3

-

(Nitrate)

Mineralization process operates through three reactions namely:1.Aminisation

2.Ammonification

3.Nitrification1.Aminisation:

Process of release of amines and amino acids from combined N compounds (proteins).

Proteins R-NH2 + CO2 + Energy + Other products(Amines)

HeterotrophicMicro-organisms

Aminisation occurs both in aerobic and anaerobic condition

End products

CO2, (NH4)2 SO4 and H2OUnder aerobic condition

Under anaerobic condition NH3, NH2, CO2, organic acids, H2S etc

2.AmmonificationProcess of reduction of amines to ammonical compounds.

R-NH2 + HOH NH3 + R-OH + energy

H2O

NH4 + OH-

Under aerobic condition the process continues

NH4+ -N NO3

- -NNO2

- -NNitrification

Under anaerobic condition (due to more hydrogen)

Org.N NH4+ -N

Lack of O2 in soil

Ammonification

Ammonium Nitrites Nitrates

(NH4) (NO3)(NO2)

Factors affecting mineralisation1.Climatic factors : temperature, rainfall,2.Edaphic factor: soil reaction, aeration,

availability of nutrients and biological activity

3. Plant or residue factor: chemical composition,

plant physical factor

Research finding

Effect of Chemical Composition of Plant Residues on Nitrogen Mineralization

Srinivas et al., 2006Central Research Institute for Dryland Agriculture,

Santoshnagar, Hyderabad,Andhra Pradesh, 500059

Materials and methods

Small sample (0.05g) of finely ground plant residues were taken & after addition of H2SO4 , heated to 1500 C on a hot plate to achieve complete oxidation

Plant residues (20)

7 crop and 13 tree

Dried and grind

Carbon Wet oxidation Nitrogen

(Kjeldahl)

Lignin: Acid Detergent Fiber (ADF)

Total soluble polyphenolFolin-Denis method

2.Laboratory incubation studies:Location CRIDA,HYDERABADSoil type Sandy loam

sand 76.4 %

Silt 5.00 %

Clay 18.6 %

BD 1.62 Mg m-3

Moisture retention 109.5 g kg-1 at 0.03 MPa

pH 6.68

EC 0.86dS m-1

CEC 11.64 cmol(P+) kg-1

OC 4.05g kg-1

Available N 62.8 mg kg-1

Available P 10.4 mg kg-1

Available K 79.4 mg kg-1

One Kg soil

one liter jar (3)

9Mg ha-1(plant residue)

Incubated (100 days, 250 C)

Soil samples drawn @ 3, 7, 12 and 20 days after incubation and subsequently at 10

days intervals

• Mineral N(NH4+NO2+NO3) by steam distillation in presence of MgO and finely ground Devarda’s alloy.

% N released from residues

at different intervals

Mineral N in residue amended soil Mineral N in control soil

N added through the residue=

-

Chemical composition of residues

PLANT RESIDUE QUALITY AND NITROGEN MINERALIZATION

Residue quality – N mineralization relationships

Relationships between residue quality parameters and N mineralization for All residues

Relationships between residue quality parameters and N mineralization for tree residues

Relationships between residue quality parameters and N mineralization for crop residues

Results of research

• High quality residues (L. ieucoceohaia and G.sepium) with high N and low lignin and polyphenol concentrations, released N rapidly.

• Low quality residues (sugar cane trash and paddy straw) immobilized N for long periods.

• Residues of intermediate quality (C. siamea and C. cajan ) immobilized N for some time and released it later.

• The per cent N mineralized from residues was strongly correlated with N concentration and other quality parameters involving N concentration (C:N ratio Polyphenol to N ratio, lignin + Polyphenol to N ratio).

Effects of chemical composition on nitrogen mineralization from green

manures of seven tropical leguminous trees

KAREN A. OGLESBY and JAMES H. FOWNES.1992

MaterialsTwigs were limited to 1cm diameter.

Alley cropping : Calliandra calothyrsus,

Cassia reticulata, Cassia siamea,

Gliricidia sepium,Inga edulis,

Leucaena leucocephala, Sesbania

Soil type : Clayey, pH in water-4.5, organic C 3.7 %, and total N 0.2 %

Incubation

15 g portions extracted in 100 mL of 2 M KCl.

50 g Soil (10 mesh)

Polythene bag

3 mg green manure g-1 soil

Incubated at 24°C for 1, 2.5, 4, 8, and 12 weeks.

At each time period, six replicate bags for each species and seven replicate bags containing only soil were harvested

The extracts were analyzed for ammonium and nitrite plus nitrate

Percent of green manure N mineralized

Total extractable inorganic N of green manure

soil-only treatments ateach time period

Initial green manure N added to each bag

=_

Chemical analysis of green manure

Carbon Wet oxidation Nitrogen

(Kjeldahl)

Lignin: Acid Detergent Fiber (ADF)

Total soluble polyphenolFolin-Denis method

CHARACTERISTICS OF GREEN MANURES USED IN THE EXPERIMENT

Species Leaf: twig ratio

Polyphenols (%) N (%)

Lignin (%)Leaves Twigs Average

Calliandra calothyrsus 2.3 4.99 1.95 4.06 2.85 13.4

Cassia reticulata 9.4 2.10 0.89 1.99 2.65 9.9

Cassia siamea 3.9 4.60 1.27 3.92 2.31 10.3

Gliricidia sepiurn 6.4 2.07 0.35 1.84 3.43 8.6

lnga edulis 2.4 4.71 1.70 3.83 2.51 18.3

Leucaena leucocephala 2.4 3.52 1.49 2.93 3.74 11.1

Sesbania sesban 0.7 2.60 0.56 1.38 1.39 14.5

N mineralization patterns

Week Leaf:twig N (%) Polyphenols (%) Lignin (%) Polyphenol:N Lignin:N

1 0.13 0.24 -0.78* -0.13 -0.89** 0.00

2.5 0.40 0.29 -0.80* -0.48 -0.94** -0.21

4 0.74 0.44 -0.71 -0.80* -0.88** -0.56

8 0.61 0.37 -0.79* -0.79* -0.90** -0.46

12 0.39 0.11 -0.59 -0.79* -0.53 -0.32

Correlations

Correlation coefficients of cumulative % green manure N mineralized at each time interval versus initial green manure properties

Relationship between N mineralized at 8 weeks and

(a) Polyphenol : N ratio (Y = 79.4 - 39.5X, n = 7, r 2 = 0.81).

Patterns of N mineralization over time were complex in the heterogeneous mixture of

materials comprising green manures.

Soluble polyphenol content and polyphenol :N ratio were confirmed to correlate well with net N

mineralization.

Results

Nitrogen mineralization of legume residues in soil in relation to their

chemical composition

Singh, J. P. and Vinod kumar.1996Location: HAU, Hisar

Location: HAU, HisarSoil type Hisar Sandy

loam Karnal Loam

pH 8.0 7.7

EC (ds /m) 0.50 0.30

OC (g/kg) 5.6 6.2

CEC cmol (P+)/kg 11.66 12.8

Materials and methods

Incubation

Replication : 3

250g soil + 5mg crop residue g-1 soil

Incubated at 350C for 56 days

Sampling (10 g)

withdrawn ( 7, 14, 21, 28, 35, 42, 49, 56, days)

2 M KCl solution

Mineral N ( steam distillation)

Characteristics of legumes residues used for study

Legumes residues

OC (g/kg) Total N g/kg

C:N ratio Lignin (g/kg)

Polyphenols (g/kg)

Black gram 428 23.3 18.4 75.0 22.4

Cluster bean 452 18.2 24.8 80.0 44.4

Cowpea 446 21.4 20.8 71.2 27.6

Green gram 416 26.0 16.0 54.1 30.9

Sesbania 440 22.6 19.5 73.9 26.7

Soyabean 462 21.4 21.6 61.2 35.7

sunhemp 438 20.1 21.8 64.3 32.2

Nitrogen Mineralization

Cumulative N Mineralized in Hisar soil

Cumulative net N mineralized and amounts of added N mineralized from legume residues

after 56 days of incubation periodLegumes residues Net N mineralized (mg/kg) Amount of added N

mineralized (%)

Hisar Karnal Hisar Karnal

Black gram 84 87 72.1 74.7

Cluster bean 53 55 58.2 60.4

Cowpea 71 73 66.4 68.2

Green gram 96 99 73.8 76.1

Sesbania 74 76 65.5 67.3

Soyabean 75 77 70.1 72

sunhemp 65 67 64.7 66.7

The percent of N mineralized was significantly correlated with total N( 0.887 N=5) and C:N (-0.871*) of the legume residues. There was no significant correlation between percentage of legume N mineralized and their lignin and ployphenol content.The highest correlation was observed between lignin +polyphenol to N ratio(84%) variation in the percentage of N mineralized.

Correlations

N mineralization potential (No) and rate constant (k) of legume residues incorporated

into the soilLegumes residues No (mg/kg) k

Black gram 88.7 0.193

Cluster bean 59.8 0.149

Cowpea 71.9 0.184

Green gram 96.9 0.199

Sesbania 67.0 0.159

Soyabean 86.6 0.159

sunhemp 70.3 0.156

Result of research • The decreasing order of N mineralization potential

values as follows: Green gram >Black gram >Soybean >Cowpea >Sun hemp >Sesbania >Cluster bean.

• All the legumes had almost reached their potential N mineralization indicating that legumes may release N rapidly and provide sufficient nitrogen during early period active growth.

• Lignin plus polyphenol to nitrogen and C to N ratio of the legumes were extremely important in predicting the amount of N mineralized and rate of nitrogen mineralization

Mineralization of nitrogen from decomposing leaves of multipurpose trees as affected by their chemical composition

Mafongoya et al.,1998

Materials and methods

Chemical analysis of plant

Carbon Wet oxidation

Nitrogen(Kjeldahl)

Lignin: Acid Detergent Fiber (ADF)

Soluble polyphenol

Tannins

NDF-N

Gravimetric method of trivalent ytterbium acetate

Heating NDF(5mg at 95OC) for 1 hr in N-butanol(5ml)containing concentrated18M HCl

Laboratory incubationSoil (2mm) + ground MPT leaves(1mm) @ 1o tons ha-1

Incubated for 8 weeks at 280C

Sampling initially and every week (upto 8 weeks)

3g soil + 30 ml 2M KCl in test tube 1 hr

Filtered

Analyzed for total N

Chemical composition of leaves of MPT species (on oven-dry matter basis). Values followed by different letters in each column are significantly different from each other at P~0.05 using Duncan’s Multiple Range Test. NDF-N N in cell wall (neutral detergent fraction), SPphenol soluble polyphenols, tannins insoluble proanthocynidins

N Mineralization pattern • Authors were observed 3 major pattern of cumulative net N

mineralization

(1) A pattern of rapid cumulative net N mineralization, as shown by sesbania, gliricidia, cajanus, and the two mixtures.

(2) A pattern shown by calliandra and leucaena that had net N mineralization rates equal to or below that of the control.

(3) A pattern shown by flemingia and acacia, where net N immobilization occurred during most of the experimental period.

Correlation coefficients relating the cumulative amount of net N mineralized to initial chemical properties of multi purpose tree

(MPT) leaves during incubation with soil.

Result of researchThe variation in net N release from prunings of different leguminous trees was significantly related to the initial N, lignin and soluble polyphenol concentrations of the leaves.

The net release of N increased with increasing N concentrations and decreased with higher concentrations of lignin and polyphenols.

Pruning of species such as sesbania, gliricidia, and cajanus, which are low in lignin, released N rapidly compared to prunings of flemingia and acacia that are high in lignin.

Nitrogen Mineralization from Soil Amended with Gliricidia and Sorghum

ResiduesSridevi et al., 2006

Materials and methodsLocation CRIDA,HYDERABAD

Soil type Sandy loam

sand 80.5 %

Silt 3.65 %

Clay 15.85 %

BD 1.64 Mg m-3

Moisture retention 103.4 g kg-1 at 0.03 MPa

pH 5.53

EC 0.51 dS m-1

CEC 10.52 cmol(P+)

OC 5.39 g kg-1

Total N 560 mg kg-1

Incubation 50 g soil

150ml

Crop residue Equivalent to 60 kg N ha-1

NDFs Equivalent to 60 kg N ha-1

sampling 5, 10, 15, 30, 45, 60, 75 and 90 days

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Mineral-N (NH4

+N02+ N03)

Residue fractionation:

Residue Soluble fractions (% )

Fiber (%)

N g kg-1 C/N

Sorghum straw 21.4 78.6 5.32 77.3

Straw NDF 2.63 160.8

Glyricidia prunings 53.3 46.7 28.60 13.4

Pruning NDF 15.36 26.6

Nitrogen mineralizationAmendment N added

(mg/ kg)Incubation period in days N mineralized

after 90 days (% of added)

0 5 15 30 45 60 75 90

Control - 7.84 14.46 24.31 31.44 35.28 37.63 39.19 40.42 -

Sorghum straw 24.39 7.84 4.52 12.41 19.91 25.15 30.33 34.17 39.06 5.6

Straw NDF 9.49 7.84 3.44 1.94 8.36 13.59 18.28 22.75 26.68 144.8

Gliricidia prunings

24.39 7.84 12.58 32.5 44.86 51.29 56.75 60.31 62.04 88.6

Prunings NDF 6.12 7.84 6.8 12.69 24.42 32.54 38.67 43.95 47.54 116.3

Rates of N mineralization from soil amended with residues and residue fractions

Result of research

• Residues with large fiber fractions of extremely low N concentration cause considerable immobilization of N, while residues with smaller fiber fractions of relatively higher N concentration release N fairly rapidly when added to soil.

Conclusion of seminar The per cent N mineralized from residues was strongly

correlated with N concentration and other quality parameters involving N concentration.

N concentration and C:N ratio are sound criteria for predicting nitrogen release in few crop residues while in other residues polyphenol/N ratio ( lignin + polyphenol ) to N ratio play a role in percent N mineralized.

The composition of residues in terms of soluble and fiber fractions determines whether and to what extent, N is immobilized or mineralized.

Thankyou