Green manures

1. Green manures
Dr. P. K. Mani
Bidhan Chandra Krishi Viswavidyalaya
E-mail: pabitramani@gmail.com
Website: www.bckv.edu.in

2. Green manures
Green manure refers to “a plant material
incorporated with the soil while green or
soon after maturity for improving the soil
to supply nutrients, particularly N, to a
standing crop”
(Soil Science Society of America, 1978)
Green manuring is a practice of ploughing or
burying the undecomposed green plant tissues
into the soil for improving structure and fertility
of the soil.

3. Green-manuring can be done in 2 ways depending on the
situation.
(i) Green-manuring in situ: this is the growing and
burying
of a green manure crop in the same field as
the one
to be manured.
(2) Green-leaf manuring: GLM refers to turning into the
soil green leaves and twigs collected from shrubs and
trees grown on bundhs, wastelands or nearby
forest
areas

5. Sesbania rostrata

6. Crops suitable for green leaf manuring
Glyricidia
Pongamia
Leucaena leucenalis
Legumes: Glyricida ( Glyricidia maculata),
Wild dhaincha (Sesbania speciosa),
Karanja (Pongamia pinnata),
Wild indigo (Tephrosia purpurea,

7. Characteristics of green manure crops
Profuse leaves and rapid growth in early life
Abundance and succulent tops
Capable of making good stand on poor and
exhausted soils
Preferable legume with good nodular growth
habit

8. Advantages of Green Manuring
 It add organic matter to the soil and stimulates
microbial activity
 Improves soil structure
 Acts as a cover crop ,facilitates penetration of rain
water, decreasing erosion and run off
 Nutrient taken up from the deeper layers by green
manure crops and return the nutrient to the
top soil
 Legume crop also add nitrogen

10. Limitations
Rainfed condition : Green manure crops will not
decompose readily due to lack of water
 GM is feasible for assured irrigation facility
 Cost of growing GM crop is more than cost of Fertilizer
 For higher Cropping intensity land is unavailable
for GM cultivation
Disease, insects and nematodes may come up due
to improper decomposition

11. Methods of Green Manuring in situ
Summer sown catch crop
Land Preparation: 3-4 ploughings followed by 1 laddering
Sowing : May-June , immediately after 1st monsoon rains.
Dhaincha and Sunhemp are generally sown in Aman
for green manuring.
Paddy field
Method of sowing: broadcasting
Seed Rate: Dhaincha : 40-45 kg/ha
Sunhemp : 40-50 kg/ha Moong : 25-30 kg/ha
Manuring: Superphosphate@150 kg/ha applied at last
ploughing(increases the P availability for succeeding Aman rice
Burial of GM crops: at the flowering stage; (Dhaincha 6-8
wks old, Sunhemp: 4-5 wks old). During decomposition there
must be adequate moisture in the field and allowed to decompose
for 3-4 weeks

13. DHAINCHA (Sesbania aculeata)

14. Sesbania Seed

16. Cultivation of Chaiti Moong at AB Farm, BCKV

20. green manure -cum-fibre crop
SUNNHEMP (Crotalaria juncea

21. Sunhemp Seed
Sunn Hemp provides as much as 20 tons per acre of green tonnage with a
maximum of 150 units of Nitrogen fixation per acre in as little as 90 days.

22. Inter row sown crop:
The seed sown between two rows; Dhaincha (paddy)
Sunhemp, cowpea (Cotton , Maize)
Green Leaf Manuring:
The suitable perennial shrubs and trees are grown on
border of paddy fields or bounds or on vacant
spaces for the purpose of utilizing their leaves and
twigs as green manure. These are incorporated in the
soil at the time of puddling of paddy field
Brown Manuring

23. Brown manuring is a technique to grow Sesbania in
standing rice crop and kill them with the help of
herbicide for manuring. After killing the color of the
sesbania residue become brown so it called brown
manuring.
Brown manuring practice introduced where Sesbania
crop @ 20 kg/ha is broadcasted three days after rice
sowing and allowed to grow for 30 days and was dried
by spraying 2,4-D ethyle easter which supplied upto 35
kg/ha N, dry matter, control of broad leaf weeds,
higher yield by 4-5 q/ha due to addition of organic
matter in low fertile soils

24. Crops suitable for green leaf manuring
Karanja (Pongamia glabra)
Glyricidia
Glyricida ( Glyricidia maculata),
Neem (Azadiracta indica)
Karanja (Pongamia glabra)
Wild indigo (Tephrosia purpurea)
Subabool
Leucaena leucenalis
24

26. Glyricidia maculata

35. Root knot nematode
Rhizobium nodule

36. Mineralization, immobilization, and C:N ratio
High C:N ratio
material added to soil
Nitrogen
availability
Available soil N is
immobilized
C02 evolution
increases
Available N
increases
through N
mineralization
Time
Nitrogen immobilization and mineralization after material
with a high C:N ratio is added to soil.

37. General purpose decay organisms vs. nitrifiers
Residues
with high
C/N ratio
added
Residues with
low C/N ratio
remain
Nitrate depression period

40. The C/N ratio of organic residues added to soil will depend upon
the maturity of the plants turned under. The older the plants, the
wider will be the C/N ratio and the longer will be period of nitrate
suppression. Obviously, leguminous tissue will have a distinct
advantage over nonlegumes since the former will promote a
more rapid organic turnover in soils

41. Sesbania rostrata - a stem nodulating green manure

42. Azorhizobium caulinodans
on
Sesbania

43. Phosphocompost

44. Principles of phospho-composting
Phospho-composting is based on sound scientific
principles. During the decomposition of organic
materials, intense microbial activity occurs. As a
result a large number of organic acids and humic
substances are produced.
Some of the most commonly produced organic
acids are: citric, malic, fumaric, succinic, pyruvic,
tartaric, oxaloacetic, 2-ketogluconic, lacticoxalic,
propionic and butyric (Stevenson, 1967).

45. Phospho-compost is a compost prepared by addition
of low grade rock phosphate and phosphate
solubilizing micro-organisms with organic wastes.
Rock phosphate, as a cheaper source of P
In the process of decomposition many organic
acids are liberated.
Due to this acidic condition, P from rock
phosphate gets solubilized and compost
becomes enriched.

46. PHOSPHOCOMPOST
Ingredients:
Oragnic wastes
Raw Cow dung
Compost
Soil
Total
Rockphosphate
Pyrite
Urea
Cultures
: 80 kg (60 kg dry+20 kg green)
: 10 kg
:
5 kg
:
5 kg
: 100 kg
: 20 kg
: 10 kg
: 2.2 kg
: 0.05 kg
Dry organic wastes: Straw, husk, waste from cattle shed, stems of
mustard , sesame, etc.
Green : Waterhyacinth, legumes, weeds, vegetable clippngs, leaves,
grasses

47. Nitrogen required for Stimulating the microbial activity
Pyrites are added due to acidification of the mixture during
composting to prevent volatilization loss of N and
also to increase P solubilization
Phosphate Rocks
Cellulose decomposer: Aspergillus awamori (fungi)
(500g mycelial mat / ton of materials)
P-solubilizers:
Bacillus megatherium.
Bacillus polymyxa,
Pseudomonas striata
(50 ml/kg of materials having 108 viable cell)

48. Divide entire Organic and inorganic component in 10 equal parts
Preparation of 1st Layer
I part Phosphate Rock(2kg) and I part Pyrite(1kg)
Urea (200g) + microbial Cultures(5g) make it a slurry
9-12//
I part cowdung (1 kg) + compost (0.5 kg) + Soil
(0.5kg) make slurry in water
Covered with Polythene sheet
g
dun
cow
l+
s oi
with
d
mu
f
er o
Lay
Dry organic wastes
4th Layer
3rd Layer
2nd Layer
1st Layer
Keep it for 3 months , yielding 65-70 kg PhosphoCompost

49. Method of Phosphocompost Making
•Select a suitable upland place, sufficient sunlight, free from water stagnation
•Prepare a base with either brick floor or spread the polythene sheet on the floor
•Collect all the ingredients (organic and inorganic) as per proper ratio for the
desired pdn level.
•Divide the entire ingredients into 10 parts
•Step-1:Take one bucket and add Raw Cow dung- 1kg, Compost- 0.5 kg,
Soil -0. 5 kg and small water, stir the material and make a slurry.
•Step-2: Take 2nd bucket and add urea-200g, cultures-5g and add water small,
make another slurry
•Step-3:Spread dry wastes followed by green wastes and make it 12″ height
•Step-4:Now add slurry from 1st bucket (cow dung etc slurry), next add slurry
from 2nd bucket and spread evenly.
•Step-5: Now spread 2 kg Rock phosphate and1 kg Pyrite
•Repeat the process Step-1 to step 5 and repeat until 10 layers is formed.
• covered the top and side portion of the heap with Layer of mud (soil+
cowdung) and subsequently cover with poly thene sheet to prevent water
•1st turnings after 4 weeks and 2nd turnings after 8 weeks
• Water is added to the heap so that moisture remains between 60 to 70%.
•Add water at each turning to maintain the moisture content between 60 and 70%.
•The compost becomes ready for field application within 90-100 days period.

50. Nutrient composition of phosphocompost
Manure
Phosphocompost
Total N
(%)
Total P
(%)
S
C: N
ratio
1.2-1.4
2.00-3.50
1.5-2.0
17.018.0
Phospho-compost application increased the PUE
of greengram (12.90%) and wheat (20.48%) over
SSP
(Mishra et al. 1982).

57. WILD INDIGO (Tephrosia purpurea)

60. Azolla video