Organic Manures 031

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					                                Organic Manures
                                      Booklet No. 31
                                Manures & Fertilizers: MFS - 1

I.     Introduction
II.    Bulky Organic Manures
III.   Concentrated Organic Manures
IV.    Effects of Organic Manures on Soil Properties


       Use of organic manures reduces the cost of production as well as environmental
degradation. Their application is essential to suppress any possible negative impact of fertilizer
on the soil and sustain soil productivity. This booklet gives an elementary knowledge on organic
manures and their importance for maintaining soil productivity. This booklet describes the
sources, preparation and types of organic matters in detail.

Dr. K. T. Chandy, Agricultural & Environmental Education

I. Introduction

         Although chemical fertilizers are the viable agricultural inputs, yet the majority of the
Indian farmers fail to avail the : advantages of fertilizer application. Investing one rupee in
fertilizer for wheat crop returns on an average Rs 2.30 in Indian condition; for paddy the return is
Rs 2.50. But poor and marginal farmers cannot exploit this potential simply because they do not
have money to spend on fertilizers. On the other hand, the cost of fertilizers has been rising with
every passing year. Since 1980 onwards, the rate of increase in cost of fertilizers has been
about 7.5% per annum. Majority of the farmers comprising poor and marginal ones cannot
afford to buy this costly input.

        In many places, fertilizer use has also been found to accentuate the problem of
micronutrient deficiency. reduced microbial population of the soil and deteriorated physical
conditions of the soil. In majority of the cases, negative impacts of fertilizer use are found due to
exclusive and improper use of chemical fertilizers not accompanied with the use of organic

       Fertilizers cannot be replaced by organic manures completely as the organic manures
can not meet the pace of nutrient requirement of the short duration high yielding varieties of
most of the crops. But the use of organic manures such as farmyard manure (FYM), compost,
green manure, and biofertilizers along with chemical fertilizers are essential to suppress any
possible negative impact of fertilizers on the soil and to sustain soil productivity.

        The term manure can be applied to both decomposed and un-decomposed products of
plant, animal and microbial origin. Based on the amount of nutrients present in these products,
organic manures have been divided into two types: bulky organic manures (farmyard manure,
compost, night soil, sludge sewage and green manures) and concentrated organic manures.
The concentrate manures are richer in nutrient content in comparison to bulky organic manures.
They include various cakes (oilcakes), blood and meat meals, fish meal, poultry manure, etc.
Different manures are briefly explained below. '

II. Bulky Organic Manures

A. Farmyard manure
       Farmyard manure (FYM) is the traditional organic manure and most readily available to
the farmers. The FYM is a product of decomposition of the liquid (urine) and solid excreta
(dung) of the livestock stored in the farm along with varying amounts of straws or other litter
used as bedding material. Unfortunately in our country, the litter is rarely used as bedding
material and about 50% of the dung is burnt as fuel in rural homes and urine is also allowed to

1. Composition
        On an average, well rotten FYM contains 0.5% nitrogen, 0.2% phosphorus and 0.5%
potash. Based on this analysis an average dressing of 25 tonnes per hectare of FYM supplies
112 kg of N, 56 kg of P2O5 and 112 kg of K2O. However, these quantities are not fully available
to the crops in the year of application. Nitrogen is very slow acting and less than 30% of it is
generally available to the first crop. About 60% of P2O5 and K2O each becomes available to the
long duration immediate crop. The remaining plant nutrients become available only to the
subsequent crops. This phenomenon is called residual effect. The average nutrient content of
different manures and manuring materials are given in Table 1.

      Table 1: The average nutrient contents of different manures and manuring materials

   Sl.No    Manuer/Manuering material           Nitrogen       Phosph-         Potassi
                                                Per cent       Orus %          Um %
   A. Animal Refuse
   1        Cattle dung (fresh)                 0.3-0.4        0.1-0.2         0.1-0.3
   2        Horse (fresh)                       0.4-0.5        0.3-0.4         0.3-0.4
   3        Sheep dung (fresh)                  0.5-0.7        0.4-0.6         0.3-1.0
   4        Night soil (fresh)                  1.0-1.6        0.8-1.2         0.2-0.6
   5        Poultry manure (fresh)              1.0-1.8        1.4-1.8         0.8-0.9
   6        Raw sewage (fresh)                  2.0-3.0           ---             ---
   7        Sewage sludge(dry)                  2.0-3.5        1.0-5.0         0.2-0.5
   8        Sewage sldge(dry,actvtd)            4.0-7.0        2.1-4.2         0.5-0.7
   9        Cattle urine                        0.9-1.2           ----         0.5-1.0
   10       Horse urine                         1.2-1.5           ----         1.3-1.5
   11       Human urine                         0.6-1.0        0.1-0.2         0.2-0.3
   12       Sheep urine                         1.5-1.7          ----          1.8-2.0
   B. Farm, Factory and habitation wastes
   1        Rural Compost (dry)                 0.5-1.0        0.4-0.8         0.8-1.8
   2        Urban Compost (dry)                 0.7-2.0        0.9-3.0         1.0-2.0
   3        Farmyard manure (dry)               0.4-0.5        0.3-0.9         0.3-1.9
   C. Straw, Stalks and Plant residues
   1        Bajara                              0.65           0.75            2.5
   2        Banana dry                          0.61           0.12            1.00
   3        Cotton                              0.44           0.10            0.66
   4        Jowar                               0.40           0.23            2.17
   5        Rice husk                           0.30-0.5       0.2-0.5         0.3-0.5
   6         Ground nut                           1.6-1.8         0.3-0.5         1.1-1.7
   7         Maize                                0.42            1.57            1.65
   8         Paddu                                0.36            0.08            0.71
   9         Tobacco                              1.12            0.84            0.80
   10        Arhar                                1.10            0.58            1.28
   11        Wheat                                0.53            0.10            0.60
   12        Tobacco dust                         1.10            0.31            0.93

Note: The figures are just indicative of average contents.
Source: Handbook of agriculture; ICAR, New Delhi.

2. Availability of manurial materials
        In India, large amounts of dung and urine are produced by vast population of domestic
animals. Although no systematic survey has been carried out by the government or any other
agency to estimate the amount of animal excreta produced in our country, estimations by
various sources indicate that roughly about 345 to 1700 million tones of animal excreta is
produced per annum in the country. Table 2 provides the potential of bovine (cattle and buffalo)
excretion terms of primary plant nutrients present In the excretion.

        Table 2: Potentiality of total annual dung and urine excretion of bovine for soil nutrients
                                          (in million tones).

 Type of        Animal            Nitrogen         Phosphorus       potash           Organic
 Animal         excretion                                                            matter
and manure
Cattle dung     744.565           1.117            0.745            0.372            139.872
Cattle urine    480.148           0.960            0.048            0.960                ---
Buffalo dung    258.022           0.387            0.258            0.129            48.508
Buffalo urine   178.753           0.358            0.018            0.358               ----
Total           1661.488          2.822            1.069            1.819            188.380

3. Collection of manurial ingredients
        Cattle urine is a rich source of plant nutrients and it can be collected in loose earth, saw
dust, straw or dry leaves. These urine soaked materials and the entire dung must be collected
and stored in manure pits. The practice of burning dung as fuel for household purposes should
be discouraged by making people to realize the loss of valuable nutrients and by providing
alternate source of fuel. There are three main systems of collecting and storing cattle refuge for
manuring purposes. These are described below.

a. The dry earth system
        This is a common system adopted by the farmers in South India. The cattle shed is
constructed with bamboo poles and palmyra leaves. Dry loose loamy soil is spread to a depth of
6 inch for absorbing urine. The urine soaked earth is removed along with dung every day and
stored in the manure pit. The urine is thus preserved easily.

b. Byre and pit method
        The cattle shed is provided with an impervious floor of cement or stone with a gentle
slope and cement channels to lead the urine to the manure pit. Though at times there is a thin
film of urine on the floor and drains, this is negligible. This system is ideal for housing milch
animals under hygienic conditions as well as preserving urine for manurial use.
c. The loose-box system
         In this method, cattle are tethered in a pit or box 3 ft deep and 10 ft wide. Length of the
pit is kept according to the number of cattle usually; it is 5 ft per cattle. Floor and sides should
be cemented and made impermeable if possible. The pits are provided with steps on one side
for animals to get in, and roof for protection against sun and rain. Straw is kept in movable
mangers for feeding the animals. Precaution should be taken to avoid flooding of the pit in rainy
season. A layer of straw or any other suitable litter is spread in the pit. The pit serves as a stall
as well as manure pit. The dung is not removed daily but covered with the litter. The urine
excreted is absorbed by the straw. Dung and urine soaked straws goes piling up on the floor
and the pit gets filled up in the course of about six months. Except for the un-decomposed upper
layer, the remaining manure can be carted straight away to the field. The un-decomposed
material is left in the pit itself which can be used later on.

        In the first two sytems, manurial ingredients collected are put into manure pits. These
pits are either erected on the floor or dug in the soil. In either case, the floor and sides should be
impervious in order to protect manure against air, sun and rain. When the manure pit is filled up,
cover it with a layer of earth to a thickness of 2-3 inches and allow the contents of the pit to
decompose for 4-5 months. A well decomposed manure is dark gray in colour and loose, friable
in texture.

4. Loss of nutrients
        The factors responsible for the loss of nutrients available in different manuring materials
are cited below.

a. Urine is not collected by farmers in this country. More than 50% of the nitrogen and the entire
quantity of potash in the excreta are lost due to non'-collection.
b. Major portion of the dung is burned as fuel (about half of the total amount produced), causing
a great loss of manurial ingredients. This results in a loss of many million tonnes of plant
c. If manurial ingredients are not collected and stored prop- erly, a considerable loss of nutrients
occurs through volatilization, de-nitrification, leaching, etc.
d. In India, the common practice with the farmers is to pile up manure in heaps in their fields at
the time of application which is a faulty practice. If manure is allowed to pile up in the field for a
few days, a considerable amount of nitrogen will be lost into the air.

5. Quantity and time of application
       For various crops, recommended dose of FYM varies from 10-25 tonnes per hectare
irrespective of fertilizers use. It should be applied at least one month before sowing or planting.
Application of FYM at the time of sowing may cause complete failure of crop by greatly reducing
the amount of available nitrogen in the soil.

B. Compost
         The organic wastes that are daily generated, require pretreatment before they are
applied to field as manure in order to destroy pathogens, suppress disagreeable odour and
facilitate the rapid release of nutrients. This treatment is called composting , and the final
product compost The process of decomposition is, hastened by adding starter dose of
nitrogenous and phosphatic materials like urine or fertilizers. A large number of soil
microorganisms feed on these wastes and convert it into well-rotten manure. The following are
the organic wastes used for composting.
1. Livestock and human waste (night soil)
--Cattleshed wastes such as cattle and buffalo dung and urine.
--Other livestock (sheep, goat, pig, poultry, etc.) and human excreta.
--By-products of slaughter houses and animal carcasses. Blood and meat wastes, bones,
hooves, leather and hair wastes.

        Human excrements are a potential source of soil improvement and can be easily used
as manure if the night soil is dehydrated as such, or after admixture with absorbing materials eg.
soil, ash, charcoal and sawdust. The mixing of night soil with an equal volume of ash and 10%
powdered charcoal produces an odorless material, containing 1.32% nitrogen, 2.8% phosphoric
acid, 4.1 % potash and 24.2% lime. The addition of 40-50% of saw dust to the night soil yields
straightaway a dry, acidic powder which may contain 2-3% nitrogen. .

2. Crop residues, tree leaves and aquatic weeds
--Crop wastes of cereals, pulses, oilseeds (wheat, paddy, bajra, jowar, gram, cowpea, linseed,
--Stalks of com, cotton, tobacco, sugarcane trash, leaves of cotton, jute, tapioca, arecanut,
water hyacinth, forest litter, etc.

       Five largest grown crops (jowar, bajra, paddy, wheat and maize) alone produce
approximately 141.2 million tonnes of residue per annum. Wastes of mature crop contain on an
average 0.5% N, 0.6% P2O5 and 1.5% K20. The nutrient potential of f cereal straw is 0.7 million
tonnes N, 0.84 m tonnes of P2O5 and 2.1 m tonnes of K20. At least half of these can be utilized
for composting.

3. Green manure legumes
--Sunhemp, dhaincha, cluster beans, cowpea, horse gram, berseem, etc.

4. Urban and rural wastes
--Solid wastes, sewage and sludge, market remnants, etc. are considered the urban and rural

        About 3 lakh million gallons sewage is produced annually i in India out of which only
Ilakh million gallons are utilized on organized sewage farms. Sewage is very useful for crops
because it has three components viz. water, plant nutrients and organic matter. A large inflow of
sewage and solid sludge to the rivers and canals poses a danger to the environment and public
health. Using them for manurial purpose avoids this dangcr. Thc average NPK contents of
sewage water arc 50 ppm, 15 ppm and 30 ppm, respectively.

5. Agro-industrial by-products
-Oilcake, paddy husk and bran, bagasse and pressmud, sawdust. fruit and vegetable wastes,
cotton, wool and silk wastes, tea and tobacco wastes, fish meal, sea weeds, algae (marine
wastes), tank silts, etc.

6. Slaughter house waste
        There are about 3000 slaughter houses in our country handling about 12 million dead-
large animals every year. Survey by Directorate of Marketing and Inspection reveals that about :
4.5 lakh tonnes of bones are available every year in the country, ! out of which 1.361akh tonnes
are collected and utilized by bone crushing mills to produce raw and steamed bone meal which
contains about 8 to 25% P2O5 and 1-3% nitrogen. Out of the total available blood meal of
55000 tonnes, only l/ utilized. It contains 10-12% N, 1-2% P2O5 and 1% K20. It is
estimated that about 0.12 lakh tonnes of meat-meal can be produced from dead animal wastes
(8-10% N and 3% P2O5). Thousands of tonnes of hoof and horn meal is produced in the

7. Aquatic plants
        Water hyacinth is a free floating weed plant which grows luxuriantly in ponds, lakes and
standing water reservoirs. It is estimated that total acreage under this weed is about 3 lakh
hectares scattered in the states of West Bengal, Bihar, Assam, eastern U.P., Andhra Pradesh,
Tamil Nadu, Orissa and Kerala. It can be used as soil mulch, green manure and compost. This
is a good source of potassium (0.1 %) and easily decomposable" without using any starter. It
yields 250 tonncs per hectare biomass and one tonne of biomass supplies 20.5 kg N, 11 kg
P2O5 and 25 kg K2 0.

8. Forest litter
        Throughout the country, about 15 million tonnes of forest litter manure may contain
0.75,0.73 and 0.075 million tonnes of N, P2O5and K20, respectively. Forest litter can be
collected and used for composting to a certain reasonable extent.

9. Agro-industrial wastes
a. Oilseed industry
        Oilseed industry produces about 0.3 million tonnes of non-edible cakes, eg. neem,
karanj, mahua, castor, etc. These cakes contain approximately 3-9% nitrogen which is readily
available to the plants. About 60-90% of the nitrogen becomes available in 2 to 3 months after
application of these cakes to the field.

b. Rice milling industry
        About 15 million tones of rice husk and 2.5 million tonnes of rice bran are annually
produced in the country. Rice husk contains 0.3 to 0.4% nitrogen, 0.2 -0.3% phosphorus and
0.3 to 0.5% potash.

c. Sugar mill industry
         The arnount of dry bagasse produced in the country is about 5.3 million tonnes. About 2
million tonnes of pressmud is also produced by sugar mill industry annually in our country.
Bagasse makes a good manure after processing from biogas plant. These by-products are very
rich in nitrogen.

d. Forest mill wastes
        Saw mills and plywood industries produce about 2.2 mil- lion tonnes per year of sawdust
but it has a limited use because of very high carbon-nitrogen ratio (500:1) and low content of
nitrogen. However, it can be used as urine absorbant or litter on cattle sheds and poultry farms.

e. Vegetable and fruit processing industries
       About 25,000 tonnes of wastes annually produced by these industries have the potential
to produce about 10,000 tonnes of compost. A large quantity of vegetable wastes can be
obtained from peals, cores, wines, piths, stems and other materials from fruit and vegetable
processing plants and vegetable marketing places.

f. Cotton mill
        Cotton stalk produced is around l2 million tonnes per year. Textile mills produce 30,000
to 33,000 tonnes of cotton dust annually which has 1.4% N, 0.6% P205 and 1.2% K2O.
g. Tea industry
         About 10 million kg of tea waste in the form of gluffs-stalks and sweepings is produced in
India. It has 0.28%-3.5%, 0.4% and 1.5% NPK respectively.

h. Tobacco wastes and tobacco seed-cake
      About 62,000 tonnes of tobacco waste and 10,000 tonnes of tobacco cake are annually
produced in the country. The cake has 4-4.5% N, 7-15% P205 and 5-5.5% K20.

i. Jute sticks
        Approximately 2.5 million tonnes of jute by-products are produced in India every year
and they can be successfully used as manuring material.

j. Fisheries and marine industry
        These are a good source of organic manures amounting to about 10,000 to 15,000
tonnes of biomass annually. Sea weeds contain 1-2% P2O5 and 2- 7% K2O and a number of
other micro-elements too.

k. Marine algae and seaweeds:
       These are good source of organic manures amounting to about 10,000 to 15,000 tonnes
of biomass annually. Seaweeds contain 1-2% P2O5 and 2 - 7% K20 and a number of other
micro-elements too.

I. Tank silt
        Tank silt consists of a mixture of fine soil particles –silt,clay and organic matter, carried
by the run-off water from the surrounding soils to the tanks, ponds and other depressed places
during heavy rains. They can serve as an active culture of microorganisms, particularly the
nitrogen fixing ones. It has been estimated that millions of tonnes of tank and river silt is
available for application on land but remain unexploited till date.

C. Green manure
          The term "green manuring" is defined as a practice of ploughing or turning into the soil
un-decomposed green plant tissues for the purpose of improving physical structure as well as
fertility of the soil. Crops for green manuring may be legumes, non-legumes and other various
green leaf plants such as weeds in their succulent and non-flowering stage.

1. Types of green manuring
       Broadly speaking, the following types of green manuring can be differentiated.

a. Green manuring in situ
       In this system, certain seasonal legumes crops are grown and buried in the same field
which is to be green manured, either as a pure crop or as an intercrop with the main crop. The
most common leguminous green manure crops grown under this system are sunnhemp
(Crotalaria juncea), dhaincha (Sesbania aculeata) pillipesara (Phaseolus trilobus), guar
(Cyamopsis tetragonoloba), senji (Melilotus parviflora) and berseem (Trifolium alexandrinum).

b. Green leaf manuring
        Green leaf manuring refers to turning into the soil green leaves and tender green twigs
collected from shrubs and trees grown on bunds, waste lands and nearby forest areas. The
common shrubs and trees used are gliricidia (Gliricidia maculata), dhaincha (Sesbania
speciosa), karanj (Pongamia pinnata) etc.
       The non-leguminous crops commonly used as green manure crops are bhang
(Cannabis sativa), kodogira (Vernonia cinerea), jowar (Sorghum vulgare), maize (Zea mays),
sun-flower (Helianthus annus), etc.

2. Green manuring crops
       A brief description of some plants suitable for green leaf manuring is given below.

a. Sunnhemp (Crotolaria juncea)
       his is the most outstanding green manure crop. It is well suited to almost all parts of the
country provided the field is not swampy and the area receives sufficient rainfall or has an
assured irrigation. This popular green manure is ready for turning in two months. Its yield of
given matter is very high ranging from 15- 20 tonnes/ha. Its seed rate is 25-30 kg/ha. Many
other species eg. C. usramensis, C. brownil, C. striata and C. anagyroids are also grown for
green manuring. Seventeen tonnes of sunnhemp can incorporate about 75 kg of nitrogen.

b. Dhaincha (Sesbania aculeata)
       It occupies the second place next to sunhemp for green manuring. Since it has the
advantage of growing under adverse conditions of drought, water logging, salinity and acidity, it
can be grown in a wide range of soil and climatic conditions. The crop is raised by broadcasting
seed @ 20-25 kg per hectare. It becomes woody after three months and, therefore, it is
essential to plough it before it turns woody.

Wild dhaincha (Sesbania speciosa)
        In Tamil Nadu, it is mainly applied in paddy. The crop is raised by broadcasting seed @
15 to 20 kg seed/ha. Plants seed when they are 5 months old. For green manuring purpose,
only 60-70 days old crop should be turned in. One hectare of crop yields about 2,500 to 3,000
kg of green matter which can provide up to 200 kg nitrogen per hectare.

3. Plants suitable for green leaf manuring
       Many species of shrubs and forest plants, both legumes and non-legumes are grown on
bunds or wastelands for the purpose of utilizing their leaves and twigs as green manure. Green
leaf manuring is common practice of the cultivators growing paddy in Andhra Pradesh,
Karnalaka and Kerala. In localities close to forests, the paddy crop is manured with green
leaves from the forest. A list of shrubs and trees which are lopped for green manuring is given

a. Gliricidia(Gliricidia maculata)
        The seedling or rooted stump are planted 6 feet apart on the borders of paddy fields or
waste lands. Each gliricidia tree grows 25-30 feet in height under favourable soil and climatic
conditions. In a year two cuttings can be had, the first at the beginning of monsoon and the
second in December. It contains 8.5% carbon and 0.48% nitrogen. The yield of leaf material per
plant is about 22.5 kg. The only drawback with Glyrcidia is that it often gets infested with mealy

b. Karanj (Pongamia glabra)
       The average yield of green leaves per tree is about 130 kg. It contains 0.5% nitrogen.

c. Madar (Calotropis gigantea)
       Madar is a commonly occuring weed along road sides. It grows well in all conditions.
The leaves are succulent, velvetty to tough, and the quantity of green matter per plant is 5 kg. It
is commonly applied as a manure to the coconut plantations.
d. Wild indigo (Tephrosia purpurea)
       It is a freely branching and spreading annual shrub found growing in fallow lands. The
twigs of this shrub are used for green manuring paddy crop in Karnataka and Kerala. It
produces 8.7 kg per plant green matter which contains 3.7 kg nitrogen on dry weight basis.

        Some other trees suitable for green leaf manuring are white tephrosia (Tephrosia
purpurea), indigo plant (Indigofera teysman), wild cassia (Cassia tora), arjun tree (Terminalia
arjuna) etc.

4. Advantages of green manuring
         The advantages generally attributed to green manuring are given below.
a. It adds organic matter to the soil. This stimulates the activity of soil micro-organisms.
b. The green manure crops return to the upper top soil, plant nutrients taken by the crop from
deeper layers.
c. It improves the physical structure of the soil.
d. It facilitates the penetration of rain water into the soil, thus decreasing the run-off and erosion.
e. The green manure crops hold plant nutrients that would otherwise be lost by leaching.
f. When leguminous plants like sunnhemp and dhaincha are used as green manure crops, they
add nitrogen to the soil for the succeeding crop.
g. It increases the availability of certain plant nutrients, such as phosphorus, calcium,
Potassium, magnesium and iron.

5. Technique of green manuring
        In the regions receiving less than 62.5 cm rainfall in uneven form, green manuring is
generally not recommended. In the case of paddy, if there is assured water supply, green
manures are applied one week before transplanting. Transplanting of paddy reduces losses of
nitrogen through volatilization. Farmers with very small holdings can grow green manures as
mixed crops or cart into their fields from other places. Green manure crops are ploughed in,
mixed with the field when they are most succulent and non-fibrous (i.e. when the flowers have
just emerged). The crop is mixed thoroughly with the soil by a soil turning plough at least one or
two weeks before sowing depending upon the nature of the green manure crop and moisture
status of the soil or field. Sowing of the crop will have to be planned in such a way as to bury
green manure at a time when it furnishes its nutrients to the subsequent main crop when the
latter needs it most. This will help in checking the loss of nutrients also.

a. Soil and climate
         Green manure crops can be grown in any type of soil provided sufficient rainfall or
irrigation is available. It improves sand or clay soils also if sown in them.

b. Sowing time
        In South India the ideal time for sowing green manure crops is June-July and August-
September, whereas in North India sowing maybe undertaken in May-June. The advantage of
establishing the crop earlier than the onset of the monsoon is to resist the damage from the
subsequent heavy rains and to retain maximum rain water.

c. Dosage
        The amount of green manure recommended for various crops differ greatly as seen in
table 3.
              Table 3: Crop wise type and dosage of green manure recommended

  Sl.No.   Name of crop                       Green manure recomended               Dosage in
  1        Paddy                              Sesbania or kolinji or sunnhemp       2300
  2        Sugarcane                          Sunnhemp                              5000
  3        Irrigated ragi                      -do-                                 1000
  4        Irrigated cholam                   -do-                                  1000
  5        Cotton                             No green manure since depression
                                              in yield takes place
  6        Wheat                              Sunnhemp                              7000
  7        Banana                             Gliricidia                            25 kg/pit
  8        Grapes                             Green leaf available (just before     25 kg/pit
  9        potato                             Lupin or buck wheat leaves            1000

6. Characteristics of Plants for green manuring in situ
       An ideal green manure crop should possess the following desirable characteristics.

a. It should preferably be a legume with good nodular growth habit indicative of rapid nitrogen
fixation even under un-favourable soil conditions.
b. It should have low water requirements for its own growth and should be capable of making a
good stand on poor and exhausted soils.
c. It should have deep root system which can open the subsoil and top lower regions for plant
d. The plant should be of leafy habit capable of producing heavy tender growth early in its life
e. It should contain large quantities non-fibrous tissues of rapid decomposability containing fair
percentage of moisture and nitrogen.

        Some of the green manuring plants along with their nutrient value utilised in various
parts of India as green manures are given in table 4.

                    Table 4: Average nutrient content of common gree manures

   Sl.No Manure/manuring material                               N (%)       P2O5       K2O
   A. Tree leaves
   1        Madar(Calotropis gigantea)                          0.35        0.12       0.36
   2        Kumbhi (Careya arborea)                             1.67        0.40       2.20
   3        Tarwar (Cassia auriculata)                          0.98        0.12       0.67
   4        Aggai, Karmal (Oillenia penlagyna)                  1.34        0.50       3.20
   5        Glyrcidia (Glyrcidia maculata)                      0.48        0.15*      0.50*
   6        Mahua (Madhuca indica)                              1.66        0.50       2.00
   7        Karanj (Pongamia pinnata)                           3.69        2.41       2.42
   8        Bijasar(Plerocarpus marsupiun)                      1.99        0.40       2.90
   9        Subabul (Leucoena leucocephala)                     1.55*       1.98*      0.50
   10       Harra (Terminalia chebula)                          1.46        0.35       1.35
   11       Terminalia arjuna                                   1.55*       0.40*      1.70*
   12       Terminalia panicu!ata                               1.70        0.40       1.60
   13       Terminalia tomentosa                                1.39        0.40       1.80
   14      Jambu (Xylia xylocarpa)                               1.37       0.30        1.61
   B. Green Manures (fresh)
   1       Lobia,Cowpea(Vigna catjang)                           0.71       0.15        0.58
   2       Dhaincha (Sesbania aculeate)                          0.62       0.13*       0.51*
   3       Guar,Clusterbean {Cyamopsis tetragonaloba)            0.34       0.14*       0.52*
   4       Kulthi, Horse gram (Dolichos biflorus)                0.33       0.15*       0.51*
   5       Matki, Moth bean (Phaescolus aconitifolius)           0.80       0.15*       0.50*
   6       Berseem (Trifolium alexandrinum)                      1.66*      0.14*       0.50*
   7       Lucern (Medicago sativa)                              1.68*      0.15*       0.51*
   8       Senji (Melilotus parviflora)                          1.60*      0.15*       0.50*
   9       Mung (Green gram) (Phaseolus aureus)                  0.72       0.18        0.53
   10      Sunnhemp (Crotalaria juncea)                          0.75       0.12        0.51
   11      Urd, Black gram (Phaseolus mungo)                     0.85       0.18        0.53

* Relative estimates

III. Concentrated Organic Manures

      Concentrated organic manures have more nutrient con- tents than bulky organic
manures. They are oil cakes and meals.

1. Oilcakes
        Oilcakes are very rich in nutrient contents and though insoluble in water, are quick acting
organic manures. Their nitrogen becomes quickly available to the plants in about a week or ten
days time after application. Mahua cake, however, takes two months to decompose. Oilcakes
need to be well powdered before application. They can be applied few days before sowing or as
top dressing (except mahua cake). Oil cakes are more effective in moist soil and wet weather
than in dry soil and dry weather.

       The use of oilcakes on food grain crops such as wheat and rice is not recommended
now on economic grounds. Cakes, especially groundnut and coconut cakes are extensively
applied as top dressing in sugarcane crop. Farmers growing betel also use oil-cakes. Table 5
provides the NPK content of various oil cakes.

2. Meals
       These are all quick acting manures suitable for all types of soils and crops. This group
includes blood meal, fish meal, horn meal, hoof meal and bone meal. Application of meat meal
and blood meal is similar to oilcakes; the latter should be powdered before application. Horns
and hooves (slaughter house remnants) are converted into meal by cooking in the bone digester
and then dry and powdering them. Most of them are processed in factories and then sent for
marketing. The NPK content of meals are given in table 5.

              Table 5: Average nutrient content of concentrated organic manures

          Sl.No Name of Manure                          Percentage compostion
                                                        Nitrogen P2O5       K2O
          1. A. Cakes: Non-edible oil cakes
               1 Castor cake                            4.3        1.8         1.3
               2 Cotton seed cake (undeco-              3.9        1.8         1.6
               3 Karanj cake                             3.9         0.9        1.2
               4 Mahua cake                              2.5         0.8        1.8
               5 Safflower cake (undecoticated)          4.9         1.4        1.2
               6 Neem cake                               5.2         1.0        1.4
             B. Edible oil cakes
               1 Coconut cake                            3.0         1.9        1.8
               2 Cotton seed cake                        6.4         2.9        2.2
               3 Ground nut cake                         7.3         1.5        1.3
               4 Linseed cake                            4.9         1.4        1.3
               5 Jambo cake                              4.9         1.6        1.9
               6 Niger cake                              4.7         1.8        1.3
               7 Rapeseed cake                           5.2         1.8        1.2
               8 Safflower cake (decorticated)           7.9         2.2        1.9
               9 Sesamum cake                            6.2         2.0        1.2
          2. Meals
               1 Blood meal                              10-12       1.5        1.0
               2 Fish meal                               4-10        3.9        0.3-1.5
               3 Meat meal                               5-10        2.5        0.5
               4 Horn and hoof meal                      13            --         --
               5 Raw bone meal                           3.4          20-25       --
               6 Steamed bone meal                       1.2         25-30        --

IV. Effects of Organic Manures on Soil Properties

       Addition of organic manures results in multi pronged positive effects on the soil. They
can be discussed as under.

1. Effects on physical properties
        The organic matter supplied by the manures is a vital component of soil. Water holding
capacity and nutrient retaining capacity of the soil are increased. It helps in developing granular
structure of the soil. This structure provides enough room for both air and water to stay in the
soil. Soil, in the presence of organic matter, develops resistance against the erosion. Manures
also impart to the soil a capacity to tolerate extremes of temperature and enable the soil to
maintain a narrow and desirable range of temperature.

2. Effects on chemical properties
        Organic manures, especially green manures, have already established their importance
in the reclamation of alkali soils. They can also correct acidity of the soil to a certain extent, if
acidity in the soil is due to presence of acid forming minerals. In other words, we can say that
organic manures impart buffering capacity to the soil. Organic matter supplied by the manures
to the soil keeps the plant nutrients bound on itself and supply to the plant in times of need.
Organic matter also counteracts the adverse effect of heavy metals supplied to the soil through
pesticides and also neutralizes acidity or alkalinity created by fertilizers.

3. Effects on biological properties
       Soil micro-organisms are like the workers in the factory that is soil. They bring about
numerous biological transformations in the soil. Organic matter serves as food as well as raw
material for these micro-organisms.


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