ME31B: CHAPTER FIVE FARMSTEAD AND FARM STRUCTURES

5.1 FARMSTEAD PLANNING

 The farmstead is the centre of the farm enterprise where the farm house and other farm structures are sited.

 Apart related from to providing farming, for the activities farmstead provides for business related to the domestic and social life of the farming family.

Factors to be Considered in Selecting a Site For a Farmstead

   It should have an easy access to the highway or road. This is necessary to avoid the expenses of maintaining an expensive private road.

b) It should be centrally located(if possible) in order to minimize travel to and from the fields.

c) There should be proximity to electric supply and other essential services e.g.

telephone lines, schools, bus routes, markets etc.

d) The site should be elevated sufficiently to aid supervision.

Other Considerations in Farmstead Planning

   

A. Water and Sewage Disposal

a) There must be adequate supply of water for the household and livestock.

b) The site should provide adequate space near the house but far away from the source of water for sewage disposal units (septic tanks).

B. Soil Conditions:

The soil should be so well drained as to assure reasonable dry conditions underfoot and to provide suitable foundation for construction.

a

Other Considerations Contd.

 

C.

Distance Between Buildings:

Some space should be allowed between buildings to reduce fire hazard. About 20 to 25 m is usually adequate. A distance of 45 to 60 m between the house and production buildings (eg.

livestock) usually satisfies esthetic requirements without adding excessively to the land area occupied by the farmstead.

D. Orientation:

The farmstead should be oriented so that the prevailing winds pass the dwelling towards the production buildings.

Other Considerations Concluded



E. Windbreaks:

Suitable trees should be planted as windbreaks to protect the buildings.



F. Esthetic Considerations:

and other areas not likely to be attractive should be located so as not to be visible from the screened by suitable trees.

Feedlots house or

5.2 THE FARM HOUSE(S):

    

T

his is where the farmer and workers live.

There are three requirements for a good house: Space, sanitary and physiological requirements.

5.2.1

Space:

Provide accommodation for the inhabitants.

adequate There are essentials like sitting kitchen, toilets, stores and even office.

room, The bedroom and the toilet are always near to each other.

The dinning room is also near to the kitchen in modern designs.

Space Requirements for a Farm House Contd.

    The dinning room and the sitting room are normally in the same place to provide more space for say gatherings.

One room can be used to store goods or it can be regarded as the utility room where some washing and ironing can be done.

For a farmer, an office is necessary.

A garage is necessary and it can be used as a workshop. The garage can also be used to store garden equipment.

Space Requirements Contd.

    Upstairs can be built.

In that case, sitting, dinning, guest house, bath and office rooms can be in the ground floor while the sleeping room can be upstairs.

A house of two floors will be cheaper than one flat because the foundation of the upstairs is not double that of one flat and also one surface is saved since the upper floor (decking) acts as the roof for the lower floor and the floor for the upper floor.

If the plan is for two bedrooms, upstairs may be cheaper.

Figure : Typical Plan For a Farm House (One Floor)

o

Bedroom Bath Toilet Kitchen Sitting and Dinning

Other Requirements of a Farm House



5.2.2

Sanitary Requirement:

Septic tank should mainly be used.



5.2.3

Physiological Requirement:

Use good insulators. Air conditioners can be used.

5.3 POULTRY FARM

     In a poultry farm, there are hatchery, brooder, broiler, layer and breeder houses.

5.3.1 Hatchery:

Fertile eggs are initially put into the incubator after which they are transferred to the hatchery to hatch.

The hatchery should be well insulated from the outside.

There is a receiving room to test the fertility of the eggs and store them in a cold room.

There is a room for washing implements. A store room is also provided.

Hatchery Concluded

   When the eggs hatch, they are put in a battery brooder for a day so that they can be sold off if desired.

Separation of sexes is effected here.

They are then transferred to the brooder house where they stay from a day old to a few weeks (See Fig. 5.1).

5.3.2 Brooder House

   Temperature should start from high and go down week after week.

This is because the chicks have large surface area per unit weight and since this controls temperature loss, the chicks lose a lot of weight.

As the production of heat is proportional to the weight of animals, chicks do not produce much heat, because of their small weight.

Brooder House Contd.

    Also the chicks' mechanisms for controlling temperature are still under development, and they do not have insulating body cover.

All these make the heating brooder houses necessary.

The brooder house is made up of many pens.

The chicks are divided into pens according to their ages to reduce cannibalism.

The walls should be well insulated and the window slanted.

Brooder House Contd.

   The brooder house should be well ventilated. Heating can be by electrical bulbs hanging on kerosine or bottle gas.

the ceiling or Heating can also be by a hot air system.

This has a boiler and some pipes on the floor.

When the chicks are big enough, they are divided into meat chicken (broilers) and laying chicken (layers)

    

5.3.3 Broiler House

The broiler is a young chick about 1 kg.

They need food and water.

They need a big house, which is not necessarily insulated unless the environment is very cold.

Feeders and water troughs have to be provided.

Automatic feeders can be used for large number of chicks e.g. 10,000.

The major design features are provision of equipment to maximize food and water intake. Broilers reach the required weight between 6 and 9 weeks.

  

5.3.4 Layers' House

There are 2 types of layers: a) Table egg layers: The eggs are not fertilized so no need for a cock.

b) Fertile egg layers: need a cock.

 

Requirements For a Layers' House a) Rooster:

elevation.

Hens like sleeping on top of an In a layer house, a rooster is provided.

The rooster can be in form of a table.

Trays are put below the rooster to collect the droppings and this can be cleaned daily. The sides of the rooster can, however, be closed to prevent the hens from going under the rooster.

Layers’ House Contd.

  The droppings can then be removed after a long while when the underneath f the rooster is full. (See Fig. 5.4)

b) Nests:

There is the need to have nests for hens to lay their eggs in. The nests are group of boxes beside each other. The top of the nest is inclined so that hens cannot sleep on top of it. The hens lay their eggs in the daytime only and artificial lighting can be provided in the night to prolong their laying period.

Layers’ House Contd.

 A small flock will require 6 m x 6 m pens. For a big flock, a 12 m x 100 m house can contain about 7000 hens.

The hens can be put in different floors to reduce the area.

 This is by caging. Two to four hens can be put in a cage which is supported from the floor of the roof (See Fig. 5.5).

5.3.5 Breeder House

    There should be many houses, each one with one cock and 4 hens.

For each house, certain types of cocks and hens are chosen.

The aim is to provide good hens that produce large number of eggs, good and large meat.

The breeder house should be entered once in a while so as not to frighten the birds.

Trap nests should be provided.

Breeder House Concluded

   These trap hens once they enter the nests to lay hens.

A man then enters the nests to take the number of the hens that laid the eggs and records the particulars of the eggs e.g. weight and size.

The major breeder difference house and between ordinary a layer house is that the breeder house has trap nests.

Example

    The chicks' accommodation is desired so that about 20 of them occupy 1 m and for broilers 5 to 10 per m 2 .

For layers, it is 3 to 4 per m 2 .

The width of farm buildings is usually 12 m and the length depends on the area and the number of animals to be sheltered.

For small structures, the width can be 6 m.

Solution

 

(

a) Space requirement: For 200 layers, the area is 200/3 = 66.67 m ; if the width of the building is 6 m, the length should be 66.67 /6 = 12 m. The buildings can be built in units e.g. with each unit 6 x 12 m. See diagram on next page.

b) Rooster:

Four birds are to be provided with 1 m length of roaster. Since the length of the building is 12 m, about 48 birds will be in a line. For 200 layers, 5 lines are needed.

Nests

   

c) Nests:

The number of nests is calculated on the provision that about 5 birds need a nest.

For 200 layers, we need 40 nests.

Two sets of nests can be provided on each side of the building with each set containing about 24 nests.

The dimensions of the nest should be 30 x 30 x 30 cm.

The floor of the building should be made on concrete.

Solution Concluded

    

Note

that in line with section 4.5.2.1, since the span is only 6 m, there is no need for a roof truss.

Pitched timber rafters or lightweight trusses can do.

The roof can be covered with corrugated sheet.

The wall should be built up to about 1 to 1.25

m and the rest can then be chicken wire to allow for ventilation.

Nests and roasters have to be provided.

Local Poultry Industry

 See attached Note on details of a Survey done on the Farm Structures of the Local Poultry Industry in Trinidad.

Tunnel-Ventilated Poultry Buildings

 This is the latest technology available for housing poultry to ensure tat optimum house temperature is maintained.

 In tunnel ventilated houses, the right air velocity and air humidity are carefully monitored and modified to maintain optimum conditions.

Tunnel-Ventilated Poultry Buildings Contd.

   The ventilation system is the negative type whereby air is drawn out of the house through the use of exhaust fans. This creates a slightly lower pressure area within the house. Air outside the house rushes in through cracks in the sidewalls and curtain openings to the partial vacuum created.

Ventilation System in Tunnel-Ventilated Buildings Contd.

    The system of ventilation keeps the birds cool in two ways: One is by passing air at the high speed of 2.5 m/s, a wind chill effect is created to cool the birds.

Secondly, by evaporating moisture from the moisture laden air.

All the equipment in the building are automated. See details in the note book.

5.4 STORAGE OF MACHINERY:

Machinery requires protection from only precipitation, wind blown dust and sunlight. It has no need for controlled temperature or positive ventilation. Machinery can then be stored in a shed or in a metal frame building.

Table 5.1 : Approximate space requirement of some farm machinery equipment. ITEM Width x Length(m)

60 hp tractor 100 hp tractor 100 hp tractor with dual tyres 6 m-combine harvester 5 bottom plough 4 row corn head-combine 5.5 m disc Mowing machine 8 row corn planter 2.4 x 3.7 2.7 x 4.3 4.0 x 4.6 9.0 x 6.0 2.4 x 5.8 3.0 x 4.0 5.8 x 4.6 2.1 x 2.1 7.6 x 3.7

Storage Structures

5.5 STORAGE STRUCTURES 5.5.1 Considerations in Designing a Storage Facility:

These include:

a) System Capacity:

The volume of a rectangular storage system is: Capacity (m 3 ) = Length (m) x width (m) x depth (m) For a cylindrical bin, the capacity is: Capacity (m ) =  (Bin diameter, m) 2 x height (m) 4 A general guide is to provide total capacity for 1-year crop. More than one bin may be provided if the farmer needs to store more than one grain or if the grains are to be dried before storage.

Considerations in Designing a Storage Facility Contd.



b) Location

: Storage structures should be located on a hard surface, near good access roads and near the place of utilization as well as production fields. The area should have room for expansion.



c) Handling Methods & Equipment:

Mechanical elevators can be used for handling and unloading of grains. Handling should be minimized to reduce breakage of grains.

Considerations Contd.

  

d) Provision for drying, aeration and fumigation of grains:

An average 13% moisture content for grains is required since grains are normally stored in tight bins where natural flow of air is slow through the material.

Alternatively, grains can be dried during storage using special means.

There should be provision of aeration during storage to lower grain temperature, equalize grain temperature throughout the bulk and to remove unpleasant odours or toxic gases after fumigation.

Considerations Contd.

  

e) Structural Requirements:

Unlike other farm building construction, grain storage structures withstand much greater product loads in addition to normal wind loads.

This entails heavy duty foundations.

Reinforced concrete is the most satisfactory material for grain storage foundation.

Steel is mostly used to construct grain storage structures.

Considerations Concluded

 This is because steel can easily be adapted to high volume and can easily be prefabricated in thin section and is relatively light in weight.

 Other requirements include those of esthetics and economics.

5.5.2 Angle of Repose

   Angle with the horizontal at which heaped materials will stand.

For a dry material e.g. grains, the angle of repose is usually equal to the angle of shearing resistance of the material i.e. angle of internal friction Granular materials like sand and grains have internal friction but are assumed to be cohesionless.

5.5.3 Storage Bins/Silos

   Bins are storage structures commonly used on the farm for storing small grains e.g. cereals and shelled corn.

They are made of steel, concrete or wood and can be either circular, square or rectangular in cross section.

Bins can be classified as shallow or deep.

Criteria for Classification of Bins

a) A bin is termed shallow when the depth is less or equal to the equivalent diameter. Equivalent diameter is used because the bin may be circular. H H D

Deep bin

D

Shallow Bin

If H < Deq., the bin is shallow i.e. H/D < 1 and if H > Deq., the bin is deep i.e. H/D > 1.

b) Another criteria is to draw a line at an angle equal to the angle of repose of the granular material from the intersection of the bin wall and the floor to the opposite bin wall. In a deep bin, this line intersects the opposite wall before passing through the upper surface of the granular material. In a shallow bin, the line meets the opposite wall at or at above the surface of the granular material. Hd 

Deep bin Shallow bin

O is the angle of repose = angle of internal friction and Hd is the depth of grain. Mathematically, for a circular bin:

If H d



D

 then the bin if shallow;

If H d



D

the bin is deep.

Third Criterion For Classification of Bins

c) The most rigorous criterion for a deep bin applicable to considerably tall structures is given as: If Hd/D > 1 M

K

O Q , the bin is deep Hd is the depth of grain; fs is the coefficient of friction; K is the ratio of lateral to vertical pressure. Silos are deep bins which are now increasingly being used for stockpiling of grains and industrial materials.

5.5.5 Design of Shallow Bins

Rankine equation is normally used in estimating the lateral pressure exerted on the wall of the bin. It states that:  3

y

= w y tan 2  /2) same as

w y

1 ( 1   sin   3

y

= Lateral pressure at a given depth y on the shallow bin (kg/m 2 ). y is the distance measured from the top of the bin (m) w is the weight density (bulk density of the material, kg/m 3 ) O is the angle of internal friction.

5.5.6 Design of Deep Bins

    K varies from 0.3 to 0.6.

For tall bins, vertical pressure causes a column action when it is filled with materials.

Lateral pressure causes bending action.

When H exceeds (2 to 2.5 D), it has been found that further increase in depth does not increase the bottom pressure.

This is because, at a certain depth, the walls of the structure take up more of thevertical load.

Design of Deep Bins Contd.

  This is unlike the shallow bins where the vertical pressure is completely borne by the floor while the wall bears only the lateral grain pressure.

K is not constant but depends on material, geometry, ratio of diameter to depth, total depth and moisture content of the material.

Because of the variation in its properties, K is not used to determine lateral pressure. Rather for deep bins, Janssen's 1895 equation is used.  3 

wR f s

( 1 

e

 )  3 is the lateral pressure at depth (h) in kg/m 2 ; W is the weight density (bulk density) in kg/m 3 ; R is the hydraulic radius = Area of bin floor = D Perimeter 4 fs is the static coefficient of friction against the wall K is the ratio of lateral to vertical pressure (0.3 to o.6)

5.5.7 Loads on Storage Walls

Apart from Rankine and Janssen equations used to estimate lateral pressures, there are many other equations. For shallow bins, the Rankine equation is used. The assumption is that grains are semi fluids. y Bin wall y P L (Resultant Lateral Pressure) 1/3 y Maximum lateral pressure occurs at the bottom of the structure. Resultant lateral pressure acts at 1/3 h from the bottom or 2/3 from the top of the structure (see diagram). Its magnitude is: P L = 1/2 w y 2 1 - sin O 1 + sin O P L is the resultant lateral load (kg/m).

Loads on Storage Walls Contd.

If the resultant force, P is known, the thickness of the wall to withstand it can be determined. It will depend on the type of support. The thickness of steel sheeting for a maximum allowable stress of 1400 kg/cm 2 required to balance a load = t > P L cm 100 x 1400 For deep bins, the vertical pressure on bin wall (kg/m 2 ) is the product of the lateral pressure and the wall friction coefficient (fs) i.e. Vs = L fs . On the floor of bin: vertical pressure = Lateral pressure at bin floor L Vs K

Concluding Remarks on Janssen Equation

   For deep bins, Janssen equation is used. The assumption is that the bulk density of grains and also that the grains are semi-fluids.

Note: There are several deficiencies with the Janssen equation.

It has been said that it does not predict dynamic loading, which occurs during unloading.

Concluding Remarks on Janssen’s Equation Contd.

  However, no matter the magnitude of dynamic loads, their duration is so temporary as to cause failure in a well designed Janssen and well equation erected predicts silo.

static pressures well which operates for most of the storage period.

The equation can safely be used with a factor of safety.