ERT 352 FARM STRUCTURES

1.1 DEFINITION Farm structures involve the study

of the erection of buildings for man, animals, crops and farm equipment.

The design and construction of farm structures is one of the major technical services agricultural engineers render to agriculture.

1.2 EXAMPLES OF FARM STRUCTURES a) Farm houses: Dwellings for

operators, retired parents, relatives, workers with families.

b) Buildings for livestock e.g. horse, dairy, beef-cattle, sheep, goat, hogs and poultry buildings.

c) Buildings for product storage e.g. hay barns, granaries, bins, silos, vegetable storages, frozen product storages, Cold rooms etc.

Other Farm Building Examples d) Buildings for crop production

especially green houses. e) Buildings for processing e.g. milk

houses, pasteurizing and bottling plants; slaughter houses, grain dryers, dehydration structures etc.

f) Buildings for equipment and supplies e.g. implement sheds, garages, farm shops, fuel storage etc

1.3 PLANNING OF FARM STRUCTURES Planning of farm structures refers to all

processes undergone right from conception to completion of the structures.

The planning stages include:  a) Conception & Feasibility: Investigate

different alternatives for investments and development of the farm, now and in the future. Check possible sources of finance for the investment. The feasibility involves studies of user requirements, site conditions, requirement from authorities, functional and technical requirements and cost. 

Stages in Planning Contd. b) Sketch Plans: Roughly sketch

alternatives to the general approach to layout, functional planning, design and construction. Choose the required layout and prepare preliminary constructional design and cost calculations.

Alternatively, drawings can be collected from reliable sources e.g. research stations. Study the drawings and evaluate them regarding the functional and technical requirements.

 

Steps in Planning Contd. c) Detailed design of every

component of the building. Complete cost and checking of designs. Final decision on construction.

The design of farm structures is essentially similar to the design of Civil Engineering structures like buildings.

The various components of the building include foundations, walls, floors, roof, columns,

beams and connectors like welds, nails, nuts and rivets. The design implies the sizing of

these components so as to make the structure stable and economical.

Roof

Column

Wall

Floor Foundation

Fig. 1.1 End View of a Typical Farm Structure e.g. Poultry House

Stages in Planning Contd. d) Working drawings, schedules, and

specifications regarding production methods and assembly and installation instructions. Preparations of a time schedule for the production of the building.

e) Bill of Quantities: The aim of quantity surveying is to provide an accurate bill of quantities, that is a list of the amounts of all materials and labour necessary to complete a construction project. See example in Note Bk.

Stages in Planning Contd. f) Invite tenders from contractors out of

which one is chosen. Tenders can be by open tenders e.g. Advertised in papers and selective tenders (meeting capable contractors). Sign contracts.

Contracting can be by:  i) Complete Contracting: The whole work

is given to one contractor. A lot of specifications is required. Gives the owner more rest. The contractor can employ best technicians to protect his reputation. 

Types of Contracts Contd.

ii) Semi-Contracting: Contracting various items needed for the building separately. There is waste of time. Best technicians may not be known to the owner.

  iii) Self-Aid: No contract is involved

and is cheaper. Used for small buildings e.g. chicken house. Construction may take a longer time.

Stages in Planning Concluded

g) Site operations including hiring of labour, provision of tools, preparation of access roads to sites, provision of temporal stores and sheds, clearing of sites, delivery of construction materials and technical inspection during construction.

1.4 ECONOMIC FEASIBILITY OF FARM STRUCTURES In addition to the actual cost of constructing

a building, which must be considered in relation to the financial capacity of the farmer, the total annual cost of the building should be determined.

This annual cost should be compared with the expected increase in income or the saving in storage costs to determine whether the new building is a worthwhile investment i.e. the economic feasibility of the building is determined.

ECONOMIC FEASIBILITY OF FARM STRUCTURES CONTD. Consider the following factors:  a) Cost of Land and Building b) Interest of Capital Money: This

represents the interest paid for money borrowed for building the house or in case the farmer used his money, the interest that could have accrued to him if he had used his capital for other purposes. The interest rate should be either the rate paid or the current rate of mortgage loans in the area. 

Economic Feasibility Contd. c) Insurance and Taxes: Insurance cost

should be included in capital investment whether or not the building is insured. The risk of fire and other hazards is borne by the insurance company if it is insured or by the owner himself if it is not. This may range from 1/2 to 1 % of the original cost of the building.

For countries where taxes are charged on buildings, this should be included. Taxes may range from 1 to 2 % of the original cost. 

Economic Feasibility Contd. d) Repairs and Maintenance: All

buildings require some maintenance but the cost varies with age, type of building, climate and environment, construction materials and use of the building.

One to three percent of initial construction cost is usually assumed as a uniform annual allowance throughout the life of the building.

Economic Feasibility Contd. e) Depreciation: Cost that takes account of

the wear and tear as well as the obsolesce of the building. Some methods can be used to calculate it.

i) Straight line method: Assumes that depreciation cost is constant for all years.

Depreciation cost = Initial Cost - Final Cost

Service life in years

 

Depreciation Contd.Assuming the total cost of erecting a building is

$ 20,000 and the estimated age is 20 years, the depreciation cost per year is

$ 20,000 - 0 = $ 1,000 per year 20 years

 Note: Final cost or salvage value is the final

value of the building when it is no longer viable for farm structure and can be assumed as zero or 5 to 10 % of the construction cost.

  

Depreciation: Sum of Digits Method

b) Sum of (years) Digit method: Depreciation is not always constant because it occurs

more in the first two years and levels off with time. This method considers this. The

depreciation cost per year can be calculated as follows:

1st year : $ 20,000 x 20 = $ 20,000 x 20 = $ 1904.76

20 + 19 + 18 + ... 210

2nd Year : $ 20,000 x 19 = $ 1809.53; Last year: 20,000 x 1 = 92.59

20 + 19 + 18 +.... 20 + 19 +...

Depreciation: Other Methods of Computation d) Other methods of computing

depreciation cost include Declining balance method, Cost depletion method and Annual depletion method.

Example: Estimate the total annual fixed costs for a farm building that

cost $ 30,000. Assume 20 years service life.

Solution: Depreciation cost = $ 30,000 - 0 = $ 1500

20 yrs

Interest on investment: $ 30,000 x 7% = $ 2100/2 = $1050

(This is halved because interest is charged on the amount invested

which is gradually written off from full cost at the start to zero at the close)

Repairs cost : $ 30,000 x 2% = $ 600

Taxes: $ 30,000 x 1% = $ 300

Insurance: 30,000 x 1.5% = $ 450

Total annual fixed cost = $ 3900

1.4.1 Example of Computation of Returns on Investment

The method used for computations of returns on investment for open-sided and tunnel-ventilated broiler poultry buildings in Trinidad is summarised below and the calculated values are stated in Table 3 for all the buildings.

The actual values used for the computations were based on information either received from the farmers themselves or data collected during a recent survey period.

Capital recovery factor, CRF = i i

i

n

n

( )

( )

1

1 1

………………… (1)

where:

i is interest rate (14%) and n is the amortization period of 10 years. This equation

was used to calculate the owning costs shown in Table 1. The other expenses like labour

and electricity are detailed in Table 1. The returns on production were computed using

the production rate of birds and the average mortality shown on Table 1. Returns on

production is equal to:

(1 – average mortality rate) x No. of birds housed x average body weight x

Price per kg of meat. …………………. (2)

Example of Computation of Returns on Investment Contd. Depreciation was calculated using straight-

line method assuming a life span of 25 years and a salvage value of 25% of original cost

of building for the tunnel-ventilated buildings and 0% for the open-sided buildings.

Tax and insurance (TIS) were calculated at 0.5% of the cost of the house per annum. Profit was calculated as:

Returns on production – (owning cost + expenses + depreciation + TIS)

Computation Contd. The calculation was based on only 7

broiler grow outs per annum because one grow out lasts for 37 days and the period between grow outs is at most one week.

For the open house, only 6 grow outs per annum are possible since one grow out lasts for 49 days and the period between grow outs is taken to be one to two weeks.

Example of Computation Concluded The cost of day-old chicks, feeds as well

as for medicine was not considered in the calculations since the contract farmers supplied these to the farmer. In return, the contract farmers bought the birds at agreed rates (Table 1), which are about ten times below market prices.

It was seen, however, that using tunnel ventilation in Trinidad could lead to profits of close to two and half times that for a naturally ventilated one.