Concepts and Definitions 
Capital stock in agriculture: The concept of agriculture refers to the activity of crop and animal husbandry (i.e. the estimates do not include forestry and fishery sub-sectors or greenhouse production structures). The physical assets include assets used in the production process covering land development, irrigation works, structures, machinery and livestock. The capital stock items are listed in the table below.

Gross fixed capital stock: The gross fixed capital stock is the value, at a point of time, of assets held by the farmer with each asset valued at “as new” prices, at the prices for new assets of the same type, regardless of the age and actual condition of the assets. The gross capital stock dataset in agriculture is the sum of the individual physical assets (Land development + Livestock (fixed assets and inventory, see livestock definition) + Machinery and equipment + Structures for Livestock).

Land Development: Land improvements are the result of actions that lead to major improvements in the quantity, quality or productivity of land, or prevent its deterioration. Activities such as land clearance, land contouring, creation of wells and watering holes are integral to the land improvement. The concept of land improvement for the database of capital stock in agriculture includes:

• On field land improvement undertaken by farmers (includes work done on field such as making boundaries, irrigation channels, etc);

• Other activities such as irrigation works, soil conservation works, and flood control structure, etc., undertaken by government and other local bodies.

Livestock (fixed asset and inventory): The concept of livestock fixed asset are the breeding stock of cattle and buffalo, camels, horses, mules, asses, pigs, goats, sheep and poultry. The concept of inventory are generally young livestock stock and those kept for slaughtering.

Machinery and equipment: The concept includes tractors (with accessories), harvesters and thrashers, milking machines and hand tools.

Net capital stock: The net capital stock is the value at a point in time of assets at the prices for new assets of the same type less the cumulative value of consumption of fixed capital accrued up to that point.

Plantation crops: The concept refers to trees yielding repeated products (including vines and shrubs) cultivated for fruits and nuts, for sap and resin and for bark and leaf products,etc.

Structures for Livestock: The concept includes sheds constructed for housing cows, buffalo, horses, camels and poultry birds. Structures have been provided for only part of the total stocks which are held by commercial concerns.

Reference period and coverage
The dataset covers the period 1975 to 2007 for approximately 200 countries with more than 5000 hectare of agricultural land.

Data source
Data on quantity of physical assets in use and prices are based on information collected from the member countries and disseminated through FAOSTAT Database. Additional information comes from number of sources such: as country investment project reports received and prepared in FAO; purchase prices of capital such as tractors, harvesters and threshers, milking machines and drought animals; implicit prices from foreign trade data on livestock, tractors, etc. Supplementary data on GDP at current and constant prices have been obtained from the United Nations Statistics Division (UNSD) and were used for preparing price indices for the individual countries.

Estimation of capital stock in agriculture
Estimates of the value of capital stock in agriculture were based on the following sequence of calculations:

• Land development = ∑ {(arable land) x (unit price) + (irrigated land) x (unit price)}
• Plantation crops = ∑ (land under permanent crop) x (unit price)
• Total value of livestock = Livestock as fixed assets used for agriculture + Livestock kept as inventory = ∑ {(number of livestock for i) x (unit price of livestock for i) x (share of total livestock used in agriculture = 0.6245) + (number of livestock for j) x (unit price of livestock for j)}
  Where i stands for camel, cattle, buffalo, goats, horse, mules and asses and j stands for pig, poultry and sheep.
  85% of the total value is treated as fixed assets and remaining 15% as value of inventory.
• Structures for livestock
  1. The number of structures have been estimated for cattle, buffalo, goat, horse, camel, pig and poultry.
  2. Value of structures has been estimated as US $1800 for cattle and buffalo, US $180 for goats and US $1.5 for poultry (birds) based on the FAO AT 2010 study. The values were applied to the 1990 and 1995 series after super-imposing price rises as estimated from implicit GDP deflator.
  3. Structures have been estimated to reflect for 30% of cattle, buffalo, horse and goat for developed countries and 5% for cattle, buffalo, horse and goat for countries in transition and developing countries. Poultry structures have been estimated for 60% of the birds uniformly across countries.
• Machinery and equipment = ∑ {(number of machinery for i) x (unit price of machinery for i) + (economically active population in agriculture) x US $35)}
  Where i stands for tractor, harvester & threshers and milking machine.
  US $ 35 has been taken from 1995 series after adjusting for price rises.
• Consumption of fixed capital =
  1. Consumption of fixed capital has been estimated for land development, plantation crops, structure for livestock and machinery and equipments.
  2. No value has been estimated on livestock.
  3. Consumption of fixed capital is estimated as 2% for land development which includes irrigation works, 4.5% for plantation and structures of livestock and 12.5% for machinery and equipment as suggested in the FAO AT 2010 study. This assumption implies a life of 50 years for land development, about 22 years for plantation and structure for livestock and 8 years for machinery and equipment.

Data limitations
The estimates cover a long period where composition and structure for some of the countries have undergone revision. For example, from 1992 the USSR has been divided into 15 countries and Yugoslavia SFR into 5 countries. Hence, 2005 prices for USSR, Yugoslavia SFR do not exist. 2005 prices of USSR and Yugoslavia SFR, therefore, have been derived by compiling weighted average prices of respective group of countries, weights being the share of the country in the group in the year 1992. Similar treatment has been given to Ethiopia and Czechoslovakia. In this process it was noted the country group “Transition Economies” did not provide a consistent series of “assets in use” for the entire period of 1975 to 2007 (e.g. USSR by aggregating 15 countries in the year 1992 was not consistent with the USSR as seen in year 1991). The ‘estimates prior to 1991’ and ‘estimates after 1992’ are not compatible due to changes in the data collection systems (including concepts and definitions) adopted in the emerging economies. However, it was decided that no arbitrary adjustments were made in the series to maintain consistency with other databases in the FAOSTAT. This limitation of the series may be kept in mind while making long-term analysis of the estimates.

In developing the dataset of gross capital stock and net capital stock, it was not possible to make any adjustment for quality change/variation on physical assets particularly regarding the varieties of machinery for countries as: (a) prices for machinery are not available for many countries; (b) price estimates are heavily dependent on implicit import/export data which are average value of different type/make of machinery. Year to year variations in the capital stock dataset are also due to change in the composition of machinery and (c) in national accounts compilation, quality changes have been accounted only in the International Comparison Project (ICP) work while making bridge comparison.The ICP for compiling purchasing power parity is being coordinated by the World Bank).

Acknowledgements
The FAO Statistics Division is grateful for the data on quantity of physical assets in use which have been collected from the FAO member countries and would like to express thanks and appreciation to countries for their help in providing data which has greatly contributed to the development of the dataset of capital stock in agriculture.