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· Value of Agricultural Commodities Produced, Australia (cat. no. 7503.0)
· Water Use on Australian Farms (cat. no. 4618.0)
AGRICULTURAL COMMODITY GROUPS
7 GVIAP is calculated for each irrigated 'commodity group' produced by agricultural businesses. That is, GVIAP is generally not calculated for individual commodities, rather for groups of 'like' commodities according to irrigated commodity groupings on the ABS agricultural censuses and survey forms. The irrigated commodity groups vary slightly on the survey form from year-to-year. The commodity groups presented in this publication are:
· cereals for grain and seed
· sugar cane
· other broadacre crops (see Appendix 1 for detail)
· fruit and nuts (includes nut trees, orchard, stone and plantation fruits (excluding grapes))
· nursery production (includes cut flowers and cultivated turf)
· dairy production
· production from meat cattle
· production from sheep and other livestock (excluding cattle)
8 The ABS agricultural censuses and surveys collect area and production data for a wide range of individual commodities within the irrigated commodity groups displayed in the list above.
METHOD USED TO CALCULATE GVIAP
9 The statistics presented here calculate GVIAP at the unit (farm) level, using three simple rules:
10 These three rules apply to most commodities; however there are some exceptions as outlined below in paragraph 15. It is important to note that the majority of cases follow rules 1 and 3; that is, the commodity group on a particular farm is either 100% irrigated or not irrigated at all. For example, in 2004–05, 90% of total GVAP came from commodity groups that were totally irrigated or not irrigated at all. Therefore, only 10% of GVAP had to be 'split' into either 'irrigated' or 'non-irrigated' using the 'yield formula' (described below). The yield formula is explained in full in: Information Paper: Methods of estimating the Gross Value of Irrigated Agricultural Production, 2008 (cat. no. 4610.0.55.006).
11 Outlined here is the yield formula referred to in paragraph 10:
Yi = estimated irrigated yield for the commodity (t/ha or kg/ha)
P = unit price of production for the commodity ($ per t or kg)
Q = total quantity of the commodity produced (t or kg)
Ad = area of the commodity that is not irrigated (ha)
Ydiff = yield difference factor, i.e. estimated ratio of irrigated to non-irrigated yield for the commodity produced
Yield difference factors
12 Yield difference factors are the estimated ratio of irrigated to non-irrigated yield for a given commodity group. They are calculated for a particular commodity group by taking the yield (production per hectare sown/grown) of all farms that fully irrigated the commodity group and dividing this 'irrigated' yield by the yield of all farms that did not irrigate the commodity group. The yield difference factors used here were determined by analysing data from 2000–01 to 2004–05 and are reported for each commodity group in Appendix 1 of: Information Paper: Methods of estimating the Gross Value of Irrigated Agricultural Production, 2008 (cat. no. 4610.0.55.006).
13 In this publication 'yield' is defined as the production of the commodity per area grown.
Commodity groups for which the yield formula is used
14 The GVIAP for the following commodities has been calculated using the yield formula, with varying yield differences:
Cereals for grain/seed - yield formula with yield difference of 2
Cereals for hay - yield formula with yield difference of 2
Pastures for hay - yield formula with yield difference of 2
Sugar cane - yield formula with yield difference of 1.3
Other broadacre crops - yield formula with yield difference of 2
Fruit and nuts - yield formula with yield difference of 2
Grapes - yield formula with yield difference of 1.2
Vegetables for human consumption and seed - yield formula with yield difference of 1
Nurseries, cut flowers and cultivated turf - yield formula with yield difference of 1
Note: a yield difference of 1 implies no difference in yield between irrigated and non-irrigated production.
15 However not all agricultural commodity groups can be satisfactorily calculated using the yield formula, in particular:
16 Meat cattle, sheep and other livestock – in some previous releases of GVIAP data the estimates were derived by taking the average of two separate models:
17 Most of the irrigated commodity groups included in these tables are irrigated simply by the application of water directly on to the commodity itself, or the soil in which it is grown. The exception relates to livestock, which includes dairy. For example, the GVIAP of 'dairy' simply refers to all dairy production from dairy cattle that grazed on irrigated pastures or crops. Estimates of GVIAP for dairy must be used with caution, because in this case the irrigation is not simply applied directly to the commodity, rather it is applied to a pasture or crop which is then eaten by the animal from which the commodity is derived (milk). Therefore, for dairy production, the true net contribution of irrigation (i.e. the value added by irrigation, or the difference between irrigated and non-irrigated production) will be much lower than the total irrigation-assisted production (the GVIAP estimate).
18 The difference between (a) the net contribution of irrigation to production and (b) the GVIAP estimate is probably greater for livestock grazing on irrigated crops/pastures than for commodity groups where irrigation is applied directly to the crops or pastures.
19 Similarly, estimates of GVIAP for all other livestock (meat cattle, sheep and other livestock) must be treated with caution, because as for dairy production, the issues around irrigation not being directly applied to the commodity also apply to these commodity groups.
20 The estimates presented in this product are underpinned by estimates of the VACP, published annually in the ABS publication, Value of Agricultural Commodities Produced, Australia (cat. no. 7503.0). VACP estimates (referred to as GVAP in this publication) are calculated by multiplying the wholesale price by the quantity of agricultural commodities produced. The price used in this calculation is the average unit value of a given commodity realised in the marketplace. Price information for livestock slaughtering and wool is obtained from ABS collections. Price information for other commodities is obtained from a combination of ABS collections and non-ABS sources, including marketing authorities and industry sources. It is important to note that prices are state-based average unit values.
21 Sources of price data and the costs of marketing these commodities vary considerably between states and commodities. Where a statutory authority handles marketing of the whole or a portion of a product, data are usually obtained from this source. Information is also obtained from marketing reports, wholesalers, brokers and auctioneers. For all commodities, values are in respect of production during the year (or season) irrespective of when payments were made. For that portion of production not marketed (e.g. hay grown on farm for own use, milk used in farm household, etc.), estimates are made from the best available information and, in general, are valued on a local value basis.
22 It should be noted that the estimates for GVIAP are presented in current prices; that is, estimates are valued at the commodity prices of the period to which the observation relates. Therefore changes between the years shown in these tables reflect the effects of price change.
RELIABILITY OF THE ESTIMATES
23 The estimates in this product are derived from estimates collected in surveys and censuses, and are subject to sampling and non-sampling error.
24 The estimates for gross value of irrigated agricultural production are based on information obtained from respondents to the ABS agricultural censuses and surveys. These estimates are therefore subject to sampling variability (even in the case of the censuses, because the response rate is less than 100%); that is, they may differ from the figures that would have been produced if all agricultural businesses had been included in the ABS agricultural surveys or responded in the agricultural census.
25 One measure of the likely difference is given by the standard error (SE) which indicates the extent to which an estimate might have varied by chance because only a sample was taken or received. There are about two chances in three that a sample estimate will differ by less than one SE from the figure that would have been obtained if all establishments had been reported for, and about nineteen chances in twenty that the difference will be less than two SEs.
26 In this publication, sampling variability of the estimates is measured by the relative standard error (RSE) which is obtained by expressing the SE as a percentage of the estimate to which it refers. Most national estimates have RSEs less than 10%. For some states and territories, and for many Natural Resource Management regions with limited production of certain commodities, RSEs are greater than 10%. Estimates that have an estimated relative standard error higher than 10% are flagged with a comment in the publication tables. If a data cell has an RSE of between 10% and 25%, these estimates should be used with caution as they are subject to sampling variability too high for some purposes. For data cells with an RSE between 25% and 50% the estimate should be used with caution as it is subject to sampling variability too high for most practical purposes. Those data cells with an RSE greater than 50% indicate that the sampling variability causes the estimates to be considered too unreliable for general use.
27 Estimates with an RSE greater than 50% at the national, state and territory level have been suppressed in this publication as they are considered too unreliable for general use. Where estimates for data items have been suppressed at the national, state or territory level, they have also been suppressed at the sub-state level. Where figures for individual states or territories have been suppressed, they have been included in relevant totals.
28 Errors other than those due to sampling may occur because of deficiencies in the list of units from which the sample was selected, non-response, and errors in reporting by providers. Inaccuracies of this kind are referred to as non-sampling error, which may occur in any collection, whether it be a census or a sample. Every effort has been made to reduce non-sampling error to a minimum in the collections by careful design and testing of questionnaires, operating procedures and systems used to compile the statistics.
ROUNDING AND CONFIDENTIALITY
29 Where figures have been rounded, discrepancies may occur between sums of the component items and totals.
30 Where figures for individual states or territories have been suppressed for reasons of confidentiality, they have been included in relevant totals.
31 Current publications and other products released by the ABS are available on the ABS website. The ABS also issues a daily Release Advice on the website which details products to be released in the week ahead.
32 Final estimates of water use on Australia's agricultural land in 2013-14 are available at the same time as the final 2013-14 estimates of agricultural land use, crop and horticultural area and production, livestock numbers and farm management and demographic information. These water use estimates will be released in Water Use on Australian Farms (cat. no. 4618.0).
33 Final estimates of the gross value of agricultural commodities from the 2013-14 Value of Agricultural Commodities Produced (VACP) collection are available at the same time as the final 2013-14 estimates of agricultural land use, crop and horticultural area and production, livestock numbers and farm management and demographic information. These value estimates will be released in Value of Agricultural Commodities Produced, Australia (cat. no. 7503.0)
34 Final estimates of agricultural commodity data are available at the same time as the final 2013-14 VACP estimates. These estimates are located in Agricultural Commodities, Australia (cat. no. 7121.0).
ABS DATA AVAILABLE ON REQUEST
35 As well as the statistics included in this and related publications, the ABS may have other relevant data available on request. Inquiries should be made to the National Information and Referral Service on 1300 135 070.
36 ABS publications draw extensively on information provided freely by individuals, businesses, governments and other organisations. Their continued cooperation is very much appreciated. Without it, the wide range of statistics published by the ABS would not be available. Information received by the ABS is treated in strict confidence as required by the Census and Statistics Act 1905.
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