APPENDIX 2 – DATA ITEM COMPARABILITY

1 The ABS Agricultural Census and Survey form can vary from year to year as a result of user requirements and improvements in form design. Outlined here are some of those variations which impacted on the availability of some commodity groups in the time series, and how these variations were dealt with in producing a consistent set of commodity groups across the time series.

HAY PRODUCTION

2 In the tables presented in this publication, for 2000-01 to 2004-05, “total hay production” was an aggregate of two separate data items:

• pastures for hay
• cereals for hay

3 For 2005-06 and 2006-07 production data for these separate data items were not collected – in these years a single data item ”pasture, cereal and other crops cut for hay” was collected. Therefore, production data (GVAP and GVIAP) for “pastures for hay” and “cereals for hay” were not able to be presented separately in the tables for 2005-06 and 2006-07.

4 From 2000-01 to 2004-05 production data for “other crops for hay” were included in “other broadacre crops” (because irrigation data was not collected for “other crops for hay” separately, thus the GVIAP for “other crops for hay” could not be estimated). However for 2005-06 and 2006-07, production data for this data item was included under “pasture, cereal and other crops cut for hay” and thus is included in “total hay production” for those two years in the tables presented in this publication.

5 This does not have major implications on the total production values (GVAP and GVIAP) of “total hay production” and “other broadacre crops” because “other crops for hay” make up only a very small proportion of these broader commodity groups (e.g. less than 3% of total hay production).

6 The category “pastures for hay” does not include the value of silage in the GVIAP and GVAP tables, as the ABS did not produce a production value for silage over the reference period. However, the volume of water applied to silage is included in the “pasture for hay” category in the “Volume Applied ML” tables presented here. Therefore, the GVIAP/ML figures presented for “pasture for hay” underestimate the true ratio for this commodity.

Value of hay

7 The 2000-01 Agricultural Census, the 2001-02, 2003-04 and 2004-05 Agricultural Surveys, and the Water Survey, Agriculture 2002-03, included separate questions about production of pastures and grasses cut for hay, and other crops for hay. However, questions on the 2005-06 Agricultural Census and the 2006-07 Agricultural Survey asked only the total production of all crops and pastures for hay. Therefore, in 2005-06 and 2006-07 an estimated average hay price has been applied to total hay production to derive the value of all crops and pastures for hay.

VOLUME OF WATER APPLIED (ML)

2000-01 and 2001-02

8 In the 2000-01 Agricultural Census and the 2001-02 Agricultural Survey, the volume of water applied to crops and pastures was not collected.

Pastures for hay/silage/seed

9 Volumes of water applied to “pastures for hay (incl. silage)” and “pastures for seed” were collected as separate data items for each year from 2002-03 to 2005-06. However, in 2006-07, the volume of water applied was collected for the aggregated category “pasture harvested for hay (including lucerne), silage or seed”. To split this aggregated category into its separate components, an average proportional split for data from 2002-03 to 2005-06 was derived and applied to the 2006-07 data.

Cereals for hay or for grazing or fed off

10 Volumes of water applied to “cereals cut for hay” and “cereals for grazing or fed off” were collected as separate data items for each year from 2002-03 to 2005-06. However, in 2006-07 the volume of water applied was collected for the aggregated category “cereals cut for hay or for grazing or fed off”. To split this aggregated category into its separate components, an average proportional split for data from 2002-03 to 2005-06 was derived and applied to the 2006-07 data.

Grazing land

11 This product displays volumes of water applied for three different types of livestock commodity groups for “grazing land” which is irrigated:

• Dairy production
• Meat cattle production
• Sheep and other livestock production

12 For each of these categories “grazing land” is made up of the data items “pastures for grazing” and “cereals for grazing or fed off”.

13 Volumes of water applied to “pastures for grazing” and “cereals for grazing or fed off” were collected on the Agricultural Census/Survey from 2000-01 to 2005-06.

The “GVIAP Proportion Method”

14 The concept of splitting the volume of water applied to “grazing land” into volumes for “Dairy production”, “Meat cattle production” and “Sheep and other livestock production” is a difficult one, because these three categories are not mutually exclusive (e.g. dairy cattle and sheep might graze on the same irrigated pastures on a particular farm).

15 The method used to split the irrigated grazing land into these three categories was to calculate the proportion of total irrigated livestock production for each and apply this proportion to the volume of water applied to irrigated grazing land. For example, consider a particular farm where:

GVIAP for Dairy = $10,000
GVIAP for Meat cattle = $5,000
GVIAP for Sheep and other livestock = $5,000
Total volume of water applied to irrigated grazing land = 100 ML

Therefore, total “livestock GVIAP” = $20,000

and volume of water applied to:

Irrigated grazing land used for Dairy production = 10,000/20,000 x 100 ML = 50 ML;
Irrigated grazing land used for Meat cattle production = 5,000/20,000 x 100 ML =25 ML; and
Irrigated grazing land used for Sheep and other livestock production = 5,000/20,000 x 100 ML = 25 ML

16 However for 2006-07, irrigation data was collected on the Agricultural Survey form in a different way. There were three separate irrigation categories:

• pasture for grazing dairy cattle
• pasture for grazing meat cattle, and
• pasture for grazing other livestock (e.g. sheep).
  

17 In order to maintain consistency with other years, the data collected for 2006-07 and presented in Water Use on Australian Farms, Australia, 2006-07 (cat. no. 4618.0) were not used in this publication. Instead, the “GVIAP Proportion Method”, as described above, was used to split “irrigated grazing land” (i.e.“total irrigated pastures for grazing” and “irrigated cereals for grazing or fed off”) into its livestock components.