WET TROPICS NRM REGION

The Wet Tropics NRM spans 8 catchments and covers 2.2 million hectares in far north Queensland of which 0.8 million hectares is land used mainly for agricultural production. The land is generally close to the coast with very high rainfall. Large areas of National Parks and State Forests cover much of the land while sugar cane growing was the most common agricultural activity.

				AGRICULTURAL LAND USE AND SELECTED PRACTICES
	Total Catchment area	Holdings in the catchment		Land used mainly for agricultural production	Land area over which herbicides were used (a)	Fertiliser applied	Maintained at least 40% ground cover in riparian areas
	Ha.	Number		Ha.	Ha.	Tonnes	Percent
Daintree River	192,032	106		12,374	4,001	6,942	30.3
Mossman River	53,847	64		4,224	2,639	10,734	36.3
Barron River	215,265	568		59,127	10,529	17,340	23.4
Mulgrave - Russell Rivers	199,972	343		29,310	16,606	59,046	35.5
Johnstone River	232,950	706		58,845	21,812	72,336	33.4
Tully River	164,634	195		32,420	14,518	69,442	34.3
Murray River (Qld)	119,743	144		24,443	23,241	23,440	47.0
Herbert River	988,401	677		583,110	34,071	129,221	40.9
Total Wet Tropics NRM	2,166,842	2,802		803,853	127,417	388,501	34.1
Source: Land Management Practices in the Great Barrier Reef Catchments, Preliminary, 2008-09 (cat. no. 4619.0).

(a) Does not include any area that had herbicide applied using spot spraying.





Daintree River catchment

The Daintree River catchment is the northernmost catchment in this survey, located about 100km northwest of Cairns. National Parks and State Forests, including the world famous Daintree Rainforest comprise the bulk of the area in the catchment. Land used mainly for agricultural production covers only a very small proportion of this catchment (6%).

Beef cattle grazing and sugar cane were the most common agricultural activities.

Grazing on improved pastures accounted for almost two thirds (62%) of the total area grazed.

In this catchment 73% of holdings growing sugar cane reported leaving their crop residue untouched, compared to rates of above 80% in most of the other catchments in the Wet Tropics NRM region.

Mossman River catchment

The Mossman River catchment is the smallest of the Great Barrier Reef catchments. It sits between Cairns and Daintree. Similar to the Daintree catchment, most of the land is comprised of National Parks and State Forests with land used mainly for agricultural activity accounting for only 8% of the catchment area. The predominant agricultural activity is sugar cane growing, with minimal other activity.

Holdings in this catchment reported high rates of surface water run-off management practices, with 92% of holdings undertaking at least one practice to manage surface water run-off. Practices most commonly utilised included using grassed or rubble spoon drains (69%) and maintaining at least 40% ground cover in riparian areas and/or constructed waterways (36%). Approximately 90% of holdings used fertiliser, with mill mud/ash being the main fertiliser used, accounting for 84% of fertiliser usage in this cane growing region. The rate of fertiliser applied in this catchment was 2.5 tonnes per hectare of agricultural land, being the highest of all 28 Great Barrier Reef catchments.

In this catchment 12% of holdings growing sugar cane reported the hot burning of trash, although the total area of trash removed by hot burn was very small, while 86% reported they left some or all of their sugar cane trash untouched.

Barron River catchment

The Barron River headwaters are near Atherton, with the river flowing north and east, before meeting the ocean at Cairns. Land used mainly for agricultural production makes up 28% of the catchment, most of this in the west, with parks and forests predominant in the centre and near the coast . The catchment features a variety of agricultural activities, with horticulture and grazing being particularly significant. Grazing accounts for two thirds of the agricultural land area, although the grazing properties in this catchment are relatively small in comparison to those operating in the bigger catchments to the south.

In comparison with other catchments in the Wet Tropics NRM region, holdings in this catchment reported relatively low rates of fertiliser application (0.3 tonnes per hectare of agricultural land). Chemical fertiliser comprised 77% of total fertiliser used. The adoption of surface water run-off management practices in the catchment was also low, with the rate of those who undertook at least one practice (61%) being the lowest of the catchments in the Wet Tropics NRM region.

In this catchment 34% of holdings engaged in horticulture reported the use of alternate or cover crops (34%) and having wheel spacing matching row spacing for all equipment (31%).

Mulgrave-Russell River catchment

The Mulgrave Russell catchment extends south from Cairns for approximately 70 km. The catchment features some of the highest rainfall in Australia with an average rainfall of around 3,000 mm. Much of the catchment is forested, with land used mainly for agricultural production covering 15% of the total area of the catchment. Sugar cane is the most commonly grown crop .

The adoption of surface water run-off management practices across the catchment was high, with 76% of holdings undertaking at least one land management practice to mitigate surface water run-off. Ensuring at least 40% ground cover remained on paddocks at the end of the 2008 dry season was the most common practice (56%). Maintaining at least 40% ground cover in riparian areas and/or constructed waterways (36%), and using contour banks, diversion banks or constructed waterways (23%) were the next most common practices.

As with most of the small catchments in the Wet Tropics NRM region, large amounts of mill mud/ash were used as fertiliser, reflecting the location of sugar mills that supply this product. In total, 74% of holdings in this catchment reported using fertiliser, with 59,046 tonnes applied, 44,467 tonnes of which was mill mud/ash.

In this catchment 38% of holdings engaged in sugar cane growing incorporated crop residue into the soil, a higher rate than reported in surrounding catchments.

Johnstone River catchment

The Johnstone River catchment contains the North and South Johnstone Rivers that discharge near Innisfail. Land used mainly for agricultural production covers 25% of the land area in the catchment, with sugar cane growing, horticulture and beef cattle grazing all common activities.

Rates of fertiliser application across the catchment were slightly lower than adjacent catchments. In total, 60% of holdings reporting fertiliser use, with mill mud/ash (51,666 tonnes) and chemical fertiliser (16,172 tonnes) the most common types of fertiliser applied. Land managers cited cost of fertiliser as the main factor in deciding how much fertiliser to apply (61%).

In this catchment 49% of holdings engaged in horticulture reported using alternate or cover crops as the most common land management practice.

Tully River catchment

The Tully River catchment has a large amount of land covered by National Parks and Forest Reserves. Land used mainly for agricultural production makes up 20% of the catchment, most of which is sugar cane growing around Tully and along the lower stretches of the Tully river. Some horticulture and beef cattle grazing are also present.

Rates of adoption of surface water run-off management practices were high with 82% of holdings undertaking at least one practice. The most common practices were ensuring at least 40% ground cover remained on paddocks at the end of the 2008 dry season (46%), the maintenance of at least 40% ground cover in riparian areas and/or constructed waterways (34%) and the use of recycling pits or sediment dams (29%).

For a relatively small catchment, significant amounts of fertiliser were applied (69,442 tonnes), including 20,250 tonnes of chemical fertiliser and 43,574 tonnes of mill mud/ash. The rate of fertiliser applied (2.1 tonnes per hectare of agricultural land), was the second highest in all 28 Great Barrier Reef catchments.

Around two thirds (67%) of holdings reported the use of controls other than chemical or mechanical for controlling weeds, pests and diseases, the highest rate of any catchment in the survey. Examples of other controls include biological, break cropping and crop or breed variety selection.

Murray River (Qld) catchment

The Murray River (Qld) catchment is a small catchment between Cairns and Townsville. The agricultural profile is similar to that of the Tully River catchment to the north, with mainly sugar cane growing, supplemented by some beef cattle grazing and horticulture. National Parks also make up a large part of the catchment with land used mainly for agricultural production comprising just 20% of the land in the catchment.

A total of 86% of holdings undertook at least one surface water run-off management practice. The most commonly reported practices were ensuring that at least 40% ground cover remained on paddocks at the end of the 2008 dry season (51%), having grassed or rubble spoon drains (49%) and the maintenance of at least 40% ground cover in riparian areas and/or constructed waterways (47%).

Herbert River catchment

The Herbert River catchment is significantly larger than other catchments in the Wet Tropics NRM region being 988,401 hectares in size, compared to the next largest catchment, Johnston River, with 232,950 hectares. It extends much further inland than the other Wet Tropics catchments. The western part of the catchment includes a significant amount of inland grazing land with large holdings and much lower rainfall than is experienced along the coast. The eastern (coastal) part of the catchment features extensive sugar cane activity. Land used mainly for agricultural production covers 59% of the catchment.

Just over 90% of holdings in this catchment reported applying herbicide. This was the highest proportion of all 28 catchments.

A total of 129,221 tonnes of fertiliser were applied in the catchment, with the amount of chemical fertiliser applied (27,212 tonnes) being the highest of all 28 catchments. The Herbert River catchment was the only catchment in the Wet Tropics NRM region to report significant use of dunder (35,992 tonnes). Use of mill mud/ash was also common (62,550 tonnes). Although significant amounts of fertiliser were used in this catchment, the application rate was relatively low (0.2 tonnes per hectare of agricultural land).

In this catchment 35% of holdings with beef cattle actively controlled stock access to riparian areas and 26% reported they had fully fenced off riparian areas and established alternate water points.

Just over 92% of holdings growing sugar cane in this catchment reported leaving some or all of their sugar cane trash untouched.