Rehabilitating Degraded Frontage Soils in Tropical North Queensland

The extensive tropical grasslands of north Queensland are grazed by beef cattle and provide a significant proportion of the water flowing into the Great Barrier Reef (GBR) lagoon. Soil sediments and nutrients eroding from the grazing lands of the Burdekin and Fitzroy catchments in north-east Queensland contributes to reduced water quality in the GBR lagoon. Degraded and eroded D-condition bare areas and eroding gullies in grazing lands provide a disproportionate amount of soil and nutrient losses from predominately native pasture grasslands used for cattle grazing. Rehabilitating these degraded areas will help improve water quality flowing onto the reef. Rehabilitation methods were evaluated on three soil types on a degraded creek frontage in the Burdekin River catchment of north Queensland over the 2011-2012 summer. These bare patches occur widely across the two catchments and consistently degraded sites have been identified by 24 years of satellite imagery. The objectives of this study were to identify mechanical methods and management practices for regenerating these bare patches. This will assist landholders in returning unproductive land into useful grazing pastures and will provide benefits to the wider community by improving water quality from grazing lands that enters the GBR lagoon

Impacts of rehabilitating degraded lands on soil health, pastures, runoff, erosion, nutrient and sediment movement. Part I: Rehabilitation methodologies to improve water quality flowing from grazing lands onto the Great Barrier Reef.

The project RRRD.024 investigated the potential to mechanically rehabilitate degraded, bare, D-condition grazing lands to improved condition in the Burdekin and Fitzroy River catchments of north-east Queensland. With successful rehabilitation there will be increased pasture health and productivity which will reduce water, sediment and nutrient runoff, with the aim of improving the quality of water flowing into the Great Barrier Reef lagoon from grazing land. There were six set objectives of the study and a three-way research approach was developed to identify and quantify mechanical rehabilitation information for these objectives. Seven key findings were identified from the study. Summary of seven key findings The success of rehabilitation of D-condition, severely eroded grazing lands was highly correlated to seven key aspects: 1. a high degree of mechanical disturbance (intervention) is required (deep ripping, blade ploughing or, adding mulch after heavy disturbance) to increase water holding and infiltration: disturbance includes overland water flow control measures 2. selecting the most suitable and responsive soil types (non-sodic clays, clay-loams and loams) 3. sowing well-adapted pasture species (tropical grasses and legume cultivars) 4. long-term total grazing control to allow for rainfall-dependent pasture establishment, seeding and spread over the first 3-7 years, depending on rainfall 5. conduct mechanical disturbance and seeding rehabilitation programs in years of predicted above average seasonal rainfall conditions (la Niña years preferably) 6. start rehabilitation before all topsoil is lost, and exposing more serious chemical and physical constraints to pasture development; and 7. plan and monitor grazing management strategies early to prevent the development and spread of bare D-condition areas by maintaining healthy soils and pastures. Grazing land management training is desirable

Pasture recovery, land condition and some other observations after the monsoon flooding, chill event in north-west Queensland in Jan-Mar 2019

Monsoonal flooding rains to 800 mm across north-west Queensland during late January and early February 2019 resulted in the inundation of hundreds of thousands of hectares of grazing land. Pastures of the Mitchell Grass Downs and the Gulf Plains that support cattle production were impacted by the rain event, and particularly so, because the land had just suffered a prolonged drought of 5-7 years. An area of some 13M hectares were affected and an estimated 0.5M head of cattle were lost from cold, wet wind exposure and flooding. The immediate post-flood assessment, of pasture reported in this document, is a record that informs agricultural practices and forms an historical baseline, for future research of ways to better understand and implement best management practices, in the tropical landscape of north-west Queensland in northern Australia

Cattle Grazing Management Effects on Pasture Composition in Semi-Arid Woodlands

Manipulating grazing pressure, controlling tree competition and burning are the main options for cattle farmers to manage land in subtropical Australian Eucalypt woodlands. These can contain \u3e175 herbaceous and 60 woody species, but only 5 are desirable perennial and productive grass (Silcock et al., 1996). Here we describe the responses of some perennial grasses to cattle grazing pressure, tree competition and spring burning

Impacts of rehabilitating degraded lands on soil health, pastures, runoff, erosion, nutrient and sediment movement. Part III: Economic analysis of rehabilitation techniques in the Burdekin River catchment to improve water quality flowing from grazing lands onto the Great Barrier Reef.

Poor grazing land condition reduces the productivity of grazing enterprises and has been linked to increased sediment loads entering the Great Barrier Reef Lagoon. There are several methods for rehabilitating degraded lands with varying levels of investment. The subsequent environmental and economic outcomes have previously been largely unquantified. This document assesses the potential economic impact of the rehabilitation treatments in the Burdekin Catchment for the project RRRD.024 – ‘Quantifying the impacts of rehabilitating degraded lands on soil health, pastures, runoff, erosion, nutrient and sediment movement’. Three mechanical intervention treatments and a control (no treatment) were evaluated on loamy alluvial soils at Spyglass Research Facility. These were: deep ripping, chisel ploughing and crocodile seeding. All treatments were seeded. Treatments varied in cost on a per hectare basis with deep ripping requiring $260.85 ha-1, chisel ploughing$210.85 ha-1, and crocodile seeding was least cost requiring $150.85 ha-1. Treatments also varied in benefits, particularly pasture yield and subsequent potential carrying capacity. From highest to lowest the potential average carrying capacity was deep ripping, chisel ploughing and crocodile seeding, with 25.3 AE 100 ha-1, 20.5 AE 100 ha-1 and 13.4 AE 100 ha-1, respectively. The control averaged 7.9 AE 100 ha-1. Despite apparent differences in costs and subsequent benefits, each treatment returned very similar economic results, particularly as measured by the internal rate of return. The internal rate of return (IRR) of chisel ploughing was highest (4.55%), followed by crocodile seeding (4.37%) and lastly, deep ripping (4.36%). This suggests that while spending more money and performing higher intervention might increase productivity the most, it does not necessary return more on a dollar for dollar basis. Despite positive IRRs, none of the treatments returned a positive net present value at the default parameters, suggesting funds could be better used elsewhere. It is recommended that producers investigate their eligibility for funding programs (such as Catchment organisations or Land Care) which assists with upfront costs of rehabilitation of degraded lands. This will allow producers to reduce losses and provide public benefits in the form of reduced sediment and nutrient runoff

The feathertop problem in Mitchell grass pastures

Seeds of Aristida latifolia (feathertop grass) in Mitchell grass (Astrebla spp.) pastures are the main cause of vegetable fault in wool from sheep grazing these areas. High stocking rates, particularly when the plants were young, reduced the build up of A. latifolia to only 4 000 plants compared with 35 000 in an adjacent field at low stocking rate. Control of A. latifolia by management strategies, (heavy grazing followed by pasture recovery in the wet season) is recommended