Availability of Nitrogen in Soil for Irrigated Cotton Following Application of Urea and 3,4-Dimethylpyrazole Phosphate-Coated Urea in Concentrated Bands.

Low nitrogen (N) fertilizer use efficiency for irrigated cotton has been attributed to the limited ability of tap roots to access N from concentrated subsurface bands, or the preferential root uptake of microbially-mineralized dissolved organic N. This work investigated how applying high-rate banded urea affects the availability of N in soil and the capacity of cotton roots to take up N. Soil was analyzed for water-extractable total dissolved N and inorganic N species after urea or urea coated with 3,4-dimethylpyrazole phosphate (DMPP) was applied at concentrations of 261, 455, 461, and 597 mg N kg of (air-dry) soil (mean bulk density: 1.

Strategic tillage in conservation agricultural systems of north-eastern Australia: why, where, when and how?

Farmers often resort to an occasional tillage (strategic tillage (ST)) operation to combat constraints of no-tillage (NT) farming systems. There are conflicting reports regarding impacts of ST and a lack of knowledge around when, where and how ST is implemented to maximise its benefits without impacting negatively on soil and environment. We established 14 experiments during 2012-2015 on farms with long-term history of continuous NT to (i) quantify the associated risks and benefits to crop productivity, soil and environmental health and (ii) explore key factors that need to be considered in decisions to implement ST in an otherwise NT system.

Influence of stormflow and baseflow phosphorus pressures on stream ecology in agricultural catchments.

Stormflow and baseflow phosphorus (P) concentrations and loads in rivers may exert different ecological pressures during different seasons. These pressures and subsequent impacts are important to disentangle in order to target and monitor the effectiveness of mitigation measures. This study investigated the influence of stormflow and baseflow P pressures on stream ecology in six contrasting agricultural catchments.

Incidental nutrient transfers: Assessing critical times in agricultural catchments using high-resolution data.

Managing incidental losses associated with liquid slurry applications during closed periods has significant cost and policy implications and the environmental data required to review such a measure are difficult to capture due to storm dependencies. Over four years (2010-2014) in five intensive agricultural catchments, this study used high-resolution total and total reactive phosphorus (TP and TRP), total oxidised nitrogen (TON) and suspended sediment (SS) concentrations with river discharge data to investigate the magnitude and timing of nutrient losses. A large dataset of storm events (defined as 90th percentile discharges), and associated flow-weighted mean (FWM) nutrient concentrations and TP/SS ratios, was used to indicate when losses were indicative of residual or incidental nutrient transfers.

Storm Event Suspended Sediment-Discharge Hysteresis and Controls in Agricultural Watersheds: Implications for Watershed Scale Sediment Management.

Within agricultural watersheds suspended sediment-discharge hysteresis during storm events is commonly used to indicate dominant sediment sources and pathways. However, availability of high-resolution data, qualitative metrics, longevity of records, and simultaneous multiwatershed analyses has limited the efficacy of hysteresis as a sediment management tool. This two year study utilizes a quantitative hysteresis index from high-resolution suspended sediment and discharge data to assess fluctuations in sediment source location, delivery mechanisms and export efficiency in three intensively farmed watersheds during events over time.

Spot Spraying Reduces Herbicide Concentrations in Runoff.

Rainfall simulator trials were conducted on sugar cane paddocks across dry-tropical and subtropical Queensland, Australia, to examine the potential for spot spraying to reduce herbicide losses in runoff. Recommended rates of the herbicides glyphosate, 2,4-D, fluoroxypyr, atrazine, and diuron were sprayed onto 0, 20, 40, 50, 70, or 100% of the area of runoff plots. Simulated rainfall was applied 2 days after spraying to induce runoff at one plant cane and three ratoon crop sites.

Dairy farm impacts of fencing riparian land: pasture production and farm productivity.

Dairy farmers are encouraged to restrict stock access by fencing riparian zones to reduce stream pollution and improve biodiversity. Many farmers are reluctant to create fenced riparian zones because of the perceived loss of productive pasture. Anecdotal reports indicate that pasture production in fenced areas is especially valued during summer months when water stress is likely to limit pasture growth in other areas of the farm.

Quantification of phosphorus transport from a karstic agricultural watershed to emerging spring water.

The degree to which waters in a given watershed will be affected by nutrient export can be defined as that watershed's nutrient vulnerability. This study applied concepts of specific phosphorus (P) vulnerability to develop intrinsic groundwater vulnerability risk assessments in a 32 km(2) karst watershed (spring zone of contribution) in a relatively intensive agricultural landscape. To explain why emergent spring water was below an ecological impairment threshold, concepts of P attenuation potential were investigated along the nutrient transfer continuum based on soil P buffering, depth to bedrock, and retention within the aquifer.

Delivery and impact bypass in a karst aquifer with high phosphorus source and pathway potential.

Conduit and other karstic flows to aquifers, connecting agricultural soils and farming activities, are considered to be the main hydrological mechanisms that transfer phosphorus from the land surface to the groundwater body of a karstified aquifer. In this study, soil source and pathway components of the phosphorus (P) transfer continuum were defined at a high spatial resolution; field-by-field soil P status and mapping of all surface karst features was undertaken in a > 30 km(2) spring contributing zone. Additionally, P delivery and water discharge was monitored in the emergent spring at a sub-hourly basis for over 12 months.

Trialling a web-based spatial information management tool with Land Managers in Victoria, Australia.

A prototype web-based spatial information management tool (called eFarmer) was tested for its useability and usefulness by 46 Land Managers and 5 extension staff in Victoria, Australia. Participants had a range of enterprises (dairy, beef/sheep grazing, cropping, lifestyle land use), property sizes and computer ownership and expertise. A follow up study was conducted with 12 dairy farmers, where features regarding assessment of nutrient losses from paddocks (Farm Nutrient Loss Index, FNLI) were added to eFarmer.