Run-off monitoring on sugar cane farms

In December 2009, the Herbert Demonstration farm site was established in the Trebonne area on Orazio and Anthony Marino’s farm. The project is supported by the Queensland Government’s Department of Employment, Economic Development and Innovation (DEEDI), Terrain Natural Resource Management (NRM), BSES and JCU staff. Combining environmental sustainability and profitable farming as the key drivers, this is a collaborative effort between growers, government, research and industry bodies and is part of the Queensland and Australian Government’s Reef Plan to improve water quality entering the Great Barrier Reef lagoon. There are demonstration farm sites also located in the Burdekin and Tully areas.

The Herbert Demonstration farm site has been divided into two sections - one section planted on a 1.6 m conventional farming system and one section planted on a 1.83 m controlled-traffic, mound-planted farming system. To date there has been six additional cultivations in the conventional farming system block compared to the controlled-traffic, mound-planted block, which has attributed to a higher cost of establishment in the conventional block. All nutrient applications to date have been identical and are based on the BSES 6 Easy Steps guidelines and in accordance with government regulations. The system’s purpose is to monitor surface water run-off from two different cane farming systems - the focus being herbicides and nutrients. Originally, the project used a Campbell CR200; however, additional project funds have allowed an upgrade to a Campbell CR800. The sensors and peripherals used are: stainless steel pressure transducer - Campbell CS450-2-L10m x 2; ISCO 3700 portable samplers x 2; calibrated 9″ Parshall Flumes x 2; telemetry; solar panel and box trailer. The parameters being measured are: rainfall; depth/flow/discharge and analyte concentration. Data is being retrieved via a Modmax modem and relayed using a NextG data connection.

In the fallow period a legume was grown on both blocks then mulched. The controlled-traffic, mound-planted block was zonal tilled and the conventional block was conventionally prepared. It is important to understand the fate of legume nitrogen under different farming practices; consequently the movement of nitrogen in the soil profile from the legume crop is being investigated for both treatments over a 12-month period.

The block has been soil mapped using electromagnetic soils mapping equipment and ground truthed. This equipment identified five distinctive soil types within the block and found areas of sodic soil not previously known. Within the five soil types, soil sampling to depths of 1 m have occurred. It was found that two of the five soil types had low levels of phosphorus (P) present; below the government guidelines for P application. To date no P applications have occurred within the block because a routine soil test taken across the block indicated that no P fertiliser applications were required.

Water sampling for nitrogen, phosphorus and pesticides has occurred on the site since September 2010. Water run-off from a number of rows in each treatment is diverted through a calibrated flume. Sensors and monitoring equipment collect a water sample automatically every time a certain volume of run-off passes from the field and through the flume. The collected water samples are then sent to labs at James Cook University and Brisbane for analysis.

The cost-effectiveness of the various ‘new’ farming system practices will be assessed on the controlled-traffic, mound-planted block and compared to the conventional block. Adopting a new farming system can bring significant capital expense. Through rigours monitoring, the Herbert demonstration farm project will assist industry gain a better understanding of the environmental, economic and social benefits of implementing new farming practices.

The site will be continued to be monitored over the next two years. Trial results will be made available to industry as they become available.

Mark Whitten, DEEDI Project Officer, can be contacted for further information.