Water Sampling Information – Nitrogen Impact
At our recent AGM an issue was raised by a grower in relation to outcome of RP20 Nitrogen Trials and in particular the positive around improved environmental footprint. Grower enquired as to avenues available to undertake surface water sampling in the Delta to determine individual farm nitrogen impact and to what extent. For any growers interested I have had discussions with BBIFMAC who have provided the following guidelines/procedures.
Sample collection: Growers can either take a grab sample of runoff at the end of the row once the water comes through or BBIFMAC sells KP samplers which if set up correctly automatically start taking a sample when the water first comes through and stops when the water stops. This is a more accurate way of taking samples as the amount of nutrient can vary throughout the runoff period however the KP samplers sell for $550. Farmacist and BPS have purchased several KP samplers from BBIFMAC and use them throughout the Burdekin. The KP samplers do need to be set up correctly and maintained properly and BBIFMAC suggests a trained person deploy them each time.
Sample storage: samples are best placed into an appropriate sample bottle (1L from lab supplier), making sure that the bottle is triple rinsed before used, and that gloves are used so that there is no contamination of the bottle neck or lid (the bare skin of fingers/hands can contain quite high levels of Nitrates which will contaminate the sample!). There should be no air gap in the bottle after being filled with the sample and it needs to be refrigerated or frozen immediately after collection (very important!). Samples sitting in the sun or in a hot vehicle will degrade very rapidly.
Sample analysis: samples can be sent off to a laboratory for analysis however this is costly (up to $150 depending on the analysis required plus freight), especially as they need to be transported cold! If just testing for Nitrogen/Nitrate BBIFMAC can analyse the samples for $30/sample and can provide the appropriate collection bottles. Phosphorus and pesticides will need to be sent away to a lab. BBIFMAC can do this but it will cost upwards of $150 per sample.
NOTE: It is important to note that just taking a once off sample is not going to give an accurate picture of runoff. It varies depending on the amount of runoff (e.g. irrigation vs rainfall) and the period of time that has lapsed since product application. BBIFMAC recommends at least 6 runoff events are sampled – preferably the first few irrigations following product application (e.g fertilising, spraying) and also the first few rainfall events after application.
If any growers require any further information or wish to undertake sampling please liaise with BBIFMAC direct.
Les Elphinstone
Manager / Company Secretary
Kalamia Cane Growers Organisation Ltd
Kalagro Ltd