Tuesday 26 July 2016

Reduce the Cost of Nutrient Loss with Precision Ag (Part 1 of 3)

Precision Ag can help you in many ways with your Farm Environment Plan (FEP). Precision nutrient management, EM maps, topography data,variable rate irrigation (VRI) and moisture probes are all tools available to help you manage your FEP and mitigate any potential issues you may face - Reducing costs to your farming operation and the environment.

I will be looking at how each of these can help you over the next few blog posts (to make sure you don't miss out pop your email address in the "Follow By Email" box, to the right). In this first blog of three I am looking into precision nutrient management.

Improving Nutrient Management with Precision Ag

The objective here is to maximise nutrient use efficiency while minimising nutrient losses into water. This can be accomplished by looking at the nutrient levels in the soils themselves as well as monitoring the moisture in the soil profile to ensure you don’t leach nutrients out with over watering. Precision Ag can help you in several ways to achieve this, this week I will look at the nutrient levels themselves.

This is done through either grid or zonal soil sampling. Instead of taking one soil sample per field or block, you sample in a grid at a resolution of one site per hectare or take samples within each known soil zone from your EM survey. Whichever way the samples are collected the sites are geo-referenced that means you can go back to the same point every time you sample so you can see how you are managing your nutrient levels over a number of years. At each site 12-15 cores are taken and placed in a bag, labelled and sent off to the laboratory for that sampling point.

Picture 1: Geo referenced sampling points in a field.
When you receive the laboratory results, they look similar to those you normally get however the critical difference is they are all geo-referenced and are at a higher resolution i.e. one per hectare. The data received can then be processed to create a nutrient zone map; with nutrient levels grouped in ranges for the given area and given nutrient.  From that layer of data application maps are made to match the soil and crop requirements.  The main nutrients commonly applied using this variable rate method are potash, phosphate and magnesium as well as lime for pH.

Picture 2: A map showing the varying Olsen P values across a field.

By only applying what is needed where it is needed means you minimise any over-application of product with financial and environmental implications, and you also maximise the crops potential on a nutrient level. By using this method you can mine nutrient-rich zones reducing nutrient levels in those areas and apply only what is required elsewhere.