This typically meant a yield reduction of at least 20%. The economic effect increases exponentially as in-field CV increases, so if the CV doubles there is four times the economic loss.
Fertiliser applicator manufacturers do provide guidelines and newer machines automatically adjust to correct distribution pattern based on factory test data.
However, it is still wise to check because the tests are usually done in Europe using different fertiliser products. The inbuilt systems also assume the machine is exactly as when new.
The FertSpread system is suitable for farmers applying nutrients with their own equipment. The system is designed to allow a farmer to rapidly determine performance of a spreader as it is operating on a given day, with a given product in prevailing weather conditions. If any factor changes the results are likely to be different.
Instruction guidelines are available as a download from the FertSpread website. They are backed up with online videos, field recording sheets and a web-based calculator so it is easy to do onfarm checks to ensure and demonstrate application equipment is performing to expectations.
The system is similar to national and international practice using baffled test trays set at right-angles to the direction of travel. Trays extend as far as fertiliser is thrown.
After the spreader has passed over the trays samples are collected, weighed and entered into the free online calculator.
The online FertSpread calculator processes the data collected in the field, calculates uniformity and generates performance reports. FertSpread calculates uniformity from data from a single pass.
The calculator assumes the other passes will be the same, a reasonable assumption and one also made by international testers. The programme mathematically applies overlap using both to and fro, and round and around, driving patterns.
An advantage of this method is that different bout widths can also be modelled. So while the field uniformity achieved at the normal farm spreading distance is calculated, a range of alternatives is as well.
Presented graphically, these help understand how bout width affects the overall field result.
Test spread-pattern checks performed to date show there is a need for wider testing by farmers. Unacceptable CVs and incorrect application rates are the norm.
The resources available on the website include general fertiliser spreading information. This includes advice from Massey, which has undertaken a large amount of research in spreading by ground and aerial equipment.
As well as machine set-up and selected bout width, a number of other factors can cause poor distribution.
Massey research shows the ballistic properties of the fertiliser particles become very important at wider bout widths. This is because the speed the particles must travel to get the spread distance makes different ballistic properties significant.
This is especially important when spreading blended products. Some types of fertiliser should not be blended if wide widths are used.
• Go to www.fertspread.nz for more information. This Ministry for Primary Industries’ Sustainable Farming Fund project was co-funded by the Foundation for Arable Research and the Fertiliser Association.
