What is FertSpread?

FertSpread is a free-to-use on-line calculator and reporting tool to support on-farm calibration of fertiliser spreading equipment. It can be used on any internet connected device: computer, tablet or smartphone.

Access FertSpread at www.fertspread.nz

FertSpread uses field test results to calculate fertiliser product Size Guide Number (SGN) and Uniformity Index (UI) ensuring that evenness of application is within the recommended ranges.

Other calculations include fertiliser flow rate, required spreader speed, and actual application rate (kg/ha).

Finally and most importantly the tool allows you to analyse your Broadcast spreader configuration and based on your test results allows you to optimise your bout widths and ensure that you’re laying consistent, cost effective fertiliser spread patterns where ever possible.

Why was FertSpread developed?

FertSpread is one output from the Sustainable Farming Fund “On-Farm Fertiliser Applicator Calibration” project. The project arose from repeated requests by farmers for a quick and simple way to check performance of fertiliser spreading by themselves or contractors.  They wanted to know that spreading was acceptable.

Fertiliser application calibration procedures suitable for farmers applying nutrients with their own equipment allow on-farm checks to ensure and demonstrate application equipment is performing to expectations.

A calibration check includes assessment and correcting of both application rate (kg/ha) and uniformity (CV). Farmers indicated that checking the paddock application rate is reasonably easy and commonly done. Very few reported completing any form of uniformity assessment.

Assessing Performance

Uniformity requires collection of samples from a spreading event and calculation of a uniformity value. It will involve either physical or theoretical over-lapping of adjacent swaths. Use of standard test trays is strongly advised, given the need for baffling to stop fertiliser bouncing out.

Weighing samples is complicated by the very small quantities involved – often a single prill in the outer containers. Scales weighing to 0.01g are required, but satisfactory options are readily available at reasonable price. If a larger sample is wanted, two or more runs at the chosen application rate should be made rather than applying some higher rate.

Analysing collected data

Analysing fertiliser spread data is a somewhat complex task. The effect of overlapping runs (either round and round or to and fro) needs to be taken into account, and then the statistics to describe how uniform application is must be made. And in most cases, calculations should consider a number of different bout widths.

FertSpread was developed to process collected field data and generate statistical reports automatically. This reduces potential errors and makes the whole process very quick and efficient.

Key outputs are measured application rate, the CV at the specified bout width and the bout width range at which CV is within accepted limits.

The results of the uniformity test are given as the bout width where the coefficient of variation (CV) does not exceed a specified level. The maximum accepted CV is 15% for nitrogenous fertilisers and 25% for low analysis fertilisers.

NOTE:   Different types of collection trays show varying levels of capture during testing. Some can lose a significant amount of fertiliser through “bounce-out”.  Experience suggests the uniformity calculations are reasonably accurate, but the application rate may be under-reported. Check the application rate by dividing the quantity of fertiliser discharged by the area covered.

This project was undertaken by LandWISE Inc with funding from the MPI Sustainable Farming Fund. It was co-funded and supported by the Foundation for Arable Research and the Fertiliser Association.