Massey University Soil Water Alert System

Dairy farmers Ben and Sharon Smith participated in a trial of the Re:Gen remote effluent management system, developed and now marketed by the Regen, a company spun out from Harmonic Aotearoa. Data collected from soils, weather stations and collection ponds provides advice to the farm about when to irrigate effluent and when to refrain, because soil water content is already high.

Re:Gen was developed based on research by Massey University on deferred irrigation. Massey has developed a new method of calculating the soil water balance, which is a representation of the amount of effluent the soil can hold before leaching or direct run-off occurs.

Using Re:Gen, the soil water balance then produces an irrigation recommendation to the farmer, delivered by text to a mobile phone and displayed on computer.

The decision-making by the computer-based model takes account of the irrigator type, to make the recommendation wholly relevant.

The soil water balance is generated with farm-specific rainfall and local evapotranspiration rates, while the recommendation also incorporates soil moisture and temperature readings from an Aquaflex on the farm and effluent pond level measurements.

All of these weather instruments are wired to telemetry devices, which call into the Re:Gen central database with readings.

The daily alerts back to farmers contain the soil moisture deficit, how much effluent can be applied through that farms irrigation system and a summary of pond level and rainfall received.

On the web-site record, access to which is password-protected, all that text info is repeated, plus summaries and graphs and trends.

Hikurangi dairy farmers Ben and Sharon Smith, Bens father and mother Edwin and Beverley, and manager Shona Grant have 88ha of irrigable land on the 100ha effective farm, but most of it is the heavy bottom of the drained Hikurangi Swamp and is regularly flooded.

Soil moisture deficits are the exception, and when they do occur JV Farms (on Jordan Valley Rd) needs to take advantage of the opportunity for effluent irrigation.

The Re:Gen product makes sure that Ben and Shona identify the windows of opportunity for effluent irrigation and how much that area of the farm can receive before the Smiths are in danger of creating run-off, and thereby possibly breaching their Northland Regional Council irrigation consent.

His experience with Re:Gen thus far has prompted Ben Smith to replace some of the 150 Bosch irrigation guns installed by Edwin 15 years ago with K-Line sprinklers for fine tuning of effluent irrigation.

K-Line reduces the application rate from 4mm/hr to 0.4mm/hr, which means that JV Farms can make use of the smaller soil moisture deficits as identified by Re:Gen.

Before Re:Gen was hooked up, those smaller deficits would not be easily identified.

While the pumping system can draw down the storage pond from full to near empty in just four hours, the irrigation application of 16mm through the guns in that time would lead to effluent run-off and possible breach of the Northland Regional Council consent. Hikurangi soils have very little natural drainage and require mole drains to bring soil moisture below field capacity. Rainfall quickly cancels out soil moisture deficits and irrigated effluent can quickly travel to surface water, which would be non-compliance with the regional council consent. However, in the absence of rain, daily evapotranspiration creates small soil moisture deficits which can be utilised for irrigation to bring soils back to field capacity.

Re:Gen is the entrepreneurial company of Bridgit Hawkins, who has a masters degree in agricultural science from Massey and is a former executive of AgResearch and Harmonic, which is a private information and technology research and development company. Harmonic hatched the Re:Gen product, which has now left the nest and is under the direction of Bridgit. Masseys irrigation specialists conceived a novel concept for effluent management on dairy farms stemming from the environmental monitoring work. A proof of concept was developed with the assistance of a Sustainable Farming Fund grant, and seed funding from Telecom operating on Massey Universitys No.4 Dairy Unit. The Re:Gen system was developed in conjunction with Massey University scientists and proved to have a range of benefits for the farm including the scheduling of effluent irrigation and quantifying the changes required to the farms effluent system. In December 2008 Harmonic was successful in securing a Technology for Business Growth grant from Foundation for Research Science and Technology to commercialise the proof of concept. DairyNZ On Farm Innovation Fund invested in a national trial of Re:Gen, conducted in 2009.

This was conducted on eight farms throughout the country, of which the Smiths Hikurangi farm was one.

Another major advantage of the Re:Gen management system is for record-keeping and verification of effluent handling, for compliance with the resource consent.

For instance, the daily pond measurements in the system shows that the collection pond has not over-flowed, nor is the cause of some pollution outbreak through leakage.

More precise application of effluent, which has nutrients for pasture, plus the records of what has been applied and when, means savings on fertilizer applications. This can equate to savings of $2,000 - $10,000 each year depending on the size of the farm.

Other benefits identified in the trial is staff management the recommendation gives a clear guide on what to do, meaning the farm owner can delegate the job of effluent irrigation with confidence.