Friday, 23 December 2016

We Hope You Have A Green Christmas!

From all the H2Grow team we'd like to wish you a Merry Christmas and Happy New Year. We will be leaving the airways clear for a couple of weeks to allow all the Christmas messages and holiday photos to get through. And will be back in touch from mid-January.

Monday, 12 December 2016

Know your Soil Better than your Bank Manager - Continued

Identifying Soil Texture

Soils are made up of particles of different sizes, the largest sand, followed by silt, to the smallest clays. Together these make up the soil’s texture. Soil texture has a direct impact on soil physical properties: porosity, water holding capacity and bulk density. Furthermore soil clay content determines soil chemical properties and the soil’s ability to hold onto nutrients.

This blog will discuss hands on ways to determine your soil texture, how texture relates to key soil physical properties and the role of clays in the soil. You can determine your soil texture at the same time as you carry out the VSA described in the previous blog post and together these practices will improve the quality of your information.

The change in a soil with depth, the cross section down through the soil, is referred to as the soil profile. It normally consists of a number of soil horizons (layers) each with different characteristics (texture and/or stone content). The picture below shows a soil profile with six distinct soil horizons. When scheduling irrigation you need to know information about the hydraulic (water) properties of each soil horizon that plant roots occupy within the soil profile to determine the amount of water available to the plant. This determines how frequently you need to irrigate (return period) and the maximum irrigation you can apply in one application (irrigation depth).

Example soil profile
Soil texture is an important characteristic because it gives a good indication of other soil properties such as water storage, drainage and nutrient supply. It is a stable soil property and is not likely to change with normal soil management. Soil texture can be estimated in the field by some practical tests involving the feel of the soil and these are outlined below. To determine the textures and get an idea for the ability of your soil to hold water it is beneficial to dig a pit and expose an open face on the soil profile so you can determine the different horizons visible down the profile. You should identify the soil texture of each of the horizons that plant roots are found to grow in, or down to about 60 cm.

Hands on method to determine your soil texture.
Found in the joint Irrigation NZ and Plant and Food resource - Click here to visit the webpage.

The graph below shows typical soil water holding capacities (WHC) for different soil textures in % or mm of water per 100 mm of soil depth. It also shows their typical permanent wilting points (WP) and field capacities (FC). The relationship between WHC, porosity and bulk density is straightforward. Sand has the largest particles, the lowest WHC and therefore the lowest porosity. This translates into the highest bulk density because less space is occupied by air. As shown by the WHC of silt and clay below, silt has a higher porosity and lower bulk density which is very similar to clay soils although clays tend to have the highest porosity. This is because clay is made up of lots of small particles which create lots of air spaces between them. Therefore clay also has the lowest values for bulk density.

Relationship between soil texture and soil water content.
Found in the joint Irrigation NZ and Plant and Food resource.
Another role of clay in the soil is in terms of nutrient management. The structure of clay's means that they tend to become negatively charged around the surface. This means that positively charged nutrients are attracted to the surface of the clay and, depending on the conditions, can move between this surface and the soil solution from where they can be taken up by plants. It is helpful to have an idea of how much clay your soil has because this will determine its ability to store positively charged nutrients such as potassium, calcium, magnesium, sodium and resist changes in pH. Clay also holds phosphorus by allowing it to be adsorbed into the clay structure; some clay's allow this more than others. This is important to note because when phosphate is adsorbed it is less likely to become available to the plant and more phosphate will need to be applied to the soil to avoid deficiency in plants.

For more information on soil texture and water holding capacity you will find a great resource by following this link.

Once you have an idea of your soil texture and water holding capacity mapping tools can be used to get an idea of the representation of this soil type across your whole farm. Simple mapping such as Google Earth images (see the Ground Truthing your Soil Variability blog) and S-Map (which will be discussed in a future blog post) are helpful resources. It is important to be aware that these are tools to increase your understanding but to provide the detail required for efficient farm management tools such as EM mapping and determining exact water holding capacity are greatly beneficial.

Blog post written by Nicole Mesman - BSc (Hons) Soil Science.

Friday, 9 December 2016

Know your Soil Better than your Bank Manager

A Practical Guide to Assessing your Soil Quality

The soil’s physical properties are vital to the ecological and economic sustainability of land. They control the movement of water and air through the soil, and the ease with which roots penetrate the soil. Damage to the soil can change these properties and reduce plant growth, regardless of nutrient status. Decline in soil physical properties takes considerable expense and many years to correct, and can increase the risk of soil erosion by water or wind.

The primary functions of the soil are to provide plants with air, water, nutrients and a rooting medium for growth and physical support (image sourced from the Landcare Research website) 
The Visual Soil Assessment (VSA) was developed by Landcare Research to give cropping and pastoral farmers a straight forward and time efficient checklist to use in the field to assess the state of their soil, primarily the physical soil quality.

The VSA can be found online here -> Visual Soil Assessment (VSA)

The VSA aims to help farmers identify changes occurring to soil physical properties so that they can assess the effect that these changes will have on their soil quality and the sustainability of their land management and long term profit.

Pictures in the VSA guide can be helpful when carrying out the assessment in the field (image sourced from: VSA Volume 1).
The assessment can be carried out quickly, reliably and cheaply with little equipment, training or technical skills. The scorecard below is to record those visual soil indicators used to assess soil quality. There is a similar scorecard for recording plant indicators. You are then able to compare the two sets of indicators to see if you have similar scores for both and if not why. For instance, is damage to soil quality not being seen in crops yet or are crops struggling to recover from previous soil damage?

VSA Scorecard (image sourced from: VSA Volume 1)
Below each indicator is a section in the online VSA booklet to refer to for assistance. Pictures are included so you can compare what you are viewing and refer to examples. You will need a spade, the score card, a surface to drop soil onto for a shatter test and a bin to contain soil. Each indicator is given a weighting and at the bottom of the scorecard you add the scores for the various indicators. Values falling within certain ranges are deemed “poor”, “moderate” and “good” quality. If your quality is poor or moderate it is suggested that you refer to Volume 2, also easily accessible from Landcare Research online. This volume contains tips on how to improve your soil quality or maintain it if it is already good.

Tips include:

  • Cultivating at the correct moisture levels to avoid smearing of soil, formation of cultivation pans and reduced infiltration when the soils are too wet. 
    (image sourced from: VSA Volume 2)
  • Use a sub-soiler to break cultivation pans and increase root growth
  • Maintain soil organic matter levels to ensure porosity, drainage and root growth.
    (image sourced from: VSA Volume 2)

By utilising these resources, you will gain a better appreciation for the state of your soil and will be able to identify when changes are occurring and why. The VSA is a simple tool and when used regularly will help with building a picture of soil quality. There are a range of other resources that can continue from the VSA, further your knowledge of your soil and assist with management. SINDI, another resource for determining soil quality, will be discussed in a future blog post along with hands on ways to identify your soil type and S-Map, how its geomorphological (land formation) history can be used to assist your farming.

The blog post you have just read was written by Nicole Mesman - BSc (Hons) Soil Science.

Wednesday, 7 December 2016

Soil Moisture 101

Soils are made up of mineral matter, organic matter, water and air. The space between the soil particles are referred to as pores, air and water occupy these pores. Macro pores allow water to filter through the soil and then drain out the bottom. Micro pores store water that is available for plants to grow.

Soil texture is an important characteristic that influences water holding capacity, drainage characteristics and water infiltration rate. The finer the texture of the soil the greater volume of micro pores and therefore greater water holding capacity compared to coarser textured soils.

The total amount of water that a soil can store is referred to as the water holding capacity (WHC) of the soil. Coarse textured soils such as sandy and gravelly soils have a low WHC while silts and clays retain more water therefore have a higher WHC. WHC is usually expressed in miilimetres (similarly to rainfall) held per depth of soil e.g. Xmm/100mm.

Here are some common terms that you are likely to come across regularly on H2Grow and resources relating to soil moisture and irrigation scheduling:

Saturation – When all the macro and micro pores are full of water. If more water is added to a saturated soil it will either drain out the bottom, pond or run-off.

Field Capacity – Macro pores are full of air, micro pores are full of water. Silt and clay soils generally reach field capacity after 2-3 days of drainage from saturation, sandy and gravelly soils much faster. Field capacity may also be referred to as full point.

Stress Point – At this point the plant has to work to harvest the water from the soil, therefore plant growth is slowed and yield potential is reduced. The plant will survive beyond this point but will become increasingly stressed. Stress point is related to crop type, rooting depth and soil type. Stress point may also be referred to as trigger point or refill point.

Wilting Point – At this point although there is still water held in the soil the plant is not able to access it as it is held to tightly (hydroscopic water). The plant will therefore permanently wilt and die. Wilting point may also be referred to as permanent wilting point.

Water Holding Capacity (WHC) – Is a measure of the water that is extractable by plants. This can be calculated by taking the difference between the soil water at field capacity and at permanent wilting point. Water holding capacity may also be referred to as total available water or available water.

Readily Available Water (RAW) – Is a measure of the amount of water in the soil that supports optimum plant growth. This can be calculated by taking the difference between field capacity and stress point. As a general rule of thumb half of the WHC is readily available to the plant, therefore RAW = 0.5 x WHC.

Soil Infiltration Rate – Is the speed at which applied water can enter the soil. It is described as the millimetres depth of water infiltrated per hour (mm/hr).

Figure 1 below may help to illustrate the difference between saturation, field capacity and wilting point.

Figure 1
While this theory is all very useful, nothing beats seeing like in the real world. So I’d encourage you the next time you’re doing a paddock walk to take a spade with you and locate what appears to be the driest and the wettest spots in a paddock. Dig a hole in these two spots and compare the soil type/texture, the depth of topsoil, depth of the roots and other obvious visual differences. You will see posts over the next month that explain how to carry out a visual soil assessment and then how to apply this in your irrigation scheduling.

Posted by Sarah Elliot from Lindsay NZ

Sunday, 4 December 2016

Is Your Irrigator in Top Nick?

The spring weather has brought more rain to many parts of New Zealand compared to previous seasons which has meant many irrigators have barely got off the starting blocks. This extended downtime is a perfect opportunity to give your irrigator a bit of TLC which will help ensure it is running at full capacity when the heat comes on.

Many simple checks and servicing like lubricating joints, replacing oil in gearboxes and looking for signs of fatigue can often be carried out by farm staff. However, should you be unsure or think that you might have detected an issue don’t hesitate to contact your irrigation dealer.

Grafton Irrigation (Zimmatic dealer based in South Canterbury) have put together a handy checklist to guide you through the checks and maintenance that will help prevent mid-season issues. The checklist covers your intake, pump shed and mainline, and pivot, hard hose, soft hose, K-line and G-set (solid set) type irrigation systems. Print yourself a copy using the link below.

This post has been written by Sarah Elliot - thanks to Grafton Irrigation for your input!

Thursday, 1 December 2016

Am I a Responsible Irrigator?

The current Government's focus on water as the way to double New Zealand's farm exports by 2025 is reflected in the increasing accessibility of irrigation to farms around the country. Although a resource consent may state a Farmers right to use this water to irrigate and an irrigation dealership would be more than obliging to install the hardware - this ability to irrigate comes with responsibility.

To achieve a high level of irrigation performance requires a well-designed, well managed and well maintained irrigation system.

Choosing an Accredited Irrigation Dealer will ensure that your irrigation system is well-designed and meets the Irrigation Design Code of Practice and Standards. To view the list of currently accredited companies, click here.

Once the system is up and running ensuring it is well managed and maintained is up the those that own and operate it. The following questions should be considered by all those who irrigate.

1. Does my irrigation system apply what I tell it to in a uniform manner?

Poor distribution uniformity and low irrigation efficiency costs money. An irrigation evaluation is a way to assess the efficiency and distribution uniformity of your irrigation system to ensure it is performing as expected.

An irrigation evaluation will help identify causes of any poor performance and (sometimes with the assistance of a qualified professional) show how these can be resolved. Increasing irrigation effectiveness and efficiency will allow you to grow more for less.

An initial evaluation (often referred to as a Bucket Test) is simple enough to carry out yourself, there are several good guides freely available to walk you through this process. For more information check out ->
- IrrigationNZ
- Irrig8lite
- DairyNZ

If you are not in favour of the DIY option then consider contacting an Accredited Evaluator, this would also be recommended if your own test identifies potential issues that warrant further investigation.

The Hydro Services Team carrying out an Irrigation System Evaluation

2. Am I applying the right amount of water to optimise growth and avoid drainage or leaching? 

Measuring and monitoring your soil moisture is the best way to manage your irrigation efficiently.  If you don’t know what your soil moisture content is then how do you know how much you need to apply? Without this information, you risk either under-irrigating which can affect plant growth or over-irrigating which can also be detrimental to plant growth and the environment. Both these scenarios impact profitability.

There are a number of options when it comes to measuring soil moisture, choosing the best option for your farm and then ensuring it is giving you accurate information however cannot be covered in one paragraph. There are many posts already on H2Grow that discuss this topic, use the “WHAT ARE YOU INTERESTED IN” menu to navigate to these, or subscribe so that you do not miss out on these in the future.

3. Is my irrigation system working as it should, and will it continue to do so in the long run?

Irrigation system checks and maintenance should be undertaken during the off-season and at scheduled times over the irrigation season (the more hours your irrigator runs for the more regularly these checks should be carried out).  Recommended irrigation system maintenance will be covered in more detail in the next H2Grow blog post, this will include a checklist that you can download and print off to help you with this task.

Keep an eye out for the next post or subscribe to ensure that you don't miss it!

Tuesday, 22 November 2016

Legumes + Efficient Water Use = Great Results at Omarama Station

Omarama Station recently played host to the "Legumes in the High Country" field day, organised by Lincoln University and Beef + Lamb NZ. There was a good turnout of farmers and industry professionals to the farm owned and run by Richard and Annabelle Subtil, 2015 winners of the South Island Farmer of the Year competition. The focus for the day was the use of legume species in the high country environment with a short session on the use of irrigation and soil moisture monitoring in the arid environment that is the Mackenzie Country.

Omarama Station (Courtesty of Richard Subtil)
Omarama Station covers 12,000ha with a mixture of dryland high country and irrigated flats. The property has had significant development work undertaken and a number of centre pivot irrigators installed that irrigate 560ha. A large water storage pond has been constructed to supply water to the irrigation system.

Dr MS Srinivasan from NIWA gave the first presentation for the day at the site of the lysimeter that has recently been installed on the station. The lysimeter is the first in the Waitaki catchment and aims to build knowledge around drainage and soil water under the developing soils at Omarama Station. The site contains three catchment sleeves one of which has soil moisture sensors installed. Any drainage water from the site is measured which gives an indication of the soil moisture status and how drainage from the soil profile is taking place.

From a soil moisture point of view the lysimeter is important as the soils at Omarama Station have exceptionally variable fertility, structure and water holding capacity. Irrigation is not new to the area however the shift from border-dyke irrigation to more efficient spray irrigation has seen a massive change in the water use efficiency on extensive properties such as Omarama Station. Soil development under irrigation is an interesting concept and soils mapped on Omarama Station have shown to have varying levels of water holding capacity based on how long they have been irrigated for in the past. Investigation has shown that the depth of soil and the water holding capacity has improved under 30 years of irrigation. 

Irrigation at Omarama Station (Courtesy of Richard Subtil)
Agri Optics has installed three sub-surface AquaCheck probes that will complement the work being undertaken at the lysimeter site. This information will flow into the decision making process that is used around timing and quantity of irrigation water applied by the team at Omarama Station. 

Derrick Moot spoke on how selection of species was important to maximising water use efficiency in moisture deficient environments such as the Mackenzie Basin. As we know lucerne is a great fit into dryland high country systems. It has the ability to maximise the water use efficiency and has a high water to dry matter conversion ratio (kg DM/mm/ha). The selection of species going forward and the development of novel species all points towards maximising the efficiency of water use in dry high country areas.

Write up by Nick Evans

Friday, 18 November 2016

Lincoln University Dairy Farm Open Day 2016

This Saturday the Lincoln University Dairy Farm (LUDF) will open its gates to showcase the operations of a commercial dairy farm.
Visitors will get an opportunity to ‘get up close’ and learn about the transformation of ‘sunshine into food’. 
Included in the program is the importance of water to enable a dairy farm to produce milk that we get to enjoy on our Weetbix every morning.
The farm will be open to the public from 1pm-4pm. This is a great opportunity for anyone in the Christchurch and Canterbury region who has not had the opportunity to visit a dairy farm before.

For more details visit

Wednesday, 16 November 2016


Firstly, I’d like to say a big hello to all our blog followers reading this - I sincerely hope you’re enjoying the H2Grow blog that we’re putting together to help you gain more understanding about irrigation and ways in which you can increase the efficiency of not only the irrigation on your property but your farming system in general. But enough about that; let me introduce myself and my motivation for bringing the H2Grow blog to life…

I was born and bred on an arable farm in Mid Canterbury. Like Sarah Elliot I have very fond memories of growing up on the farm and following my Dad and Poppa around on the farm from a very young age. I had pet lambs, and calves, rode ponies, helped feed out, shifted break fences, drove tractors and as I got older, shifted gun irrigators. Because of my love for farming and everything outdoors after I finished high school I went to Lincoln University to study a Bachelor of Agricultural Science. I loved my time at Lincoln, however was getting itchy feet as lots of my friends were travelling so in the third year of my four year degree I decided to get my own travel fix while still continuing my studies by undertaking a year of ‘Study Abroad’ at Colorado State University in the USA. I had an absolute blast and got to take specialist papers on things such as irrigation and Precision Agriculture that we couldn’t do here in NZ which made me think how we could adopt some of the cool things they were doing on farms in the USA back here in NZ. So, I came back to NZ, completed my degree and fresh out of Uni and a bit green, started New Zealand’s first specialist Precision Ag company Agri Optics New Zealand in conjunction with my parents. Over the years we’ve grown the company both in terms of size and also the range of products and services that we offer. We’re now up to a staff of four people and we offer our products and services across the whole of New Zealand.

Discussing the benefits of precision agriculture technologies and practices at a North Otago field day following some very successful trials on the property
While I’m not as hands-on on the cropping farm that I used to be in my younger days, I still keep my hands in the mix with helping with Precison Ag decision making. I also have moved (slightly) further south to Geraldine, South Canterbury where my husband’s family have a sheep & beef farm. The two types of farming are completely different and both offer their unique challenges and advantages. I feel privileged to be involved with both & hopefully with increases in efficiency and the use of technology will be able to take these farms forward sustainably and allow our daughter the upbringing on the farm that my husband and I both have such fond memories of.

Hard at work dosing ewes and lambs on our lease block with Paige learning the ropes
It’s been a great journey so far and I’m sure the future will be just as exciting!

Jemma Mulvihill

Monday, 7 November 2016

Introducing: SARAH ELLIOT

I considered starting this post to introduce myself boasting my passion for New Zealand agriculture - but how often do you read that statement and dismiss it much like you dismiss the over-use of superlatives in rural advertising?

So why is agriculture in NZ so important to me?

My fondest memories of growing up on our sheep and beef farm in Waitotara (South Taranaki) are “working” on the farm with Dad; riding shot-gun opening gates, feeding out, chasing sheep in the yards, probably just being a general nuisance. With endless area to explore, countless animals to play with, green grass and glorious mud your perspective of farming as a child is sublime!

My enthusiasm to participate in rural community events also grew from a young age. I credit this to the fantastic and friendly people in rural communities!

Working as a Jilleroo on Meda Station, a 1.25 million acre Brahman cattle station in the Kimberley’s 
By my latter years of secondary school when I was browsing university brochures I was drawn to the agricultural courses. But rightly or wrongly the school career guidance suggested with my exam results I should extend myself so enrolled into a Bachelor of Technology majoring in Product Development. I graduated with honours and was awarded the 2004 Product Development prize for my final year project with renowned NZ company Gallagher.

Summer university employment tracking milk losses in the Whareroa Fonterra plant one year and manufacturing TechnoGrazing™ system hardware for Kiwitech another also grew my appetite for solving challenges and looking for better solutions.

But what does this have to do with a blog aiming to help farmers improve irrigation efficiency?

After several years working abroad, when the opportunity came up to work with a team of guys who had just commercialised the world’s first true variable rate irrigation (VRI) system I felt it ticked all the boxes for me. I was going to be using my skills and experience as a mechanical design engineer to develop cutting-edge technologies to benefit the people, industry and environment that I love.

John Wright and I at a field day on his property, Wainono Dairies. John and his wife Sarah were early adopters of the Precision VRI system.
I have now been working in the irrigation industry for over five years and my primary role has been introducing farmers to Precision VRI technology and working with them to get the maximum benefit for their farm. I have had the pleasure of working with leading dairy farmers from NZ and Australia, poppy growers in Tasmania, onion producers in South Australia, turf growers in Queensland, cropping farmers, sheep and beef farmers from small scale to large. What strikes me as common to all the farms is that they can have the best technology in the world, but it won’t make a scrap of difference unless the person pressing go understands “why”. And this is the reason why I shoulder-tapped some people who know some things about efficient irrigation and together we formed H2Grow.

I also have a selfish agenda in wanting to increase knowledge of better, more efficient farming practices…  

My husband and I own and run Waikora Station, a 2333ha hill country property in the Hakataramea Valley, South Canterbury. It’s been a tough two years due to extremely dry conditions but experiencing this has grown my appreciation of the challenges faced as farmers. Like many other farming families we hope that one day our son may have the option to take over if he wants, but to make this possible it has to be sustainable (another currently on-trend word for you). And it doesn’t take long to realise how the consequences of our decisions affect the economics of our operation and impact the environment where we live and the community we live in.

Hamish and I on our farm, Waikora Station, in the Haka Valley

Thursday, 27 October 2016

Introducing: ANGUS KNOX

Continuing on with our series introducing the contributors to the H2Grow blog - today we'd like to let you get to know Angus Knox, Precision Ag Technician (Field Services) with Agri Optics New Zealand.

While Angus may not have grown up wearing Red Bands and riding shotgun in the farm ute his fresh perspective, smarts and injection of enthusiasm are what our industry needs to continue to thrive and grow into the future.


Six months ago I had perhaps slightly more knowledge of agriculture in general than your average city boy. But I had no idea of what Precision Agriculture was, or how it was being used to change the landscape of Agriculture in New Zealand.

Originally from Dunedin, I moved to Christchurch in 2012 with the intention of studying engineering (after a year of studying law and commerce at Otago University). I eventually found my niche and completed a BSc majoring in Geology and Geography with an endorsement in Environmental Science in 2015.

After a few months working as a GIS Analyst in Wellington, I began to get cabin fever and moved back to Canterbury to find something that would provide a balance between field and office work. Enter Agri Optics. Prior to starting at Agri Optics I had been exposed to some of the technology and sensors we use during my studies but the application to agriculture was entirely new to me.

I admit, I was pretty apprehensive about the steep learning curve I faced to educate myself about how these solutions could actually be used to benefit farmers in the real world. The thing that has struck me the most since coming on board, has been everybody’s willingness to share their knowledge. From the whole team here at Agri Optics to client farmers, I’ve had no shortage of expertise to draw on.

As a newcomer to the industry, it is clear to see that there is no future of agriculture in New Zealand without Precision Ag becoming widely adopted across all kinds of farming operations. The combination of Variable Rate Irrigation (VRI),  soil moisture probes and EM soil surveys have the potential to drastically reduce water wastage and potential nutrient leaching by making sure the right amount of water goes where it’s needed and doesn’t get put where it’s not.

Precision nutrient management and variable rate nutrient application is another tool that has impressed me. Anything that can help maximise yields while simultaneously reducing unnecessary use of additives and chemicals has to be a good thing.

As essentially an agricultural layman, it seems that the sooner we all get on board with adopting this technology, the sooner it will pay for itself. I have thoroughly enjoyed the last five months learning about our country’s largest and most challenging industry. I can only imagine where Precision Ag will take us in the years to come!

Angus Knox - Precision Ag Technician (Field Services), Agri Optics NZ

Wednesday, 5 October 2016

Improving Irrigation Efficiency for Only $50 cont.

Here is the much anticipated second installment from the Improving Irrigation Efficiency field day run by The Waihao Wainono Group and Morven Glenavy Irrigation. Dr Anthony Davoren, renowned Irrigation Consultant with Hydroservices, shares how drainage through the soil profile can be measured. With this key piece of information we can improve our irrigation management, and know when to turn the irrigator on (or off) to ensure all irrigation that is being applied is going to benefit the grass or crops we are growing.

Thank you to Dr Anthony Davoren, Waihao Wainono Group and Morven Glenavy Irrigation.

Thursday, 29 September 2016

Improving Irrigation Efficiency for Only $50

Dr Anthony Davoren is renowned as one of New Zealand’s leading irrigation consultants, establishing Hydroservices in 1983. If you have a question about irrigation management, soil and soil water assessment or surface and groundwater water resources then Tony will have the answer. What sets Tony apart is his practical, hands-on approach and the way he communicates information in a way that farmers can easily understand and relate to… I mean how many other speakers will you find presenting from a hole in the ground!

The Waihao Wainono Group and Morven Glenavy Irrigation recently hosted a field day focusing on improving irrigation efficiency. H2Grow is lucky enough to be able to share with you some short videos from this day. In the first in this series Tony explains how the root depth of the pasture or crop you are growing should be considered when deciding on the most appropriate soil moisture measuring equipment for your property.

Considering Root Depth when Measuring your Soil Moisture Levels

Keep a look out for the next video in this series where Tony explains how to measure drainage so that you can better manage your irrigation and prevent irrigation water, and nutrients, draining through the soil... and his top tips of how to greatly improve your systems irrigation efficiency for as little as $50!

Thank you to Dr Anthony Davoren, Waihao Wainono Group and Morven Glenavy Irrigation.

Wednesday, 21 September 2016

Soil Properties Critical when Applying Effluent

Dairy effluent is a great source of nutrients for growing pasture. But if not managed properly effluent can also be a significant source of contaminants which harm our waterways. Understanding how soil properties affect nutrient loss is a key to maximising the benefits of effluent on farm and minimising its impacts on waterways.

Soil texture and structure determine the amount of water that can enter and be retained within a particular soil, and the rate of transmission of excess water through that soil. So effluent irrigation systems should be matched to soil properties to minimise runoff and leaching. The rate at which effluent can be applied to the land for maximum production benefit is determined by the soil’s properties including structure, porosity and infiltration rate.

The nature of the effluent and cattle treading on soils can affect the infiltration rate. Treading damage, which occurs most when the soils are wet, significantly reduces the infiltration rate. For some soils this can result in accumulation of effluent below slopes and in hollows. It can then enter surface waterways.

Movement of water through soil pores is generally described as hydraulic conductivity. When hydraulic conductivity of the soil is low, irrigation of effluent will result in ponding and run-off once the total water capacity of the soil is exceeded or if application rate exceeds infiltration rate.

Low rates of hydraulic conductivity are found in soils that are poorly drained, and ponding and runoff often occur with high rainfall. Many of these soils are artificially drained to reduce the incidence of ponding and water-logging, and this carries a risk that effluent can bypass the soil and be directed rapidly into waterways

Leaching occurs as excess water moves through the soil. So soils with lower water holding capacity are more susceptible to leaching, while soils with high water holding capacity (deep silt loams) can store significant quantities of effluent.

The soils that have low available water holding capacities, are the shallow to moderately deep soils, as well as sandy or stony soils. Effluent irrigation on these soils is likely to result in leaching unless it is applied at low rates and in small doses. The irrigation system on these soils must be capable of low rates of application to gain the maximum nutrient benefit.

Drainage and the level of biological activity of the soil at the application site are important. Aim to apply effluent at a rate that keeps it in the root zone so that the nutrients can be utilised by pasture.

Permeable soils with a deep water table and no drainage limits are best for putting effluent on. However, on stony soils the risk of effluent draining directly to ground water would be an issue to consider. In such situations, application depths and rates should be adjusted to account for this risk.

Another issue is "bypass flow". When effluent application rates are higher than infiltration rates, water can enter continuous macro-pores that are open at the soil surface, and then move very rapidly via so-called "bypass flow" through a relatively dry soil matrix. This means little opportunity for the water to be retained within the root zone and high leaching of nitrate is likely to occur. Bypass flow of farm dairy effluent can occur in soils that undergo shrinkage and fissuring during drying, especially when these soils have been previously compacted by treading.

Efficient effluent storage provides flexibility when it comes to application and helps maximise nutrient uptake (image: DairyNZ)
A key to avoiding over application can be having adequate effluent storage so that irrigation can be deferred if conditions aren’t right. DairyNZ has released a new smart-phone app to help farmers apply effluent more efficiently. The Dairy Effluent Spreading Calculator app provides dairy farmers and effluent spreading contractors with guidance around nutrient application rates based on the depth and type of effluent they apply.

H2Grow would like to thank Bala Tikkisetty for this blog post. Bala is a sustainable agriculture advisor at the Waikato Regional Council.

If  you are keen for further information about best practice for applying effluent you will find a raft of useful information on the Waikato Regional Council website.

Or alternatively contact Bala directly, email or call (freephone) 0800 800 401.

Wednesday, 14 September 2016

Introducing: NICOLE MESMAN

Today's contributor profile introduces Nicole Mesman. Nicole's energy is inspiring. Her intellect and fortitude to challenge the conventional are just two of many reasons that we hope she does not spread her wings too far astray in the future, as agriculture is sure to benefit from retaining talent of her calibre.


I am a born and bred Cantabrian, from Christchurch, however I am continuing to spread my wings and experience the rural Mid-Canterbury. My childhood was filled with tramping, skiing and hunting holidays and from a young teenager I would say that I wanted to work with and in the environment and outdoors. Aside from rabbit shooting and hunting I never really did a lot on farms growing up. Lincoln drew me in at the end of high school, not for agriculture though but for biogeoscience (which I would realise was a fancy name for soil science). 

Once I got to Lincoln though my perspective and direction started to change. It’s hard not to get roped into agriculture when at Lincoln. Especially when your friends are doing projects like putting nappies on cows, monitoring cows grazing throughout the night and separating different swards of grass from endless piles of clippings. They were always looking for helpers, the fun we had!

It was a third year soils paper that introduced me to precision ag. We were out digging holes at Craige Mackenzie’s to create a soil map and also determine if the properties of the soils we found agreed with his EM map (the relationship was a good one I will add). After this I spent my summer making cakes out of soil, sand and water to review soil moisture sensors and then continued with my honours which analysed the effect of grazing and irrigation on soil physical properties. 

After Lincoln I worked for Lindsay as a summer student looking at their irrigation systems and EM mapping on various farms before going on to work for Ballance Agri-Nutrients. I am constantly learning more about agriculture and farming and I love it. Whenever I can find out about someone’s operation, learn from them and likewise share what I have learnt with them is a very good day.

Nicole fills up most of her weekends with outdoor pursuits; tramping, skiing, hunting and learning the ropes of day-to-day farm jobs

Nicole Mesman

Monday, 12 September 2016

Introducing: NICK EVANS

Second in our series of H2Grow contributor profiles we would like to introduce Nick Evans. Nick is a Precision Ag Technician at Agri Optics NZ based in Methven. His enthusiasm and fresh perspective coupled with learnings through his Lincoln University studies are an asset to the H2Grow Team.


Nick analysing EM survey data of an irrigated area for a customer 
I grew up in rural town Ashburton so exposure to agriculture was certain. Once getting under way in high school and after getting sick of washing trucks for my parents my dad sorted me out with a job working for a friend of his out in Wakanui. From then my interest in ag progressed. It wasn’t long before I would show up in the school holidays, be given a list of jobs to do and was left to looking after the farm whilst the boss went off on holiday.

After all of this exposure during my school years I was tossing up between engineering and a B Com Ag at Lincoln. Lincoln obviously won the day and I started my first three years of study. Meeting a huge range of people from all parts of the country meant that some strong friendships were also created. One of the perks of these friendships are the all-important farm tours when I go to visit. 

After the BCom I completed a Master of Management in Agribusiness over 18 months. This grew my skills and knowledge particularly around how to understand and interpret scientific papers and studies. Agricultural innovations were a part of the course and this was my first real exposure to Precision Ag. It was from there that my interest in the area grew.

On a day to day basis you will find me enjoying my time the most when I get the opportunity to work with farmers to implement Precision practices. The challenge is in tailoring it to meet the needs and requirements of the farm and the farmer. 

Nick Evans - Agri Optics NZ Ltd

Friday, 9 September 2016

We Have a Winner [COMPETITION]

We are very happy to announce that the winner of the Garmin GPSMAP64s is... 


Congratulations Simon, we're sure you'll be chuffed with this very handy handheld GPS unit. 

From the whole H2Grow Team we'd like to thank everyone that entered this competition, and we hope that you find something of interest in this blog in the future.

We would also like to apologise for the delayed competition winner announcement, this was due to unforeseen circumstances. Apologies for any inconvenience this may have called. 

Thursday, 8 September 2016

Introducing: CHRIS SMITH

I recently read an opinion piece in a farming paper questioning the credibility of some of the "informative" material that fills our letter boxes (and social media feeds) on a daily basis. And I think rightly so, as a reader and purchase decision maker I like to know how the person behind the insightful content became a knowledge source about it. And what is their relationship to the topic - do they have hands-on experience, have they studied in the field or been involved in research trials, is their role purely marketing a product or service or otherwise. Often this relationship is revealed, but not in every case.

This leads me to the motivation behind the series of posts to follow, as it may have been rather impolite of our H2Grow team not to have formally introduced ourselves and our many guest contributors we have tapped the shoulders of to cover topics that our core team are not intimately familiar with.

So without further adieu we would like to introduce Chris Smith...


Chris Smith - Operations Manager (Acting) for Agri Optics NZ Ltd
From 1988 to 1990 I attended Shuttleworth Agricultural College were I attained my Higher National Diploma (HND) in Agriculture. I followed this up with winning a scholarship with the John Edgar Trust for Farming’s Future Leaders in addition to my Fertiliser Advisers Certification (FACTS).

After studying at Shuttleworth Agricultural College I worked my way up the ladder in both the dairy and arable industry in the UK into farm management. When I left the UK in 2007 I was managing a 1800 ha estate in Berkshire which consisted of a large arable area, we also contract farmed the neighbours estates, ran numerous environmental schemes, and many non-farming enterprises!

It was here I attained my BASIS qualified in crop protection, integrated pest management plus bio-diversity and environmental training. Our team were early adopters of Precision Agriculture (PA) in the late 90’s, with grid soil sampling, variable rate inputs, using aerial imagery, information transfer and yield mapping.

The success of our farming team was recognised with many competition wins including Berkshire's Best Farmed Farm, Best Wheat, Barley and OSR Crops for several years. I was also chairman of the Berkshire Agricultural Training Board.

In 2007 I moved to NZ to manage an arable unit in Southbridge, where I learnt the differences between the UK and NZ farming. From there I moved out of farm management to Agri Optics NZ Ltd in 2012, to follow my passion for PA.

On a day to day basis, I study technologies and farming systems, and match our services to help farmers achieve their goals. I analyse data from EM surveys, nutrient maps and many other sources plus moisture probe information to see what its telling us. Using this wealth of information I investigate potential new technologies and solutions, and establish how, or if, they are going to be beneficial to our clients moving forward.

More recently I have added to my qualifications, completing the intermediate sustainable nutrient management course at Massey University.

I have always been really interested in PA. Since joining Agri Optics I have found the greatest satisfaction comes from helping others use PA and when they see how it can benefit their business’s sustainability.  I love working with forward thinking people, looking for new solutions and enjoy the journey it takes us on. On a personal note, my family are a huge inspiration to me!

Chris Smith - Agri Optics NZ Ltd

Tuesday, 6 September 2016


Only three more days to grab the chance to win a Garmin GPSMAP64s!  Simply subscribe to this blog to go in the draw to win.  

To subscribe and enter the draw type your email address in the "Follow by Email" box (top right). Receive bonus entries by clicking "Like" on the Growsmart Precision VRI Facebook page (@growsmartprecisionvri) or commenting on one of the win-win competition posts on the page... Full terms and conditions can be found below... Good luck!

Win-Win H2Grow Competition Terms and Conditions:
1.             By entering this competition each entrant will be deemed to have accepted these terms and conditions and to have agreed to be bound by them.
2.             This competition is open from 1pm (NZ time) on August 12th 2016
3.             This competition closes at 1pm (NZ time) on September 9th 2016
4.             To enter you need to subscribe to the H2Grow blog by either;
a.             Filling out the “Subscribe to H2Grow” competition entry form
b.             Subscribe online by visiting and entering your email address in the “FOLLOW BY EMAIL” box
5.             An additional entry will be granted for each of the following;
a.             Liking the Growsmart Precision VRI (@growsmartprecisionvri) Facebook page
b.             Commenting on one of the “Win-Win” competition posts on the Growsmart Precision VRI (@growsmartprecisionvri) Facebook page
6.             The winner will be announced on and the Growsmart Precision VRI Facebook page by 5pm (NZ time) on September 9th 2016
a.             By entering this competition, the winner agrees to their names being published.
b.             The winner will be contacted via email. A postal address will be requested to send the Garmin handheld unit.
7.             This competition is open to New Zealand residents only.
8.             Failure to supply all requested personal information at the time of submitting an entry might result on the entry being invalid.
9.             The prize is not transferable or exchangeable, and cannot be redeemed for cash.
10.           Lindsay International ANZ PTY Ltd is not liable for damage to prizes sent by post or courier.
11.           The winner will be drawn at the Lindsay NZ Marketing Office, 382 Hurstlea Road, Hakataramea Valley, Kurow
12.           Employees or the immediate families of Lindsay International ANZ PTY Ltd and/or Agri Optics NZ Ltd are not eligible to enter this competition.
13.           The decision of judges in relation to any aspect of the competition is final and no correspondence will be entered into.
14.           Under the Privacy Act 1993, all individuals have the right to access and correct their personal information by contacting Lindsay International ANZ PTY Ltd in writing to Lindsay NZ, 382 Hurstlea Road, Hakataramea Valley, Kurow
15.           By subscribing to the H2Grow blog all entrants are deemed to have given H2Grow (a collaboration of Lindsay International ANZ PTY Ltd and Agri Optics NZ Ltd) and Lindsay NZ consent to contact them using the contact information supplied in their entry in the future.
16.          This promotion is in no way sponsored, endorsed or administered by, or associated with, Facebook.

Tuesday, 30 August 2016

PAANZ Workshops - Technology to Reduce N Leaching

If you are a farmer or involved in the primary sector and wanting to further understand the issues around N leaching and the potential solutions available to better manage nutrients on farms then the "Technology to Reduce N Leaching" workshop may be of interest to you.

These workshops are being run by Precision Agriculture Association NZ in the North Island on the following dates:

1st September - Palmerston North
2nd September - Hastings 

For more information visit

Friday, 19 August 2016

Downfalls of a Long Irrigator

Up until the early 2000’s when dairy conversions were a plenty, the centre pivot irrigators that were being installed seemed to be getting longer and longer. It seemed that the longer the pivot you could put on, the cheaper the per ha cost of the system became. However, several studies more recently carried out have brought to light the negative effects and inefficiencies of some poorly designed long pivot irrigators.

A standard pivot in the USA is a quarter mile long (approx. 400m) which enables it to irrigate a half mile by half mile section, the development of centre pivot technology has primarily been based on these standard specifications. Akin to the common Kiwi approach of creating innovative solutions to suit our farming conditions Kiwi’s went about lengthening these standard pivot designs. It didn’t take long though for farmers and irrigation installers to realise that there was a major trade-off between system length and the instantaneous application rate of water going on out towards the end of the irrigator. The problem being that the further out you get the faster the machine is travelling, therefore the higher the instantaneous application rate needs to be. This introduces major issues including crop and soil damage and surface ponding. With surface ponding comes runoff, bypass flow and leaching – all things that should be avoided!

Alarm bells should start ringing when you start talking about pivots longer than 660m. Now, a pivot longer than 660m isn’t necessarily bad, but you need to consider the design carefully to ensure that you are irrigating within tolerances of the soil and farming system. The Irrigation New Zealand Design Code Of Practice has some great information about what soil features should be considered during the design process.

In a nutshell, when looking at the length of an irrigator, you need to consider:
  1. Soil type
  2. The infiltration rate of that soil
  3. And the maximum instantaneous application rate of the pivot
The latter should not exceed the infiltration rate of the soil as otherwise the negative outcomes previously mentioned are likely to occur. There are also other properties such as the water holding capacity and the effective crop root depth that should be factored into the design to ensure that you are getting enough water to the plant, but not over-watering and causing problems.

The other issue is engineering. A longer, higher discharge rate machine must have bigger pipes which means more weight and stress on motors and gearboxes (and soil). And also all the water has to be pressurised to meet the requirements of only a little of the water right at the end of the machine - which is not energy efficient. A short machine can cover the extra capital cost per hectare very quickly by reducing operating costs, obviously each situation is different, but it may be worth getting your irrigation dealer to help you do some figures.

If you do happen to have a very long pivot, you may be experiencing some of the problems mentioned inherent with the design. If you are seeing some of these issues, there are a few steps you can take to help improve the performance of your system.
  1. Increase the wetted footprint of your sprinklers, effectively lowering the instantaneous application rate over any particular point. You can do this by alternately attaching sprinkler drops to the forward and rear truss rods, changing the sprinkler heads on your machine to sprinklers with a larger throw, or putting tees in and increasing the number of sprinklers while still slinging them over truss rods. This will only go so far towards solving the problem but it may help.
  2. Using Variable Rate Irrigation could help depending on the variation in your soils and your topography. By knowing more about the physical constraints beneath your irrigator, you can then use Precision VRI to better manage to those constraints. Agri Optics can help with their EM Mapping and Data Management services.
  3. And the most expensive capital-wise, but potentially the most effective and highest potential for reducing operating costs is to decrease the length of your pivot. This may mean reconfiguring pivots on your farm to still irrigate the greatest area. There is a significant capital cost, but if you do the numbers as some research studies have shown, it could well be worth it to increase your irrigation efficiency.
The one thing in common with all of these approaches is that you need to know the characteristics of your soils (including the variability in soils) and then design your system to work within the constraints.

But there is no substitute for a well-designed system. For well-designed irrigation solutions or to discuss how you could improve the efficiency of your centre pivot contact your local Zimmatic dealer.

We hope you find the information in this post useful. The information was supplied by Stu Bradbury who has many years of experience creating irrigation solutions from the ground up so to speak. The ideas began to spark while spinning spanners and installing irrigators in the early 2000's. He has gained a wealth of knowledge through numerous research studies and much trial and error over the years. Stu's current role is VRI Solutions Advisor for Lindsay NZ.

Stu Bradbury working on a Precision VRI system on a centre pivot

Thursday, 11 August 2016

Event Reminder: B+LNZ South Canterbury Farming for Profit Technology Expo - August 11th

Farmers in Canterbury and North Otago don't forget to head along to the Phar Lap Raceway in Timaru tomorrow for the B+LNZ South Canterbury Farming for Profit Technology Expo.

There is a great line up of presentations including a number relating to precision agriculture and efficient irrigation. And if you would like to meet some of the connections and contributors to the H2Grow blog in person than be sure to grab a front row seat in the following presentations:

4pm - Variable rate irrigation and the latest irrigation technology from Lindsay, manufacturers of Zimmatic, Growsmart and FieldNET irrigation solutions.

4:30pm - The benefits of EM surveying and precision agriculture products and services offered by Agri Optics NZ.

For full details of the agenda click here.

... and I will give you a heads up that H2Grow will be kicking off an exciting competition from 1pm tomorrow. Entries can be made at the Technology Expo and online, so head along tomorrow or watch this space for more details!!

From your friendly H2Grow Team

Wednesday, 10 August 2016

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

In the last two blogs we looked at how Precision Ag can help with managing the nutrient and moisture levels in the soil profile. This blog looks at how an EM survey can assist in relation to the physical characteristics of the land for your farm environment plan.

As an EM survey is conducted, the readings are logged by 2 cm horizontally accurate RTK GPS. This allows us to not only build a great picture of your soil profile but also the surface of the area surveyed as well. This in its own right can be a very powerful tool for overall land management and also the farm environment plan. As the flow of water can cause the movement of soil and nutrients.

With this layer of data we can make 3D contour or water flow maps. So you can see where water will move in a rain or irrigation event and where potential areas of soil/nutrient issues may occur, so buffer zones may be necessary to mitigate this potential problem.

Picture 1: 3D elevation map showing the potential water flow across the area.
Our software platform, VA Gateway, can model the flow of water and we make an animated model of how the surface water will react over time. On the first image (picture 2) below you can see the surface water after a rain event then moving down the images how the water moves from the higher area and ponds in others. This sort of information is of great use to the client for highlighting potential issue zones.

Picture 2: Simulator showing the water flow after a large rain event.
Picture 3: The water is flowing from the higher areas.
Picture 4: The water is ponding in the low lying areas.
With variable rate irrigation application maps on ‘hilly’ land we can combine the EM and slope maps, to take into consideration the severity of slope over the EM. That is to say it may be a soil type that requires a higher water rate but when you take into consideration the degree of slope, then higher application rates would be moving down the slope as well infiltrating the soil profile, so therefore a lower application rate is needed on the steeper sloped areas to reduce the chance of runoff. By managing the potential flow of water across your property you are also managing the movement of soil and nutrients.

Picture 5: At the top left the EM zone map, on the bottom left the slope map. On the right the two maps have been combined to form an application map using both characteristics.
In Picture 5, on the right side is the application map where is red low EM, green Medium EM and blue high EM - the matt colours indicate low slope, the bright colours higher slope.

So with the use of Precision Ag you can gather very comprehensive maps showing the levels variability in nutrient levels, in soil characteristics and in topography for your property. By measuring these variables you can then monitor them and manage them, which are prime requisites for your farm environment plan.

Agri Optics NZ Ltd

Tuesday, 2 August 2016

Reduce the Cost of Nutrient Loss with Precision Ag (Part 2 of 3)

In the last blog post we looked at nutrients and how Precision Ag can help with your Farm Environment Plans (FEP). This blog post looks at how an EM survey can help with identifying your soil types for your Farm Environment Plan.

An EM survey illustrates the relative variability in soil characteristics including soil texture that can be potentially related to water holding properties within that soil profile, this can help you manage water application through the use of variable rate irrigation technology. When combined with the use of soil moisture probes you have the data and technology you need to be able to retain nutrients within the soil profile itself. 

EM surveys can be ground-truthed to find the correlation between the EM value and water holding capacity (WHC).  From that you can create a WHC map and site-specifically place moisture probes to monitor the soil moisture levels within each identified zone.

Ground-truthing sites are identified within each zone (shown on the left). The graph illustrates the correlation between the EM values and WHC in the top 55cm of the soil profile for this paddock.
In the image above we can see the correlation between EM value and WHC at this site has an R2 of 0.97 (R2 quantifies goodness of fit. It is a fraction between 0.0 and 1.0, higher values indicate that the model fits the data better). We can then use the equation in VA Gateway, one of the PA software platforms supported by Agri Optics, to create a water holding capacity (WHC) map out of the EM values map.

The EM map converted into a Water Holding Capacity map
This water holding capacity map can then be used in conjunction with soil moisture probes and VRI to maintain the moisture levels between field capacity and critical moisture. This not only reduces any potential yield loss from moisture stress but it also ensures that you aren't saturating the soil profile, and therefore avoid leaching nutrients out of the root zone.

It’s all about balancing crop requirements, real-time moisture levels, rainfall (when it comes!) and application rates with irrigation return times as precisely as possible to keep everything at an optimum level.

An AquaCheck soil moisture probe graph showing soil moisture levels and how they are affected my irrigation or rain events on this soil profile.
As can be seen above by keeping the moisture between upper and lower readily available water levels you ensure yield isn’t compromised and eliminate leaching. The rooting depth used for the probe profile can be tailored to the crops specific needs on the moisture monitoring website.

Next time we will discuss how the EM maps and topography data can help you with your FEP.

Chris Smith

Agri Optics NZ Ltd