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.

Chris Smith

Agri Optics NZ Ltd

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

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.

Chris Smith

Agri Optics NZ Ltd

International Recognition for Precision Ag Advocate

Here on the H2Grow blog we showcase leading edge precision agriculture technologies and practices often through case studies of growers achieving success through there application. But in today’s post we would like to showcase a true leader in precision agriculture – Craige Mackenzie. Craige is a leading advocate and role model within New Zealand, a pioneer in the adoption of precision farming techniques.

Craige has recently been awarded the 2016 PrecisionAg® Farmer of the Year. This is a huge accolade and NZ should be very proud that the award has gone to one of our own!

The PrecisionAg® Institute recognises outstanding people, programs, and organisations that are making a difference in the precision ag industry. Each year’s winners have devoted their careers to the technology that improves crop production stewardship, agronomy, and efficiency.

Craige and Roz Mackenzie at Greenvale Pastures

Craige’s focus has been on utilising precision agriculture systems to maximise nutrient and irrigation efficiency for improved farm sustainability, both environmental and financial.

Craige and wife Roz farm Greenvale Pastures, a 200ha fully irrigated cropping operation near Methven specialising in vegetable and small seed production. They are also 50:50 equity owners in Three Springs Dairies, a high-output dairy farm with 1,200 milking cows. Their adoption of precision ag technologies has resulted in improved seed quality and yield with reduced inputs.

The utilisation of Growsmart Precision VRI has led to annual water savings of 32% and resulted in vastly improved water management on their variable soils. Resulting in three years of no measured nitrate losses to the groundwater!

In this recent video Craige and Roz share some of their secrets to farming sustainably and profitably through by employing precision ag.

In 2010 Craige and daughter Jemma established Agri Optics Ltd., New Zealand’s first precision agriculture service company providing precision ag tools and services to NZ farming systems with a focus on field sensing (crop sensing and Electro Magnetic soil surveying) and spatial data management solutions. Agri Optics NZ is now recognised as New Zealand’s leading precision agriculture company. And are also coincidentally partners in the H2Grow crusade.

This post has been put together by Sarah Elliot (Lindsay NZ), and I would personally like to congratulate Craige for being recognised with this prestigious award - Congratulations!!

Managing Environmental Compliance with Precision VRI and EM Mapping

Farm Fast facts:

Farm Name: Seadown Dairies

Cows Milked: 620

Length of VRI Pivot: 565m

Production: 1705/ha, 278000 KgMS

Pasture Grown/Harvested: 17,000 KgDM /14,500 KgDM

Key Benefits from VRI system: Reduced track maintenance, reduced pugging damage less water wasted.

Sustainable farm management was a major driver behind Brendan Caird’s decision to install Lindsay Growsmart Precision VRI with FieldNET on his 565m pivot. A major feature of the farm is a spring fed stream that flows through the middle of the irrigated area of the property. Totalling an area of approximately 5 ha, the streams and springs add to the visual appearance of the property and have been fenced and planted into a riparian zone. However without VRI effective irrigation management would have been considerably more difficult. By installing the VRI system Brendan is now able to work around mother nature and reduce his farms overall impact on the environment.

Riparian Zone in the middle of the VRI Pivot

The costs of irrigating his races and tracks were also a big part of the equation.

“Stock flows better, track maintenance is reduced and water is not wasted on unproductive areas” says Brendan who uses VRI to improve the conditions on the farm races. Nearly 5Ha of the 93Ha irrigated area is able to be avoided which includes races and waterways which allows Brendan to utilise that saved water elsewhere.

With an allocation of only 3.2mm/ha/Day irrigation practices need to be as efficient as possible at Seadown Dairies to maximise water use for grass production. Brendan also finds benefit in the VRI system to help remove paddocks from the irrigation round that are set to be re-sown. In the case of the 2016 season Caird planted fodder beet and set an irrigation plan to avoid the paddock whilst it was being cultivated. You can see the effects of this below. The yellow is the paddock that was avoided. The pink is for zones that were a part of the avoid zones.

As Applied Irrigation for the season. Note the paddock in Yellow.

Agri Optics conducted an EM survey on the property and the major soil zones were able to be identified see (http://www.agrioptics.co.nz/portfolio/em-survey/ for more info). The next step that Brendan and his team are working on is to begin irrigating to the EM soil zone plan. With multiple soil management zones identified on the property the goal is to water according to the relative requirements of each soil zone. This is aided by soil moisture sensing equipment to give the exact time that irrigation is required. Further to this Brendan can also be sure that soils are not being overwatered and water is not being wasted which Brendan says helps make his farm environment plan more comprehensive.

Blog this week by Nick @ Agri Optics
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