Category Archives: Soils

Soil Moisture Monitoring


HydroServices continues to monitor our crops weekly using neutron probes to assess soil moisture status.

We use their measurements and reports to plan our irrigations.  We also consider predicted weather using MetService, and HortPlus services. But we don’t always get it right.

For example, on 3rd November we irrigated our onion crop, aiming to get the irrigator around to the peas for the following day. At the time we were told of a 10% chance of significant rain. After filling our profile, we got a lot of rain and most was effectively wasted. You can see that in the HydroServices report here>.

Since November we’ve pretty much kept within the target range of full point to stress point with 15-18 mm irrigation events.

We are finding that 15-18 mm is around the most we want to apply for efficient irrigation. If we apply larger amounts we get surface run off to low spots. While we can prepare a budget that says we applied it, we are not able to account for the full amount in soil moisture readings.

Surface ponding onions
Surface ponding in onions crop following 20 mm irrigation application

The low spots in our onion paddock are easily seen in this image. We could help drainage from the wheel tracks by furrow dyking to hold water where it falls, and by ripping a slot to allow drainage through the compacted track. But we also observe increased run off from the beds to the wheel tracks when heavy applications are made.

In field crops such as vining peas and process sweetcorn we also see lower application efficiencies if we attempt deeper irrigation events. So it is not just wheel track compaction that is involved. We think our soil’s infiltration rate slows significantly once it gets wet. It just won’t let the extra soak in fast enough.

Monitoring variability in soil moisture

We are familiar with soil moisture changing over time, and aware that there are differences between different soils and different crops. But what about variation within a crop on the same relatively similar soil?  Is any soil the same?

The MicroFarm is collaborating with Wintec Research & Development to investigate using cost effective sensor technologies to monitor soil moisture at a large number of points in a paddock.

Installing Sensor Array
Gert Hattingh from WINTEC Research & Development installing wireless sensor node at the MicroFarm


In our first trial on a sweetcorn crop, we established an array of sensors connected wirelessly and to the cloud. At each of nine positions, three sensors measure soil moisture at 10cm, 30cm and 50cm depth.

At three positions the sensors are running in parallel with HydroServices neutron probe measurement sites. This provides in-situ calibration and enable us to compare the moisture patterns of the new sensors against the industry “gold standard”.

View the neutron probe data here>

WINTEC has developed ways to present the data on-line and allow it to be queried. We look forward to seeing our soil moisture in near real time, viewable by soil depth at various positions across the crop. We will be focusing on improving our understanding to better manage and operate our Drumpeel Farms linear move irrigator.

Monitoring Variability in Peas

Peas are one crop that has huge variation. It’s hard to know if the crop will yield four tonnes per hectare or twelve. Even within small sampling plots we measured yields less than 4 t/ha and greater than 13 t/ha.

Our peas were planted into wet soil and had cold weather afterwards. Then they were savaged by pigeons. So right from the start there was variation. There were bald patches, slow germinating plants and plants with growing tips nipped out.

Counting the number of peas in 1m2 to assess paddock population. Repeating measurements shows variability.
Counting the number of peas in 1m2 to assess paddock population. Comparing repeated measurements allows statistical variability to be calculated.

We put some cover cloth over plants and observed different growth. After three weeks we removed the covers and could see difference. We got a sensor that measures ground cover and compared covered and uncovered areas. There was as much as 50% difference with covered plants much bigger. We think some of the difference is pigeon related. But maybe the covers also have other effects.

After crop cover was removed, greater growth and fuller ground cover was obvious
After crop cover was removed, greater growth and fuller ground cover was obvious

We visited a number of pea crops in Central Hawke’s Bay. We saw the same variability in young crops and old. The rate of maturation is critical for vining peas as they have to peak the day (hour?) they are harvested. We’ve identified condensed flowering as a target for pea crops. We want flowering to start and stop in a short period, and pods to fill evenly to be similar maturity for harvest. In variable paddocks (uneven soils, dry areas) flowering can start and finish at different times. A long period means later pods will still be filling while the first are already getting past their prime.

This crop shows areas of delayed and advanced flowering. All is to be harvested at the same time so some will be ready and some not.
This crop shows areas of delayed and advanced flowering. All is to be harvested at the same time so some will be ready and some not.

We had cool conditions at the MicroFarm and think this extended the flowering period. We could see pods filling while new flowers were starting to bloom.

Variation occurs on a single plant when long flowering times see pods filling while new flowers are opening.
Variation occurs on a single plant when long flowering times see pods filling while new flowers are opening.

The variability is a problem at harvest. Setting beater speed is a difficult task when the TR range is wide; hard enough to get tougher pods open yet soft enough to save the tenderest young peas. The problem is very obvious then, but it started long ago.

Peas taken and hand sorted from a single sample from the harvester - those on the left are mature, those on the right too young and damaged.
Peas taken and hand sorted from a single sample from the harvester – those on the left are mature, those on the right too young and damaged.

Monitoring Variability in Onions

Our first MicroFarm onion crop is extremely variable. The view below was taken from on the linear move irrigator, a useful vantage point

Variability is obvious when viewed from the irrigator
Variability is obvious when viewed from the irrigator

We want to measure variability so we can better assess it. If we can measure objectively we can make better decisions. We are interested in spatial variability and temporal variability.

The image above shows spatial variability: some parts of the paddock are better than others. We want to understand why some plants have done quite well, while others have done very poorly. If we can identify patterns, it can help us identify causes.

There are two patterns showing up in the image. There seems to be a large area where growth is poor. Perhaps that is a lower, wetter area? We can also see that every third bed is stronger than those on either side. That pattern is quite strong across the whole paddock and matches planting pattern from our three bed planter.

We wanted to map our crop so we could look for more patterns. We took a GPS connected sensor that measures the amount of ground cover and went up and down the beds.

Ground cover map of MicroFarm onion crop from data collected in early December

In the image above, the sensor data is displayed as a colour scheme. Green is highest ground cover (the biggest plants and most continuous planting). Red is lowest ground cover (small plants or larger gaps between plants or both). We used a cheaper GPS without correction so our bed readings have strayed off line. But even still, we can see the same pattern as in the photo above.

Will this pattern reappear in future years? Temporal variability seeks to understand how crop performance changes from year to year. If we can identify “always high”, “always low” and “sometimes high/sometimes low” areas we can develop management strategies to suit. Sensor based mapping is one of the best ways to identify such zones.

Autumn Open Day

Website Open Day StripThe LandWISE MicroFarm held its second Open Day in April 2014. The two crops for discussion were sweet corn and green beans.

MicroFarm IrrigationWeb

Green beans are a relatively new crop here, and questions over best management remain. The MicroFarm Discussion Group selected a few options this season.  Some may require following up with more investigations.

Plant arrangement and population

Tasman Harvesters Director, Gary Cutts returned from a trip to Europe where he saw most green beans are planted on 15” or 381mm rows. Gary was very keen to try the narrower row spacing. He has noticed smaller canopy crops that do not fully fill the allocated row space are difficult to harvest well.

This season we have planted one MicroFarm paddock at 15” or 381mm spacing, increasing the in-row spacing to keep the population near the norm.  At half the usual spacing for crops such as process sweetcorn or maize, fitting tyres into the mix is a challenge.

McCain Foods Field Officer, Ben Watson was interested to know what plant population might be optimal. He set up four rates from 300,000 to 370,000 plants per hectare.


Ballance AgriNutrients’ Mark Redshaw has used double rate phosphorous in one half and no phosphorous in the other. Other nutrients are the same, at rates determined following soil testing at Hill Laboratories.

Herbicide strategy

Scott Marillier and Vaughan Redshaw at Fruitfed Supplies selected a standard herbicide programme for most of the area. Haydn of Greville Groundspraying applied 600mL/ha BASF Frontier and 500mL/ha Magister as a pre-emergent spray. This was followed by 3L/ha BASF Basagran (Bentazone) at two trifoliates.

In two half paddocks, they left out the pre-emergent, and applied 1.5 L/ha Basagran (bentazone) at cotyledon stage, then 3 L/ha at 2 trifoliates.


By the end of February the buried drip installed by ThinkWater had applied four 10mm irrigations. That was enough to keep just above stress point. In early March the crop justified 10mm applications every two days. We are seeing some bypass as the deeper soil shows increasing moisture. The outside rows planted are outside the area irrigated with drip. The differences are very evident.

HydroServices’ soil moisture monitoring showed the un-irrigated paddocks were stressed from early on. Funding constraints have prevented us getting the dream irrigation system so we started using our mini-gun, applying 35mm at the end of February.  While adequate on pasture, it is not ideal for crops.

Irrigation has continued with a second round in early March applying another 35mm. Windy conditions at the start of the month affected application patterns, and some days we did not bother irrigating at all. View the edges of the paddocks to see the difference!

The Netafim dripline extends under the first part of the sweetcorn in paddock 3. Again, the difference between irrigated and unirrigated is extremely obvious.

More information on the main LandWISE website

Many thanks to:

Centre for Land and Water, ThinkWater, Netafim, HydroServices, McCain Foods,
Ballance AgriNutrients, BASF Crop Protection, FruitFed Supplies, Agronica NZ,
Nicolle Contracting, Te Mata Contractors, Drumpeel Farms, Greville Ground Spraying,
True Earth Organics, Tasman Harvesting, Plant & Food Research and Peracto Research for support with this work.

Foundation MicroFarm Sponsors

Ballance web150  BASF web  CLAW-light-150

Sweetcorn Planted

MicroFarm paddocks 3 and 4 were planted in sweetcorn on 18 December 2014. This is destined for McCain Foods in Hastings.

Following harvest of vining peas, the paddock was sprayed off with glyphosate by Hayden Greville Groundspraying. Key weeds were Indian Doab (Cynodon dactylon) but others including Bindweed (Convolvulus arvensis?) and the usual Heretaunga Plains crop weeds were noted.

The paddocks were strip-tilled by Drumpeel Farms on 13 December using the 12 row Orthman strip-tiller.


A video of Hugh Ritchie with the machine was made by James Powrie of Eco-Eye with funding from and the Queensland Department of Agriculture, Fisheries and Forestry.

The sweetcorn was planted on 18 December by Nicolle Contracting using their John Deere 8-row MaxEmerge XP planter.

WP_20140131_016 web

On 9 January 2014, evidence of Cutworm and Argentine Stem borer justified Haydn Greville Groundspraying applying Agronica Alpha Scud (Alpha Cypermethrin) at 200mL/ha in 300-600L of water.

Fertiliser application plans were  Mark Redshaw. At planting Paddock 3 received 150 kg/ha DAP/PhasedN supplied by Ballance AgriNutrients. It was sidedressed between rain showers with 200 kg/ha of Sustain on 1 February 2014.

The Paddock 4 sweetcorn received 250 kg/ha Cropzeal 20N at planting. This was supplemented on 1 February 2014 with a side dressing between rain showers of 200kg/ha urea supplied by Ballance AgriNutrients.

Soil moisture monitoring by HydroServices has shown the crop reaching deficit levels. With no irrigation option for these blocks, we were to some extent saved by regular rainfall but are actively seeking a suitable irrigation option. Monitoring data are posted in Irrigation Monitoring.

Spot spraying with Agronica Leopard  to control remaining spots of Indian Doab was started on 4 February

Estimated harvest date is early April, before the frost.

Removing compaction

After seven years of pasture, the legacy of compaction from orcharding remains.

We have ripped the whole area several times to a depth of about 300 – 350mm, but excavations continued to show signs of compaction related drainage issues. The compaction plaguing us is deep, sitting between about 400mm and 500mm.

With the sub-soil reasonably dry after the late pea crop was harvested, we took the opportunity to start addressing the compaction by deep ripping. Using Scott Lawson’s narrow tines, Stu Mawley and staff spent serious hours busting the hard layer. Shear-bolts happily gave way keeping tractor speed to about 1.7 km/h; not fast. While the narrow tines help avoid bringing sub-soil up, we still found some big lumps.


Compacted soil lifted by deep ripper – lump has been shaved and cut by spade, revealing soil mottling

We think some of the hardest lumps are from areas where the old orchard trees were burnt. We’ve seen that the heat from the big fires can “fuse” the soil, but didn’t expect it would remain significant after seven years and a number of cultivations.

Paddocks 1, 5 and 6 were cross ripped twice, first to about 500mm and then to about 650-700mm depth. With the tines at 762mm centres, we were able to rip between the buried drip irrigation laterals (but only parallel with them of course!).

A couple of days after ripping, Stu levelled the paddock with a hoe and roller. The intent was to shift soil to remove the corrugations from orchard rows so the bean harvester can pick up the crop. The second benefit was a traditionally prepared seed bed, ready for Patrick Nicolle to plant beans for McCain Foods.

Hoe and roll

Stu Train doing final levelling pass after ripping and before planting

Many thanks to Te Mata Contractors Stu Mawley and drivers Leroy and Stu Train for tractors and work time. And thanks True Earth Organics Scott and Vicky Lawson for the rippers.

TeMataContractors125  TrueEarth100

Open Day

The first MicroFarm Open Day was held on Thursday 5th December. The event received significant media coverage, including a two page spread in Rural News.

We are grateful for the excellent presentations made by our speakers, and for the quality of discussion that followed. Attendees travelled from South Canterbury, Manawatu and Gisborne to join local growers, contractors and their support industry colleagues.

Sarah Pethybridge’s presentation on Plant Growth Regulators helped understand this complex topic. The first demonstration results were being assessed, samples having been harvested the day before.


Short “theory” presentations in the Green Shed

  1. Why a MicroFarm; what we expect to learn – Dan Bloomer, LandWISE (and others)
  2. Soil nutrient picture; what we found, what we’ve done – Mark Redshaw, Ballance AgriNutrients
  3. Inoculants for legumes; our first trial and hopes – Weston Hazelwood, BASF Crop Protection
  4. Plant Growth Regulators; compressing pea flowering – Sarah Pethybridge, Plant & Food Research
  5. What the MicroFarm still needs – Dan Bloomer, LandWISE

Outside practical demos and discussions

  1. Buried drip for vegetables – Anthony Waites, ThinkWater
  2. Soil moisture monitoring; water use messages – Melanie Smith, HydroServices
  3. Soil compaction; penetrometers, VSA and a plan – James Powrie, Hawke’s Bay Regional Council
  4. Herbicide selection – Vaughan Redshaw, Fruitfed Supplies
  5. Plant Growth Regulator treatments; a first scoping study – Tim Robinson, Peracto

Download a printable pdf Open Day Programme here

The MicroFarm is a genuine community activity, as shown by the sponsors and supporters listed below. We are unsure of all the outcomes, but we know there will be much learning along the way.


Visual Soil Assessments completed

To establish a base-line soil quality Mark Redshaw took soil samples in winter for testing by Hill Laboratories. These showed generally good fertility.

At the end of September, Dan Bloomer (LandWISE) and James Powrie (HBRC) completed Visual Soil Assessments. We took the samples on Tuesday before a significant rain event and stored them in the shed until Friday when we had time to assess them. The soil was relatively wet, possibly influencing the scores.

We used Graham Shepherd’s VSA methodology to assess structure, porosity, colour, mottling, worms and clod development. We did not detect tillage pans in the field when taking the sample spits, and erosion is not an issue at our site. You can down load more from the main LandWISE website. More on assessing soil condition here, and a VSA summary sheet here>

Five of the six micro-paddocks showed good physical condition. Block 4 was notably poorer with clear evidence of compaction from vehicle traffic. This is perhaps unsurprising, as the Block is the first inside the gate through which all tractors and trucks enter the fields.

Images of the six Block samples and another sample taken under the fence line are shown in this picture gallery.