Category Archives: Monitoring

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.

Satellite Imagery

A large part of Heretaunga Plains horticulture was photographed for us by satellite at the end of November.

World View 2 satellite coverage of the Heretaunga Plains on 23 November 2105
World View 2 satellite coverage of the Heretaunga Plains on 23 November 2105

Part of our OnionsNZ Variability project, the World View 2 coverage targeted our crop and other onion crops east of Hastings.

By capturing four bands of light, Blue, Green, Red and Near Infrared, we are able to get a “normal” colour image like an aerial photo, and a biomass map using the NDVI index.

The satellite image pixel size in 0.5m x 0.5m, so we get at least two pixels across each onion bed.

World View 2 NDVI image captured 23 november 2015 of MicroFarm onion and vining pea crops
World View 2 NDVI image captured 23 November 2015 of MicroFarm onion and vining pea crops

In the NDVI image, the onion crop is lower left paddock, the vining peas upper right. Red areas indicate low or no biomass, yellow light, green moderate and blue heavy cover. Note however that the value of each colour is slightly different for each crop.

Because the pea canopy is full ground cover while the onions are only roughly half ground cover, we had to use different value bands to see variation within each crop. If we used the same range, either the peas would all be blue, or the onions mostly yellow and red.

The striping effect in the onions is the onion beds. Some adjacent beds have quite different canopy densities.  The red edge around the onions is bare soil and light canopy in the outer beds. The blue area in the centre is influenced by charcoal from an old bonfire site. Even taking these things into account, there is a reasonably large amount of variation in this crop.

Red spots in the pea crop are patches with no plants. The red headlands show light canopy areas and the red strip centre right the irrigator access track. There are three different seed lines of Ashton peas making up the pea crop. These are not discernable in the satellite image. The crop was harvested on 14 December, and there was no significant difference seen in hand harvested plots or in the viner.



Phosphate Starter Fertiliser for Onions?

Some growers have observed that adding phosphate fertiliser at planting time seems to improve the growth of onions, especially at early stages.

To test this, we’ve set up a small trial with our Ballance AgriNutrients partners. In each of 5 small plots, we placed the equivalent of 250 kg/ha of triple superphosphate 50 mm below and beside the onion seed.20150814_170007_P-Trial_640

We’ll track development of the plants in the treated plots and in corresponding neighbouring plots to see if there is a significant difference.

Why five plots?

Having replicated plots means we can better understand if any differences are “real” or “due to chance”.  We know there is always variation in any paddock in any crop, so how can we tell if our treatment (added P) caused any difference we see?

In crude terms: If the difference between our “Plus-P” plots and our “No-P” plots is greater than the difference between the different “Plus-P” plots, we can assume the difference is real.

Generally four replicated plots would be OK for a first look at something like this. It lets us run an ANOVA test to check statistical differences. We put five plots in, partly to cover the chance of one being damaged by field operations including turning our irrigator.

Check out the LandWISE/FAR “On-Farm Trial Guide” series for explanations and templates if you want to do a trial that you can really learn from. It includes a downloadable spreadsheet that will do your ANOVA stats and interpret the result for you.

Thanks Ballance  Ballance web150

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.

Spring at the MicroFarm

Two thirds of the way through spring our micropaddocks are approaching full canopy. Onions that progressed so slowly over winter are growing rapidly and peas planted in September are well established. A key question now is when to irrigate.

ThinkWater installed flushing sub-mains in our drip irrigation block and that system is all primed. We expect to run the dripline every couple of days, applying 10mm of irrigation.

Ritchie from ThinkWater finishing the flushing valve installation on the buried-drip in paddock 2
Ritchie from ThinkWater finishing the flushing valve installation on the buried-drip in paddock 2

With wheels and a sprinkler package from WaterForce, our Drumpeel linear irrigator is finished, fully commissioned  and tested and has completed its first lap of the MicroFarm.

Drumpeel Linear irrigating our onions
Drumpeel Linear irrigating our onions


Thanks to a radiometer from Steve Green and anemometer from Plant and Food Research we have a full set of climate readings on-site. HortPlus use the radiation and wind speed together with temperature and humidity to produce PET readings so we can track water use as well as rainfall. See details here>

We complement the climate data with soil moisture monitoring. Our weather station has an Aquaflex sensor which is tracking dryland pasture soil water content.

We need to adjust PET to our crops’ individual ET values. This means reducing potential pasture water use to a partial crop cover water use. The crop factor is a combination of crop type, ground cover and soil surface evaporation and prior to canopy closure most growers will be making best estimates. We have been working with a developer on a simple sensor to help assess groundcover. Figure 2 shows sensor images and percentage of ground cover (green) in two areas of peas.

So what is the actual soil moisture in the different paddocks? HydroServices installed neutron probe tubes into our crops and gives weekly status reports. The neutron probe data is collected as a number of depths through the profile, so it also helps determine active root depth. We just got to trigger point in before 18mm of rain fell. A week later we got another 8mm to top things up.

This spring we also tried Cosio® cover cloth on the onions and the peas. We were a bit late getting the covers and so didn’t get all the information or benefits we hoped for. We covered the onions at early two leaf stage and left them on for several weeks. In that time they caused some plant form disturbance and the more horizontal leaves did appear to get some chemical burn. Next time the covers will be on much earlier, possibly from planting, and off at two leaf stage.

We also covered the peas. This was in part due to frustration of pigeons consuming vast quantities of seed then later nipping the shoot tips of the survivors. More shotguns earlier next season! Although there was likely some seed loss before we got the covers on, we did see significantly more growth in the covered areas. When we first took the covers off, our ground cover sensor suggested as much as 50% more under the covers. The plants were notably taller and visibly covered more ground. Weeks later there is still a significant difference.

Vining peas after three weeks covering by Cosio cloth
Vining peas that were covered by Cosio cloth for three weeks showed 15% more ground cover

Once again though, the pea crops have high variability, both population count and plant size. When we harvest a whole crop in a matter of hours, being days apart in maturity is not acceptable.

The MicroFarm discussion group determined to put strong focus on preparation and planting next time. Peas can be a profitable crop, especially in combination with a second crop such as sweetcorn or beans. But if we don’t get even germination, even development and higher yields, it can be a great disappointment. We think growers should pay attention to this crop, aim to do well from it, and avoid temptations to do everything as cheaply as possible.

Crop covers laid on onions and peas

Following the lead of Dr Charles Merfield at the BHU Future Farming Centre at Lincoln, we’ve laid some trial crop covers at the MicroFarm.

Crop covers laid over onions and peas at the MicroFarm
Crop covers laid over onions and peas at the MicroFarm

Merf first used the covers in an attempt to control the Tomato Potato Psyllid on biologically grown potatoes. His first season trial showed unexpected benefits including greatly reduced potato blight. You can view Merf discussing the trials on Rural Delivery here>

Scott Lawson has been using the covers at True Earth Organics in Hawke’s Bay. His observations are of significant benefit on a number of crops. He bought cloth to cover potatoes, a crop he struggled to produce one TPP arrived. After potatoes, the cloth was going back in the shed but instead he put it on to other crops and has seen benefits in those as well.

We have placed 6 x 8m covers on our onions in Paddocks 1 & 2. We also put covers on to our peas crops, largely to gauge the effect of pigeon attacks at germination.

Green Beans Planted

MicroFarm Paddocks 1, 2, 5 and 6 have been planted in Green Beans, destined for McCain Foods in Hastings.


These paddocks were previously in vining peas, and issues with compaction and paddock humps were noted. See the post, Removing Compaction for more details.

A number of different options are being observed, including:

  • row spacing
  • plant population
  • varieties
  • fertiliser programme
  • herbicide strategy
  • drip irrigation dryland
  • and hopefully spray irrigation

Row spacing

At the instigation of Gary Cutts of Tasman Harvesting, responsible for harvesting the beans in Hawke’s Bay, Paddock 1 has been planted with a 15″  (381mm) row spacing. This compares to the standard 20″ (508mm) spacing in the other three paddocks. (Originally beans here were planted on 30″ (762mm)rows.)

Gary has noted that in lighter canopies planted on wider spaced rows, some beans get lost at the edges of the harvest swath. He believes we should try the closer spacing which is common in Europe.

Others in the MicroFarm discussion group has raised the potential increase in disease risk with a more closed canopy, so this will be monitored with interest.

Getting the beans planted at the narrow spacing was a challenge as the Monosem NG plus 4 planter being used would not close up enough. The units are capable, but the current toolbar arrangement with wheels in the way is not.

Instead, Patrick and the Nicolle Contracting staff used their John Deere 8-row MaxEmerge XP planter set on 30″ spacing, and simply moved the whole machine across 15″ to do intermendiate rows. This resulted in some planted rows being driven over – the group decided that was an acceptable limitation for a first look.

Preparing the JD MaxEmerge for 15″ row planting

Rain after planting may have aided emergence even in these rows although it may be delayed and less successful.

Tough bean seedlings emerging through wheel track

Plant Population

Ben Watson of McCain Foods is leading a plant population comparison in Paddock 6. Here four different plant desities are being tried, all on the standard 30″ (762mm) row spacing planted with the Monosem planter.

Population/ha                           In-row spacing

  1. 377,358 (standard)            5.3 cm
  2. 363,636                               5.5 cm
  3. 333,333                               6.0 cm
  4. 307,692                               6.5 cm
Bean planting P6 Airey 4 web
Planting the population trial with Nicolle Contracting Monosem

Fertiliser Programme

Ballance AgriNutrients’ Mark Redshaw developed a fertiliser programme based on soil test results and crop requirements. Paddocks 1, 2 and 6 each received 250 kg/ha Mila complex at planting.

As an alternative, Paddock 5 received no nitrogen at planting. The southern half received a double rate of phosphorous, and the northern half received no phosphorous.

Herbicide Programmes

The northern half of Paddock 2 and southern half of Paddock 5 (both nearest the centre access track) are receiving an alternative herbicide programme. The rest is being treated with a relatively standard approach.

Standard Programme                             Alternative Programme

Pre Emerge                                              
600 mL/ha Frontier                                  No product applied
500 mL/ha Magister

Cotyledon Stage
No product applied                                 1.5 L/ha Bentazone

2 Trifoliates
3 L/ha Bentazone                                    3 L/ha Bentazone

BASF supplied Bentazone and Frontier. FruitFed Supplies sourced Magister for us.

All herbicides are being applied by Haydn Greville Groundspraying

Soil Moisture Monitoring

HydroServices installed neutron probe access tubes in Paddock 2 (dripline) and Paddock 5 on 14 February.

20140214_neutronprobeinstal 20140214_neutronprobe

Results from soil moisture monitoring are posted on the Irrigation Monitoring page.

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.