Category Archives: Monitoring

Pea Sampling

20140114 DripIrrigatedPeaCrop

Pre-harvest samples were taken from the four pea paddocks on 16 January. They show a wide range in crop maturity and yield expectations.

Four 1 m2 samples were taken in each half hectare paddock. We counted plants, weighed the fresh vine and took it to the McCain Foods mini viner and tenderometer for processing. Each sample was processed, peas weighed and TR tested.

Indicative tonnages averaged for each paddock range from 4.2 to 5.6 t/ha and tenderometer readings from 86 to 105. Within this, there is an even greater range reflecting the variability noted across the region. The lowest sample tonnage was 3 t/ha and the highest 6.8 t/ha. Notably, these were from the same paddock. The lowest TR readings were 78 and the highest 113.

Paddock 2 has buried drip irrigation. It has a much bigger canopy – 39 t/ha fresh weigh compared to the 26 t/ha average of the other paddocks. This paddock is slower maturing, still flowering where others stopped some time ago. While it has the lowest mean TR reading, it has about the average yield at present. If left to get to equivalent maturity, the yield could be close to the higher end of our four paddocks.

Summary of Pre-harvest Pea Sampling
Paddock Plants/m2 Fresh Vine t/ha Peas t/ha TR Irrigated Treated
1 69 29.6 5.57 105 No -
2 53 39.4 4.91 86 Drip Nodulator
5 79 24.9 5.06 94 No -
6 62 23.1 4.19 93 No Nodulator

 

Irrigation demand: alike as two peas?

Article first published in The GROWER, December 2013

We tracked water use since planting in the first two crops of peas at the MicroFarm. We want to learn as much as we can about our soil and irrigation.

HydroServices’ Melanie Smith, our specialist support for soil moisture monitoring, established three neutron probe access tubes in each of our first two crops. These were read weekly and analysed to give a Paddock soil moisture content down to 80 cm.

Both pea crops were planted on the same day with the same drill. One had some nitrogen starter-fertiliser because our discussion group wondered if it would make a difference, but that is another story. For now, we are talking irrigation management.

We saw significantly different patterns from our two crops. Significant in that considering the usual 30 cm root depth, one crop needed irrigating a week before the other. Significant in that one would get through to harvest at the start of December without needing to be irrigated. The other would need irrigation. What was going on?

Let’s look at two graphs: Paddock 3a and Paddock 4a which are the two crops in question.

HydroServices_Block 3_Peas_2013-11-25  HydroServices_Block 4_Peas_2013-11-25

The top parts of these graphs show soil water content in the top 30 cm. We see that in each case the Full Point (116 mm) and Refill Point (82 mm) is the same. So we have 34 mm of readily available water our plants can access from the first 30 cm depth of soil.

The graphs show Paddock 4 reached Refill Point a whole week before Paddock 3. In fact, Paddock 4 hit Refill Point almost three weeks before Paddock 3, and but for a chance 12 mm rainfall would have gone into critical deficit in early November.

Let’s compare these graphs a bit more closely.

We see they tracked about the same to start with, then at the beginning of November Paddock 4 suddenly used significantly more water from the 0 ‑ 30 cm root zone than did Paddock 3. This is around the time the canopies reached full ground cover.

Our observations of the crops suggest Paddock 3 had more canopy so we thought it would be using more water than Paddock 4. Looking at the lower parts of Graphs 3a and 4a, we see that Paddock 3 used more water from deeper in the profile at 40 – 50 cm.

We did some Visual Soil Assessments and found more evidence of soil compaction in Paddock 4. Being the main gate access into the area it has seen more tractors, trucks and paddock forklift activity. So we expected to see compaction limiting root development.

Now lets look at the water content in the whole soil profile, right down to 80 cm, presumably well past any pea roots (Figures Paddock 3b and Paddock 4b).

HydroServices_Paddock 3_Peas_0-80_2013-12-03   HydroServices_Paddock 4_Peas_0-80_2013-12-03

The first thing to notice is much higher water storage, because 80 cm of soil has more readily available water than 30 cm of soil. So now Full Point is 314  mm and Refill Point is 232 mm giving 82 mm of readily available water for our crop to grow before we would need to irrigate.

When we compare these two graphs we get a different picture. Now we see the two crops using similar amounts of water through until 14 November. After that, Paddock 3 (the fuller canopy and better soil condition) used slightly more water than Paddock 4, and actually hit Refill Point a day or so earlier.

Overall, it seems our Paddock 3 crop is getting more water from deeper in the profile, accessing water from 50 ‑ 80 cm deep.

For a lower price crop like peas, reducing costs makes a big difference. Can avoiding compaction save the need to irrigate? 

How deep are your crops’ roots?

Starter Nitrogen for Vining Peas

Purpose

One question raised in the MicroFarm Discussion Group was whether a starter fertiliser might enhance vining pea yields.

MicroFarm soil testing showed bckground fertility was good. So it was questionable whether to apply anything. Numerous Plant & Food Research and Foundation for Arable Research trials have demonstrated no economic response of seed peas to applied fertiliser. Would vining peas be any different?

Process

Mark Redshaw, our Ballance AgriNutrients Advisor, put a simple comparison together in Paddocks 3 and 4, both planted with the same Ashton variety on the same day.

Background soil fertility (0-15 cm) was measured before any fertiliser was applied. Available N was 121 in Paddock 3 and 82 kg N/ha in Paddock 4. Other key fertility indicators (pH, Olsen P, MAF K) were within optimum ranges suggested for peas in both paddocks. The only limiting factor was Sulphur. Sulphate levels ranged from 1-3mg/kg.

Treatments

At planting:

  • Paddock 3 received 100 kg/ha of PhasedN (25.3%N, 28.5%S and 5.7%Ca)
  • Paddock 4 received 100 kg/ha of Sulphur Gain Pure (95%S)

Soil conditions were not ideal with moisture levels quite high, and compromises being made around fertiliser rates due to size of paddocks.

The fertiliser was applied with the planter to avoid an extra pass- but separation of product and seed was compromised due to soil conditions. High slug numbers were noted.

NicolleGreatPlains

With the exception of fertiliser practice both paddocks were managed identically during the season. Neither paddock was irrigated.

Results

Paul Johnstone, a Plant & Food Research member of the Discussion Group, and colleagues observed the comparison, took measurements and analysed the data collected.

At maturity they harvested plants from three sample areas (each 0.75 m2) in each paddock. For each sample they:

  • Determined the plant population
  • Calculated total plant biomass and fresh yields
  • Calculated the key components of yield (number of pods per plant, number of peas per pod, and mean mass of individual peas)
  • Measured quality using TR score.

Observations

General

Visually, Paddock 4 appeared to have a weaker canopy throughout the season. Soil investigation also indicated the paddock had poorer soil structure related to historical compaction.

Plant population

Paddock 4 had more plants per m2 than Paddock 3 but there was little evidence to suggest this was related to the starter fertiliser. In both paddocks, plant populations were considerably lower than the planting target of 110 plants per m2.

Crop roots were not inspected for nitrogen fixation activity.

Yield and yield components

Overall fresh yields varied greatly, ranging from 7.8 to 13.8 t/ha across the individual samples. On average there were between 5-6 pods per plant, with each pod containing 6 peas averaging around 0.4 g per pea.

Starter fertiliser practice did not affect total plant biomass, fresh pea yield or the components of yield (pod number, pea number and mean pea mass) even when variable plant population was considered.

Maturity

TR scores were 120 in Paddock 3 and 126 in Paddock 4. These are higher than optimal for processing (usual target is 110-115) indicating that the crop was harvested a day or two late.

There was no effect of the different starter fertilisers on TR scores.

Bottom line

At this site there was no evidence of a yield or quality response to increased N supply at planting.

This was despite a visually weaker canopy where no N fertiliser was applied. The canopy weakness may have been related to soil compaction in the paddock rather than N deficiency.

Pre-trial soil available N measurements showed fertility was moderate in both paddocks. This might have masked any crop responses to the applied fertiliser treatment.

So this comparison supports research that, at least on moderately fertile paddocks, there is no benefit from applying starter fertiliser to vining peas.

Thanks to Ballance AgriNutrients, Hill Laboratories, Plant & Food Research, Nicolle Contracting and the Centre for Land and Water for their support with this MicroFarm study.

ballance_logo_100  HillLabs100  PlantandFoodweb100  nicolle_contracting_100  CLAW-light-100

 

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.

Programme

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.

SponsorsPanel

Growth Regulators – Gibberellic Acid

The first of the plant growth regulators was applied to the vining peas planted in September.

Peracto’s Tim Robinson applied two treatments at a rate of 200 L/ha on 17 October 2013.   The first treatment applied gibberellic acid at 8g/ha, the second at 16g/ha.

The peas were 10 – 15 cm tall. The air was 7oC, 73% RH and foliage had morning dew.

There are very visible growth differences where the gibberellic acid was applied.

20131022_PeasGA@16g

Top photo: Vining peas 5 days after gibberellic acid applied at 16g/ha. The treated plants are a rectangle 10m x 3mrunning along the drill rows from photo centre to top right. Treated plants are significantly taller, and yellower than untreated plants.

Bottom photo: Vining peas 12 days after gibberellic acid applied at 16g/ha. The plants are still a slightly different colour, still twice as tall as untreated plants. One treated plant is flowering – no untreated plants are flowering.

20131029_PeasGA@16g

Thanks to those supporting the Plant Growth Regulator work:

PGRSponsors

 

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.