“Massive turnaround” due to precison ag

Adam invested about 3,000 Australian dollar in the trial. “Which I got more than returned on saving on fertiliser”, he explains. “But the trial was more about growth and getting that right. And our cellery crop on the site went from 70% being excellent to 98% being excellent. It gave us a significantly better yield.”

Precision agriculture in celery, leek and some cover crops

Over two years Australian vegetable growing operation Schreurs & Sons and a team of the Soil Wealth ICP (Integrated Crop Protection) have partnered to use precision agriculture in celery, leek and some cover crops. The demonstration site of 24 acres (9.71 hectare) is located at Adam Schreurs’ Cora Lynn farm, about 80 km south-east of Melbourne, Victoria.

During the trial, Adam and the team have aimed to improve nutrition, irrigation and drainage management and focussed on insect pest and beneficial monitoring as a basis for soil and crop health.

A range of technology was used, including EM38 mapping, gridded soil sampling, variable rate fertiliser spreading, remote monitoring of insect pests and beneficial identification traps with cameras, as well as drones.

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Having a more uniform size of celery, Schreurs & Sons lifted its yield. – Photo: Soil Wealth and ICP project

High-quality cash crop

Adam, who is the field director at Schreurs & Sons, explains there was a lot of variability in nutrition across the demonstration field. “Before we started with precision agriculture, we had patches that were quite poor and some deficient areas.”

An important aim of the trial was to achieve a more consistent and high-quality cash crop through more precise application of nutrients – where the soil and crop needed it. Variable rate application allowed fertiliser to be applied at different rates depending on the changes in soil chemistry across the block.

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Adam Schreurs: “Before we started with precision agriculture, we had patches that were quite poor and some deficient areas.”- Photo: Schreurs & Sons

Results after variable rate application

Large areas of the trial site have improved uniformity of nutrient availability due to the gridded soil sampling and variable rate fertiliser spreading. Gridded soil sampling results show that large areas of the trial site showed the following after variable rate application:

• Improved from lower pH (5.2-5.7 [CaCl2]) to higher (5.8-6.3)
• More consistent Potassium (K) (100-249mg/kg)
• More consistent Phosphorus (P) (71-430mg/kg)
• More consistent Magnesium (Mg) (200-399mg/kg)
• Lower average Sodium (Na) (50-99mg/kg) down from 100-199mg/kg
• Huge difference in inputs

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The paddock had been farmed on for 100 years and as long as Adam remembers, there had been great variability. – Photo: Soil Wealth and ICP project

Change in application rates for most inputs

The spreader maps of the case study show a change in application rates for most inputs, with a shift to more consistency over time and less variability in minimum and maximum across the trial site. SOP (sulfate of potash) rates varied from 0-500kg/ha in the first year (total amount of 2,061kg) with a high degree of variability in the north. This narrowed to range between 250-700kg/ha in the second year (total amount of 1,163kg).

Lime rates varied from 0 kg/ha in areas where there was optimal pH to over 11 kg/ha in problematic spots in the north of the block in 2018. Lime was not applied in 2019 to those areas that received higher rates of lime in 2018, indicating some problem areas had been ameliorated.

However, there were also areas that did not receive lime in 2018 that received higher rates in 2019 to manage the slight decrease in pH. There was a huge difference in inputs – and costs – for a relatively small block for farmer Adam Schreurs.

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The team at the trial farm more actively used and calibrated a remote monitoring insect trap. – Photo: Soil Wealth and ICP project

Improvements in soil constraints

In addition, there have been improvements in soil constraints such as soil texture, salinity and water held in the soil profile, as measured by the EM38 mapping. Soil that historically caused reduced yields due to waterlogging or other soil structure problems like compaction, performed well.

There was also a reduced soilborne disease risk on the trail site. The most significant reductions were in Pythium spp. (to moderate levels) and Rhizoctonia spp, both important and potentially destructive pathogens of celery. This may be due to the precision agriculture activities at the trial site as well as other factors such as soil moisture, temperature and variation in planting times.

Early detection of relative pest pressure

More precise nutrition and drainage management corresponded to improvements and consistency in the celery nutrient uptake during the summer growing season. A comparison of field (Horiba hand-held meters) and lab (Hortus) sap testing showed the value in faster in-field monitoring across a number of sample points in the trial area.

Good correlation was found between field and lab testing with Ca, Na and K with some disparity in N. Most of the key elements were within the ideal plant tissue ranges from early maturity, late maturity and at harvest, with the exception of the N lab test.

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A weather station on the demo site. – Photo: Soil Wealth and ICP project

Remote monitoring insect trap

The team at the trial farm more actively used and calibrated a remote monitoring insect trap with the assistance of IPM Technologies. One of the benefits of the remote monitoring was the early detection of relative pest pressure and indication of the reliability of flights (timing and duration), which has been changing in the region over the years.

This provided time saving as well as piece of mind knowing there was a ‘backup’ system in place. However, it was important to have conventional scouting to correctly identify pest species and inform control options at the farm.

More uniform than the other sites of the farm

And perhaps most importantly the crops in the second year were the best quality Adam Schreurs has had. “Even though there was still so much variation in crop growth and head weight from row to row and across the farm, the harvest from the demo site in 2020 was so uniform”, Adam says. “It was really noticeable when it was coming off the block. It was a fantastic result – it beat the best crop of the farm.”

We‘ve gone from an underperforming site to a site that is more uniform than the other sites of the farm

The paddock had been farmed on for 100 years and as long as Adam remembers, there had been great variability. “We always had issues. We did go out and hand sampled the soil in areas that were poorer but we never solved those variable spots. It was quite amazing to see how we were able to bring that into line. We‘ve gone from an underperforming site to a site that is more uniform than the other sites of the farm.”

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There was much less variability in the celery crop. – Photo: Soil Wealth and ICP project

Easier grading and packing of celery

The results meant easier grading and packing of celery by staff and ability to supply customers with a product that better met their specifications. “But having a more uniform size, we lifted our yield overall as well”, Adam points out. “Crop uniformity means there are no smaller products that are going to a lower priced market.”

Adam now wants to take things even further, he says. “I would like to do the sampling even in smaller areas on the demo site to get even more uniformity. And for the rest of our property I will get the grid sampling done across the board. There’s certainly lots of things I have learned along the way. All the used technology has delivered a good demo of what can be used in the field and what we can get out of it.”

Schreurs & Sons specialises in growing celery, leek and baby spinach. The farm now covers 100 acres (40.5 hectare).