Pathfinder farmer finds confidence to

Pathfinder farmer finds confidence to cut back

South Canterbury arable farmer Andrew Darling says an on-farm trial where wheat yields were unchanged despite a significant drop in applied nitrogen rates has given him the confidence to continue to cut back.

WORDS AND IMAGES SUPPLIED BY HEATHER CHALMERS, FOUNDATION FOR ARABLE RESEARCH

Andrew says that he was looking to become more sustainable in terms of crop inputs even before the sharp rise in nitrogen fertiliser prices, which have at least doubled in the last two years. Nitrogen is now his single biggest cost. This led him to sign up as a Foundation for Arable Research Pathfinder farmer; growers who are ready to embrace new ideas and technologies and identify sustainable pathways for the rest of the sector. The Pathfinder initiative is part of FAR’s Growers Leading Change, which provides a farmer-led framework for arable farmers to develop, test and introduce new ideas, technologies and ways of working. Andrew and his wife Amy lease Poplar Grove Farm at Kingsdown, just south of Timaru, from his parents Warren and Joy Darling. Andrew is the fourth generation on the farm, made up of a 250ha home block and a 250ha leased neighbouring property. The mainly dryland rolling downs farm is fairly typical for an arable farm south of Timaru in the type of crops it grows. The biggest area is planted in feed wheat and feed barley. Sunflowers, which attracted numerous selfie takers when planted alongside the main road two years ago, are supplied to Rolleston-based Pure Oil, along with oil seed rape, for processing into high-value cooking oil. Turf ryegrass for seed and fava beans are also grown. The farm is all crop, with no livestock, as the heavy clay soils are not suitable for dairy grazing. In 2015, the farm attracted headlines when Warren Darling set a world record yield for barley of 13.8 tonnes/ha. The record was overtaken last year by a Lincolnshire grower in the United Kingdom, Tim Lamyman, with a yield of 14.2t/ha. The family has been unable to replicate the record yield since. “The year we tried, it happened to be a perfect year for growing feed barley. The recipe for growing a good crop hasn’t changed, but we have always been two

LEFT: Farmer Andrew Darling and his father Warren. Dual sensor cameras installed last season on the roof of their tractor automatically varies nitrogen application rates RIGHT: Pathfinder farmer Andrew Darling is using information from a hand-held leaf nitrogen measurement tool to help cut back applied nitrogen in his crops BELOW: South Canterbury arable farmer Andrew Darling; his family has been unable to replicate a 2015 world record feed barley yield

to three tonnes short of obtaining that record crop. Even though we set up crops for optimum yield there are always weather events such as hail, lack of sunshine or lack of rain.” This is leading Andrew to question their highcost, high-input cropping programme in favour of an approach which is less prescriptive, more responsive to the season and better utilises the soil nutrients and beneficial insects already available on the farm. “With a high-input programme, we are relying on a lot of chemicals that you can see are slowly getting banned around the world. We need to get more profitability out of what we are doing and maximise our inputs,” Andrew says. “We want to understand more about what we are doing. We also want to know how far we can go in reducing nitrogen applications without sacrificing yield, as yield is always key.” While the farm has a consistent soil type, soil testing showed that fertility levels were more variable than they realised. This led them to start 1ha grid soil sampling seven years ago, using this information and crop requirements to apply phosphate (P), potassium (K) and lime (for pH) at variable rates across paddocks. A quarter of the farm is tested every year. “Some areas of the farm haven’t had nutrients applied for seven years, as they have a sufficient base of fertility.” While there has not been an overall saving in phosphate and potassium so far, nutrients are being moved to where they are required to provide more even yields, although this is more difficult on a rolling downs farm compared to one on the plains, Andrew says. Nitrogen is also no longer being applied at a blanket rate. Dual sensor cameras installed last season on the roof of their tractor automatically varies nitrogen application rates depending on a crop’s density and greenness. The cameras are calibrated to the type of crop and growth stage. This, along with soil nitrogen testing reduced nitrogen applications by 15 per cent last year, compared to the blanket rate, with no impact on yields. The Darlings have invested in tools and technologies including a Yara N-tester, a hand-held leaf N measurement tool used to identify the N requirements of plants. This is used as a calibration tool for sensor cameras on their tractor. Andrew says he doesn’t just rely on the sensor reading, but also his “gut instinct” around how much to apply. He is working on overlaying his yield and nutrient maps for better decision making. The Darlings haven’t ploughed, or burnt any crop residue for 15 years, instead working to build soil organic matter and maximising the biology in the soil. Andrew also wants to learn more about the beneficial insects available on his farm to reduce reliance on foliar insecticides. Many of these measures, while saving costs, also have a flowon environmental benefit. For the 2020 harvest, the Darlings relied on the N-tester for applications on two replicated strips in a wheat crop, with the remainder of the paddock receiving a standard application. The crop yielded 12t/ha across the paddock, regardless of N application rate. Grain protein was also the same, despite 120kg of urea/ha less being applied in the trial area. The reduced rate areas used 16.5 units of N per tonne of yield compared with 21 units under a standard application. “That was a light bulb moment that we can cut back and since then the price of N has doubled.” Buoyed by the results, the Darlings have done the opposite this year. Instead of trialling 2ha, they have applied N under variable rates over the whole farm, apart from a few strips in wheat and barley given a standard blanket application as a comparison. FAR researchers, as well as other experts, will provide input and support for the Darlings’ Pathfinder project. FAR senior cereals researcher Jo Drummond, who is the key researcher for the project, says farmers and growers associate reduced N rates with reduced crop yields and profits, but it is possible to reduce N without reducing profit. It was a matter of keeping a crop green “enough” by understanding the supply and demand requirements, knowing what N was in the soil now and what would mineralise through the course of the season. Nitrogen fertiliser is the biggest on-farm cost, so it is important for growers to make sure it is being used in the most efficient way possible, she says. “It’s great to see Andrew and Amy using tools and technologies to really understand soil supply and crop uptake, which can provide opportunities to cut back on fertiliser use without compromising on yield and profitability. Likewise, understanding the population dynamics of beneficial predator and parasitoid species can reduce the need for foliar insecticides, not just on your own farm, but across a region.”