Lincoln Agritech has been awarded two Ministry of Primary Industries three-year Sustainable Farming Fund (SFF) contracts to: 1) investigate the use of catch crops to reduce nitrate leaching; and 2) assess the feasibility of using optical sensors for nitrogen fertilised dairy pastures.
Catch crops for reduced nitrate leaching is a project that continues Dr Peter Carey’s PhD studies at Lincoln University where he studied the use of catch crops to mitigate nitrate leaching under winter forage grazing. In autumn and winter, non-lactating dairy cows are eating large quantities of feed over a relatively short period of time to build up body condition and depositing large volumes of urine onto bare soil at a time when there is minimal plant growth. The conversion of the nitrogen (N) present in urine to soil mineral forms, such as nitrate, can lead to large N leaching losses (80-120 kg N/ha) through field drainage. Sowing a crop immediately following winter forage grazing, however, can be problematic, but hardy cereals (such as oats) can still establish in these cool conditions and once the soil warms, can rapidly mop up some of this soil-N, reducing the amount available for leaching. A number of lysimeter and field trials have shown that sowing a catch crop can reduce nitrate leaching losses by as much as 40%, as well as improving N-use efficiency and farmers’ profitability. The aim of the project is to upscale this applied research into working winter crop rotations in Canterbury and Southland and adapt it to the various soil and climatic conditions.
The catch crops SFF programme is supported by industry and leading dairy farm companies including: Plant and Food Research, Craigmore Farms, Dairy Holdings, Ballance Agri-Nutrients, Ravensdown, Agricom, Luisetti Seeds, DairyNZ, Foundation for Arable Research (FAR), South Island Dairy Development Centre (SIDDC), Irrigo Centre Ltd, and Lincoln University’s Centre for Soil and Environmental Research. Ultimately, success will be measured by establishing the practice of sowing winter catch crops as a normal part of winter forage management and demonstrating effective alternatives to farmers that lower nitrate leaching losses after winter forage grazing.
The second project, Optical sensors for N-fertilising dairy pastures, will assess using optical sensors for variable rate application (VRA) of N-fertilisers on dairy grazed pastures. New Zealand intensive dairy farming systems rely heavily on N-fertiliser to maintain pasture production. These fertilisers are often applied uniformly over the paddock - irrespective of the variability that might exist in the paddock. This results in poor use of N-fertilisers, with under or over application in some areas of the paddock, causing unfavourable economic and environment consequences, such as lost yield and nitrate leaching to the groundwater.
Optical sensing technologies are commonly used for assessing biomass and N-status in arable crops; however, these technologies are not used for monitoring pastures. Previous Lincoln Agritech research has demonstrated that using optical sensors for pasture systems can reduce N-fertiliser amount by up to 30% and nitrate leaching by up to 13%, whilst maintaining the same pasture yields. This project will assess and adapt current commercial sensor systems for VRA of N-fertiliser in pasture systems.
This research programme is supported by Stratford Farms in Temuka, Irrigo Centre Ltd, MHV Water, North Otago Irrigation Company, Advanced GPS Ag, Topcon, Ballance Agri-Nutrients, DairyNZ, AgResearch, and Plant and Food Research.
Image: Drilling the catch crop trial plots with a variety of oats, triticale, and Italian ryegrass at Craigmore Farming’s Te Awa farms in Te Pirita, Canterbury.