A field day showcasing the Dairying Better ‘n Better program’s on-farm fertigation trial was held last week at Harrisville, presenting preliminary findings of the project to those who attended. The trial is currently in its second and final year, with fertigation being compared to traditional broadcast fertiliser application in ryegrass pasture under centre pivot irrigation.
Approximately 20 dairy farmers and industry representatives attended the day, and they were provided with the preliminary facts and figures of the second year of the trial. Jackpot ryegrass was planted in 2018. Nitrogen is the only nutrient being applied through the fertigation system, with one quarter of the pivot area being fertilised using Easy N liquid fertiliser, and one quarter fertilised via broadcast urea for a comparison. Pasture dry matter yields are being taken before and after grazing, and fertiliser and irrigation events are being recorded. Pasture samples have been taken for analysis. Results so far this season indicate the fertigation quarter slightly ahead on pasture growth and utilisation.
Farmers also heard from Noel Matthews, Regional Business Manager from Incitec Pivot. Noel reminded farmers of the nitrogen cycle, and discussed the many ways that nitrogen can potentially be lost in the system. Options such as fertigation and coated urea can reduce nitrogen losses provided application is managed accordingly. For example, Easy N needs to be applied to the soil surface otherwise the urea component will volatilise into the atmosphere.
Pat Daley, from Daley’s Water Service reiterated the message of the importance of irrigation scheduling to avoid over or under watering. A farm walk generated discussion about grazing pressure and the challenge of balancing grazing utlisation with intensive feeding of high producing cows.
Benefits of the fertigation system include labour and fuel savings, which then lead to cost savings on repairs and maintenance of machinery. The liquid fertiliser is immediately available to the plants and can be distributed more evenly (provided the irrigation system has an even distribution uniformity) compared with granular fertilisers. Applying smaller amounts more often enables a more optimum growth rate, and liquid fertilisers aren’t as volatile, reducing potential losses to the atmosphere. Final project results will be available following the completion of the 29018 ryegrass season.