Autumn is a good time to assess the impact of the previous season on your soil and prepare it for the coming months.
Ballance Environmental Management Specialist Ian Power says because maintenance fertiliser rates on dairy farms are connected to milksolids production, the end of the season is a natural review point.
“Applying all or some of your maintenance fertiliser in autumn reduces your spring workload and prepares pasture and stock well for winter and the following season,” says Ian.
Product choice is particularly important in autumn. “Think about the potential for nutrient leaching over winter, as this affects the profitability of your fertiliser investment and may cause environmental problems.”
Phosphate, for example, moves slowly in the soil. Losses are related to erosion carrying soil into waterways or fertiliser drifting into them during application, rather than leaching. If these two factors are managed well, autumn application carries no additional risk, while giving phosphate time to get where it’s needed to support spring growth.
Sulphur and potassium are more prone to leaching. “Sulphate sulphur is inclined to leach on pumice, peat and poorly drained ash soils and on free-draining sedimentary soils if rainfall or irrigation is high,” advises Ian. “On these soils, using a product containing some elemental sulphur in autumn will deliver better results than one containing only sulphate sulphur.”
Potassium also leaches readily in most soils, especially over winter when rainfall, drainage and leaching are typically at their greatest. Soils with low cation exchange capacity also pose a risk.
For dairy farms, Pasturemag is a fertiliser that comes in a variety of formulations to achieve the benefits of autumn maintenance, while managing the risks. There are a number of options for potassium content and the peat and pumice formulations contain elemental sulphur, which will become slowly available to plants as it is converted to sulphate sulphur by soil bacteria.
Pasturemag has a couple of other bonuses for dairy farms. “Taking advantage of autumn growing conditions is good for your stock, pasture and feed budget,” says Ian. “Pasturemag contains nitrogen to help boost pasture covers. Even better, it’s in the form of SustaiN, which will help protect your nitrogen from ammonia volatilisation. People often associate this with warm, dry, windy conditions, but research has shown temperature is not the major factor. Rain following application is crucial. Urea needs five to 10 millimetres (mm) of rain within eight hours of application to minimise volatilisation losses. Autumn can definitely be fickle on the rain front.”
Magnesium is another strong point with Pasturemag. Low soil magnesium levels around calving can trigger grass staggers and milk fever. A typical application of Pasturemag meets normal magnesium maintenance requirements for most dairy operations, helping to prevent these problems. “In a high-production dairy operation it’s hard to meet magnesium demands through pasture alone, so you’ll still need to be vigilant,” warns Ian. “However, the more you deliver via pasture, the less you’ll have to supplement by dusting or drenching.”
Pasturemag’s convenient nutrient combination prevents any one nutrient limiting your farm’s potential. Its granular formula is easy to handle and can save on spreading costs, compared to other types of application.
For help with soil testing, nutrient budgets and product advice for autumn fertiliser application, talk to your local Fonterra Farm Source representative or Ballance Nutrient Specialist.
1 Black, AS, Sherlock, RR, Smith, NP, Cameron, KC, Goh, KM, (1985), Effects of form of nitrogen, season and urea application rate on ammonia volatilisation from pastures, NZ J. Ag. Res., 28: 469-74
Article supplied by Ballance Agri-Nutrients