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Since the advent of granulated fertiliser, seed and fertiliser have been sown together in combination drills. But as acreage and machine output increased, the practicalities of sowing fertiliser and seed together has become an issue. As a result, the popularity of combination drills has decreased and the jobs of spreading fertiliser and sowing seeds are usually two separate tasks.
But is this the right approach from a farming perspective? Tipperary-based agronomist and input supplier Tom Butler doesn’t think so.
Young seeds and seedlings have a very high requirement for phosphorus and Tom thinks that the closer the seed is to the source of phosphorus, the higher the chances are of that seed germinating, growing and developing into a viable tiller.
“Just because a soil sample says a field is at phosphorus index 3, it doesn’t mean that it is. A lack of seed-to-soil contact is probably costing an index. Phosphorus clings to soil, but dead roots and thrash reduce the seed’s contact with soil. There is evidence too that glyphosate ties up nutrients, all of which reduces the seedling’s ability to get enough phosphorus,” Tom says.
For almost a decade, Tom has been involved in the liquid fertiliser business, manufacturing and spreading liquid fertilisers for tillage and grassland farmers from his base in Templetuohy, on the Tipperary, Laois and Kilkenny border.
Knowing the science behind crop establishment, Tom has been tinkering with a way of getting fertiliser in contact with seeds at sowing. Initially, he focused on cereals, but buoyed by the better results when sowing seed and fertiliser together in tillage crops, and the higher yields, he has now moved into grass seeds.
Last year, he purchased a new Aitchison seed drill for sowing grass seeds. A liquid fertiliser tank is mounted on the tractor’s front linkage and the fertiliser is piped to the back of the tractor and pumped out through little outlets on the coulters where the seeds drops into the soil.
The tractor travels at 4.5mph. Because the coulters on the Aitchison are placed a bit further apart at 15cm, Tom prefers to go over the field twice, sowing at a 30° angle on the second run.
“The best results are achieved when the field has been sprayed off and cut for silage or grazed tight.
“At least 1.5t/acre of lime should be spread to help break down the thrash. It works best if the field is rolled between the first and second sowing, as it helps to prevent clods forming.”
The liquid fertiliser goes out at a rate of 300kg/ha, equivalent to 24 units/acre of nitrogen and 16 units/acre of phosphorus. Manganese and zinc are also included. Potassium is not included, but Tom says it isn’t important for germination, but does need to be broadcast after germination.
Cost-wise, the liquid fertiliser works out at €55/acre and Tom is charging €60/acre for sowing, which includes the fertiliser application. This does not include the cost of potash fertiliser.
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