CHRIS Martin of Agrovista focused on soil health, while Simon Brown of Amazone presented the results of precision sowing trials on oilseed rape and wheat at an open day at Brian Robinson Machinery near Northallerton last month.

The ‘over-cultivation’ of UK soils for the past five decades and beyond could be remedied using a variety of techniques and achieving the correct pH was one significant factor that was often overlooked, said Mr Martin.

“The pH level has a knock-on effect on almost every aspect of soil health,” he stressed. “For example, nitrogen mineralisation requires the activity of specific microbes, whose efficacy peaks at a pH of 6.5-7.

“However, it is estimated that about 40 per cent of soil samples show a pH below the optimum level. Money that is spent on fertiliser will be wasted unless the soil pH is balanced. Both phosphate and potash, for example, are prone to lock-up and will be unavailable to the growing plant. A liming rotation with the aim of achieving a soil pH of 6.7 will produce an average optimum result of 6.5 across the whole farm.”

Soils in North Yorkshire were typically high in magnesium and this could lead to a ‘tight’ structure that was prone to swelling and cracking and difficult to manage. He suggested that an application of gypsum (calcium sulphate) would have a remedial effect.

“Calcium sulphate will react with the soil and improve its friability,” he said. “Nevertheless, standard gypsum is highly insoluble and it is difficult to produce an even spread. There is a new product that contains gypsum in a liquid, soluble form and this could offer an alternative.

“I would also strongly recommend the tissue testing of the leaves during the growing period, to check for any magnesium deficiency. This advice includes land which is high in magnesium, due to the potential for lack of availability. Our research indicates that demand in young plants is relatively low and increases at the onset of the flag leaf stage, but the standard guidelines lack this level of detail,” he said.

Manganese was another key nutrient and he suggested application as a seed treatment, while molybdenum was required in very small quantities but could have a negative effect on yields where it was lacking.

“Over the past five decades we have over-cultivated our soils and yields have levelled off, despite genetic advances in plant breeding,” said Mr Martin. “Organic matter also plays a very important role in soil health and slurry and digestate are two of the best options, as they have a low carbon to nitrogen ratio. We must also tackle soil erosion, because our topsoil is being washed away into water courses and that is not good for farming, or for the environment.”

Mr Brown said a precision sowing trial oilseed rape produced a respectable yield of 5.1 tonnes/ha, which was achieved by aiming for a low plant population through 50cms row spacings and with 5cms between each seed.

“We know that a low plant population will optimise yields, but in a season where germination rates are poor this policy can cause problems,” said Mr Brown. “Precision planting allows each seed to become embedded in the soil in a way that cannot be matched by standard sowing techniques and a DAP fertiliser was applied down the spout. These results were encouraging.”

The winter wheat was precision-sown at 80 seeds per square metre, with 25cms rows. This system reduced yields by an average four per cent, but a financial benefit was gained through the saving on seed costs, he reported.

“It showed the potential for almost doubling seed head numbers and bushel weights were higher, with no noticeable increase in weed infestation.

“The low seed rate reduced seed inputs, but the low row numbers meant that the overall yield recorded showed a slight deficit, compared with the control plots.

“Wheat drilled in this way could be weeded mechanically and this method is being given more consideration in the current climate, due to the spotlight on chemicals and their effect on the environment.

“It is also forecast that seed prices are set to increase, so the cost advantage of precision sowing wheat might look even more attractive in the future.”

Mr Brown also covered the latest thinking on straw incorporation, commenting that moving from a cultivation depth of 10cms to 15cms would increase diesel consumption by ten litres/ha.

He pointed out that using the correct combine header settings and ensuring that straw chopper knife settings were sharpened before application were crucial to the successful incorporation.

Meanwhile, decisions on whether to use tines or discs for minimum tillage techniques would depend on the target operation depth.

“A rigid tine set-up will not permit the machine to follow the land contours and is usually only suitable for deeper cultivation techniques.

“A set of discs will work at shallower depths and will follow the land contours. It will also give even depth control, even at working widths of up to 12 metres,” said Mr Brown.