The ability of Golden Bay dolomite to flocculate heavy soils is well known. Flocculation is the technical term for the grouping together of small soil particles that provide space large enough for water to percolate through and air to enter as the soil drains.
The ability of air to move into the soil and gases to move out is every bit as important as the application of nutrients. In order for this interchange to happen to best effect soils must be able to withstand heavy treading over winter without becoming severely pugged or the surface sealed.
Graham Shepherd’s Visual Soil Assessment manual states that treading damage on compacted moist soil may reduce pasture production by up to 27%, with a reduction in growth of up to 45% where soils are badly pugged.
There is a difference between a little scuffing, or ‘hoof cultivation’, that repairs rapidly once stock are removed, and pugging. Stirring of the top soil by feet can be beneficial as it rapidly incorporates dung and dead plant matter speeding the formation of humus.
Pugging is not inevitable; we work with many farmers where even in very wet conditions cows create little damage. Animals know in advance of the onset of dirty weather and provided they have access to plenty of high energy fibrous feed they will fill up, turn with their tails into the weather and wait for it to pass before moving.
One common misapprehension is that pasture quantity and quality do not occur together, often expressed as “ I would love to grow better quality feed however I can’t afford to grow less.” Quantity and quality come in the same basket and the role of air in the soil in achieving optimum performance is often ignored.
Beneficial soil organisms require a steady supply of air for maximum activity and it is this activity that ensures a steady supply of nutrients, of which nitrogen is one, for plant uptake. Plant roots also require oxygen for growth with autumn and winter important times for root development. Poor root development over winter markedly reduces spring growth.
Presently poorly aerated and drained pastures or areas within properties are easily identified both by colour and length of leaf. In the wettest situations areas of pasture are more yellow than green with urine patches very obvious. Urine contains nitrogen and pastures on waterlogged soils respond dramatically however applying nitrogen fertiliser is not the answer.
With thousands of kilograms of nitrogen held in the top 25cm of each hectare of soil the key to making it plant available at any time, and particularly over winter and early spring, is increasing the quantity of air able to enter and leave the soil.
Management of stock over winter remains the most important aspect of a farms ability to grow winter and early spring feed.
With a winter application of Golden Bay Dolomite at 200 – 300kg/ha the physical structure of the soil can be enhanced as well as providing a steady supply of plant available calcium and magnesium over the critical lambing and calving time.