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Nutrient removalPotashPotash removal is the other main factor which needs to be linked to soil analysis to determine correct fertiliser policy. Potash in grainPotassium content of grain is typically 0.5-0.6% K in dry matter for all cereals. This equates to around 5.6 kg of potash (K2O) per tonne of grain at 85% dry matter. Potash in strawThis is of increasing importance as more straw is baled because of the economic pressures caused by lower grain prices. Around 80 - 95% of the barley crop is baled and the reduction in numbers of mixed farms means that a far greater proportion is now sold off farms and not recycled through animals and manure. About half of the wheat crop is also baled and this could rise with developing opportunities for sale into industrial uses. Potash content in straw is much more variable than in grain and is different for winter and spring wheat and barley, and for oats, and is affected by growing conditions.
Phosphate removalPhosphate content of straw is very much lower than potash. Removal of straw thus has little effect upon Typical removal standards
On light soils, where it is more difficult to maintain potash at a satisfactory level, it is important for cereal growers to note that baling the straw from a typical 7 t/ha grain crop removes an extra 40-80 kg/ha of potash over and above that in the grain. This is worth around £8-16/ha.
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