Crop desiccation is used as a pre-harvest herbicide and harvest aid on cereal crops including wheat and oats and on oil seed rape. As a systemic herbicide it is not a true desiccant as it can take weeks rather than days for the crop to die back after application. In the UK, it began to be applied to wheat crops in the 1980s to control perennial weeds such as common couch which was very effective and meant that sowing of the next crop could occur sooner. Use as a harvest aid in the UK increased after the introduction of strobilurin fungicides which
Crop rotation crop rotation comes from the interrelationship of nitrogen fixing-crops with nitrogen demanding crops. Legumes, like alfalfa and clover, collect available nitrogen from the soil in nodules on their root structure. When the plant is harvested, the biomass of uncollected roots breaks down, making the stored nitrogen available to future crops. Legumes are also a valued green manure: a crop that collects nutrients and fixes them at soil depths accessible to future crops. In addition, legumes have heavy tap roots that burrow deep into the ground, lifting soil for better tilth and absorption of water. Cereal and grasses are frequent cover