Harvesting and storage

Intro

The first thing you will have to remember, is that hemp is a multi-purpose crop. Which means that different parts of the crop are harvested depending on the variety of hemp that is planted. For example, when harvesting for grain, the shortest varieties of the hemp plant are used reaching from 0.9 to 2.7m tall, whereas hemp varieties used for fibre grow can grow upwards of 3.0m. These different varieties need different harvesting techniques both for characteristical differences and for the different products that are harvested from the plant.

Sometimes hemp is planted for both grain and fibres but this can cause problems when one product is all ready mature when the other is not, it also lowers the total production of either seed and fibres. On the other hand it can spreads the risk as there two products that can be used, so in the case of a strong frost that destroys the seed, the fibres could still be used and sold.

Harvesting and storage of  hemp seed
Hemp seed does not reach its maturity stage uniformly. between plants and even on the same plant seeds can differ in ripeness. So when determining maturity, farmers needs to determine the optimum seed yield (minimal loss). In Canada, the harvest of hemp seed takes place between 100-120 days after seeding, (agric.gov) this takes place in the beginning of October. By then the male plants have all ready died off and the flowers of the female plants have shed.

For the harvesting of hemp seed, a combine tractor is used. When harvesting, the mostly used technique is straight combining, the headers is aimed at the top third part of the plant to minimise the amount of plant material going through the machine. As you can see in the picture, on the top of the plant contains plant material, the rest is just stalk. When the plant goes through the combine, the seed is separated and stored, the rest is filtered out and put back on the field in case it is not used for fibres.

Withing 3-4 hours after harvest, the seeds needs to be aerated to ensure optimum quality. If the seeds gets heated up there is a chance that is starts to oxidise which result in loss of quality. (agric.gov) The optimal moisture content for hemp seed is between 8-9 percent. For the storage of the seed there are a few options available:
- Hopper bins
- Flat metal bins
- Mini bulk bags

In all cases, the seed must be well aerated and rotated when seasons change to prevent the build up of moisture.

Hemp fibres
At the moment, there is not a lot of fibre production from hemp in Canada. Experiments are being done and commercial options are being considered but until now there is not big commercial production yet.

Sources:
http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/crop15539/$file/HempHarvestStorage.pdf?OpenElement
http://innvista.com/health/foods/hemp/harvesting-hemp/