Agronomy

Hemp is an annual crop. Planted in late Spring when soil temperatures are warming up, it achieves a remarkable rate of growth often reaching a height in excess of 3 metres by August. Following harvest the crop is stored by the grower prior to delivery to our factory where the straw is processed and the outer fibres separated from the woody inner core. Until now the processing method required the hemp straw to be retted in the field (retting is the bacterial process that starts to break down the lignin and pectin that holds the fibres together) but the new factory can process unretted straw. This de-risks hemp growing as the time between cutting and baling can be much shorter and also considerably increases the yield potential as cutting can be delayed and field losses are much reduced. A cutting period of mid to late August will allow baling 2 to3 weeks later, so growers can expect to clear their fields by mid- September.

Previous Cropping

Hemp has an excellent role to play in a number of rotational situations with its twin advantages of late drilling window and good weed control. The two broad categories of use are : In a cereal rotation as an alternative to the main combinable break crops of rape & pulses. As a following crop to late cleared root & vegetables, where hemp gives time to prepare the ground rather than being forced to muddle in earlier drilled crops. Our latest sown crop in 2008 was drilled on 12 June and yielded 5.5T/ha.

Seed

The seed, about the size of a peppercorn, should be sown at a rate to achieve a plant population of approximately 150 stems per square metre. This is essential to produce thin stems and good quality fibre. Hemp seed is light & fragile and some air seeders can be very aggressive, damage can be avoided by slowing down fan speeds whilst still achieving good distribution.

Drilling

Hemp should be drilled after the risk of hard frosts has passed and when soil temperatures have reached 10°C plus. This can normally be expected from the third week of April onwards and crops have been drilled successfully up to the beginning of June. Leave a one metre gap round the headland, this will help with inspection of the crop and facilitates harvesting.

A successful hemp crop depends entirely on good establishment.

Like all small seeded spring crops it requires a well prepared and friable seedbed. Endeavour to conserve moisture and drill into moisture rather than into a dry seedbed in the hope that it will rain soon. On all but the lightest soils, land should be ploughed in the Autumn and left to overwinter. Emergence should occur 5-7 days after drilling. Crops that establish quickly and evenly will rapidly grow away from any pest and weed problems. In a dry spring careful attention must be given to moisture retention. Hemp will not penetrate through soils that are compacted or capped so drilling depth (normally 2-3cms) and soil conditions are critical.

Pigeons are a serious pest at the very early stage of plant growth. They must be kept off from drilling day until the plant is past the cotyledon stage and has the first two true leaves. This will occur in the space of 7 to 10 days.

Fertiliser

Nitrogen is a vital component of yield. Depending on soil indices we would recommend up to the following of phosphate and potash:

Heavy soils      112 N 60 P      120 K kg/hectare
Light soils        112 N 60 P      150 K kg/hectare

Hemp is not a greedy crop and returns a substantial quantity of nutrients to the soil. As Hemp thrives on organic matter there may be good opportunities both agronomic and financial to utilise farm yard manure or Sewage Biosolids as a source of nutrients. Because of the need to comply with the protocols and audit trails of our end fibre users and the UK environmental regulations, no applications should be made without prior approval by Hemp Technology .

We recommend checking the lime status and avoiding situations where pH is less than 6.5.

Harvest

There are two possible harvest routes, these are:

1. Hemp for straw - mown with specialised cutter & square baled or disc mown and round baled.
2. Dual hemp – both seed and straw are harvested.

Please discuss with us which is the right route for your farm.

1. HEMP FOR STRAW – SHORT CUT AND SQUARE BALED

Hemp Technology is encouraging the use of the proven forage harvester system. This is now our preferred method of harvesting.

If individual growers prefer we will accept crops cut with a disc mower but such crops must be round baled. While cutting costs will be cheaper and the cutting of the crop is in the control of the grower storage and transport costs will be higher.

Baling

Once the crop has dried and the majority of green has gone it is ready to be rowed up and baled. A Hemp Technology agronomist will give the final go ahead. Most large square balers should be suitable, take care with pressure settings as too high can cause problems for knotting mechanisms. Discussion with manufacturers can be helpful eg. Hesston balers can be fitted with deflectors which prevent straw getting into knotters.

2. DUAL HEMP FOR SEED AND STRAW

Dual hemp provides considerable opportunity for increased margins, but will delay harvesting until September and greater management input will be required to get the timing of the operations correct. Hemp seed will come off the combine at 16-18% moisture and needs to be dried to 8% moisture within 6 hours. Recent results have been excellent and the straw left after combining can then be cut with the new multi cutter and square baled (alternatively it can be mown and round baled.) Growers producing a dual crop must have a contract for both parts, if you would like to pursue this route please contact us for further details. Due to the extra management required for dual cropping we strongly recommend it be done in minimum blocks of 20 hectares.

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The remaining information applies to straw produced from all methods:

Storage

Bales should immediately be removed from the field and stored under cover. Stacking on pallets is recommended on anything other than good quality concrete floors as hemp straw is very absorbent. Please note that bales of hemp do not shed rainwater. Intake to the factory is a year round operation on a “just in time basis” and a monthly increment in the price is paid. Please alert the company if you have specific requirements for movement.

If growers are unable to store all of their crop it is intended to provide a storage facility; this will involve delivery direct from the field and a payment package to reflect the costs involved.

Haulage

Hemp Technology can usually recommend a specialist haulier but growers are welcome to find their own. Payment for straw is on a delivered factory price; some guidance on price is given in the appendix but each situation needs to be costed individually. All incoming loads must be booked in and must be sheeted if at risk of rain.

Straw Quality

The grower is responsible for delivery to the factory where every load is tested to ensure suitability for processing. We would encourage all growers to check their bales before despatch as rejected bales are a waste of expensive haulage and are subject to a disposal charge at the factory.

The main points to watch for are:

• Moisture Content – we aim for 16 % and can accept up to 18 % with deductions. This has proved very achievable over the years, but watch for wet patches when baling e.g. on headlands and ensure safe storage.
• Weed Content – a good stand of hemp will allow very little weed competition to survive but in conditions of poor establishment weed can be a problem. Please try to avoid baling any patches of weeds and do not send in weedy bales, as we cannot process them.
• Stones – These can cause damage in our factory, please tailor field operations to avoid baling up stones. Deductions will be made for stone contamination, in extreme cases there may be rejections.
• Plastic is, thankfully, not a common problem but one that causes major difficulties for our fibre customers. Please take care to ensure fields and particularly gateways are clear of all plastic and other detritus.

Following Crop

Hemp is an excellent break crop providing a good barrier to pests and diseases. It has been of particular use as a break crop in situations where resistant grass weeds are becoming a problem. Its deep roots are very beneficial for soil structure. The majority of our growers follow hemp with a different crop but some have repeated hemp for several years without any apparent difficulties. Where following Hemp with autumn cereals growers have successfully direct drilled with heavy cultivator drills. Slug activity after hemp is minimal compared with oil seed rape.