Fields across Jersey have very different levels of soil health and yields, which this report attempts to make sense of. This year’s hemp crops in the tunnels and fields have taught us – when soil organic matter is 4% +, with a fungal : bacterial biomass of 1:1, hemp captures more photosynthesised carbon to build its biomass, resulting in improved yields.
When suitable levels of beneficial bacteria, protozoa and nematodes are present, hemp seems to have better resistance to pests and disease, (whitefly, caterpillar and aphid and even mould).
Soil Regeneration strategies that appeared to work best for hemp.
- Understanding soil health, through biological and soil organic matter analysis
- Apply biologically complete compost (if required) gets microbes back into the soil and F:B to 1:1
- If there is any soil biology, employ cultivation techniques that preserve it
- Coating the seed with beneficial microbes and humus prior to planting increases strike rate
- Planting a companion crop with the hemp provides nutrients and weed suppression
- Applying foliar feeds of beneficial microbes, seaweed with fulvic extracts, gives Hemp better resistance to caterpillars and mould.
- Beef cattle can be used to clean up the crop after harvest and before winter cover crop is planted, helps get nitrogen into the soil.
- No till drills or Air seeding do not work into a strong lay of rye grass.
- If cultivation is required to mechanically terminate the crop or prepare the soil surface for hemp, power rota tilling is preferential to breeze ploughing, which is preferential to deep ploughing as the best way to conserve the soil food web.
- Stick to the five soil health principles will regenerate fields the quickest.
Ongoing regeneration practices Five Soil Health principles.
- No ploughing or minimal ploughing when necessary.
Keep a living root in the ground all year to keep the soil food web alive and functioning.
- Integrate grazing animals where possible – the manure and tearing action of herbivore releases root exudates to feed the soil microorganisms.
- Manage the soil food web as you would manage above ground animals, give them shelter, food and water.
- Refrain, where possible, from using organic and inorganic pesticides, herbicides etc. – they are just as effective at killing pests as they are at killing beneficial microbes. Anything that compromises the soil food web, weakens hemps resistance to pests and disease, becoming a vicious (expensive) cycle to control.
Degenerative soil strategies.
- Ploughing – destroys soil health and burns off 50% of the soil carbon as CO2, reducing optimal soil organic matter levels of >5% The action also compounds deep compaction and raises naturally occurring salts to the surface creating surface compaction. Spreads weeds such as thistle.
- Chemical or biological salt based fertilisers compromise microbes and pollute the environment.
- Leaving a field bare/fallow compromises the remaining SFW.
Soil regenerative and pest management strategies for fields and poly tunnels.
- Maintaining a healthy soil food web with microbial top ups and a growing root at all times is easier than rebuilding soil health every year.
- Minimal or no tillage – provides home and sustenance for soil microbiome
- Suitable green manures, keep a living root in the soil at all times
- Apply cover crops, nutrient conserving crops and possible brake and smother crops as required.
Green manure crops refer specifically to cover crops grown to supply nitrogen and increase soil organic matter. Cover crops are usually grown to conserve topsoil, prevent erosion, improve soil structure, increase organic matter, and capture and hold nutrients during the non-growing season. Examples of green manure cover crops include:- clover, cereal rye, soybean, and alfalfa. As a complement to nitrogen from soil organic matter, a vigorous green manure cover crop may be the most economical organic source of additional early season nitrogen for hemp. In Jersey, green manures crops are beneficial because they grow though autumn, winter and early spring and can develop substantial bio mass to suppress weed emergence.
Green manure crops fall into several categories:-
- Nitrogen-fixing crops – leguminous crops planted to nitrogen enrich soils Examples include beans, vetches, clovers, peas, soybeans, lupins, and alfalfa. The cereal rye / vetch crop we have air seeded acts as a combined green manure / nitrogen fixing crop that should self-terminate in the summer. If not it can be crimper rolled or terminated by mob grazed cattle.
- Cover crops: these are crops sown to cover soils and prevent erosion. They include vetch, Sirius peas, oats, clovers, winter cereal rye, and lentils.
- Nutrient conserving crops: as the name suggests, they minimise nutrient leaching and add more nutrients into the soil. They include ryegrass, oil radish, buckwheat and red clover.
- Break crops: they are crops that interrupt the lifecycle of pests or diseases. They include alfalfa, mustard, brassica and cereal rye
- Smother crops: these are crops grown to outcompete weeds . They include cereal rye, buckwheat, yellow sweet clover and oil radish and hemp.