Describe cultivations, to include single and double digging, rotary cultivation, forking, raking, consolidation; ‘no dig’ method; bed systems.
Addition of Organic and Inorganic Material (grit/sand/lime): Organic materials (Bulk Organic Matter): Farmyard manure (long for heavy soils/short for light soil) contains plant foods, becomes Humus. Good physical and chemical effect on the soil; generally acidifying. Garden compost: as above can be richer in plant foods; but unpredictable nutrient content. Leaf mould: good physical effect on the soil but limited/minimal plant foods. (See 2.2). Inorganic material: Grit and sand: addition of grit or course sand to heavier soils and digging in. Tends to improve surface penetration and surface drainage (but limited effect if the movement of water is impeded due pans or high water table); Lime: addition of lime to heavy soils to flocculate the colloids. Helps break down the soil (calcium carbonate/garden lime or calcium hydroxide/hydrated lime will alter the soil Ph, calcium sulphate Gypsum will not).
Mulch Avoid compaction
Breaks up the soil, aerating the soil, relieving compaction and improving drainage.
Allows perennial weeds to be dug out and annual weeds to be dug in.
On heavier soils allows for good weathering, breaking up clods overwinter.
Good way to incorporate manure, compost and green manures into the soil.
Bring soil pests to the surface for hand picking or the birds.
Enables varying depth of cultivation.
But it is time consuming and needs skill to do it neatly and not leave a lot of levelling to be done later.
Single digging, one spit deep, not breaking up the subsoil layer, any additions laid in the bottom of the trench. Topsoil layer dug over into the trench. Keep as level as possible.
Modern double digging, trench 2 spits wide, bottom forked over, additions forked into the bottom. Topsoil layer dug over into the trench. Keep as level as possible.
PREPARING A SEED BED
Traditional seed bed preparation: digging, weathering, cultivating to break up lumps/forking over, first raking to level, treading, second raking for final levelling and to raise a tilth, rake in a base dressing of fertiliser.
Use of a rotavator (once considered a surface cultivating machine but now often used to replace digging): Good for large areas to be cultivated quickly; Finer tilth can be produced; Annual weeds can be chopped up and buried. BUT Perennial weeds are chopped up/propagated and spread; Deep use difficult; Soil structure can be broken down too fine and lost by repeated mechanical action; Can be hard work. Hard to be sure of evenness across the site.
Use of a fork to turn over the topsoil, returning it inverted to the same place. Can be used as a form of cultivation on light sandy soils or to help break up soil previously dug and weathered.
lump of soil
Break down big clods with a hand cultivator/forking over;
Roughly rake level.
Break down big clods with a hand cultivator/forking over;
Roughly rake level.
Tilth Production (final stage of secondary soil cultivation): The production of a fine crumbly, friable textured surface layer of soil; Through repeated raking in two directions; Major stage of seed bed preparation; Final levelling if needed; with rake or board Apply base dressing of fertiliser; Rake in fertiliser.
Consolidation/gardener’s tread (using the heel of the boot or by shuffling and or by the use of the back of a rake) to re-establish the capillary action of the soil, remove air pockets;
To suit the use or the plant (Brussels sprouts like firm soil).
NO DIG GARDENING
Often as raised beds; Apart from the normal soil disturbance of sowing planting or harvesting, the soil is left and not dug in the normal way. Once created, bulky organic matter is shredded and applied to the surface as required in the normal way of the rotation. It is naturally drawn down into the soil by the action of worms. This allows for the soils’ fertility to build up as the soils’ bacteria are undisturbed and operate in the soil at their preferred level. Weed seeds are not brought to the surface to germinate.
Traditional allotment growing is based on single rows of crops at varying distances apart being grown across the area, using the gaps between the rows for access; The bed system separates the growing area into distinct beds, usually 1.2 - 1.5 m wide, middle can be reached from either side, with paths 38/45 cm between and crops being grown in blocks, where the rows are often much closer together as access is from the paths and not from between the plants; The beds can be temporarily marked out each season and the crops grown on flat beds, much as normal. Or permanent raised beds can be created, either by digging up into raised beds or creating a structure.
Bed systems allow for: More flexibility in planning (rotation by vegetable family type) Improved ease of access from the paths (even when the soil is wet) for weeding and harvesting; No soil compaction between plants – beds should never be stepped on; Manure/compost can be used only where crops are to be grown (good if in limited supply); Size of crop can be controlled by their spacing (more medium size vegetables can easily outweigh fewer but bigger vegetables).
(See raised beds for their extra advantages).
Limitations: Cost of building; Possible need for extra topsoil, if imported look out for the quality; Need for extra-irrigation as raised. Seep hose often used on surface in lines (coning effect); If raised by digging giving a domed surface – problems with irrigation and rain running off and uneven growth pattern; Possibly need for more planning.
Addition of organic and inorganic material (grit/sand, lime).
Avoidance and removal of compaction (pans and surface ‘after capping’; mulching, green manure, timing of cultivation, ‘sub-soiling’).
Growing a green manure crop; Protects soil structure; Absorbs plant foods from the soil; Chopped down and dug into the soil to break down, releasing the plant foods back to the soil and becoming BOM/humus in the soil; Usually a planned or catch crop to keep the soil covered; Involves work.
Quick mulches - Old compost, coarse compost, strawy manure -Can be intended to break down and become Humus over a season.
SLOW BREAKDOWN MULCH
Slow breakdown mulches, Bark, wood shaving, shredded paper, will break down slowly – several seasons but used mostly for annual weed control and prevention of capping of soils. As they break down they will use nitrogen in decay process so reduce fertility temporarily.
Pans – layers in the soil that impede the passage of water and the growth of roots: Cultivation/plough pan; Chemical/iron pan. If suspected do a pit test.
Plough pan can be avoided by ploughing or rotavating at different depths in the soil and cultivating when the soil is not too wet.
Pans are broken up by sub-soiling on a large scale or deep digging in the garden. Surface “after capping”: Surface: walking/working wet soil. If soil sticks to boots it is too wet to walk on/wait until dried out. If you have to go on the soil, use planks to walk on. (Correct timing of cultivations). After capping: Usually caused by heavy rain or irrigation that breaks down the surface tilth, then dries out quickly causing a crust to form. On seed beds this can stop seedlings breaking through to the surface. Avoid heavy irrigation of seed beds, in other situations mulching and green manuring can be used to protect the soil surface.
Usually caused by heavy rain or irrigation that breaks down the surface tilth, then dries out quickly causing a crust to form. On seed beds this can stop seedlings breaking through to the surface. Avoid heavy irrigation of seed beds, in other situations mulching and green manuring can be used to protect the soil surface
Managing soil water content: identify poor drainage (surface symptoms, soil colour, soil smell, indicator plants, surface run off);
Identify poor drainage: Surface symptoms – indicator plants (rushes, reeds, moss, buttercups, docks). Laying water. Yellow patches in crops/lawns; Pit test – high water table, soil smell (sour/metallic), soil colour (grey mottling/or rust patches); Obvious surface run off – paths/patio/bases of banks.
indicator plants (rushes, reeds, moss, buttercups, docks).
identify causes of excess water (compaction, run off e.g. patios, high water table);
Obvious surface run off – paths/patio/bases of banks.
identify appropriate ways of dealing with excess water (soakaway, french drain, raised bed, appropriate planting);
drain pipe filled with coarse rubble Y& surface replaced
French drain or interceptor drain: drainage trench filled with gravel to the surface, for rapid water entry. Ideal for edges of patios or base of banks. Collected water is piped away to a drainage system or soak away:
identify appropriate irrigation methods (watering can, hose, sprinkler, seep hose; time of day; depth of wetting).
ROSE (WATERING CAN)
Good for accurate watering: greenhouse/bowls/hanging baskets, but slow for big jobs.
hosepipe, spraying exquipment
Good for big areas of the same crop. Can be left working. Can use/waste a lot of water (cost of water/meter?). Can cause puddling and compaction in lower areas. Best for level sites.
Good for crops in lines. Water only goes on to the soil/not wasted.
Watering in the cool of the evening reduces the risk of leaf scorch, leaves the soil wet (field capacity), plants take up water over night but the stomata are closed so plants become turgid. Less water loss from the soil by evaporation.
DEPTH OF WETTING
It is easier to keep moist soil moist, rather than trying to get dry soil moist. When you do irrigate give enough water to do a good job of wetting the soil to a good depth. The heavier the soil type the better the water will spread sideways. Many books say apply an inch (2.5 cm) each watering. Crops vary in water needs. Some crops – Potatoes, need irrigation to increase of crop, Carrots need irrigation to increase root size Leafy salad crops need to grow fast to retain fresh texture and need regular watering. Maize is deep rooted and can survive some drought conditions.
NO DETAIL OF DRAINAGE AND IRRIGATION SYSTEMS ARE REQUIRED.
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