Tag Archives: Soil fertility

HARDENING TRANSPLANTS – VEGETABLE GARDENING

Introduction
The transplanting process can be a shock to rapidly growing seedlings especially when set out into the cold windy garden in the spring. This is especially true for transplants started in the greenhouse, cold frame, hotbed or home. These young seedlings can be made somewhat resistant to heat, cold temperatures, drying and whipping winds, certain types of insect injury, injury from blowing sand and soil particles and low soil moisture by a process termed “hardening.”
The term “hardening” refers to any treatment that results in a firming or hardening of plant tissue. Such a treatment reduces the growth rate, thickens the cuticle and waxy layers, reduces the percentage of freezable water in the plant and often results in a pink color in stems, leaf veins and petioles. Such plants often have smaller and darker green leaves than non hardened plants. Hardening results in an increased level of carbohydrates in the plant permitting a more rapid root development than occurs in non hardened plants.
Cool-season flower and vegetable plants can develop hardiness allowing them to withstand subfreezing temperatures. Unhardened cabbage seedlings have been reported to be damaged by temperatures of -2 degrees C (28 degrees F) while hardened cabbage will tolerate temperatures as low as -6 degrees C (22 degrees F).
Warm-season types of plants even when hardened, will not withstand temperatures much below freezing. If transplanted to the garden or field prior to the average last killing spring frost, such plants should be provided protection by hot caps or other such devices.
Method
Any of the following can be used to harden transplants. A combination of all these techniques at one time is more effective.
1. Gradually reduce water – water lightly at less frequent intervals but do not allow the plants to wilt severely.
2. Expose plants to lower temperature than is reported as optimal for their growth. If biennials are exposed to cold for an extended period, they may bolt in lieu of developing properly. Note: Placing the plants outside during the day to encourage hardening and then bringing the plants back into the warm house during the night often reverses the hardening process. Plants could be placed in a cold frame or other area that does not freeze during the night hours without lose of the hardening process.
3. Do not fertilize, particularly with nitrogen immediately before or during the hardening process. A starter solution or liquid fertilizer could however be applied to the hardened transplants one or two days prior to transplanting into the garden or at the time of transplanting.
4. Gradually expose the plants to more sunlight. This results in the development of a thicker cuticle layer thereby reducing water loss.
Cautions
Hardening is not necessary for all transplants. We recommend that with the exception of tomatoes, plants that are susceptible to frost should not be hardened. Overly hardened plants while withstanding unfavorable outside conditions are slow to get started and may never overcome the stress placed on the plant during the hardening process. We also recommend that plants be hardened for no longer than seven to ten days before planting to the garden site.

CROP ROTATION AND SOIL FERTILITY

Crop rotation is “The practice of alternating the annual crops grown in a specific field in a planned pattern or sequence so that the crops of the same species or family are not grown repeatedly without interruption on the same field”.
-US National Organic Program definition-

OR leaving soil in the best position it can be for continuing/next crops – that includes cover crops, rotations, green manures, catch crops etc.

BENEFITS OF CROP ROTATION
Preventive Pest Management
Crop rotation may limit the growth of populations of agricultural pests including insects, nematodes, and diseases caused by bacteria, viruses, and fungi through regular interruption and replacing crop host species with different plant species that do not serve as hosts. The use of specific crop and cover crop rotations may also be used to control pests through allelopathy, an interference interaction in which a plant releases into the environment a compound that inhibits or stimulates the growth or development of other organisms.
Reduced Weed Competition
Carefully designed crop rotations may also serve to outcompete problematic weed species through shading, competition for nutrients and water, and/or allelopathy.
Distribution of Nutrient Demand Placed On Soil by Crops
Different crops place different nutrient demands on the soil.
Making Efficient Use of Nutrient Inputs
Cropping species that access nutrients from different depths within the soil horizon may make the most efficient use of nutrient inputs. Efficient use of agricultural nutrients may further prevent nutrient losses/leaching and associated environmental pollution.
Nitrogen Fixation
Annual cover crop rotations using nitrogen-fixing (legume) cover crops may contribute significant amounts of nitrogen to succeeding crops as well as adding organic matter to the soil.
Improving Soil Quality
Cover crop rotations allow soils to remain undisturbed for various periods of time during which the processes of soil aggregation can take place. The use of a perennial grass rotation lasting 6 months to one year or more may significantly contribute to organic matter accumulation, stimulate soil biological activity and diversity, and improve soil physical properties.
Increased Crop Yields
The rotation effect – Yield of crops grown in rotation are often higher than those grown in monocultures, even when both systems are supplied with abundant nutrients and water.
Growing a diversity of crops in a given year spreads out labour needs throughout a season. The diversity of crops reduces the economic risks caused by variations in climate and/or market conditions.
TEN BASIC PRACTICES OF CROP ROTATION
Rotate the location of annual crops each year. This is especially true for crops in the Solanaceae family (e.g., peppers, eggplants, tomatoes, potatoes, etc.). Do not follow one crop with a closely related crop species, as pests and diseases are shared by closely related crops. When growing a wide diversity of crops, attempt to group crops into blocks according to the following criteria:
(1) Plant family
(2) Similar timing/maturation periods
(3) Type of crop (i.e., root vs. fruit vs. leaf crop)
(4) Crops with similar cultural requirements (e.g., irrigation, plastic mulch, dry farmed, planted to moisture crops, etc.)
(5) Follow nitrogen-fixing cover crops and/or legume forage crops (e.g., clover, alfalfa) with heavyfeeding crops (e.g., corn) to take advantage of nitrogen supply.
(6) Follow long-term crop rotations (e.g., 1-year perennial rye rotation or pasture rotations) with disease-sensitive crops (e.g., strawberries).
(7) In diverse annual production systems, heavy-feeding crops (crops with high nutrient demands) should be followed by medium-light or shallow-rooted crops, followed by deep-rooted crops.
(8) Always grow some crops that will produce and leave a large amount of residue/biomass that can be incorporated into the soil to help maintain soil organic matter levels.
(9) Grow deep-rooted crops (e.g., sunflower, fava beans, etc.) that may access nutrients from lower soil horizons, alleviate soil compaction, and fracture sub-soil, thus promoting water infiltration and subsequent root penetration.
(10) Use crop sequences known to aid in controlling weeds.
(11) Use crop sequences known to promote healthy crop growth (e.g., corn followed by onions followed by Cole/Brassicaceae crops) and avoid cropping sequences known to promote pests and diseases (e.g., monocultures in general or peas followed by potatoes specifically).
In conclusion, crop rotation is primarily about a cultural system that is based on natural principles. It is about building a fertile living soil and an environment that supports the healthy growth of plants and natural biological control—a situation where synthetic pesticides and fertilizers are unnecessary and even counterproductive.
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