After the harvest ends, the hardest work for a grower begins. This includes not only harvesting the bountiful fruits of your labor of love and removing, cleaning and storing seeds from your many progeny, but also preparing your garden patch for the next growing season.
This is strenuous work and involves a strong back and unyielding determination to improve your garden soil. Patch preparation for the next growing season should begin as soon as the harvest begins.
The most important of these chores involves soil preparation. Incorporating large amounts of organic matter into the garden greatly enables the grower’s chances for larger yields. Boosting organic matter levels beyond 6% will satisfy the growth requirements of most plants. It is not uncommon that well-worked plots often achieve organic matter levels greater than 10%.
Healthy, fertile soil is an organic mixture of decaying plant materials and water, air and mineral nutrients. Organic matter consists of decomposing plant and animal material.
One of the best ways to improve soil fertility is to add reams of decaying plants. Building organic matter is a slow process. Native soils in many regions, including most of North America, are composed of only 3 to 5% organic matter, while some growers strive to maintain levels approaching 10% or more.
The yearly battle to supplement and then replenish the soil's organic matter is a never-ending chore. Bacteria and microbes continuously consume these materials in a cycle referred to as the soil food web. Organic matter added to the soil raises the soil's cation exchange capacity (CEC) or simply its nutrient-holding capacity.
This factor, along with organic matter's ability to hold more water and oxygen, greatly profits the soil and can tremendously boost yields. Helping poor soils, either sandy or clay-based, by increasing organic matter improves the soil by providing a naturally enhanced supply of nutrients in an easy-to-open storage can.
Tilth or bulk density is also assisted by changing the soil's structure. Organic matter binds or clusters the soil together making it easy to dig. This factor along with the organic matter's ability to hold more water and oxygen greatly increases the soil's fertility.
Begin any preparations by taking soil samples and determining a base line for future reference. The importance of a soil test cannot be understated. While organic matter can be added at any time, you need to know the current standing of your soil. This helps to determine if any additions are required to lend a helping hand in modifying the soil's many nutrient components. Discerning the soil's current levels of organic matter and its CEC helps determine what is needed.
Next, the soil's pH level is determined, then the major nutrients nitrogen (N), phosphorous (P) and potassium (K), then the macronutrients of calcium and magnesium, and finally, the minor nutrients such as iron and manganese.
Vegetables grow best in a pH range from 6.5 to 7.2 with 6.8 thought to be optimal for most. Any discussion about soil nutrient levels is complex. Recommendations listed in your lab report will provide a good base of support. Many growers tend to push soils that are high in NPK.
Calcium (Ca) is considered a major nutrient when growing most fruit and vegetables. Plants use Ca in late summer as the fruit begins to expand and develop. Maximizing its uptake during this time can greatly reduce the incidence of blossom end rot, splitting and pitted or catfacing of fruit. A soil supplemented with Ca often requires additions of gypsum or calcium magnesium sulphate. It is important to note that many local conditions will leave soil deficient in Ca despite high ppm levels overall. This is often caused by insoluble calcium bicarbonate molecules tying up the vital macronutrients, rendering it useless to the plant's roots.
Working in a minimum of four inches or more of well-rotted organic matter will compensate you with big dividends. Materials such as grass clippings, leaves, yard waste and compost are the most readily available supplements for urban and rural growers. Other manures can be added as well. Cow, chicken, horse, sheep and rabbit manures are some of the most popular choices.
Fresh sources of manures should be avoided until harmful nitrogen is consumed by bacteria or leached out. Instead use older manures as they are usually free of most weed seeds and contain less ammonium nitrate. Fresh, ripe manures cause wild top growth and poor fruit set.
An application of these types of organic matter into the top 18 to 24 in. of your soil is most advantageous for many reasons. Chiefly, the new additions are able to lift the soil's organic matter percentage and raise its nutrient-holding capacity while increasing the oxygen content and the water holding potential of your soil.
Many organic manufactured products are now available and are of great advantage to many small plot and indoor growers. Products such as organic fertilizers and pelletized composts are great ways to encourage healthy garden and greenhouse practices.
Other more common bagged supplements include kelp meal, alfalfa meal and corn meal. Kelp and alfalfa meal add natural rooting hormones. Corn meal aids in disease fighting capabilities. All three add some nitrogen as well.
Humic acid is another great way to improve the soil's CEC. In sandy soils, it can quickly and permanently raise the CEC. Humic acid is a natural by-product of thousands of years of organic matter decay. The result is a blackened, porous structure that lasts a lifetime in the soil. The porosity of the HA particles brings with it a great chelating or holding power for nutrients, water and oxygen.
Other popular products used to enhance soil are perlite, vermiculite and peat moss. All work in similar ways to augment the top soil.
Jersey greensand is another supplemental product. Considered a soil conditioner, it will raise the calcium levels of soil and it can permanently raise CEC while adding some minor amounts of potassium to the top soil.
Other more common soil supplements include sulphur (S), gypsum, lime, or dolomite limestone and magnesium (Mg) sulphate or epsom salts.
Important tips on adjusting pH
- Sulphur is used to lower pH slowly as bacteria break it down, releasing acids
- Aluminum sulphate dramatically and instantly lowers pH
- Gypsum is used to maintain pH, adds Ca and S and improves tilth
- Lime (calcium carbonate) raises pH and adds calcium
- Dolomite limestone raises pH and adds Ca and Mg
- Magnesium Sulphate adds Mg and S while lowering pH moderately
Adding new biomass to the soil is a natural off-season step that is becoming more common. Certain grasses, grains and legumes are used in gardening to gain an advantage on Mother Nature. Cover crops begin to get the mixture working prior to planting.
They protect the soil from wind and water erosion while conserving moisture and preventing weed germination. The organic matter contribution is an added benefit to the soil as certain types of crops can extract nutrients from the soil and leave them in readily available forms for quick uptake by the plants once they are ploughed back into the soil.
Some types of cover crops pull nitrogen from the air (fix nitrogen), while others consume nitrogen. The fixers help put atmospheric nitrogen back into the soil while the consumers conserve and prevent leaching of the elements to the surrounding watershed. When roto-tilled back into the soil they give back the nitrogen.
Good cover crops for a fall planting include winter wheat, winter rye and oats. They are fast growing and relatively easy to roto-till. They do not fix nitrogen but they are fast growing and add organic matter quickly. These essential crops can be sown during most times of the year. They can store large amounts of nitrogen from the soil for use in the next growing season.
Broad leaf crops like buckwheat and sudan, martin or sorghum grasses are best planted in spring or early to mid-summer. If you have an open area during August due to lost plants or early harvest, it might be a good idea to get buckwheat or one of the others up and growing. The benefits are rapid growth and phosphorus fixation from the soil. Frost intolerance makes this a good rotational crop when combined with tilled early spring legume crops that fix nitrogen.
Many growers are taking advantage of phosphorus fixation by planting buckwheat after the last frost and ploughing it down before planting vine growth crops such as cucumbers and melons. Legume crops like vetch and clover fix nitrogen but generally require a spring or summer planting.
Bacteria and fungi
Beneficial bacteria, fungi, earthworms and a host of other organisms thrive on the addition of organic matter and the fresh carbon it brings along for the ride. Healthy garden patches depend on good microbial activity to provide a constant and steady supply of nutrients to vigorous plants with burgeoning root systems.
The microbes feed on the tasty morsels you add in the form of organic matter and begin to leave behind nutrients in the soil that can be quickly absorbed by the plant's developing root system. It is also important to feed the bacteria with sugars. High fructose products are best and include molasses, corn syrup and maple syrup. Bacteria will thrive when fed often with these sugary blends.
Inoculation of cover crop roots at planting with beneficial endo-fungi and bacteria like nitrogen-fixing azospirillium are considered to be of major importance. Deep rooting sudan grasses are thought to allow for overwintering of fungal spores. Flourishing resident populations of bacteria and fungi results in time and money savings while reducing the need to re-inoculation crops with costly new inoculants.
There you have it, basic soil preparation in a nutshell. Treat the soil with kindness and a jungle-like green canopy will be the reward for your efforts. As the shoots begin to poke into the shimmering sunshine, it is important to remember the beginning of the next season starts at the end of each prior growing season. Well-balanced soil is the key component in growing for maximum yields.
Soil preparations always start with hard work and determination to improve the garden's production. Building your soil is a continuing process that never ends. Organic matter is consumed at a fast pace during the growing season.
Annual replenishment is required to unlock the right combination of desire and skill involved increasing your harvest. Consider the information above as your future guide to a great garden, and always remember that the green is keen, but it's what's underneath that makes a difference because bigger roots mean bigger fruits.