Soil
Marijuana Horticulture
by Jorge Cervantes
Soil is one of three main types and all shades of gray and brown in between. Soil is the product of millions of years of geology.
Clay soil, also known as “heavy soil” or “adobe” in North America, is common in coastal areas and is very widespread inland. It is difficult to work with.
Clay soils hold water well and provide slow, even drainage. Clay soils are slow to warm in the spring, but hold warmth well into autumn when sunlight is fading. The density of clay does not allow for proper air circulation, and root growth is inhibited.
Prepare cay soil at least a month before planting, adding lots of compost and manure. Clay soils can hold water too well, which can smother roots. Adding organic matter will lighten the heavy soil, thus creating air pockets, improving drainage, and promoting root growth.
The month delay gives the manure a chance to col so it wont burn the plants.
Use low sodium manure that contains few salts. Cows are given sodium nitrate to make them gain weight, but that same salt in their manure can lock up nutrients available to the plants, stunting their growth.
Do not be fooled by anyone who suggests adding sand to break up clay soil. Sand and clay create cement; add straw to make bricks!
One gardener had a backhoe operator excavate a pit 10 feet square by 2 feet deep, built a 2-foot retaining wall around it, then filled it will 400 cubic yards of river loam. This expensive, laborious soil transformation paid off in one outstanding crop after another over years.
A long term option is to annually till in compost, manure, and other organic amendments.
Raised beds are an excellent option for clay soil. Till the clay when it is damp and workable, and add manure / compost in heaps; plant directly in the mounds.
Pile subsoil in a ring around the plant, making a bowl to catch rain water.
Sandy soil is found near large bodies of water, in deserts, and in many inland areas. It is comprised of small, medium, and large particles and is easy to till even when wet. Plants can achieve excellent root penetration. Sandy soil feels and looks gritty.
Sand is easy to work and warms quickly in the spring, but it does not hold fertilizer well, especially when over-watered – the nutrients wash out. Compost helps bind the large particles providing food and air circulation, but in hot climates the organic matter decomposes rapidly and is soon consumed by bacteria and other soil organisms.
For best results keep sandy soil cool, retain moisture with mulch, and cultivate often, adding additional compost. Winter season cover crops will hold moisture and prevent runoff while retaining life in the soil.
Loam soil has all the advantages of clay and sand; it holds moisture and water like clay but is quick to warm and has god drainage and a work-friendly structure like sand. It is the perfect growing medium.
Most soils are a combination of sand and clay. Silty loam falls in between and feels almost greasy when rubbed in your hand, though it is less slippery than clay. The ultimate soil for growing plants is loam found in ancient river bottoms and lake beds where sedimentary soil builds up. It is dark, fertile, and crumbly in the hand.
Forest soils vary greatly in pH and fertility. The needles and deadfall from the trees usually make the soil acidic
Most of the forests remaining in North America and Europe are on hillsides. Flat land is used for farming,recreation, and urban sprawl.
Long needle pines grow in poor soils such as those found in mountainous and tropical regions. They have deep rots to look for all the elements in the soil. When a layer of humus evolves, short needle conifers dominate. The roots on these trees spread out on the surface to search for nourishment and bury roots to anchor it in place.
Jungles are usually low-growing, hot, moist, and dense. The soil is shallow and alive. The hot weather makes ll foliage that falls to the ground decompose quickly. Often nutrients are available to plants, but the soil does not have a chance to build density. Layers of tropical soils can be very thin. However, through much of Mexico and Central America volcanic eruptions brought much rock and minerals to the surface. Mountain valleys and lowlands are full of alluvial plains that are packed with nutrient rich soil.
Grasslands often have wonderful soil that recycles nutrients. Sunshine is likely to be good, but detection could be a problem in wide open spaces. Plant in areas that are protected from wind and curious eyes.
Mountain soils are often very rich in minerals but lack humus. Alpine valley hold the best alluvial-plain soil that is the product of volcanic rock erosion. Hillsides are generally less fertile, and soil must be amended to grow a good crop.
Bog soils are moist and spongy. Bogs are filled with vegetation and often have very rich soil. They present a perfect place to grow individual plants. Cut a square yard of moist sod from the ground, turn it over, and plant. Marsh ground supplies sufficient water on its own. Add a bit of time release fertilizer during transplanting and another handful of flowering formula during a check-up in early August.
Most often, it is easiest to change or amend native soil that will produce scrawny plants. You can grow in containers so you can control all factors, but just remember, containers require more maintenance.
Worms work wonders with soil. Grow your own crop of worms in a worm bin. Worms grow and reproduce in layers of food scraps, soil, and manure. They produce worm castings, an excellent fertilizer / amendment or compost tea ingredient.
Soil and water pH levels are exceptionally important. Cannabis does best with a soil pH of about 6.5.
Raising alkaline levels is somewhat easier than raising the acid level. If your soil is too alkaline, 1.2 oz of finely ground rock sulfur per square yard of sandy soil will reduce soil pH by one point. Other types of soil will need 3.6 oz per square yard. Well-decomposed sawdust composted leaves, and peat moss also hep to acidify soil and lower pH.