Глава 10. Growing in the Ground

 

Some growers have the opportunity to grow plants directly in the ground. Many greenhouses are built directly over the earth. Growing directly in the soil has many advantages over container growing. A considerable amount of labor may be eliminated because there is no need to prepare labor-intensive containers with expensive medium. Another advantage is that the plants' needs are met more easily. Before using any greenhouse soil, it is necessary to test it. The pH and fertility of soils vary so much that there are few generalizations that can be made about them. The most important quality of any soil is its texture. Soils which drain well usually are composed of particles of varying size. This creates paths for water to flow and also allows air pockets to remain even when the soil is saturated. Soils composed of very fine particles, such as mucks and clay, do not drain well. Few air particles are trapped in these soils when they are saturated. When this happens, the roots are unable to obtain oxygen and they weaken when they are attacked by anaerobic bacteria. These soils should be adjusted with sand and organic matter which help give the medium some porosity. Materials suitable for this include sand, compost, composted manure, as well as perlite, lava, gravel, sphagnum moss, styrofoam particles and foam particles. Low lying areas may have a very high water table so that the soils remain saturated most of the time. One way to deal with this problem is to create a series of mounds or raised beds so that the roots are in ground at higher level than the floor level. Once soil nutrient values are determined, adjustments can be made in the soil's fertility. For marijuana, the soil should test high in total Nitrogen, and the medium should test high in Phosphorous and Potassium. This is covered in subsequent chapters. to Growers use several methods to prepare the soil. Some prefer till the whole area using either a fork, a roto-tiller or a small tractor and plow. The marijuana plant grows both vertical and horizontal roots. The horizontal roots grow from the surface to a depth of 9–18 inches depending on the soil's moisture. They grow closer to I the surface of moist soils. The vertical root can stretch down several feet in search of water. In moist soils, the vertical roots may be short, even stunted. Soil with loose texture, sandy soils, and soils high in organic matter may have adequate aeration, porosity, and space for roots and may not have to be tilled at all. Most soils should be dug to a depth of 6–9 inches. The tighter the soil's texture, the deeper it should be tilled.

 

If the soil is compacted, it is dug to a depth of two feet. This can be done by plowing and moving the soil in alternate rows and then plowing the newly uncovered soil. Soil texture adjustors such as gypsum are added to the bottom layer of the soil as well as the top layer, but soil amendments such as fertilizers or compost are added only to the top layer, where most of the plant's roots are. Then the soil is moved back into the troughs and the alternate rows are prepared the same way. A variation of this technique is the raised bed. First, the whole area is turned, and then aisles are constructed by digging out the pathways and adding the material to the beds. With the addition of organic soil amendments, the total depth of prepared soil may stretch down 18 inches. Some growers use planting holes rather than tilling the soil. A hole ranging between 1 and 3 feet wide and 1½ and 3 feet deep is dug at each space where there is to be a plant. The digging can be facilitated using a post hole digger, electric shovel, or even a small backhoe or power hole digger. Once the hole is dug the soil is adjusted with amendments or even replaced with a mix. No matter how the soil is prepared, the groundwater level and the permeability of the lower layers is of utmost importance. Areas with high water tables, or underlying clay or hardpan will not drain well. In either case the garden should be grown in raised beds which allow drainage through the aisles and out of the growing area, rather than relying on downward movement through soil layers. Soils in used greenhouses may be quite imbalanced even if the plants were growing in containers. The soil may have a buildup of nutrient salts, either from runoff or direct application, and pesticides or herbicides may be present. In soils with high water tables the nutrients and chemicals have nowhere to go, so they dissolve and spread out horizontally as well as vertically, contaminating the soil in surrounding areas. Excess salts can be flushed from the soil by flooding the area with water and letting it drain to the water table. In areas with high water tables, flushing is much more difficult. Trenches are dug around the perimeter of the garden which is then flooded with nutrient-free water. As the water drains into the trenches, it is removed with a pump and transported to another location. Pesticides and herbicides may be much more difficult to remove. Soils contaminated with significant amounts of residues may be unsuitable for use with material to be ingested or inhaled. Instead, the garden should be grown in containers using non- indigenous materials. Usually plants are sexed before they are planted in the ground. If the soil showed adequate nutrient values no fertilizer or side dressing will be required for several months. Several growers have used ingenious techniques to provide their gardens with earthy environments. One grower in Oregon chopped through the concrete floor of his garage to make planting holes. The concrete had been poured over sub-soil so he dug out the holes and replaced the sub-soil with a mixture of composted manure, vermiculite, perlite, worm castings, and other organic ingredients. He has been using the holes for several years. After several crops, he re-digs the holes and adds new ingredients to the mix. A grower in Philadelphia lived in a house with a backyard which was cemented over. He constructed a raised bed over the concrete using railroad ties and filled it with a rich topsoil and com posted manure mixture, then built his greenhouse over that. The growing bed is about 15 inches deep and the grower reports incredible growth rates.