Compost Tea or Me
Chemical fertilizer has been in use only since the 1940’s. So if we embrace the past with a renewed understanding of the whole intricate system, we can prosper while at the same time make the earth a better place.
Soil biology has to come from the soil, if you are growing in a substrate that won’t support microbial activity, then you need to make adjustments to the mix so it will. The idea of applying compost tea preparations on a near daily basis is flawed.
Mother Nature has a way of evolving so that the ecosystem is efficient. Nature relies on decomposing litter be it plant or animal to support the evolution of the ecosystem. Through the long evolutionary cycle the system has become efficient. In an effort to duplicate nature, you must start with a rich soil so that the liquid feed program is not relied upon to supply the plants entire nutritional needs. Two growers in my area last year learned this the hard way. Whether you call it global warming, or the coming of the next ice age, we have had three unusually dark and cold springs, each year colder than the one previous. Snow and hail prevailed through the entire month of April in 2008. When these two organic growers shipped their tomatoes, were nutritionally bankrupt because the source of nutrients was left up to the liquid feed program. Plants that were fertigated on a Monday still didn’t need watering on Friday because of the low transpiration rates due to the cold dark weather.
If a grower has to rely on the liquid feed program to supply the nutritional needs of the plant then expensive injectors have to be installed to deliver the comparatively weak compost tea to the crop. Most organics are less concentrated in their nutritional levels so more pounds of organics have to be used compared to chemical fertilizers.
In order to supply the crops requirements, the feed is a thick slurry. When this is applied to the surface of the pot, the residue remains there while the soluble components infiltrate the soil. Over time, the fine particulate matter made up organic matter a biological slime becomes thicker and begins to create a patina that supports algae growth. Soon this layer becomes a barrier to oxygen. The plants root system suffers from this lack of oxygen unless the bulk density of the soil is very low with corresponding/high porosity. Plants growing in a soil with high porosity fail to form an adequate interface with the surrounding and much heavier soil in the landscape.
My major market area has clay so we don’t mind if our soil has a higher bulk density just so long that it has adequate drainage. After a couple decades of conducting % air and water holding capacity studies of greenhouse soils, I started to use a much easier method for estimating soils suitability for container production. When a soil is at saturation, I add enough water to the surface to make a puddle 3/8 of an inch deep. If the puddle disappears in less than three seconds, the soil is too porous. If the puddle lasts longer than seven seconds, the soil is too dense. I look for water to drain from the surface in about five seconds.
Moisture from the heavy native soil can’t move to the bedding plants growing in the soil-less mix.
The soil plant interface.