Chemistry: fertilizers – Processes and products – Organic material-containing
Reexamination Certificate
2000-10-06
2003-11-11
Langel, Wayne A. (Department: 1754)
Chemistry: fertilizers
Processes and products
Organic material-containing
C047S05810R, C047SDIG001, C071S021000, C071S023000, C071S024000, C071S027000, C071S028000, C071S034000, C071S058000, C071S063000, C071S903000
Reexamination Certificate
active
06645267
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to plant growing media, and to a process for converting composted organic materials produced by optimised composting procedures into plant growing media for agronomic and other uses.
BACKGROUND OF THE INVENTION
The successful production of crops in greenhouses requires an adequate and consistent quality of growing media for the crops. This can range from natural soils to soilless hydroponics. The key characteristics of growing media include consistent bulk density, ease of use, freedom from plant diseases and pests, and the ability to supply plant nutrients and water.
A high proportion of the potting soils and the like currently commercially available utilize peat, derived from harvesting natural peat bogs. For example Kim in U.S. Pat. No. 5,662,724 describes an artificial soil composition in which the major ingredients are in percentages by weight 10-30% peat, 10-30% granular soil, 40-60% sewage sediment, and 24-45% sewage pulp sludge. This practice of using peat in potting soils and the like can be environmentally unsound and results in the loss of environmentally sensitive bog areas.
Composting is a common process used to recycle organic wastes. The composting process reduces the volume of organic material and stabilizes nutrients, particularly nitrogen. Composting curtails environmental pollution and reduces, often significantly, the amount of recyclable organic matter requiring another method of disposal, which often is to dump it into a landfill site. Composting can also be used to process materials which cannot easily be dumped into a landfill site, such as the liquid raw manures obtained from the intensive rearing of farm animals in barns. Further, composting can be applied to waste organic materials derived from certified organic agricultural procedures. During the composting process, carbon and nitrogen compounds in the organic wastes are transformed by successive microbial populations into more stable complex forms which chemically and biologically resemble humic substances.
The commercial viability of existing composting facilities is primarily based on the operator receiving a fee for accepting the organic material from waste generators. The emphasis in most of these waste management composting facilities is the composting of large volumes of material to reduce the amount of material. The retention time in the composting channels or windrows is minimized to allow the maximum flow through. Sometimes the compost is allowed to cure outside the composting system to complete the bio-stabilization process. Under some commercial systems, little effort is made to maximize the quality of the finished compost material.
BRIEF SUMMARY OF THE INVENTION
This invention seeks to overcome the long term consequences of the use of peat based growing media by providing agronomically acceptable growing media which are based on what are essentially otherwise waste materials. In a more particular embodiment, this invention seeks to provide agronomic growing media which are acceptable for certified organic cultivation in the greenhouse environment, as well as in field and garden use.
The fertility, and consequently usefulness, of agronomic growing media involve a complex series of interactions between the medium and the plants being grown in it. These include media pH, the form of the available resident nutrients, temperature, moisture content, media atmosphere, and the microbial populations present. The incorporation of compost into plant growing media can influence all of these factors. However, the indiscriminate use of poor quality compost in plant growing media can be counter productive, and can result in production fertility problems.
The development of the composting process to minimize the volume of waste organic material going to landfill sites has resulted in substantial quantities of compost becoming available, in which the quality of the compost can be maximized, so that the compost provides as much benefit in the growing media as can reasonably be achieved.
This invention utilizes high quality compost from optimized standard composting processes. This invention requires the composting process to be completed under strictly controlled conditions to produce fully bio-stabilized compost of known values of nitrogen, phosphorous and potash. The composting process is also completed under conditions which minimize the loss of nutrients due to volatilization and leaching. The amount of nitrogen, phosphorous and potash in the compost can be influenced by the selective use of the raw organic matter to be composted.
Further, the compost can be derived from certifiably clean “organic” materials, and thus can provide plant growing media suitable for certified organically grown food crops.
DETAILED DESCRIPTION OF THE INVENTION
Thus, in its broadest embodiment, this invention seeks to provide a process for preparing plant growing media consisting essentially of:
(i) screening a fully bio-stabilized compost material to provide a retained fraction of particles under about 1 cm diameter, and a rejected fraction of particles having a diameter in excess of about 1 cm;
(ii) screening the retained fraction from step (i) into three further fractions to provide a rejected fines fraction below 1 mm, a medium fraction of from 1 mm to 4 mm, and a coarse fraction of from 4 mm to 1 cm;
(iii) remixing metered amounts of the retained medium and coarse fractions from step (ii) with an agronomically acceptable amount of humified organic matter having a particle size of less that 1 mm, and a cation exchange capacity of from about 10 meq/100 g to about 400 meq/100 g; and
(iv) remixing metered amounts of the product produced in step (iii) with an agronomically acceptable amount of a suitable bulking agent, to provide plant growing media product suitable for agricultural use.
Complete bio-stabilization in itself is not a new process in the context of the composting process. This invention requires the use of compost prepared by a process in which the bio-stabilization process has been fully completed during the composting process. The retention time in the composting process, depending upon moisture, temperature, aeration and feedstock mixes, must be sufficient to allow for full bio-stabilization. In addition, all good manufacturing practices for making compost that minimize losses of nutrients due to volatilization and leaching must be followed. The water content of the feedstock material is also adjusted to ensure optimum bio-stabilization, so that the final compost product used to make this invention is a dry particulate material.
In the first step of the process of this invention, the fully bio-stabilized and nutrient rich compost is screened to provide a retained fraction and a reject fraction. The particles greater than 1 cm diameter are rejected and further processed.
In the second step of the process of this invention, the compost fraction retained in the first step is separated into specific particle size components. The retained compost fraction is screened and separated into three fractions, which are:
(a) “coarse” particles between 4 mm and 1 cm diameter;
(b) “medium” particles between 1 mm and 4 mm diameter; and
(c) “fine” particles below 1 mm diameter.
These three fractions are accumulated conveniently in separate metering hoppers. The third fraction of fine particles below 1 mm diameter is separated and used for other purposes.
In the third step of the process of this invention, metered amounts of the coarse and medium fractions are transferred to a mixer scale and remixed under controlled conditions. The weight ratio of coarse fraction to medium fraction may vary, depending on the desired characteristics of the plant growing media. Preferred ratios are 1:1 and 2:3 by weight of medium to coarse.
In the fourth step in the process of this invention an appropriate amount of humified organic matter is added to the coarse/medium mixture from the third step. The humified organic matter can be any suitable organic matter with a particle size less than about
Hendry Robert G.
Wilkes Robert A.
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