Development of soil-less substrates capable of degrading organic nitrogen into nitrate as in natural soils

Abstract

Soil-less substrates are unable to catalyse nitrification because the addition of a high concentration of organic substances suppresses nitrification. We used a previously developed multiple parallel mineralization method, which enables the use of organic fertilizers in hydroponics, to support nitrification in soil-less substrates. In this method, microorganisms immobilized on porous substrates produced inorganic nitrate from organic substances, as in a natural soil. Phosphate and potassium ions were also released. Microorganisms produced nitrate from organic substances when immobilized on polyurethane resin, rockwool, vermiculite, oyster shell lime, and rice husk charcoal. The optimal amount of organic substance added daily to 100 mL of substrate held 6 mg of organic N. The optimal incubation temperature ranged from 25 to 42 °C. A high relative humidity (51% or higher) was more suitable than drier conditions (20%). The optimal amount of fish fertilizer added to the substrate was 6 mg organic N. The lower the C/N ratio of the organic substance, the better the result. Vegetable plants grew well on inoculated substrates but not on uninoculated substrates. These results show that soil-less substrates can be used to create artificial soils in which plants can be grown with the addition of organic fertilizer, as in a natural soil.

Spontaneous Cell Lysis by <i>Pelomonas saccharophila</i> MRB3 Provides Plant-Available Macronutrients in Hydroponic Growth Media and Accelerates Biomass Production of Duckweed

“…7). Recently, a great deal of interest has been directed toward utilizing organic wastes as cheap nutrient sources in hydroponic farming, but this is challenging because most nitrogen and phosphorus in organic wastes exist in plant-unavailable forms [25][26][27]. Thus, autolytic bacteria, such as MRB3, deserve further exploration to reduce the medium cost of hydroponics and accelerate nitrogen and phosphorus recycling in our society.…”

Generation of Fusarium oxysporum-suppressive soil with non-soil carriers using a multiple-parallel-mineralization technique

“…The inoculation of MPM microorganisms can therefore be an eco-friendly method to control Fusarium wilt and other root diseases in hydroponic systems, although it will be necessary to test it to determine its effectiveness against other pathogens. In addition, the MPM microbial ecosystem contains more than 50,000 microbes 8 , making it difficult to identify the relationship between disease suppression and specific components of the microbial ecosystem. It will be necessary to see whether it is possible to reproduce the observed disease control in a microbial ecosystem composed of a smaller number of microorganisms, as this would facilitate its implementation on an operational scale.…”

“…Hydroponic conditions with no solid medium, cultivation with MPM solution suppressed root diseases such as bacterial wilt disease and Fusarium wilt 2 , 3 , 7 . When the MPM culture solution is inoculated into a non-soil carrier, the carrier acquires the ability of a natural soil to degrade organic matter into inorganic nutrients 8 . This non-soil medium may also suppress the growth of pathogenic organisms such as Fusarium species 9 .…”

Crop Hydroponics, Phyto-hydroponics, Crop Production, and Factors Affecting Soilless Culture

“…35 Computer based technology, sensor based technology, drone systems, cloud based technology, etc. are utilized in soilless crop production 36 (Figure 2).…”