Modified Humic Substances as Soil Conditioners: Laboratory and Field Trials

Abstract

The paper is devoted to the development and performance testing of a soil conditioner based on leonardite humic substances (LHS) modified with 3-aminopropyltriethoxysilane (APTES). The modified HS were obtained by adding APTES to LHS solution at different mass ratios of LHS and APTES, followed by the investigation of siloxane structures using 31Si NMR spectroscopy. The Urbic Technosol was used as a model soil. The size and amount of water-stable soil aggregates were estimated using wet sieving and laser diffraction, respectively. Toxicity was evaluated by monitoring microbial substrate-induced respiration (SIR) and seedling bioassay. Laboratory column experiments demonstrated an increase in water-stability of the 3–5 mm soil aggregates after LHS-APTES application. Field tests showed an increase in the average weighted diameter of micro aggregates (from 59 to 73 μm) and water-stable macroaggregates (from 1.6 to 2.9 mm) due to the LHS-APTES amendment. A substantial increase in SIR from 5 to 9 mg CO2 (kg h)−1 was detected. Better survival of seedlings was observed. The obtained beneficial results indicate that APTES-modified HS can be successfully used as a soil conditioner. The formation of extended siloxane networks was suggested as the main mechanism of the observed improvement in the structure of the amended soils.

Formation of Humic-Like Substances during the Technological Process of Lignohumate® Synthesis as a Function of Time

“…Humic-based amendments (humic product, HP) are increasingly used in agriculture [1][2][3][4][5][6] and are being currently considered as a major category of biostimulants [7,8]. HPs are manufactured by industrial companies from various humic resources (mostly lignite, peat, and composts), as well as lignocellulose wastes [9][10][11][12].…”

Effects of Humic Substances and Mycorrhizal Fungi on Drought-Stressed Cactus: Focus on Growth, Physiology, and Biochemistry

“…The inclusion of both Hs and/or AMF had a direct positive influence on soil quality under drought. Humic substances enhanced the structure of soil by forming complexes with soil clay particles, which can help to stabilize the clay [ 38 ]. It can also enhance the nutrients in soil, especially AP, N, and Ca.…”

Mass Spectrometry as a Crucial Analytical Basis for Omics Sciences

“…One of the reasons for the interest in humic substances is their use for increasing soil fertility [ 173 ] and possible antiviral [ 174 ] and other biological activity [ 175 ]. The use of mass spectrometry, in this case, makes it possible to determine the relationship between the composition of the samples used and the results of their application.…”