Monoammonium Phosphate Effects on Glyphosate in Soils: Mobilization,Phytotoxicity, and Alteration of the Microbial Community

Eurasian Soil Science - Application of monoammonium phosphate has been demonstrated to re-immobilize glyphosate sorbed by soil under model laboratory experiment conditions. This effect was most...     

Slow nitrogen release from humic substances modified with aminoorganosilanes

Purpose

The purpose of the present study is to evaluate slow-release nitrogen capabilities of soil amendments obtained by modification of humic materials from peat and lignite with alkoxyorganosilanes carrying different amine substituents.

Materials and methods

The humates from lignite and peat were modified using (3-aminopropyltriethoxy)-silane (APTES) and (1-aminohexamethylenene, 6-aminomethylene)-triethoxysilane (AHATES). The obtained derivatives were characterized using elemental analysis and Fourier transform infrared spectroscopy. Nitrogen release in the form of ammonia or nitrate was evaluated using dissolution tests under sterile aqueous conditions as well as long-term soil experiments. Ammonium and nitrate were determined using ion-selective electrodes. Activity index (AI) was calculated from the dissolution tests. For soil trials, arable Retisol was sampled from 0- to 5-cm layer in Yaroslavl region (Russia). The soil experiments were conducted over 78 days using (NH₄)₂SO₄ as an activator of nitrification and 3-amino-1,2,4-triazole as an inhibitor of autotrophic nitrifying bacteria.

Results and discussion

Modification of lignite and peat humates leads to an increase in nitrogen content up to 2 and 4.3 %, respectively, in case of APTES, and up to 3 and 6 %, respectively, in case of AHATES. All humic derivatives gradually released N upon dissolution in water over 6 days up to 51 % of the total N. The AI values ranged from 4 to 13 %. Amendment of soil with the modified humic materials induced an increase in nitrate content resulting from nitrification of released ammonia by soil microflora. This was confirmed by aminotriasole experiments. The nitrogen release occurred slowly: over the first week of incubation, it did not exceed 36–69 % of the total N content. The higher release rate of ammonium nitrogen was observed for CHS-AHATES versus CHS-APTES derivative, whereas no difference was seen between the two peat derivatives, which showed release rate on the level of CHS-AHATES derivative. Positive effect of all modified humic materials lasted over 78 days.

Conclusions

Modification of lignite and peat humates with two aminoorganosilanes carrying one and two nitrogen atoms in the amine substituent brought about twofold to threefold enrichment of the parent humic materials with nitrogen, which was capable of slow release upon incubation in soils. It was released in the form of ammonia and transformed to nitrates by autotrophic nitrifying soil microflora. There was no clear relationship established between structure of amine substituent of organosilane and slow-release properties of the corresponding humic derivatives. The conclusion was met that principal application of aminoorganosilane derivatives of humic substances (HS) is soil structuring, whereas nitrogen-fertilizing capabilities might be considered as beneficial added-value feature of these humic products.

     

Assessing the Efficiency of Humic Substances as Washing Agents for Oil–Contaminated Soils and Peats under Model Experimental Conditions

Two humic preparations of different origins have been compared as washing agents for oil-contaminated soils and peat under model experimental conditions using a sample from the plow horizon of soddypodzolic soil artificially contaminated with oil or diesel fuel and a sample of high-moor peat contaminated with crude oil because of a spill occurred 15 years ago. Soil and peat were washed by shaking with solutions of the humic preparations Gumat Sakhalinskii and Lignogumat in a 1: 10 (m/v) ratio. Control samples were washed with distilled water. Washing with a synthetic surfactant (sodium dodecyl sulfate) was also added to the experimental design. After washing, soil and peat samples were air-dried and used for the determination of the total content of petroleum hydrocarbons; the characterization of their hydrocarbon composition; and the assessment of hydrophobicity from the contact angle and the efficiency of colonization by oil-destructing microorganisms Rhodococcus sp. and Candida sp., which are components of the preparation Bioros recommended for oil contaminations. It has been shown that the extraction efficiency of petroleum hydrocarbons by humic preparations did not differ from the extraction efficiency by water and was less than that by sodium dodecyl sulfate in all cases. No appreciable changes in the contact angles of soil and peat have been observed at the use of water and humic preparations as washing agents, while the contact angle decreased to less than 90o after washing with sodium dodecyl sulfate, which indicated the hydrophobicity of the surface of substrate particles. It has been found that humic preparations favor the colonization of soil and peat by oil-destructing microorganisms Rhodococcus sp. and Candida sp. Based on the obtained results, humic preparations have been recommended for further study as preparations favoring the ability of oil-destructing microorganisms to colonize oil-contaminated substrates.     

The influence of topography on the spatial distribution of fertility indices in an ameliorated agrolandscape in the area of terminal moraines

The effect of geomorphic conditions on the morphological, chemical, and physical properties; the biochemical activity; and the distribution of soil microorganisms in the plow horizon of ameliorated swampy podzolic soils has been studied along the catena on a gentle slope of the northeastern aspect of a moraine hill. The indices of soil fertility gradually improve from the top of the hill to the adjacent hollow. In this direction, the soil acidity becomes weaker under the impact of liming, the soil texture becomes somewhat heavier, and the contents of humus and the major nutrients increase in parallel with the increase in the number of soil microorganisms and their enzymatic activity.     

Protective Activity of Humic Substances in Wheat Seedlings in Water Deficit Conditions

We conducted a comparative evaluation of the protective effect of humic substances (HSs) derived from coal and peat in seedlings of soft wheat Triticum aestivum L. in water deficit conditions caused by a PEG-6000 hyperosmotic solution. The protective effect of HSs was found to increase with an increase in the content of phenolic fragments. This finding may indicate that the antioxidant activity of HS was the main protective activity mechanism of HS in water deficit conditions.     

Adding of Substandard Sunflower Seeds as an Energy Supplement to the Ration of Dairy Cows

Substandard sunflower seeds surpass the sunflower meal and oil cake by their level of metabolic energy by 1.2–1.5 times and can replace these high-calorie feed materials in the rations of cattle. In mixed feed, whose structure includes the substandard sunflower seeds (5% in mass), the share of the cleavable protein decreased by 1.3% and digestibility of the dry matter increased by 2.3% as compared to mixed feed, whose structure includes sunflower cake (8% in mass). Both variants of the mixed feeds were used in the experiment on cows of the white-and-black breed with the live weight of 600 kg and average daily milk yield of 25–28 kg within the first lactation phase in the structure of the total feed mix ration. The metabolism and digestive processes in the rumen of the animals fed with the substandard sunflower seeds proceeded without any disturbances. In the ruminal fluid, the concentration of the ammonia nitrogen was lower by 6.75 mg % on average. Furthermore, in the milk of the cows, the content of the milk fat increased by 5.2% and the urea content decreased by 9%.     

Particle-Size,Microaggregate-Size,and Aggregate-Size Distributions in Humus Horizons of the Zonal Sequence of Soils in European Russia

Eurasian Soil Science - Experimental data on size distribution of micro- and macroaggregates and primary soil particles were obtained by laser diffraction analysis of the samples of humus horizons...     

Differentiation of the Cadastral Value of Agricultural Lands in Tyumen Oblast

Eurasian Soil Science - According to the results of land assessment, the cadastral value of agricultural land in Tyumen oblast varies from 2900 rubles per hectare for peat-podzolic soils to...