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The objective of this work was to determine the potential of using of solid and liquid digestate, as biofertilizer and soil amendment, and to address adverse unfertile soil erosion problems after analysing areas of potential use. We found a high concentration of organic carbon in a solid fraction of the digestate, which indicates a significant potential for returning carbon to the soil. The influence of digestate fertilization on soil fertility as a function of the amount of available phosphorus (P 2 O 5 ) and potassium (K 2 O) in the 0-40 cm layer was found to be very important. The soil fertility category was changed from "high" (200-300 mg kg -1 ) to "very high" (>300 mg kg -1 ) according P 2 O 5 , using only 170 kg ha -1 of nitrogen in solid and liquid digestate rate. Fertilization with all phases and rates of digestate tend to increase the amount of K 2 O. The solid digestate fertilization using the 170 kg ha -1  N rate showed a significant increase (5 times) of mineral nitrogen content in the 0-40 cm soil layer. The advantage of solid digestate as a soil improver has been highlighted because it has a positive effect on soil fertility, quality, sustainability and durability. The amount of mobile humic acids (MHA) in eroded loamy Retisol increased 1.6 times in soil 0-40 cm layer with a fertilization rate of 170 kg ha -1 and 1.5 times - of 85 kg ha -1 of solid digestate compared to the untreated. Similar trends of MHA but in lower amount were identified when liquid digestate was applied., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The importance of agricultural practices to greenhouse gas mitigation is examined worldwide. However, there is no consensus on soil organic carbon (SOC) content and CO emissions as affected by soil management practices and their relationships with soil texture. No-till (NT) agriculture often results in soil C gain, though, not always. Soil net CO exchange rate (NCER) and environmental factors (SOC, soil temperature [T], and water content [W]), as affected by soil type (loam and sandy loam), tillage (conventional, reduced, and NT), and fertilization, were quantified in long-term field experiments in Lithuania. Soil tillage and fertilization affected total CO flux (heterotrophic and autotrophic) through effect on soil SOC sequestration, water, and temperature regime. After 11 yr of different tillage and fertilization management, SOC content was 23% more in loam than in sandy loam. Long-term NT contributed to 7 to 27% more SOC sequestration on loam and to 29 to 33% more on sandy loam compared with reduced tillage (RT) or conventional tillage (CT). Soil water content in loam was 7% more than in sandy loam. Soil gravimetric water content, averaged across measurement dates and fertilization treatments, was significantly less in NT than CT and RT in both soils. Soil organic carbon content and water storage capacity of the loam and sandy loam soils exerted different influences on NCER. The NCER from the sandy loam soil was 13% greater than that from the loam. In addition, NCER was 4 to 9% less with NT than with CT and RT systems on both loam and sandy loam soils. Application of mineral NPK fertilizers promoted significantly greater NCER from loam but suppressed NCER by 15% from sandy loam., (Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.)

Methodology for the determination of humus and humic materials content in soil after dichromate oxidation using a multichannel automatic photometer (Multiskan MS) has been developed. The study presented here demonstrates the benefits of using this methodology for the rapid, reliable and accurate determination of humus and humic materials content in various soils. The method is characterised by good data repeatability and low labour and reagent inputs. Photometric estimation is assessed in various respects, and determination procedures are presented. We have compared the data obtained by the titrimetric method and the photometric method with the photometer Multiskan MS. The methods are well correlated. The regression equations and determination coefficients relating to the data obtained by different methods have been calculated. The best statistics of a comparison between the titrimetric ( y) and photometric ( x) methods of humus determination were obtained with a series of standards prepared from the soil samples of known humus content: R(2)=0.99; y=1.05 x-0.37; BIAS=0.24% of humus; SED=0.27% of humus.

Given the growth in the number of biogas power plants and the increase in the generation of waste from energy production, it is relevant to study the sustainable nature of this waste. Digestate is a product of the anaerobic digestion process, and is a valuable bio-fertilizer containing organic matter and nutrients necessary for agricultural plants' growth. The study showed that different rates of liquid and solid phases of anaerobic digestate influenced the contents of carbon and nitrogen in genetically young soil in alluvial deposits—Fluvisol. The application of solid digestate (SD) considerably increased soil organic carbon content (SOC) in the 0–10 cm soil layer; however, SOC did not reach the 20–30 cm layer. Liquid digestate (LD) significantly increased SOC in the deeper layers. The levels of mineral nitrogen (Nmin) and water extractable organic carbon (WEOC) increased in the 0–10 cm soil layer soon after fertilization with LD and SD. The mobile components of the soil (Nmin and WEOC) were characterized by high variability during the growing season. Within the 2-month period, their concentrations decreased drastically and were close to those of unfertilized soil. The research indicates that anaerobic digestate had a greater effect on mobile forms of carbon and nitrogen in the soil than on their total amounts. [ABSTRACT FROM AUTHOR]

The objective of the present study was to estimate the distribution of soil organic carbon (SOC) and its forms (protected and labile organic carbon) and total nitrogen (Ntot), plant available phosphorus (P2O5) and pottassium (K2O) within 0-30 cm layer of a ploughed horizon in agricultural soils as influenced by tillage and fertilisation. Research was carried out in two regions of Lithuania: in Central (sites I and II) and Northern (site III) parts of Middle Lithuanian Lowland. Tillage systems, including conventional tillage (CT) and no-tillage (NT), straw management methods and mineral fertilisation were investigated on a loam and sandy loam top layer of glacial morain Eutric Endocalcaric Endostagnic Cambisol in site I. Five fertilisation treatments were tested in a grassland with a sandy loam top layer of glacial morain Endocalcaric Albic Brunic Endogleyic Arenosol in site II: without fertilisation and fertilisation with separated liquid and separated solid digestates at rates of 85 and 170 kg ha-1 N. The field experiment on a glaciolacustrine Eutric Endocalcaric Amphistagnic Endogleyic Cambisol with clay loam in site III involved the following tillage systems: conventional tillage (CT), ploughless tillage (PT), ploughless tillage with lime sludge incorporation (PT + LS) and no-tillage with a cover crop for winter mulch (NT + WM). Long-term NT caused pronounced stratification of Ntot, available K2O and SOC within the arable layer of Eutric Endocalcaric Endostagnic Cambisol. The highest accumulation of SOC and chemically protected-humified carbon in the grassland on an Endocalcaric Albic Brunic Endogleyic Arenosol was determined at the highest digestate rate of 170 kg ha-1 N. High SOC accumulation potential was shown by PT + LS in a Eutric Endocalcaric Amphistagnic Endogleyic Cambisol. This significantly increased the share of humified carbon fraction bound with calcium in 0-10 and 10-20 cm soil layers. Reduction of tillage intensity by applying PT and NT + WM increased the concentration of labile organic carbon in the soil, especially in the upper 0-10 cm layer. The lime sludge application reduced the amount of labile organic carbon by its incorporation with calcium in this amendment, while increasing the stability of carbon compounds. In Eutric Endocalcaric Endostagnic Cambisol, the mean results of 0-30 cm layer revealed that the share of F4 carbon fraction, resistant to degradation, in the SOC was significantly higher under NT than under CT. [ABSTRACT FROM AUTHOR]

The most important component of agricultural system are soils as the basis for the growth of plants, accumulation of water, plant nutrients and organic matter. The main task of our research was to ascertain changes in soil organic carbon (SOC) and mobile humified carbon fractions in digestate-treated soils. We have performed three field experiments using the same design on two soil types in 2019–2020. We studied the fertilization effects of different phases of digestate on Retisol and Fluvisol. Fertilization treatments: control; separated liquid digestate 85 kg ha−1 N; and 170 kg ha−1 170 N; separated solid digestate 85 kg ha−1 N; and 170 kg ha−1 N. We have found a greater positive effect on the increase in SOC because of the use of the maximum recommended fertilization rate of the solid digestate. The content of mobile humic substances (MHS) tended to increase in grassland and crop rotation field in digestate-treated soil. In our experiment, maximum concentration of SOC was found in 0–10 cm soil layer, while in the deeper layers the amount of SOC, MHS and mobile humic acids proportionally decreased. We concluded, that long-term factors as soil type and land use strongly affected the humification level expressed as HD (%) in the soil and the highest HD was determined in the grassland soil in Fluvisol. [ABSTRACT FROM AUTHOR]