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The integration of organic fertilisers into agricultural practices is one approach to enable more efficient agricultural management systems to decrease adverse environmental impacts of agriculture. In this context, the objective of this research was to determine the impact of long-term crop rotation and organic and mineral fertilisation on soil humus content, humic and fulvic acids, organic matter humification in organic and sustainable agricultural management systems with low (1.90-2.01%) and moderate (2.10-2.40%) initial humus contents. Long-term field experiments with different agricultural management systems started in 1960 at the Lithuanian Research Centre for Agriculture and Forestry and soil humus dynamics experiments were conducted from 2006 to 2017. Results of the long-term use of organic and sustainable agricultural management systems with different crop rotations and fertilisation revealed the positive effect of the applied supplies on soil humus, especially for farmyard manure in combination with green manure. The incorporation of farmyard manure and biomass of white mustard resulted in a lower degree of humification when compared to green manure alone, green manure + mineral N, and farmyard and green manure + mineral N. In the low humus content soil, the degree of humification under all agricultural management systems was significantly improved, on average by 0.9% compared to soil with a moderate humus content. Keywords: green manure, crop rotation, organic and sustainable agriculture, humus, humic and fulvic acids., Introduction One of the most important indicators of soil fertility is the soil organic matter and/or humus content. Under normal conditions, humus is of utmost importance as it supplies most [...]

Growing perennial grasses is often cited as one of the possible and most affordable solutions for mitigating climate change. This practice is also recommended for sustainable soil management in agriculture. Our experiment involved timothy grass (Phleum pratense L.), red clover (Trifolium pratense L.), and their mixture; tall oat grass (Arrhenatherum elatius L.), alfalfa (Medicago sativa L.), and their mixture, with the aim of diversifying the annual rotation; and periodical, twice-per-season cultivated plots in the same area (the bare soil fallow). Soil samples were collected in late October after plant vegetation's first, second, and third growth years from three field replicates at the soil layers 0–0.1 m, 0.1–0.2 m, and 0.2–0.3 m and plant roots—at the beginning of November in the second cultivation year. After three years, the SOC content increased in all the study areas occupied by plants, regardless of their species composition, while it decreased in fallow plots. Grass roots were characterized by the highest C/N ratio (38.2 and 45.5). The roots of the red clover–timothy grass mixture also reached a C/N ratio greater than 30. Based on our research, choosing a combination of at least two plants, such as legumes and grasses, is possibly more effective for enriching the soil with carbon compounds in a short period. [ABSTRACT FROM AUTHOR]

This study is designed to evaluate soil organic matter (SOM) quality indicators: molecular indicators of dissolved organic matter (DOM) and hydrophobicity of humic acid (HA), distribution of quantity in humified and labile fractions of histosols during renaturalization. The aim is to determine the differences in the qualitative composition of humic acids at the molecular level, which are decided by the previous tillage and genesis, and to evaluate the impact of anthropogenization on the peat soil according to hydrophobicity, as well as to estimate the impact of soil genesis and removing peat layer. Soil samples were taken from the three Sapric Histosol (according to WRB2022) profiles and the 0–30 cm layer in three field replicates (Lithuania, Radviliskis mun.). Our study suggested that in the differently managed drained Sapric Histosol under renaturalization, the most significant changes occurred in the topsoil layer (0–30 cm), in which an increase in the content of SOM particles 106–2 µm in size. It is expedient to grow perennial grasses and legumes to maintain the soil organic carbon stability mobile humic acids to mobile fulvic acids ratio (MHA:MFA 0.83 to 0.86). An evaluation of the quality of HA (E4:E6) revealed their highest maturity in the unfertilized perennial grasses (3.88) and crop rotation (3.87) with grasses. The highest concentrations of hydrophilic groups (ratio of the C=O to O-H) were found in Sapric Histosol under deciduous hardwood forest (12.33). The lowest hydrophilicity (9.25 and 9.36) was of the crop rotation Sapric Histosol with removed peat layer. The most sustainable use of drained Sapric Histosol in the context of the sustainability and quality of its humus substances should be associated with the formation of perennial grass and clover grassland and the cultivation of deciduous hardwood. Therefore, the horizon forms on the top part of the profile, which protects deeper Histosolic material layers from its mineralization. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) content can greatly affect soil quality by determining and maintaining important soil functions. The study examined SOC, humic substances and molecular composition characteristics of acid soil (Dystric Retisol) with different long term (54 years) fertilization in Western Lithuania. Farmyard manure (FYM 60 t ha−1) and alternative organic fertilizers (wheat straw, green mass of lupine and oats, rape stubble and straw) applied on the two soil backgrounds – acid and limed. The experimental design included the following treatments: 1) unlimed soil; 2) unlimed soil + FYM; 3) unlimed soil + alternative organic fertilizers; 4) limed soil (1.0 rate every 5 years); 5) limed soil + FYM; 6) limed soil + alternative organic fertilizers. The result indicates that application of organic fertilizers exerted a significant positive effect on SOC accumulation (0.1–0.4% more carbon than the control). The combination of soil liming and FYM resulted in the accumulation of valuable humic acids. The higher amount of humic acids (0.67% of C) was maintained under FYM applied plots. The application of organic fertilizers and liming exerted the transformation of carbon compounds changes in the direction of polymerization of humic acids, which creates more favourable conditions for carbon sequestration. [ABSTRACT FROM AUTHOR]

The aim of the research work was to study the chemical properties of most cultivated perennial Fabaceae and Poaceae plants: common cocksfoot (Dactylis glomerata L.), reed canary grass (Phalaris arundinacea L.), tall fescue (Festuca arundinacea Schreb.), perennial ryegrass (Lolium perenne L.), common lucerne (Medicago sativa L.), common sainfoin (Onobrychis viciifolia Scop.) and switchgrass (Panicum virgatum L.), and to link them to methane (CH4) and biogas yields under laboratory conditions. The results of chemical analyses showed that the biomass of legumes was most suitable for biogas production: high digestibility: 78.4-73.5% dry matter (DM) and low cellulose concentration 20.8-24.4% DM, were determined to be most suitable for anaerobic digestion. The biomass of L. perenne and F. arundinacea was best-suited for anaerobic digestion due to the highest content of water-soluble carbohydrates (WSC) 16.4-20.3% DM, and the lowest content of cellulose 27.3-28.9% DM and acid detergent fibre (ADF) 31.3-32.8% DM. The best yields of methane were obtained from O. viciifolia - 277.7 L CH4 kg-1, D. glomerata - 213.9 L CH4 kg-1 and L. perenne - 205.7 L CH4 kg-1. The correlations corroborated that the methane yield depended on the chemical composition of the biomass. Methane yield positively and significantly correlated with WSC - 0.761** and digestibility - 0.744** (P = 0.01), and negatively correlated with cellulose - 0.793**and ADF - 0.762**. The best results of specific methane yields were demonstrated by O. viciifolia (1453 m3 CH4 ha-1 DM), M. sativa (1326 m3 CH4 ha-1 DM) and L. perenne (1060 m3 CH4 ha-1 DM). This study with seven species of perennial grasses could serve as a basis for more advanced experiments on how to choose grass species for the best methane yield. [ABSTRACT FROM AUTHOR]

Research was conducted to determine the effects of perennial legume and their mulches on cereal grain yield and the alterations to clay loam Cambisol properties. The perennial legumes (Trifolium pratense L., Medicago sativa L.) as well as their mixtures with festulolium (x Festulolium) were studied in conjunction with their aboveground biomass management methods: removal from the field (cut twice for forage), mixed management (the first cut was for forage, the second and third cuts were mulched) and mulching (four times) in an organic arable farming system. Mulching of legumes biomass resulted in a higher total nitrogen (N) used for green manure. A similar amount of N was accumulated for lucerne and lucerne-festulolium mulch when using mulching and mixed management. Legumes used for mulching caused the amount of mineral N in soil to increase in late autumn (62.7–82.9 kg ha–1) and decrease in spring (39.5–64.0 kg ha–1). This mineral N had a positive impact on crop yield (r = 0.68–0.71*); however, mineral N in autumn had a negative impact on soil sustainable organic compounds (r = −0.71*). The results indicate that the most suitable treatment was the legume-festulolium mixture, which used the biomass under mixed management. [ABSTRACT FROM AUTHOR]

Anaerobic digestion is an optimal way to utilize organic materials or energy crops for bioenergy production. The current study set out to evaluate the impact of different rates of nitrogen present in mineral and organic (digestate) fertilizers on the changes in soil nitrogen. The soil of the experimental site is an Endohypogleyic Calcaric Luvisol in which cocksfoot (Dactylis glomerata) cultivar 'Amba' was grown. The experimental findings of 3 consecutive years (2013-2015) suggested that soil total nitrogen (Nt) content (0-30 cm layer) was higher in the treatments that had received biogas digestate fertilization compared to the untreated control. The significantly highest Nt concentration was established in the treatments applied with the highest biogas digestate nitrogen rate (N450). Fertilization with mineral nitrogen (Nmin) and digestate nitrogen resulted in a relatively higher Nmin accumulation in the upper soil layer (30 cm) compared to the deeper layer (30-60 cm). With the changes in mineral nitrogen, the most intensive soil Nt transformation processes occurred in the upper soil layer. Significantly higher Nmin concentrations were determined in the plots applied with mineral nitrogen compared to the other experimental treatments. The highest values of soil Nmin were determined in July: 47.7 in the 0-30 cm and 17.4 mg kg-1 in the 30-60 cm layer. [ABSTRACT FROM AUTHOR]

The present study was aimed at setting up and testing an experimental procedure to evaluate the anaerobic degradability of grasses and legumes by short term batch tests. The experiment was performed with the manometric OxiTop Control system. Biogas release of the 3 plant species (cocksfoot, lucerne and and fodder galega) of the 3rd cut was influenced by their chemical composition. The greatest differences between species were obtained in nitrogen, water soluble carbohydrates, hemicellulose and cellulose. Cocksfoot biomass had the lowest ADL concentration and the highest hemicellulose content, which was 3.5 times higher than that of lucerne and 11.0 times higher than that of fodder galega. According to the chemical composition, cocksfoot seems to be the most appropriate feedstock for biogas production, because it contains the lowest concentration of ADL, ADF and ash, the highest concentration of NDF and hemicellulose, WSC and the most appropriate C:N. The curve of biogas production from legumes, which contain more nitrogen and proteins, less hemicellulose was sharper, but biogas pressure was more than twice lower compared to that of cocksfoot. It was concluded that perennial grass cocksfoot of the late (3rd) cut was proved to be much more suitable for the biogas production compared to the legumes lucerne and fodder galega. [ABSTRACT FROM AUTHOR]

Re-naturalisation was investigated in 2012 on a peat bog (Pachiterric Histosol) with a non-removed peat layer at the former Radviliskis Experimental Station of the Lithuanian Institute of Agriculture in the site of the long-term field experiment, which had been completed 12 years ago. Peat samples were taken from 0-10, 10-20 and 20-30 cm layers in 3 field replicates. Chemical analyses were carried out at the Chemical Research Laboratory of Institute of Agriculture, LRCAF. The previously differently used peat soil contained different stocks of organic carbon (SOC). SOC stocks in the soil occupied with grassland were greater than those in peat soil previously not used for agriculture. The largest stock of MHA was in fonner unfertilised perennial grasses (0-30 cm)- 78.67% compared with other treatments. MHA content increased with increasing depth. The lower stability of carbon compounds in 0-30 cm layer was determined in the peat previously un-used for agricultural purposes, which had the highest relative share (40.9%) of dissolved organic carbon (DOC), characterized by the highest lability. We concluded that the most efficient way to conserve and sustain organic carbon in peat is to grow perennial grasses under non-intensive management system. [ABSTRACT FROM AUTHOR]

It is widely believed that soil disturbance by tillage is a primary cause of the loss of soil organic carbon (SOC) and that substantial SOC sequestration can be accomplished by conversion from conventional ploughing to reduced tillage. The objective of our study was to find alterations of the organic C content in soil humic and granulodensimetric fractions depending on soil tillage and crop rotation. The field experiment was carried out at the Joniskelis Experimental Station of the Lithuanian Institute of Agriculture on a drained clay loam Endocalcari-Endohypogleyic Cambisol (CMg-n-w-can). Two technologies -- reduced tillage (RT) and conventional tillage (CT) -- were compared in crop rotations with different proportions of overwintering and spring crops (0%, 25%, 50%, 75%, and 100% overwintering crops). The results of 2004-2006 are presented. Tillage had a greater influence than crop rotation on all soil C fractions. RT promoted the formation of all fractions of humic acids and FA1 and FA3 fractions of fulvic acids in the entire plough layer. Increasing the proportion of overwintering crops in the rotation to 100% tended to strengthen this effect. The C content in particulate organic matter (POM), light fraction (LF), and both clay-sized sub-fractions, expressed per unit mass of soil, significantly increased under RT in the top 15 cm of soil. The introduction of overwintering crops into the rotation and increasing their proportion had a significant positive influence on C content in POM and LF in the whole plough layer. [ABSTRACT FROM AUTHOR]