Long-term influence of tillage and fertilization on net carbon dioxide exchange rate on two soils with different textures.

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.

The potential of digestate as a biofertilizer in eroded soils of Lithuania.

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 (P2O5) and potassium (K2O) 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 P2O5, 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 K2O. 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.