The decomposition of fresh crop residues added to soil for agricultural purposes is complex. This is due to different factors that influence the decomposition process. In field conditions, the incorporation of crop residues into soil does not always have a positive effect on aggregate stability. The aim of this study was to investigate the decomposition effects of residues from two different cover crops (Brassica napus var. oleifera and Secale cereale) and one main crop (wheat straw) on soil aggregate stability. A 105-day incubation experiment was conducted in which crop residues were mixed with sandy loam soil at a rate of 6 g C kg⁻¹ of soil. During the incubation, there were five water additions. The decomposition effects of organic matter on soil conditions during incubation were evaluated by determining the soil functional groups; carbon dioxide (CO₂), nitrous oxide (N₂O), and methane (CH₄) emissions; soil microbial biomass carbon (MBC); and water-stable aggregates (WSA). The functional groups of the plant residues and the soil were analyzed using Fourier transform infrared spectroscopy (FTIR) and a double exponential model was used to estimate the decomposition rates. The results show that the decomposition rate of fresh organic materials was correlated with the soil functional groups and the C/N ratio. Oilseed rape and rye, with lower C/N ratios than wheat straw residues, had faster decomposition rates and higher CO₂ and N₂O emissions than wheat straw. The CO₂ and N₂O flush at the start of the experiment corresponded to a decrease of soil aggregate stability (from Day 3 to Day 10 for CO₂ and from Day 19 to Day 28 for N₂O emissions), which was linked to higher decomposition rates of the labile fraction. The lower decomposition rates contributed to higher remaining C (carbon) and higher soil aggregate stability. The results also show that changes in the soil functional groups due to crop residue incorporation did not significantly influence aggregate stability. Soil moisture (SM) negatively influenced the aggregate stability and greenhouse gas emissions (GHG) in all treatments (oilseed rape, rye, wheat straw, and control). Irrespective of the water addition procedure, rye and wheat straw residues had a positive effect on water-stable aggregates more frequently than oilseed rape during the incubation period. The results presented here may contribute to a better understanding of decomposition processes after the incorporation of fresh crop residues from cover crops. A future field study investigating the influence of incorporation rates of different crop residues on soil aggregate stability would be of great interest.

The development of new options to reduce ammonia (NH₃) emissions during slurry manure storage is still required due to the shortcomings of the current technologies. This study aimed to identify to what extent untreated and acid-treated biochar (BC) and pure acids could reduce ammonia nitrogen (NH₃-N) volatilization and increase nitrogen retention in slurry digestate. The NH₃-N emissions were effectively reduced by H₂SO₄ and H₃PO₄ acids, untreated BC when applied mixed into the digestate and acidified BC treatments applied on the surface of the digestate. Acidification increased the specific surface area and number of O-containing surface functional groups of the BC and decreased the pH, alkalinity and the hydrophobic property. Compared to untreated BC, the ability of BC to reduce NH₃-N emissions was greater when it was acidified with H₂SO₄ and applied to the digestate surface. The effect on digestate pH of acidified BC when applied mixed into the digestate was not different, except for H₂O₂, from that of the addition of the respective pure acid to digestate. The total N concentration in digestate was not significantly correlated with NH₃-N emissions. These findings indicate that acidified BC could be an effective conditioner to reduce NH₃-N emissions from slurry digestate storage.

Chemical Composition and Quality of Cultivated and Natural Blueberry Fruit in Estonia: Nutrition studies suggest that blueberries help keep us healthy and these possible health benefits may be due to the antioxidant capacity as well as other natural compounds in blueberry fruit. Different taxa of Vaccinium species (Bilberry - Vaccinium myrtillus L.; lowbush blueberry - Vaccinium angustifolium Ait.; half-highbush blueberry - Vaccinium corymbosum x Vaccinium angustifolium ‘Northblue’ and ‘Northcountry’) were analyzed for surface color, size, sugars, titratable acidity, soluble solids, fat, protein, vitamins and anthocyanin content. The blueberry fruit were harvested from three commercial blueberry plantations and from one natural habitat in 2003. The fruit of V. angustifolium were collected from two different areas: one plantation was located on mineral soil and the other on peat soil (abandoned peat pits). The anthocyanin content ranged from 125 to 405 mg·100 g^-1 of fresh berry in different species and cultivars. Half-highbush blueberry ‘Northblue’ had the largest berry size but ascorbic acid and anthocyanin contents were low. V. myrtillus had the lowest total energy value, but the highest anthocyanin content. Glucose and fructose content was higher in fruit of V. angustifolium compared with the other species. The soil type (mineral or peat soil) did not affect anthocyanin and ascorbic acid content of V. angustifolium fruit but titratable acids and moisture content was higher in fruit of V. angustifolium grown on peat soil, compared with mineral soil.

ISHS IV International Conference Postharvest Unlimited 2011 EFFECT OF CONTROLLED ATMOSPHERE STORAGE ON STORAGE LIFE OF ONION AND GARLIC CULTIVARS