Effect of sampling date on nitrogen mobilization during incubation experiments
SummaryThe influence of time of sampling on nitrogen mobilisation in incubation experiments at 20°C with humus and mineral soil samples has been systematically investigated. After five and seven samplings, respectively, during the years 1967 and 1968, it has been established that the amounts of mineral nitrogen formed vary considerably more after incubation than other characteristics investigated in samples taken at different times.The variation is great in both humus layer and mineral soil (0–5 cm) and decreases somewhat when the incubation time increases from six to nine weeks.The dry weight, density, ignition loss and Kjeldahl nitrogen of the sample vary relatively little on different sampling occasions, usually with a variation coefficient by about five per cent.The mineral nitrogen after incubation showed rather large coefficients of variation (up to 57 per cent) for the years investigated.For this reason the time at which samples are collected for incubation experiments cannot be considered irrelevant.
SUECICA Intensive fertilization with nitrogen as a stressing factor in a spruce ecosystem I . Soil effects
ODC 232.322.411: 181.343-174.7 Soil studies were carried out before and after clear felling o f an intensively fertilized young spruce plantation on old arable land. Particular attention was devoted to nitrogen mineralisation, nitrification, and leaching. Notable anzounts of nitrate in the soil occurred before felling only on plots receiving high doses of amrnonium nitrate, after clear felling also on some plots with no or low nitrogen supply. Marked quantities of nitrate nitrogen were observed in the deeper soil layers during the fertilizer experiment in plots with high fertilizer additions. The soil reaction indicated an acidification as a result of fertilizer treatment. In a pot experiment with soil Jrom the field experiment the nitrate leaching by percolation was studied. Most of the leaching of nitrate nitrogen occurred in the first phase o f the experiment. After the vegetation was established, the nitrate concentration in the percolating water rapidly decreased. Ms received 1974-07-28
The incidence of dead and dying fish in the Moray Firth, September 1963
Dead and dying fish were reported from the Moray Firth during a period of 15 days in September 1963. The initial mortalities were in the inner Firth, but they later spread outwards, especially eastwards along the southern shores of the Firth. Mass mortalities of the lugworm (Arenicola marina) also occurred in Scottish waters in 1962 and 1963, and at Balintorein Easter Ross fish and lugworm mortalities were contemporary.