Scientia Silvae Sinicae ›› 2005, Vol. 41 ›› Issue (5): 180-183.doi: 10.11707/j.1001-7488.20050532
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Tian Kun,Yue Cairong
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Soil samples archived over four decades were used in an incubation experiment to measure the effects of reforestation on nitrogen dynamics in old agricultural fields. Samples collected from 0 to 7.5 cm and 35 to 60 cm depths in Calhoun,South Carolina USA at intervals ranging between five and nine years since 1962 were incubated aerobically at 30 ℃ for 30 days using a system specially designed to maintain constant soil moisture. Mineral N was measured in 2 mol·L-1 KCl extracts. The ratio of mineralized N to total N rapidly decreased in the first two decades of forest development. Within 20 years after planting, plenty of available N had been accumulated in the biomass, which had a significant negative correlation with soil total N (rtop-0.828~-0.898; rdeep-0.848~-0.989). It indicated that agricultural inputs of N were important to early tree development. Significantly, by age 40, soil mineral N had increased to 50%of that in the beginning of tree planting. The accretion of mineralizable N suggests that forest floor is serving as an increasingly important source for this nutrient. Further, it indicates that forest managers have the opportunity to manipulate a large pool of forest organic matter to sustain soil N supply.
Key words: conrersion of cropland to forest, N-mineralization, nitrogen dynamics
Tian Kun;Yue Cairong. Effects of Afforestation on Abandoned Cropland on Soil Nitrogen Mineralization[J]. Scientia Silvae Sinicae, 2005, 41(5): 180-183.
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