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土壤有机C、N的定量动态变化是评价不同土地利用方式对土壤质量影响的重要内容。本文比较了研究地区种植黑麦草(LoliummultiflorumLam.)、百喜草(PaspalumnotatumFlugge.)、桔树(CitrusreticulataBlanco.)和马尾松(PinusMassonianaLamb.)的四种土地利用方式对植物生物量和土壤有机C、N多年变化的影响。试验初期,四种土地利用方式的植物生物量几乎处于同一水平。经过10年长期试验后,黑麦草和百喜草的累计生物量分别是桔树的3.68和3.75倍,马尾松的2.06和2.14倍。地下部生物量的差异更为明显,黑麦草和百喜草两种草类地下部累计生物量都较桔树和马尾松高10倍之多。这表明草类较之乔木更有利于提高土壤有机C、N的含量。土壤有机C、N的含量变化主要发生在0-40cm土层。统计计算表明,10年期间,种植黑麦草和百喜草可使土壤有机C、N贮量每公顷分别约增加1.5吨和0.2吨,而种植桔树使土壤有机C、N贮量每公顷分别约减少1.2吨和0.02吨,种植马尾松使土壤有机C、N贮量每公顷分别约减少0.4吨和0.04吨。表4参10。
Quantitative dynamic changes of soil organic carbon and nitrogen are important contents to evaluate the impact of different land use types on soil quality. In this paper, we compared the effects of four land use types of Lolium multiflorum Lam., Paspalumotatum Flugge., Citrus reticulata Blanco and Pinus Massoniana Lamb on the plant biomass and soil organic C, N The impact of years of change. At the beginning of the experiment, plant biomass of the four land-use types was almost at the same level. After ten years of long-term trials, the cumulative biomass of ryegrass and bahia was 3.68 and 3.75 times for orange trees and 2.06 and 2.14 times for masson pine, respectively. The differences of the biomass in the lower part of the ground were more obvious. The accumulated biomass of the lower part of ryegrass and hippophae was ten times higher than that of the orange tree and masson pine. This shows that grass is more conducive to improving soil organic C, N content than the tree. Soil organic C, N content changes occur mainly in 0-40cm soil layer. Statistical calculations show that planting ryegrass and hippophae during 10 years can increase soil organic C and N storage by about 1.5 tons and 0.2 tons per hectare, respectively, while planting orange trees makes soil organic C and N stocks per hectare About 1.2 tons and 0.02 tons respectively. Planting Pinus massoniana decreased soil organic C and N storage by about 0.4 tons and 0.04 tons per hectare respectively. Table 4 Reference 10.