不同培肥措施下复垦土壤氮素转化特征

为揭示不同复垦年限和培肥措施对采煤塌陷区复垦土壤氮素转化特征影响,分别采用间歇淋洗好气培养法、室内恒温控湿好气培养法和硝酸盐消失法研究了5种培肥措施下复垦4,8年土壤矿化、硝化、反硝化作用规律。结果表明:随复垦年限增加,土壤的矿化量(Nt)和矿化势(N0)均有增加,但土壤矿化率(Nt/N)及矿化势占全氮的比例(N0/N)无明显变化;不同培肥措施下,复垦8年土壤生物有机肥配施化肥处理(MCFB)Nt、N0、Nt/N和N0/N分别较单施化肥处理(CF)提高65.22%,65.21%,60.42%和60.76%。土壤硝化率和达到最大硝化速率需要的时间(Tmax)受复垦年限影响较小,不同施肥措施均可提高土壤硝化率,但处理间差异不显著;最大硝化速率(Vmax)随复垦年限增加而增大,复垦4,8年土壤Vmax和Tmax总体以MCFB效果优于其他培肥处理。土壤硝态氮损失率和硝酸盐消失速率随复垦年限的增加而增加,经过7天培养,不同培肥措施下复垦4年土壤硝态氮损失率以单施有机肥处理(M)最高,达78.72%,硝酸盐消失速率以MCFB处理最低,与不施肥对照(CK)一致;复垦8年土壤反硝化作用在不同处理下无显著差异。通过短期氮素转化作用强度比较,复垦土壤硝化作用>反硝化作用>矿化作用。综合来看,培肥对复垦土壤氮素转化作用提升效果明显,生物有机肥配施化肥更有利于土壤有效氮的保持和提高,减少氮素损失。

Nitrogen Transformation Characteristics of Reclaimed Soil Under Different Fertilizer Application Measures

In order to reveal the effects of different reclamation years and fertilization measures on nitrogen transformation characteristics of reclaimed soils in coal mining subsidence areas, intermittent leaching and aerobic culture method, laboratory aerobic incubation method with constant temperature and controlled humidity, and nitrate loss method were used to study the regularities of soil mineralization, nitrification and denitrification in reclaimed soil for four years and eight years, respectively, under five fertilization measures. The results showed that as the increasing of reclamation years, both cumulative mineralized nitrogen (N_t) and potentially mineralizable nitrogen (N₀) increased, while mineralization rate (N_t/N) and the proportion of N₀ to total N (N₀/N) did not change significantly. Under different fertilization measures, the N_t, N₀, N_t/N and N₀/N of eight years reclaimed soil in MCFB treatment (application chemical fertilizer combined with biological organic fertilizer) increased by 65.22%,65.21%, 60.42% and 60.76%, respectively, compared with chemical fertilizer treatment (CF). The soil nitrification rate and the time needed to reach the maximum nitrification rate (T_max) were less affected by reclamation years, and nitrification rates of different fertilization treatments were all higher than that of CK treatment, but there was no significant difference between treatments. The maximum nitrification rate (V_max) increased with the increasing of reclamation years. Treatments of MCFB could improve V_max and T_max more effectively than other treatments in soils reclaimed for four and eight years. Nitrate loss and nitrate disappearance rate increased with the increasing of reclaimation years. After seven days of cultivation, in the reclaimed soil for four years, the nitrate loss was the highest in organic manure treatment(M), reaching 78.72%, and the nitrate disappearance rate was the lowest in MCFB treatment, which was consistent with CK. There was no significant difference in soil nitrogen denitrification among different treatments for soil reclaimed for eight years. The sequence of short-term nitrogen transformation intensity was nitrification>denitrification>mineralization. On the whole, fertilization had obvious improvement effect on nitrogen transformation characteristics in reclaimed soil, and chemical fertilizer combined with biological organic fertilizer was more conducive to the maintenance and improvement of soil available nitrogen and reduce nitrogen loss.