施氮模式对番茄氮素吸收利用及土壤硝态氮累积的影响

Effects of Models of N Application on Greenhouse Tomato N Uptake,Utilization and Soil NO_3^--N Accumulation

采用田间小区试验,以番茄为指示植物,研究不同施氮模式:农民习惯施肥(N-farmer)、减施化肥氮26%(74%N-farmer)、减施化肥氮26%结合调节土壤C/N(74%N-farmer+S)、减施化肥氮26%结合调节土壤C/N和采用滴灌(74%N-farmer+S+D)、减施化肥氮45%结合调节土壤C/N和采用滴灌(55%N-farmer+S+D)的集成模式对设施番茄氮素吸收利用及土壤硝态氮累积的影响。结果表明,55%N-farmer+S+D模式下番茄产量最高为108349kg.hm-2,产投比最高为26.1;与N-farmer模式相比,74%N-farmer、74%N-farmer+S、74%N-farmer+S+D和55%N-farmer+S+D模式的氮素利用率和氮素农学利用效率均有增加,其中55%N-farmer+S+D模式的氮素当季利用率为9.56%,氮素农学效率为43.67kg·kg-1,均显著高于N-farmer模式(P<0.05);氮肥生理利用效率在各施氮模式间没有显著差异,55%N-farmer+S+D模式的效率最高为598.06kg·kg-1;55%N-farmer+S+D模式的氮素果实生产效率和收获指数分别为493.81kg·kg-1和53.84%,均高于N-farmer模式。氮平衡结果表明,N-farmer模式的表观损失最高,55%N-farmer+S+D模式显著低于N-farmer模式;相同土壤剖面中不同模式硝态氮含量随番茄生育进程均呈先增高后降低的趋势;番茄盛果期和拉秧期,74%N-farmer+S、74%N-farmer+S+D和55%N-farmer+S+D模式在0～100cm剖面累积的硝态氮含量均低于N-farmer模式,拉秧期N-farmer模式累积的硝态氮含量最高达705.24kg.hm-2,74%N-farmer+S+D模式累积的硝态氮含量最低为453.75kg.hm-2;番茄在3个不同生育期,土壤硝态氮多累积在0～40cm土层,硝态氮的相对累积量约为50%。综合以上分析结果,集成模式55%N-farmer+S+D具有明显优势,能够提高氮肥的吸收和利用效率,减少土壤硝态氮的残留。

Continuously excessive nitrogen（N） input in vegetable-greenhouse is one of the major problems in China, especially in Shouguang, Shandong Province, the famous vegetable production base, which has cause the imbalance of C/N, the decrease of utilization rate of N and fall of fruit quahty. Besides, over accumulation of soil nitrate-nitrogen（NO3-N ） in protected vegetable fields will give a serious menace to the quality of groundwater. Aiming at these problems, a field experiment was conducted to study the effects of different N levels（ 1 000, 740, 550 kg·hm^-2） and models of applying N fertilizer（reducing chemical N fertilizer, reducing chemical N fertilizer combined to adjust soil C/N ratio, reducing chemical N fertilizer combined to adjust soil C/N ratio and adopting drip irrigation） on tomato N uptake, N utilization and NO3-N residual in soil. The main results were as follows：tomato yield were increased after applying N fertilizer and yield growth rate reached over 20%. The maximum production（ 108 349 kg·hm^-2） and value cost ratio（26.1 ） appeared in the model of 55%N-farmer＋S＋D. Compared with the local farmer＇s conventional model of applying N fertilizer（N-fanner）;N use efficiency and N agronomic efficiency of reducing chemical N fertilizer combined to adjust soil C/N ratio and adopting drip irrigation measure（74% N-farmer,74%N-farmer＋S,74 %N-farmer＋S＋D and 55%N-farmer＋S＋D） were all increased, N use efficiency of 55%N-fanner＋S＋D was 9.56% and N agronomic efficiency was 43.67 kg·kg^-1, respectively, which were both significantly higher than N-farmer （P〈0.05）. There was no significant difference of N physiologic efficiency among the models, the maximum value was 598.06 kg·kg^-1 in the model of 55%N-farmer＋S＋D. N fruit production efficiency and N harvest index of 55%N-farmer＋S＋D was 493.81 kg·kg^-1 and 53.84%, respectively, higher than N-farmer. The research on N balance indicated that N surplus（apparent N losses ） was more higher in N-farmer than others models, the apparent N of 55%N-farmer＋S＋D was 186.24 kg·hm^-2 which was significantly lower than N-farmer（P〈0.05 ）. In the same soil depth, the amount of NO3-N of different models of applying N fertilizer increased from the flowering stage to the full fruit stage, but decreased from the full fruit stage to last harvest. The NO3-N accumulation in the soil layer of 0-100 cm of the models of 74 %N-farmer＋S, 74%N-farmer＋S＋D and 55%N-farmer＋S＋D were lower than that of N-farmer. The NO3-N accumulation of the model of N-farmer model was 705.24 kg·hm^-2, which was higher than others models at last harvest. 74%N- farmer＋S＋D model accumulated less NO3-N in the soil, which was 453.75 kg·hm^-2. Nitrate accumulates mostly in the soil layer of 0-40 cm and less in deep soil layers, relative nitrate-N accumulation account for more than 50%. The results of all the above-mentioned indicated that the model of 55%N-farmer＋S＋D is the feasible N management practice.