施用化肥对砂姜黑土碳库管理指数的影响

摘要

To analyze the negative properties of lime concretion black soil, an experiment using six different application concentrations of N fertilizer of 0, 360, 450, 540, 630, 720 kg N hm-2 was conducted over four years in Mengcheng City, China. The effects of the N fertilizer application rates on soil organic matter fraction and the carbon management index (CMI) in lime concretion black soils were systematically studied using the data obtained at this test location and through analyzing the change in soil organic matter fraction and CMI. The results showed that the application of N fertilizer increased the total organic matter (TOM) and labile organic matter (LOM). The ranges of TOM and LOM were 17.49~19.46 and 3.10~3.52 g·kg-1, respectively, and the increased values of TOM, LOM and non-labile organic matter (NLOM) compared with no fertilizer treatment were between 1.53~3.53, 0.10~0.52 and 1.02~4.30 g·kg-1, but had no significant differences among the rates of N application. The range of change of the high labile organic matter (HLOM) was between 0.46~0.62 g·kg-1, had a decreasing trend with increasing N fertilizer application, and showed significant differences between the high N fertilizer application rate and no fertilizer application (P<0.05). However, the medium labile organic matter (MLOM) was comparatively low, and was affected by the nitrogen application rates. Its value increased when N was greater than 540 kg N·hm-2, which was a critical value of N fertilizer application rate. However, there were no significant differences between different N fertilizer treatment amounts. of all the treatments, soil NLOM could be advanced to cause an increase in total organic matter, with CMI not affected by the N fertilizer application rate. Maize yields from application of N fertilizer treatments were clearly higher than no fertilizer treatment conditions with the highest yield of 11 137.90 kg·hm-2 for 720 kg N·hm-2 N fertilizer application rate. Correlation analysis showed the relationship between LOM and HLOM was the most significant, having the highest relevance. Carbon management index was significantly related to LOM (P<0.01), with a correlation coefficient of 0.910**. There was a significant positive correlation between TOM and LOM (P<0.05), and no significant difference between TOM and CMI (P>0.05). The maize grain yield was very significantly correlated with TOM and LOM (P<0.01), with no correlation with CMI (P>0.05). Therefore, the addition of chemical fertilizer can increase the total organic matter in lime concretion black soil, mainly due to increases in stable organic matter, and labile organic matter, thereby changing the fertility in these areas.%针对安徽省砂姜黑土的不良属性，在安徽蒙城砂姜黑土上进行了4年的施肥定位试验，施肥方式为年施氮量（以 N计）0、360、450、540、630、720 kg·hm-2，玉米季占55%，通过研究连续施肥措施下砂姜黑土耕层土壤活性有机质组分的变化特征，分析了单施化学氮肥对土壤有机质组分及碳库管理指数的影响。结果表明：施用化学氮肥有利于提高土壤总有机质质量分数和活性有机质质量分数，变化幅度分别为17.49~19.46、3.10~3.52 g·kg-1，化肥施用水平之间差异不显著，相比不施肥，施肥土壤的总有机质质量分数增加1.53~3.53 g·kg-1、活性有机质质量分数增加0.10~0.52 g·kg-1、稳定态有机质增加1.02~4.30 g·kg-1。处理间高活性有机质质量分数变化范围为0.46~0.62 g·kg-1，施用化肥后降低，高量氮肥与不施肥处理间差异显著(P<0.05)；中活性有机质质量分数在2.21~3.25 g·kg-1之间，且与氮肥施用水平有关，年施氮量（以N计）高于540 kg·hm-2时其值增加，但各施用水平间无显著差异(P>0.05)。施氮对CMI的影响不显著，土壤总有机质增加的有机质组分主要为稳定性有机质。施氮处理的玉米籽粒产量明显高于不施氮处理，年施氮（以N计）720 kg·hm-2的玉米籽粒产量最高，达11137.90 kg·hm-2。相关性分析结果显示，3种活性有机质之间，活性有机质和高活性有机质相关性最高，关系最为密切；碳库管理指数与活性有机质呈极显著正相关，相关系数为0.910；总有机质含量与活性有机质含量显著正相关(P<0.05)，与碳库管理指数无显著相关性(P>0.05)；玉米籽粒产量与总有机质、活性有机质极显著正相关(P<0.01)，与碳库管理指数显著相关(P<0.05)。由此可知，化学氮肥可促进砂姜黑土耕层土壤总有机质和活性有机质的提高，且二者均能够反映砂姜黑土施用化肥后的肥力变化情况；提高砂姜黑土总有机质的有机质组分主要是稳定态有机质；要提高玉米产量需要较高的氮肥用量。