有机无机不同用量配施对煤矿复垦土壤氮素利用及矿质氮含量的影响

采煤塌陷新复垦土壤有效氮含量低而有机无机培肥过程中氮有效性变化尚不明确,依托定位培肥试验基地(山西省孝义市水峪煤矿采煤塌陷复垦土壤),设置8个不同处理包括3个有机无机不同用量配施处理(鸡粪与化肥1∶1氮量在100,150,200 kg/hm~2配施,表示为MF100、MF150、MF200),与单施不同用量化肥氮(0,100,150,200 kg/hm~2,表示为IF0、IF100、IF150、IF200)相比较,以不施肥为对照(CK)。通过测定玉米产量、植株吸氮量、氮肥利用率及作物收获后土壤剖面矿质氮含量,确定适合该矿区复垦土壤施肥处理和最佳氮肥用量,从而为高产高效培肥矿区复垦土壤提供科学理论依据。结果表明:(1)施氮量为150 kg/hm~2的等养分条件下,MF150比IF150玉米籽粒产量提高了12.45%,差异显著(P0.05);同时MF150处理与IF200、MF200处理间差异均不显著(P0.05)。(2)玉米地上部吸氮量随施氮量的增加而增加,且等氮量条件下,鸡粪和化肥配施能显著提高玉米吸氮量(P0.05),增幅为39.45%～41.46%。(3)等氮量条件下,鸡粪和化肥配施较单施化肥处理能显著提高氮肥回收率;不同施肥模式的氮肥偏生产力均随施氮量的增加呈现下降趋势;IF100处理氮肥农学利用率最高为24.08 kg/kg,并且该处理与MF150无显著差异,而等氮量下MF150较IF150处理的氮肥农学效率显著增加(提高了49.56%)。(4)作物收获后0—40 cm土壤剖面矿质氮含量随土层深度而增加,但是等氮量各施肥处理间无显著差异,40—60 cm剖面中单施化肥氮各处理矿质氮残留量较配施各处理提高了约18%。总之,MF150施肥处理不仅提高作物产量、吸氮量和氮肥利用率,而且土壤剖面矿质氮残留较少,可作为培肥该矿区复垦土壤或与本试验土壤类型相似的低产农田的推荐施肥量。

Effects of Different Dosages of Organic and Inorganic Fertilizers on Nitrogen Utilization Rate and Mineral Nitrogen Content in Coal Mining Reclaimed Soil

The content of available nitrogen (N) is generally low in coal mining subsidence reclamation soil. Appling organic and inorganic combined fertilizers can improve soil N fertility, whereas N availability is unclear after fertilization, especially in a new coal mining reclaimed soil. This experiment was conducted in coal subsidence reclamation soil of Shuiyu Coal Mining, which located in Xiaoyi City, Shanxi Province. The experiment included eight treatments which were three organic-inorganic combined treatments (application rate of chicken manure and chemical fertilizer was 1:1, and N at 100, 150 and 200 kg/hm², expressed with MF100, MF150 and MF200), four single application of different amounts of chemical fertilizer nitrogen (N at 0, 100, 150 and 200 kg/hm², expressed with IF0, IF100, IF150 and IF200), as well as control (no fertilization, CK). We evaluated corn yield, aboveground nitrogen uptake, nitrogen use efficiency and mineral nitrogen content in soil profile after crop harvest, so that the suitable fertilization treatment and optimum nitrogen application rate were determined, which could provide scientific theoretical basis for reclaiming mining area soil in a way of high-yield and high-efficiency fertilization. The results showed that:(1) Under the condition of 150 kg/hm² nitrogen fertilizer, the grain yield of MF150 was 12.45% higher than that of IF150 (P<0.05). Furthermore, there was no significant difference in grain yield among IF150, IF200 and MF200. (2) Nitrogen uptake of corn aboveground increased with the increasing of nitrogen application rate, while at the same nitrogen rate, the combined application treatment significantly increased nitrogen uptake by 39.45%~41.46% relative to single chemical fertilizer treatment (P<0.05). (3) At the same nitrogen rate, combined fertilizer treatment could significantly improve nitrogen recovery rate compared with single chemical fertilizer application. The partial productivity of nitrogen fertilizer in differentfertilization patterns showed a downward trend with the increasing of nitrogen application rate. The highest nitrogen agronomic efficiency (24.08 kg/kg) was observed in the IF100 treatment, and there was no significant difference between MF150 and IF100. However, at the same nitrogen rate, agronomic nitrogen efficiency of MF150 significantly increased by 49.56% compared with IF150. (4) After harvesting, mineral nitrogen content in 0-40 cm soil profile increased with soil depth, whereas at the same nitrogen rate there was no significant difference among different treatments. At 40-60 cm depth, the residual mineral nitrogen content of single chemical fertilizer application increased by about 18% compared with the combined fertilizer treatment. In a word, MF150 not only improved grain yield, nitrogen uptake and nitrogen use efficiency, but also reduced residual mineral nitrogen content in soil profile after plant harvest, hence MF150 could be used as a recommended fertilization treatment for this coal mining subsidence reclaimed soil or low-yield farmland similar to the soil type in this experiment.