施氮与间作对玉米和马铃薯钾吸收与分配的影响

【目的】探讨不同氮水平下间作对作物钾吸收、分配与利用的影响，为高效施肥提供依据。【方法】采用两年田间小区试验，以常规玉米施氮量N 250 kg/hm2为基础，设:不施氮（N0）、1/2常规量（N1）、常规量（N2）、3/2常规量（N3）四个处理，调查了间作玉米和马铃薯对钾素的吸收、分配及利用效率。【结果】随施氮量增加，单作玉米、间作玉米和单作马铃薯产量逐渐增加，以N2、N3产量最高，而间作马铃薯产量在N1水平达到最高，氮肥用量增加到N2反而下降；玉米马铃薯有间作增产优势，土地当量比（LER）随着施氮水平增加逐渐降低。单作和间作玉米吸钾量随着施氮水平提高先增加后减少，在N1或N2水平钾吸收达到最大，单作马铃薯吸钾量随施氮量增加逐渐增加，间作马铃薯则先增加后减少，分别在N3和N1水平达到最大。不同施氮水平下，间作玉米较单作玉米提高钾吸收量15.7~20.0 kg/hm2（2013年）和22.6~78.3 kg/hm2（2014年），在低氮（N0、N1）水平下增加显著；玉米钾吸收量主要集中在秸秆，占钾吸收总量的64.5%~75%（2013年）和61.6%~74.5%（2014年），间作增加的钾主要分配到了籽粒中，钾吸收量的分配在马铃薯中没有明显差异。间作提高了玉米钾利用效率，对马铃薯没有显著影响，随着施氮量增加，钾吸收土地当量比逐渐降低。【结论】施氮水平和种植模式对玉米马铃薯钾吸收有极显著交互作用；在施氮肥为常规水平的一半，即N 62.5 kg/hm2时，间作增产和促进钾吸收潜力达最大，随着施氮量的增加，交互作用对钾的吸收优势逐渐减弱。因此，适当施氮可充分发挥间作促进钾吸收的优势。

Effects of N application on potassium absorption and distribution of maize and potato in intercropping system

[Objectives]The study aimed to explore the effects of the intercropping of maize and potato on potassium absorption, distribution and utilization of crops in different N application levels.[Methods]A 2-year field experiment, included four N levels (unfertilized, N0; 1/2 conventional fertilized, N1; conventional fertilized, N2 and 3/2 conventional fertilized, N3), was conducted to study the effects of the nitrogen fertilization and intercropping on potassium absorption and distribution as well as absorption of maize and potato.[Results]The yields of maize and potato were increased with the increase of N application in monoculture maize, and intercropping of maize and potato and monoculture potato, the yields were the maxima in the N2 and N3 levels. However, yields of intercropping potato first increased then reduced, the maximum was in the N1 level. Intercropping of maize and potato had advantage of the yield increases, and land equivalent ratio (LER) reduces with the increased of N application. The potassium uptakes of monoculture maize and intercropping maize were first increased and then decreased with the increase of nitrogen application, and reached the maxima in the N1 or N2 levels. The potassium uptakes of potato were increased with the rise of N application in monoculture, and first increased then reduced in the intercropping, reached the maxima in the N3 and N1 levels, respectively. The intercropping increased potassium uptakes of maize by 15.7–20.0 kg/hm2 (2013) and 22.6–78.3 kg/hm2 (2014) than those of the monoculture, and the difference was significant in the low N levels (N0 and N1). The potassium uptakes of maize were mainly concentrated in the straw, accounting for 64.5%–75% of the total potassium absorption (2013) and 61.6%–74.5% (2014), and the increased potassium was mainly allocated to the grain. However, potassium distribution of potato was no significantly different. The intercropping raised potassium use efficiency of maize, and had no significant effect on potato. Potassium absorption of LER was decreased with the increase of N application.[Conclusions]There is very significant interaction between the nitrogen application and the intercropping on potassium uptakes of maize and potato. When the N application level is 50% of currently used level (62.5 kg/hm2), the potential of increasing yields and potassium uptakes in the intercropping is the maximum. The potassium uptakes of the interaction will gradually be weakened with the increase of N application. Therefore, appropriate N application is neccessary for promoting potassium uptakes in the intercropping system of maize and potato.