长期平衡施肥对潮土微生物活性和玉米养分吸收的影响

利用中国科学院封丘农业生态实验站农田生态系统养分平衡长期定位试验地,研究氮磷钾平衡施肥(NPK)与缺素施肥(NK、PK、NP)对土壤微生物生物量、酶活性、呼吸强度以及玉米养分吸收的影响。结果发现,与不施肥对照(CK)相比,NPK处理玉米根系与茎叶生物量、籽粒产量以及植株氮磷钾吸收量均大幅提高,NP处理次之,PK与NK处理则无显著影响;同一处理玉米茎叶与根系养分含量接近,而籽粒的全氮和全磷含量较高、全钾含量偏低;与NPK处理相比,缺施氮、磷或钾肥均直接导致玉米植株相应养分的明显亏缺或其他养分的过量富集,但在根系、茎叶和籽粒部位的累积情况存在一定差异。与CK相比,所有施加磷肥的处理(NPK、NP、PK)土壤微生物生物量(碳、氮、磷)、脱氢酶、转化酶、脲酶与碱性磷酸酶活性以及土壤微生物代谢活性和土壤基础呼吸强度均显著升高(p<0.05),土壤微生物代谢熵则显著下降(p<0.05),而缺施磷肥的NK处理除显著提高脲酶活性外(p<0.05),对其他指标均无显著影响。结果表明,氮磷钾平衡施肥在促进土壤微生物繁育和保育微生物代谢活性以及促进作物生长和保证养分吸收等方面显得非常重要,而缺素施肥中以缺施磷肥的不利影响最为突出。

Effects of long-term balanced fertilization on microbial activity and nutrient uptake of maize in a fluvo-aquic soil

A long-term stationary field experiment on nutrient balance for farming ecosystem in the Fengqiu National Agro-ecological Experiment Station was made use of to investigate effects of fertilization, balanced or unbalanced, on microbial biomass, enzymatic activities, and soil basal respiration as well as nutrient uptake of maize plants in a fluvo-aquic soil. The experiment was designed to have five treatments: fertilizer NPK, NP, PK, NK, and CK (without fertilization). The root biomass, straw biomass, grain yield, and total uptakes of N, P, K of maize plants were all greatly increased in Treatment NPK, and were also significantly increased in Treatment NP, but were not significantly affected in Treatment PK or NK. In the same treatment, straws and roots were similar in nutrient content, while grains were relatively higher in total N and total P contents of, but lower in total K. Compared to Treatment NPK (balanced fertilization), the other treatments, lacking one or other nutrient, showed significant decrease in the nutrient in question and/or significant increase in the other nutrients in maize plants, and differed betweenthe treatments in nutrient distribution among roots, straws, and grains. In addition, in all the treatments that had P (NPK, NP, PK), the soils were higher in microbial biomass C, N, P, activity of dehydrogenase, invertase, urease, and alkaline phosphatase, microbial metabolic activity, and basal respiration, but significant lower in microbial metabolic quotient. However, P-deficienct treatment (NK) fertilization did not show any significant effects on these soil biological parameters, except for a significant increase in urease activity. The findings demonstrated the role of P, as well as balanced fertilization with N, P, and K in promoting soil microbial growth and metabolic activity, as well as enhancing crop growth and nutrient uptake.