长期施磷对玉米和土壤C∶N∶P及有机质稳定性的影响

Effects of Long-term Phosphorus Fertilization on Maize and Soil C∶N∶P and Organic Matter Stability

【目的】研究长期施用不同量磷肥对农田土壤和作物碳(C)∶氮(N)∶磷(P)生态化学计量学、微生物活性及土壤碳库数量和稳定性的影响,为农田养分调控和生态系统稳定提供科学依据。【方法】以沈阳农业大学长期(28 a)地膜覆盖与施肥定位试验为平台,设置3个施磷处理:不施磷肥(P 0)、67.5 kg P_(2)O_(5)/(hm^(2)·a)(P_(1))、135 kg P_(2)O_(5)/(hm^(2)·a)(P_(2))。2015年秋季收获期采集0~20 cm土壤和玉米植株不同器官(根茬、茎秆、叶片、籽粒),测定土壤和作物C、N、P含量,土壤呼吸速率及土壤颗粒有机碳与矿质结合态有机碳含量。【结果】与不施磷肥相比,长期施用磷肥增加土壤全磷、速效磷、碱解氮含量及土壤pH,降低土壤C/P和N/P,对土壤有机碳、全氮含量及C/N无影响。施用磷肥增加了玉米器官磷含量,从而降低了N/P,但对玉米器官的C、N含量无影响。施用磷肥抑制了土壤呼吸速率(微生物活性),而对微生物量碳、可溶性有机碳、呼吸熵、微生物熵无显著影响。施用磷肥对土壤颗粒有机碳与矿质结合态有机碳的含量及其占总有机碳的比例无影响。【结论】长期施用磷肥因增加土壤和作物P含量而降低N/P和C/P,降低土壤微生物活性,但是对土壤有机碳库数量及稳定性无影响。

【Objectives】Understanding the effects of long-term phosphorus(P)fertilization on soil and crops carbon(C)∶nitrogen(N)∶P ecological stoichiometry,microbial activity and C pool stability are vital for nutrient balance in cropland.【Method】The study was based on a long-term(28 a)fertilization experiment at Shenyang Agricultural University,included three treatments:no phosphorus fertilizer(P 0),67.5 kg P_(2)O_(5)/(hm^(2)·a)(P_(1)),135 kg P_(2)O_(5)/(hm^(2)·a)(P_(2)).We collected soil and maize organs(root,stem,leaf,and seed)in 2015,and measured C,N and P contents in soil and maize organs,soil respiration rate,soil C pools(particulate organic carbon and mineral associated organic carbon).【Results】Compare with no P fertilization,long-term P fertilization increased soil total P,available P,alkali hydrolysable N,and soil pH,decreased soil C/P and N/P ratios,but did not change soil organic C content,total N content,and C∶N ratio.P fertilization increased P contents in maize organs and thereby decreased their N/P ratios,but had no effect on C and N in tissues.P fertilization decreased soil respiration rate(microbial activities),but had no effect on microbial biomass carbon,dissolved organic carbon,microbial quotient and respiratory quotient.P fertilization had also no effect on soil particulate organic carbon and mineral associated carbon pools.【Conclusions】Long-term P fertilization increases P concentrations in soil and crops and deceased their N/P and C/P ratios,deceases soil microbial activities,but does not affect soil carbon quantity and stability.