长期施肥下不同肥力紫色水稻土氮磷活化能力

Effects of Long-term Fertilization on Soil Nitrogen and Phosphorus Activation in Purple Paddy Soil with Different Fertility

【目的】探讨长期施肥下紫色水稻土氮、磷养分活化能力及其与pH和有机碳的量化关系,为土壤培肥提供参考。【方法】选取连续36年不施肥的低肥力(LF)、氮磷钾平衡施肥的中肥力(MF)和有机无机配施的高肥力(HF)处理,研究不同肥力土壤氮磷养分含量及其活化度的演变特征,分析土壤pH、有机碳与氮磷活化度的关系。【结果】MF和HF土壤的作物产量显著高于LF土壤。LF土壤全氮、全磷含量基本稳定,碱解氮含量显著增加而有效磷含量略有降低,MF和HF土壤全氮、全磷、碱解氮和有效磷含量均呈极显著增加趋势;LF、MF、HF土壤全氮含量年增加量分别为5.5、14.2、17.0 mg/kg,碱解氮年增量为0.40、1.05、1.32 mg/kg,全磷年增量为0.8、17.1、18.0 mg/kg,有效磷年增量为-0.03、2.05、1.85 mg/kg。MF和HF土壤氮磷活化度比LF土壤提高8.15%~428.77%;氮活化度与pH和有机碳不存在线性关系,磷活化度与pH呈极显著负相关,与有机碳呈显著正相关。年施N 240 kg/hm^(2)、P_(2)O_(5) 120 kg/hm^(2),氮含量于13年后、磷含量于9年后达到饱和。【结论】氮磷钾平衡施肥或有机无机肥配施是提升西南丘陵区水稻土氮磷养分含量及其活化能力的重要措施。

【Objective】The study was carried out to reveal the impact of long-term fertilization on the capacities of soil nitrogen (N) and phosphorus (P) activation,and their correlations with p H and soil organic carbon (SOC) in purple paddy soil with different fertility,with a view to providing references for soil fertilization.【Method】Based on a 36-year different fertilization experiment of purple soil,different fertilization treatments including no fertilization (LF),balanced chemical nitrogen (N),phosphorus (P) and potassium (K) fertilizer (MF),and chemical N,P and K fertilizer plus organic fertilizer (HF)were set.Dynamics of soil total and available N and P contents,and nutrient activation rates under different fertility were measured,and relationships between soil p H,SOC and nutrient activation rates were analyzed.【Result】Crop yields under MF and HF were significantly higher than those under LF.The contents of total N and P had no significant changes,available N content efficiently improved,while available P slightly decreased under LF treatment.However,total and available N and P contents significantly increased under MF and HF treatments.There were variation in promotion of N and P content under different fertility paddy soil.For example Under LF,MF,and HF treatments,the annual increase rates of total N contents were 5.5,14.2,and 17.0 mg/kg,0.40,1.05,and 1.32 mg/kg for available N,0.8,17.1,and 18.0 mg/kg for total P,and-0.03,2.05,and 1.85 mg/kg for available P,respectively.Compared with the LF treatment,N activation rates under MF and HF treatments increased from 8.15%to 428.77%.There was no significant linear relationship between N activation rate and p H or SOC.A significant negative correlation was observed between P activation rate and p H,while there was a significant positive linear correlation between P activation rate and SOC.If the annual application amount of N was 240 kg/hm^(2) and amount of P_(2)O_(5) was 120 kg/hm^(2),the purple soil was N-saturated after 13 years and it was P-saturated after 9 years.【Conclusion】In the purple paddy soil regions of Southwest China,balanced fertilization with N,P and K or application of chemical fertilizer with organic fertilizer could promote soil N and P contents and activation rates.