引用本文:许杏红,王艳玲,姚 怡,殷 丹.长期施肥对红壤旱地团聚体磷素储存容量的影响[J].土壤学报,2020,57(3):730-738. DOI:10.11766/trxb201902010582
XU Xinghong,WANG Yanling,YAO Yi,YIN Dan.Effects of Long-term Fertilization on Phosphorus Storage Capacity of Soil Aggregates in Red Soil Upland[J].Acta Pedologica Sinica,2020,57(3):730-738. DOI:10.11766/trxb201902010582
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长期施肥对红壤旱地团聚体磷素储存容量的影响
许杏红, 王艳玲, 姚怡, 殷丹
南京信息工程大学
摘要:
土壤磷素储存容量(SPSC)是基于磷饱和度(DPS)概念提出与发展的指标,可以有效地评估及监测土壤磷素的存储状态及释放潜能。以红壤旱地长期肥料定位试验地(1988—)为依托,以无机肥区的NK、NPK、NP、PK、NPKCa、NPKCaS及有机无机配施的1/2NPK(CK)、1/2NPK+花生秸秆还田(PS)、1/2NPK+稻秆(RS)、1/2NPK+鲜萝卜菜(FR)、1/2NPK+猪厩肥(PM)共11小区的土壤为对象,采用湿筛法获得各粒级团聚体样本,分析红壤旱地及各粒级团聚体SPSC的变化特征,探讨土壤供磷水平对SPSC的影响,评估红壤旱地磷素的流失风险,预测红壤旱地可继续容纳外源磷的“安全寿命”。结果表明:在无机肥区,长期未施磷肥的NK处理土壤SPSC高达265 mg•kg-1,分别为NPK、NP、PK、NPKCa与NPKCaS处理的1.9倍、1.6倍、1.9倍、2.0倍和2.4倍;各粒级团聚体对土壤SPSC的贡献率由高到低依次为1~0.25 mm、 0.053~0.25 mm、 > 2 mm、 1~2 mm;按现有施磷量,红壤旱地仍可以继续安全施用磷肥30年。在有机无机肥配施区,与CK处理相比,配施猪厩肥(PM)处理的SPSC呈现出负值且高达-333 mg•kg-1,应立即停止施肥或调整施肥量;而配施花生秸秆(PS)、稻秆(RS)及鲜萝卜菜(FR)处理的SPSC仍为正值且处理间差异不显著,各粒级团聚体对土壤SPSC的贡献率由高到低依次为1~0.25 mm、 > 2 mm、 0.053~0.25 mm、 1~2 mm;按现有施磷量,可继续安全施磷41年、30年、14年,CK处理则可安全施磷51年。由SPSC与TP、Bray-P的相关关系可以发现,当SPSC > 10 mg•kg-1时,红壤旱地磷是绝对“安全”的;当-10 mg•kg-1 ≤ SPSC ≤ 10 mg•kg-1时,红壤旱地磷处于极度不稳定状态,极易或已经开始向周围环境或水体释放,需随时监测或停止施磷;当SPSC < -10 mg•kg-1时,红壤旱地磷已经向周围环境或水体释放,应立刻停止施磷,并调整施肥方案,降低土壤磷素的环境风险。
关键词:  长期施肥  红壤旱地  土壤磷素储存容量(SPSC)  磷饱和度(DPS)  土壤磷素流失风险
基金项目:国家自然科学基金项目(41571286, 41571130053)
Effects of Long-term Fertilization on Phosphorus Storage Capacity of Soil Aggregates in Red Soil Upland
XuXinghong, WangYanling, YaoYi, YinDan
Nanjing University of Information Sciences and Technology
Abstract:
【Objective】Soil Phosphorus Storage Capacity (SPSC) is an index developed on the basis of the degree of phosphorus saturation (DPS), and can be used to effectively assess and monitor the status and release potential of soil phosphorus storage. Therefore, based on a long-term (1988—) fertilization experiment in a field of upland red soil, this paper tracked variations of the SPSCs in the red soil and its various fractions of soil aggregates and discussed impacts of soil P input on the SPSCs.【Method】A total of 33 soil samples were collected from the surface soil layers of the 11 treatments of the experiment, i.e. NK, NPK, NP, PK, NPKCa NPKCaS, CK, PS (1/2NPK + peanut straw), RS (1/2NPK + rice straw), FR (1/2NPK + fresh radish) and PM (1/2NPK + pig manure), for fractionation into soil aggregates ( > 2 mm, 2.0 ~ 1.0 mm, 1.0 ~ 0.25 mm and 0.25 ~ 0.053 mm) with the wet-sieving method, analysis of SPSCs in the soil and aggregates, exploration of effects of P input on SPSC, discussion on relationships of SPSC with soil total phosphorus (TP) and available phosphorus (Bray-P). In the end, the risk of soil phosphorus loss was assessed and “safe life” of the soil continuing to accommodate exogenous phosphorus.【Result】Among the inorganic treatments, Treatment NK was the highest in SPSC, reaching up to 265 mg•kg-1, which was 1.9, 1.6, 1.9, 2.0 and 2.4 times that respectively of treatment NPK, NP, PK, NPKCa and NPKCaS. The fractions of soil aggregates exhibited an high to low order of 1 ~ 0.25 mm, 0.053 ~ 0.25 mm, > 2 mm, 1 ~ 2 mm in rate of contribution to the soil total SPSC. So, based on the current phosphorus application rate, it was estimated that the upland of red soil might remain safe for 30 years. Among the combination treatments, Treatment PM displayed a negative value in SPSC, reaching up to -333 mg•kg-1. In this case, P application should be stopped immediately or fertilizer application rate should be adjusted. Treatment PS, RS and FR remained to be positive in SPSC value and did not vary much between them and followed an high to low order of 1 ~ 0.25 mm, > 2 mm, 0.053 ~ 0.25 mm, 1 ~ 2 mm in SPSC contribution rate of soil aggregates. So based on the current phosphorus application rate, the soil under the treatments might remain safe for 41, 30 and 14 years, respectively. However, the soil under Treatment CK may remain safe for 51 years.【Conclusion】According to the correlation analysis of SPSC, TP and Bray-P, when SPSC stay exceed 10 mg•kg-1, application of phosphorus in the upland of red soil upland is absolutely "safe"; if it is in the range of -10 mg•kg-1 ~ 10 mg•kg-1, phosphorus in the red soil is extremely unstable and extremely liable to get leached into the surroundings or water; when SPSC stay below -10 mg•kg-1, urgently calls for immediate halt of P application and readjustment of fertilization schemes so as to lower the risk of P polluting the environment.
Key words:  Long-term fertilization  Upland red soil  Soil phosphorus storage capacity(SPSC), Degree of phosphorus saturation(DPS)  Soil P loss risk