磷肥在砖红壤中淋溶特征的研究初报

在实验室用土柱对发育于片麻岩的砖红壤进行磷肥淋溶特征研究。结果表明：随着施肥量增加，PO4^3-累计渗漏量相应增加，但不是简单的线形增加关系，在施P量为106．1kg／hm^2与70．7kg／hm^2之间，P累计渗漏量存在一个“跃变”点：磷素在砖红壤中移动性弱，当施P肥水平为141．5kg／hm^2时，活性磷未能穿透12cm土层；在低灌溉量下，磷的渗漏量与灌水量几乎呈线形增加的趋势，但高灌溉量下，则无显著差异，且在等量灌溉下，多次灌溉比单次灌溉更能促进磷肥的运移。     

Performance and environmental effects of forage production on sandy soils. V. Impact of grass understorey, slurry application and mineral N fertilizer on nitrate leaching under maize for silage

A field experiment with maize for silage was conducted to assess the effects of mineral nitrogen (N) fertilizer application rates (0, 50, 100, 150 kg ha^?1), slurry application rates (0, 20, 40 m³ ha^?1) and the use of an understorey with perennial ryegrass on nitrate (NO₃)‐leaching losses. Leachate was collected using ceramic suction cups. Soil mineral N (SMN) was determined to a depth of 90 cm at the end of the growing season. Higher levels of N supply with mineral fertilizer or slurry resulted in higher leaching losses. The grass understorey significantly reduced the losses. The amount of N lost to the groundwater was positively related to SMN at the end of the growing season, with leaching losses representing less than 0·45 of SMN on average. Leaching losses were positively related to the N surplus, which was calculated from the difference between N input (N from fertilizer, slurry and atmospheric deposition) and N output (N removed with maize herbage mass and bound in the understorey biomass in spring). In view of the large variation in weather conditions between the experimental years, it is suggested that for the sandy soils in this experiment N‐leaching losses under maize can be estimated satisfactorily from SMN and the calculated N surplus.     

不同形态磷在砂土中的移动性研究(英文)

预测土壤中磷的长期淋洗性需要了解土壤特性和不同形态磷的行为.本研究用模拟试验评估了不同磷负荷砂质土壤中不同形态磷的移动性.分别从浙江省衢州市和温州市采集具不同磷含量的蔬菜地土壤,每一地点分别采集2个深度的土壤(0～10 cm和10～30 cm),表层土壤(0～10 cm)通过添加不同量的磷酸盐、CaCO和无定形氧化铁,形成研究需要的不同磷含量和不同磷形态的系列土壤样品;淋洗柱长30 cm,由10 cm经培养处理的表层(0～10 cm)土壤和未经培养处理的亚表层土壤(10～30cm)构成,每一淋洗土柱连续经历12个循环的0.002 mol?L-1CaCl2溶液淋洗,收集的淋洗液用于分析钼酸反应总磷(TRP)、可溶态钼酸反应磷(DRP)和颗粒态钼酸反应磷(RPP);试验结束后鉴定土壤中水溶态磷、MehlichⅢ-P和磷的化学形态变化.结果表明:添加无定形氧化铁和碳酸钙可显著改变砂土中磷的形态,降低土壤磷的有效性;无定形态氧化铁在降低土壤磷有效性方面的作用大于碳酸钙;淋洗液中磷的形态主要为DRP,颗粒态磷占总磷的比例为1.2%～39.8%;TRP和DRP的损失与培养处理后表土中磷含量存在显著的相关.相关分析和淋洗试验后土壤中磷形态变化结果都表明:表土柱中淋移的磷主要来源于水溶性磷(H2O-P)和NaHCO3-P,与NaOH-P、HCl-P和残余磷的相关不明显;从表土淋失的磷有27.1%～54.2%被淋出土体,其余下移至10～30 cm土层中.研究结果还表明,添加无定形氧化铁可增加土柱中颗粒态磷的迁移.     

肥料氮素在土娄土中的淋溶

采用室内土柱恒温条件下模拟研究粪肥或／和尿素混施入土娄土耕层后在多次灌溉下对铵态氮、硝态氮和水溶性有机态氮的淋溶深度和数量的影响。结果表明：三种施肥处理淋出液中氮素形态均以硝态氮为主，且淋溶到９０ｃｍ土层以下，有机、无机肥混施后减少了无机肥中硝态氮的淋溶率；无机肥和有机、无机肥混施处理以铵态氮次之，其量与土层深度呈对数式衰减，显著淋溶到３０ｃｍ土层；而有机肥处理以有机态氮次之，显著淋溶到３０ｃｍ土层，５０ｃｍ以下含量甚微。硝态氮和水溶性有机氮随灌溉水向下迁移，对底土具有培肥作用。     

土壤有机质对交换性酸测定结果的影响

为探讨土壤有机质对两种常用的土壤交换性酸测定方法(BaCl_2-TEA提取法和KCl淋溶法)结果的影响,选取了85个不同有机质质量分数的酸性土壤并采用BaCl_2-TEA提取法和KCl淋溶法测定其交换性酸含量.结果表明,BaCl_2-TEA提取法测得的土壤交换性酸含量远大于KCl淋溶法的测定结果.KCl淋溶法测得的土壤交换性酸含量与土壤pH值间的负相关性极有统计学意义(r=-0.79**),而BaCl_2-TEA提取法测得的土壤交换性酸含量与土壤pH值间的相关性无统计学意义(r=-0.08).但BaCl_2-TEA提取法测得的土壤交换性酸含量却与土壤有机质质量分数间的正相关性极有统计学意义(r=0.94**).此外,由KCl淋溶法测得的土壤交换性酸进一步计算得到的盐基饱和度与土壤pH值间的相关性(r=0.69**)也大于BaCl_2-TEA提取法(r=0.25*).通常土壤酸化越严重,土壤pH值越低,交换性酸含量越高,盐基饱和度越低.可以得出,土壤有机质会使BaCl_2-TEA提取法的测定结果产生较大的正误差,而对KCl淋溶法的影响较小.由于土壤有机质中的腐殖酸会与BaCl_2-TEA提取法中的有机弱碱TEA发生反应,增加TEA用量,从而使计算得到的土壤交换性酸的结果偏高.因此,对于高有机质质量分数的酸性土壤,不宜采用BaCl_2-TEA提取法测定其交换性酸含量.但在KCl淋溶法中,由于K~+对Al~(3+)的交换能力较弱,使得该方法测得的土壤交换性酸含量偏低.因此,可乘以1.5左右的校正系数,以便能真实地反映出土壤交换性酸含量.     

尿素在砖红壤中的淋失特征——Ⅰ．NH^＋4-N的淋失

通过室内大型模拟土柱研究不同尿素施甩量与砖红壤中NH4-N的淋失关系。结果表明：各施肥处理渗漏液中20cm处NH^ 4-N的最高浓度值与施肥量大小成正相关，60cm和120cm处渗漏液中NH^ 4-N浓度值与施肥量关系不大，但120cm处渗漏液中NH ^4-N浓度仍超过水体富营养化标准0．2mg／L。在砖红壤中，尿素以NH^ 4-N形态大量淋失的可能性不大。     

Performance and environmental effects of forage production on sandy soils. II. Impact of defoliation system and nitrogen input on nitrate leaching losses

A field experiment was conducted over a 4‐year period to determine NO₃ leaching losses from grassland on a freely draining sandy soil. The experiment consisted of all combinations of five defoliation systems; cutting‐only (CO), rotational grazing (GO), mixed systems with one (MSI) or two silage cuts (MSII) plus subsequent rotational grazing, and simulated grazing (SG), four mineral nitrogen (N) application rates (0, 100, 200, and 300 kg N ha^?1 year^?1), and two slurry levels (0 and 20 m³ slurry ha^?1 year^?1). Due to the high N return by grazing animals, leaching losses in the rotational grazing systems generally were associated with NO₃‐N concentrations which exceeded the EU limit for drinking water. NO₃ leaching losses in a rotational grazing system could be reduced by lowering the N fertilizer intensity and the inclusion of one or two silage cuts in spring. However, even in the unfertilized mixed systems, N fixation by white clover exceeded the amounts of N removed via animal products, which resulted in NO₃‐N concentrations well above the EU limit for drinking water. In terms of leaching losses, the cutting‐only system was the most advantageous treatment. NO₃ leaching losses on grassland could be predicted by the amount of soil mineral N at the end of the growing season and by the N surplus calculated from N balances at the field scale. From the results obtained a revised nitrogen fertilization policy and a reduced grazing intensity by integrating silage cuts are suggested.     

岩石-土壤-四川牡丹元素迁移体系中的微生物效应

[目的]研究四川牡丹岩土环境背景以及微生物在元素迁移过程中的作用,为了解营养元素的表生地球化学行为规律及微生物在元素迁移体系中的作用提供理论依据。[方法]利用ICP-OES测定四川牡丹生境母岩、土壤以及种子的大量(P,S,K,Ca,Na,Mg,Al)、微量(Fe,Mn,Cu)营养元素含量,同时利用Illumina高通量测序技术测定根际土壤中细菌、真菌的组成和结构。[结果](1)四川牡丹生长土壤以弱碱富钙为主要特征,元素组成基本保留了母岩特征;(2)元素从母岩到土壤中的迁移富集系数排序为:CaNaSPMgKAlFeMnCu,植物吸收系数排序为:PSKCuMgCaNaMnFeAl;(3)碱土金属淋溶率和铝铁率对土壤细菌的多样性(Alpha)影响显著,但对真菌的影响不显著;(4)P,Mn的迁移主要受母岩控制,而Ca,Mg,Fe,S等元素的迁移富集受到了微生物的影响。[结论]细菌和真菌在元素迁移体系中的作用相似,主要参与Fe,S,Mg,Ca的相关反应过程。     

噻虫嗪在农田土壤中环境行为的研究进展

噻虫嗪是当前全球销售量最大的新烟碱类农药之一。随着噻虫嗪在农业生产中的广泛使用,噻虫嗪在土壤环境中的迁移转化和归宿问题开始成为研究热点。本文总结了噻虫嗪在农田土壤中的残留、降解、吸附以及迁移与淋溶等环境行为及主要影响因素,系统综述了噻虫嗪对土壤微生物以及土壤动物(蚯蚓、蚂蚁等)的影响,并针对噻虫嗪在农田土壤中环境行为相关研究存在的不足提出了未来研究应该关注的重点和方向,以期为噻虫嗪的科学安全使用以及保障农田土壤生态系统健康提供科学依据。     

Mineral‐nitrogen and phosphorus leaching from vegetable gardens in Niamey,Niger

Urban and periurban agriculture (UPA) contributes significantly to meeting increasing food demand of rapidly growing urban populations in West African cities. The often intensive high‐input vegetable production within UPA results in large positive nutrient balances, being presumably linked to strong nutrient leaching which needs quantification. This study aimed at estimating leaching losses of mineral N and P in three representative urban gardens of Niamey, Niger, using ion‐exchange‐resin cartridges installed below the crop rooting zone at 0.6 m soil depth. In 2007, a year with below‐average annual rainfall (425 mm as compared to 542 mm), mean leaching of mineral N amounted to 5.9 and 7.3 kg N ha^–1 for two gardens with > 80% sand fraction and only 2.2 kg N ha^–1 for a garden with 40% silt and clay. Apparent annual P leaching was 0.7 kg P ha^–1 in all three gardens. Additional multiannual studies are necessary to assess the effect of inter‐ and intraannual variation in precipitation on nutrient leaching in intensive UPA vegetable production of semiarid West Africa.