根据北京市2013-2020年大量元素水溶肥料的检测数据,分析北京市大量元素水溶肥料各检测指标的合格情况以及重金属含量和污染情况.结果表明,北京市大量元素水溶肥料年度平均合格率为84.35％,主要检测项目单项合格率均在90％以上;5种重金属元素的合格率均在90％以上,其中As的合格率最低,超标量最高;2013年的As元素达到了轻污染的程度,2014-2020年5种重金属含量全部为清洁等级.北京市大量元素水溶肥料产品虽然仍存在养分含量不足、重金属超标等问题,但污染情况逐年好转.

建立凯氏定氮仪法测定植物营养液中铵态氮和硝态氮的方法.将10 mL植物营养液置于凯氏定氮管中,加入4.5 mol/L氢氧化钠溶液10 mL,利用锌–硫酸亚铁还原剂将营养液中硝态氮(NO3––N)转化为铵态氮(NH4+–N),经蒸馏后被定量吸收在硼酸溶液中,用标准酸进行滴定,计算营养液中总氮含量;不加锌–硫酸亚铁还原剂时,测定营养液中的NH4+–N含量,采用差减法计算出营养液中NO3––N含量.方法的检出限(以铵态氮计)为0.15 mg/L,硝态氮和铵态氮测定结果的相对标准偏差分别为1.23％～2.75％、0.83％～2.84％(n=5),加标回收率为98.7％～100.8％.该方法满足LY/T 1228—2015《森林土壤氮的测定》标准要求.

为探讨生物炭对农田化肥面源污染的防控效果,本文以北运河流域(北京段)下游"上壤下砂"、施肥量大、易漏水漏肥菜田为研究对象,分析了田间条件下不同用量生物炭配合化肥底施和施炭基肥对土壤氮磷纵向迁移、结球生菜产量品质及土壤微生物数量的影响.结果表明:与单施化肥(T1)相比,①化肥配施生物炭750 kg·hm-2(T2)、2250 kg.hm-2(T3)、4500 kg.hm-2(T4)和施炭基肥(T5)处理20～40 cm 土壤硝态氮含量分别降低41.20％、39.60％、24.20％和 13.78％,0～20 cm土壤有效磷(Olsen-P)含量分别提高26.30％、24.70％、32.60％和 11.20％,40～60 cm土壤Olsen-P含量分别减少27.30％、26.10％、33.50％和41.30％,T3和T5处理20～40 cm土壤Olsen-P含量分别减少19.90％和12.50％,表明农田配施生物炭或者施炭基肥可提高耕层土壤供磷量,并有效阻控耕层硝态氮和Olsen-P向下层土壤淋溶迁移;②化肥配施生物炭(T2～T4)对结球生菜产量、维生素C(Vc)和硝酸盐含量均无显著影响,施炭基肥(T5)处理结球生菜生物产量显著增加了14.36％(p<0.05),Vc含量显著提高了20.00％(p<0.05);③T4和T5处理土壤细菌数量分别减少57.49％和47.50％(p<0.05),且T5处理土壤真菌数量减少46.67％(p<0.05).综合考虑不同土层氮磷、结球生菜产量品质及土壤微生物数量变化,推荐生物炭配施量为750?2250 kg?hm-2,并建议进一步加强生物炭对农田土壤微生物群落的影响监测.

pH是土壤重要的理化指标之一,但是常规测定方法中使用去CO2蒸馏水测定土壤pH的方法,不利于快速测定大批量土壤样品.本实验通过对比方法,分别采用去CO2的蒸馏水和不去CO2的蒸馏水测定国标土样和北京市土样,对比CO2的存在与否对土壤pH测试结果的影响.结果表明,蒸馏水中CO2的存在与否对土样pH的影响较小,差值稳定在0.03～0.04之间,且在误差范围之内,测定时只要对检测数据进行校正,土壤的pH完全可直接用不去CO2蒸馏水检测;去CO2蒸馏水可降低碱性土壤pH 0.03～0.04个单位,去CO2蒸馏水可增加酸性土壤pH 0.03～0.04个单位.

By years of investigation and analysis of compound fertilizer and organic fertilizer qualities in Beijing metropolitan agricultural region,the quality status and problems of them were showed in the study.The quality of compound fertilizer was better than that of organic fertilizer in Beijing.Their product percent of pass was 87.2% and 24.5% respectively.Rejected items of compound fertilizer included the nutrition content,water content and the percentage of water soluble phosphorus to total available phosphorus in the fertilizer.The main rejected items of organic fertilizer were organic matter content,pH,total nutrition content and water content in it.Low level production technology of organic fertilizer enterprises,lack of corresponding management mechanism and forceful supervision and management were the main reasons of low organic fertilizer quality in Beijing.Finally,countermeasures and advices were suggested for those problems.

为解决生产过程中快速分析有机肥料中五氧化二磷、氧化钾的含量,试验用电感耦合等离子体发射光谱仪(ICP-OES)法测定五氧化二磷、氧化钾,介绍该法实验原理、测定方法。其结果表明,该法与NY525-2002相比用时少,效率高,数据准确可靠,可满足中控分析要求。

土壤铵态氮、硝态氮是作物吸收氮素的最主要的2种形式。近年来,随着土壤铵态氮、硝态氮检测量的增加,土壤样品采集的集中性与检测时间分散性的矛盾日益凸显。为了能合理地安排工作,确保土壤中铵态氮、硝态氮含量检测结果的准确性,特对土壤及浸提液中铵态氮、硝态氮浸提液在恒温、常温下的流失性状况进行研究,探索出对于土壤中铵态氮、硝态氮的测试过程中处理及测试过程中适宜的储藏条件。

Growth and nutrient absorption of alfalfa was surveyed. Yield and nutritious matters constitution in four cuts of alfalfa was different. Maximum nutrition absorption and crude protein accumulation was reached from early branching stages to the appearing bud stages. Optimal harvest was at the appearing bud or early florescent stage with highest yield of crude protein. Alfalfa could harvest 4 times in a year, Hay yield of first cuts was highest with productivity account for 36.9 % and crude protein yield 36.5 %.