Effect of long-term application of fertilizers on soil quality and rice yield in a salt-affected coastal region of India

The studied soils were collected from a 24-year long-term fertilizer experiment with rice (Oryza sativa L.) grown on tropical Typic Endoaquepts during monsoon season only. The organic carbon (OC) and total nitrogen (TN) status of the soils improved with the N₁₀₀P₂₂K₄₂ treatment than the initial values at the start of the experiment. The available P status of the soils depleted in the N₁₀₀P₁₁K₂₂ and N₀P₀K₀ treatments than the initial value. Soil microbial biomass carbon (MBC) and basal soil respiration (BSR), activities of urease, acid and alkaline phosphatases as well as fluorescein diacetate hydrolyzing activity (FDHA) were the highest in the N₁₀₀P₂₂K₄₂ treatment. The highest percentage of MBC in OC in the N₁₀₀P₂₂K₄₂ treatment revealed the accumulation of organic matter with an overall improvement in nutrient status of soil, since MBC is a labile pool of plant nutrients. Long-term application of fertilizers (N₁₀₀P₂₂K₄₂) had no deleterious effect on microbial and biochemical soil quality parameters. Rice grain yields were inconsistent with N₁₀₀P₀K₀ and N₀P₀K₀ while that of N₁₀₀P₂₂K₄₂, N₁₀₀P₁₁K₂₂ and N₁₀₀P₂₂K₀ increased gradually during the course of the experiment for each block period of six years. The grain yield of rice showed high significant correlation with the microbial and biochemical soil parameters.     

肥料重金属含量状况及施肥对土壤和作物重金属富集的影响

本文对肥料中重金属的含量状况以及施肥对土壤和农作物重金属累积影响的研究进展进行了系统分析和总结。过磷酸钙中锌（Zn）、 铜（Cu）、 镉（Cd）、 铅（Pb）含量高于氮肥、 钾肥和三元复合肥,有机-无机复混肥料中的Pb含量高于其他化肥。有机肥如畜禽粪便、 污泥及其堆肥中的重金属含量高于化肥,猪粪中的Cu、 Zn、 砷（As）、 Cd含量明显高于其他有机废弃物,鸡粪中铬（Cr）含量高;污泥和垃圾堆肥中Pb或汞（Hg）含量高。商品有机肥Zn、 Pb和镍（Ni）含量高于堆肥,Hg含量高于畜禽粪便。多数研究表明,氮磷钾配施与不施肥相比土壤Cd和Pb含量增加,施用有机肥比不施肥提高土壤Cu、 Zn、 Pb、 Cd含量。施用化肥对农作物重金属富集的影响不明确,而施用有机肥可提高作物可食部位Cu、 Zn、 Cd、 Pb 的含量,影响大小与有机肥种类、 用量、 土壤类型和pH以及作物种类等有很大关系。在今后的研究中应着重以下几个方面, 1）典型种植体系下土壤重金属的投入/产出平衡; 2）不同种植体系下长期不同施肥措施对土壤重金属含量、 有效性影响的动态趋势; 3）典型种植体系和施肥措施下土壤对重金属的最高承载年限; 4）现有施肥措施下肥料中重金属的最高限量标准。     

我国农田氮肥施用现状、问题及趋势

氮素在作物产量和品质形成中起着关键作用。本文综述了什么是合理施氮,包括施氮量、施氮方法和时期,也包括与有机肥和秸秆还田措施的配合等。指出我国农田氮肥施用的主要问题是施肥过程和施肥后的严重损失。依据农户调查所获得的田块尺度施氮量,与田间试验合理施氮量对比分析表明,过量施氮田块占总调查田块的大约33%。依据区域尺度单位播种面积平均施氮量,与作物平均推荐施氮量对比分析表明,全国过量施氮面积占播种面积20%、合理面积占70%、不足面积占10%。总体而言,过量施氮现象还相当普遍,特别是在蔬菜和果树等经济作物上。本文提出了一种估算国家尺度氮肥需求量的方法,可估算出全国合理需氮量范围,称之为氮肥需求量估算法。用三种不同方法估算的我国1980~2010年间的氮肥需求量与实际氮肥使用量比较表明,如仍然依照现在的粗放施肥习惯,应该为现在的实际氮肥使用量,5年平均为N 27.9×106t左右,正好处于合理需氮量范围的中线。在改善施肥技术基础上,我国2006~2010年间5年氮肥平均使用量应该在N 19.6×106t左右;用五种方法预测的我国未来氮肥需求量表明,如果改善施肥技术,我国2020、2030、2050年合理氮肥需求量分别为N 21.0×106t、21.7×106t、23.1×106t;如施肥技术得不到实质性改善,依然粗放施氮,则氮肥需求量应处于合理使用量范围的中线,分别为N 30.4×106t、31.4×106t、33.4×106t。进一步分析了我国粮食产量和氮肥施用量与美国和西欧的差异,我国农田有机肥和碳投入对增加土壤有机碳氮库的重要性。     

不同施肥措施对滨海盐渍土有机碳含量的影响

通过在滨海典型盐渍区开展的田间试验,研究不同施肥措施对土壤有机碳以及土壤EC、p H、体积质量、全氮含量的影响。结果表明,与对照相比,不同施肥措施均能显著提高0~30 cm土层土壤的有机碳含量及密度。农家肥、商品有机肥和无机肥的施用均能显著增加作物生物量和产量,并能明显改善盐渍化农田的理化特性,具体表现在能明显降低表层土壤的p H和体积质量,提高土壤全氮含量,但农家肥和商品有机肥的施用使表层土壤的EC值有所升高。经过相关性分析表明,土壤有机碳含量与土壤EC、全氮、C/N比和作物生物量呈极显著正相关关系,与p H、体积质量呈极显著负相关。     

水、磷对紫花苜蓿产量及水肥利用效率的影响

【目的】紫花苜蓿作为畜牧业生产中最主要的优质绿色饲料,是发展草食畜牧业的物质基础,同时它也是一种需水需肥较多的作物。如何从技术方面提高单位面积苜蓿产量,实现苜蓿高产栽培是科学研究人员及生产者研究的重点。北京市东南部接壤的蓟县、宝坻及南部接壤的廊坊、武清等地区,是北京市在生态和环境优先发展原则下畜牧养殖业外移的重要承接区域,苜蓿在当地种植缺乏科学指导,年干重产量仅为7500~10000 kg/hm2,盐碱地年产量更低,为4500~6000 kg/hm2。本研究通过苜蓿水肥试验确立紫花苜蓿达到高产的最佳磷肥施用水平和灌水量,为京南地区苜蓿高产及水肥的高效利用提供可借鉴的水肥管理技术。【方法】实验在低磷砂壤土条件下进行,选用紫花苜蓿中苜2号品种,设置全生育期不灌水（W0）、以及返青后及第1、2茬刈割后灌水且每次灌水25 mm （W1）、50 mm （W2）、75 mm （W3）4个灌水处理;每个灌水处理下设置不施磷（F0）、施P2O5 105 kg/hm2（F1）、210 kg/hm2（F2）3个施磷量处理,研究了灌水和施磷对紫花苜蓿产量、水分和磷肥利用效率的影响。【结果】1）灌水对1、2茬苜蓿产量的影响有显著差异,对3、4茬及全年产量的影响无显著差异;施磷肥对第3茬苜蓿产量没有显著影响,但对第1、2、4茬及全年苜蓿产量的影响均存在显著差异。2）灌水和施磷肥对紫花苜蓿的水分和肥料利用效率均有显著影响,随着施磷量的增加,苜蓿的水分利用率逐渐增大,说明施磷可以提高水分利用效率;随着灌水量的增加,苜蓿的磷肥利用效率呈先增加后降低的趋势,说明适当的增加灌水量可以提高苜蓿的磷肥利用效率。【结论】综合考虑紫花苜蓿产量、水分和肥料利用效率等指标,最优试验处理为每次灌水量50 mm,施P2O5 210 kg/hm2,其次为每次灌水量25 mm, 施P2O5 210 kg/hm2。     

铜基叶面肥及控释肥对辣椒生长发育和叶片保护酶等生理特性的影响

【目的】针对辣椒喜肥、耐肥、对水分要求严格的特点,采用铜基叶面肥、控释肥两种新技术,研究了叶面喷施铜基叶面肥和土施控释肥对辣椒产量、矿质养分在植株体内的分布、保护性酶活性以及果实品质的影响,为提高果蔬产量和改善品质提供理论依据。【方法】分别于2011年4~11月和2012年3~9月,在山东农业大学南校区土肥资源高效利用国家工程实验室新型肥料中试基地, 以赤峰牛角王为供试辣椒品种设置肥料盆栽试验,试验设8个处理: 1）喷清水土壤不施肥对照（CKW- NF）;2）喷清水+土施普通肥（CKW+CCF）; 3）喷清水+土施控释肥（CKW+CRF）; 4）喷清水+土施控释肥+保水剂（CKW+CRF+W）; 5）喷铜基叶面肥土壤不施肥（CBFF-NF）; 6）喷铜基叶面肥+土施普通肥（CBFF+CCF）; 7）喷铜基叶面肥+土施控释肥（CBFF+CRF）;8）喷铜基叶面肥+土施控释肥+保水剂（CBFF+CRF+W）。采用称重法测定辣椒产量,于收获期取果实及叶片鲜样用于果实品质和生理生化指标测定,植株各部位干样用于微量元素测定。【结果】1）两年内喷施铜基叶面肥和土施控释肥均能提高辣椒产量,其中叶面喷施铜基叶面肥+土施控释肥+保水剂（CBFF+CRF+W）组合对辣椒产量的提高幅度最大,与CKW+CRF+W相比2011年增产24.1%,2012年增产29.0%。2）相同的土壤施肥条件下,与喷清水相比,喷施铜基叶面肥能够显著提高辣椒植株体内的铜浓度。其中,土施控释肥加保水剂基础上喷施铜基叶面肥处理的辣椒果实中铜浓度比叶面喷清水显著提高了103.9%;土施控释肥条件下,叶面喷施铜基叶面肥较喷清水处理下的果实铜浓度增加了41.5%。3）喷施铜基叶面肥后,辣椒叶片的超氧化物歧化酶（SOD）和过氧化物酶（POD）活性升高,而过氧化氢酶（CAT）活性下降。CBFF+CRF+W处理下的辣椒叶片SOD活性较CKW+CRF+W处理显著提高了26.6%,CBFF+CRF+W组合的叶片的POD活性和CAT活性与CKW+CRF差异显著。4）与喷清水处理相比,无论在土壤施用控释肥还是土壤施用控释肥+保水剂的条件下,叶面喷施铜基叶面肥均使辣椒果实可溶性蛋白和维生素C的含量显著提高,其增加幅度在12.8%~178.4%。【结论】综合考虑几种肥料组合,叶面喷施铜基叶面肥和土施控释肥可在一定程度上调控植株微量元素的积累,改善辣椒营养品质,提高辣椒产量。     

新型生物炭基氮肥对土壤一冬小麦系统氮素累积及相关生物活性的影响

通过田间试验,研究了掺混型、吸附型和反应型3种新型生物炭基硝酸铵氮肥在冬小麦生长过程中对土壤氮素累积及冬小麦对氮素的利用状况和相关生物活性的影响。试验处理包括CK（不施氮肥,不施生物炭）、硝酸铵氮肥、生物炭、掺混型生物炭基氮肥、吸附型及反应型生物炭基氮肥。研究结果表明：不同工艺制备的生物炭基氮肥对土壤铵态氮的累积具有显著影响,吸附型和反应型处理在冬小麦生长季铵态氮平均值大于对照（CK）,对于总氮、硝态氮和亚硝态氮累积量的影响不显著。除了生物炭单施处理外,其他处理均比CK显著提高冬小麦地上部的总氮累积量,但对冬小麦的氮素利用状况无显著影响,且三种炭基氮肥处理问无显著差异;施用不同类型生物炭基氮肥对土壤微生物量氮含量和硝酸还原酶活性具有提高作用,而对微生物量碳含量、亚硝酸还原酶和脲酶活性无显著影响。     

Utilization of biochar impregnated with anaerobically digested slurry as slow‐release fertilizer

We examined the possibility of an environment‐friendly slow‐release fertilizer (SRF) made of biochar impregnated by anaerobically digested slurry. The biochar materials were produced from three types of feedstocks (orange peel, residual wood, water‐treatment sludge) at different temperatures of 300°C, 500°C, and 700°C via pyrolysis. The release behaviors of the water‐soluble K⁺, Ca²⁺, and Mg²⁺ were similar for all impregnated biochars and the commercial SRF used. The water‐retention capacity was greatly improved by mixing the biochar‐SRF with the soil. The yield of lettuce was lower for the biochar‐SRF applications of 3.7 to 34.2 t ha^–1 than for the commercial SRF application of 51.4 t ha^–1. This might be due to excessive increase of soil pH for the biochar‐SRF application. Based on these results, the authors concluded that the biochar impregnated with nutrients could become an effective slow‐release K⁺ fertilizer.     

Effect of mineral nitrogen fertilizer forms on N2O emissions from arable soils in winter wheat production

Nitrogen fertilizers are supposed to be a major source of nitrous oxide (N₂O) emissions from arable soils. The objective of this study was to compare the effect of N forms on N₂O emissions from arable fields cropped with winter wheat (Triticum aestivum L.). In three field trials in North‐West Germany (two trials in 2011/2012, one trial in 2012/2013), direct N₂O emissions during a one‐year measurement period, starting after application of either urea, ammonium sulfate (AS) or calcium ammonium nitrate (CAN), were compared at an application rate of 220 kg N ha^?1. During the growth season (March to August) of winter wheat, N₂O emission rates were significantly higher in all three field experiments and in all treatments receiving N fertilizer than from the non‐fertilized treatments (control). At two of the three sites, cumulative N₂O emissions from N fertilizer decreased in the order of urea > AS > CAN, with emissions ranging from 522–617 g N ha^?1 (0.24–0.28% of applied fertilizer) for urea, 368–554 g N ha^?1 (0.17–0.25%) for AS, and 242–264 g N ha^?1 (0.11–0.12%) for CAN during March to August. These results suggest that mineral nitrogen forms can differ in N₂O emissions during the growth period of winter wheat. Strong variations in the seasonal dynamics of N₂O emissions between sites were observed which could partly be related to weather events (e.g., precipitation). Between harvest and the following spring (post‐harvest period) no significant differences in N₂O emissions between fertilized and non‐fertilized treatments were detected on two of three fields. Only on one site post‐harvest emissions from the AS treatment were significantly higher than all other fertilizer forms as well as compared to the control treatment. The cumulative one‐year emissions varied depending on fertilizer form across the three field sites from 0.05% to 0.51% with one exception at one field site (AS: 0.94%). The calculated overall fertilizer induced emission averaged for the three fields was 0.38% which was only about 1/3 of the IPCC default value of 1.0%.     

不同灌溉施肥模式下土壤湿胀干缩特征曲线及其滞后效应

采用淹灌、间歇灌2种灌溉模式与不施氮肥、含氮复合肥、缓控释氮肥、有机无机氮肥4种施肥模式配成8个处理开展水稻种植田间试验,研究了不同灌溉施肥模式下土壤湿胀干缩特征曲线及其滞后效应。结果表明:指数模型能较好地描述不同灌溉施肥模式下的土壤收缩过程与土壤膨胀过程;各模式下土壤干缩特征曲线与湿胀特征曲线指数模型中的a值(干土的比容积,即干土体积质量的倒数)和b值(单位含水量变化时土壤比容积变化的自然对数单位值)存在差异;土壤干缩曲线与湿胀曲线不完全重合,二者的b值及其差异也不同,存在滞后现象;土壤湿胀干缩效应受多种土壤性质的影响,其中主要通过土壤孔隙结构与持水性质的影响体现。