几种利用乳中尿素氮浓度估测尿氮排泄量模型的评价

本文利用34组国内外报道的荷斯坦牛乳中尿素氮浓度和尿氮排泄量的实测数据，对目前提出的部分利用MUN估测尿氮排泄量的模型进行了比较。结果表明，Zhai（2005）提出的模型[UN（g/d）：10．1×MUN（mg／dL）＋47.3]预测效果较好（P〉0．05）。划分MUN浓度范围分别建立模型可能会提高预测的准确度。此外，根据34组数据做简单回归：UN（g/d）=12．78×MUN（mg/d1）＋28．15（n=34，R2=0．59）。     

重庆南温泉洗浴废水用作植物灌溉水的可行性研究

重庆市温泉资源丰富,温泉洗浴废水运用于绿地灌溉可以节约成本,缓解城市的水危机。温泉洗浴废水对植物生长有正负两方面的影响,与植物的种类,温泉洗浴废水的水质等因素有关。实验以重庆市常见的两种绿地植物——冷水花木春菊为研究对象,对温泉洗浴废水中影响植物生长的pH、固体悬浮物、高锰酸钾,总溶解性固体4个常见指标进行了浓度值对比实验。运用对相对电导率拟合Logistic方程求半致死浓度值的方法,确定绿地植物所能耐受的上限阀值。以此为基础对温泉废水进行相关处理,使温泉废水既可以达到灌溉绿地的水质标准,又能最大限度地降低废水处理成本,从而充分利用水资源。     

三峡库区不同植被覆盖对土壤氮的影响

不同植被类型影响着土壤养分的积累、分布与循环,而土壤氮素是植被生长的重要限制性元素。通过分析宜昌点军区3种植被类型(柏树地、橘树地、菜地)覆盖下土壤氮素的变化情况,研究了不同植被对土壤氮素各形态的影响。结果表明,土壤全氮、硝态氮和微生物氮都是柏树地显著大于菜地和橘树地,而菜地和橘树地之间无显著性的差异;土壤矿化氮和微生物氮/全氮的变化顺序是柏树地橘树地菜地。说明不同植被覆盖对土壤氮有显著的影响,柏树地更有利于土壤氮的积累,氮的有效性也最高,由此认为柏树长期生长有益于土壤氮的改善。     

1例藏獒三氮脒中毒的生化检验及治疗

用三氮脒以3.5 mg/kg的剂量对患有附红细胞体病的藏獒进行肌肉注射,隔日用同等剂量的三氮脒肌肉注射,24 h后,藏獒发生以神经症状为主的中毒现象,并表现出食欲废绝,后肢发软,四肢抽搐呈划水状,卧地不起,昏迷,体温正常临床症状。经血清生化检验,藏獒的尿素氮、肌酸激酶等的生化指标明显升高,血糖降低占病例的100%。经过5 d的药物治疗后,中毒藏獒基本恢复健康。     

Effects of soybean variety and Bradyrhizobium strains on yield,protein content and biological nitrogen fixation under cool growing conditions in Germany

Soybean (Glycine max (L.) Merr.) is able to fix atmospheric nitrogen in symbiosis with the bacteria Bradyrhizobium japonicum. Because these bacteria are not native in European soils, soybean seeds must be inoculated with Bradyrhizobium strains before sowing to fix nitrogen and meet their yield potential. In Central Europe soybean cultivation is still quite new and breeding of early maturing soybean varieties adapted to cool growing conditions has just started.Under these low temperature conditions in Central Europe the inoculation with different, commercially available Bradyrhizobium inoculants has resulted in unsatisfactory nodulation. The aim of this study was: (i) to test the ability of commercially available inoculants to maximize soybean grain yield, protein content and protein yield, (ii) to study the interaction of different inoculants with different soybean varieties for two different sites in Germany under cool growing conditions over three years and (iii) to determine the variability of biological nitrogen fixation. Field trials were set up on an organically managed site at the Hessische Staatsdomäne Frankenhausen (DFH) and on a conventionally managed site in Quedlinburg (QLB) for three consecutive seasons from 2011 to 2013. Three early maturing soybean varieties—Merlin, Bohemians, Protina—were tested in combination with four different Bradyrhizobium inoculants—Radicin No.7, NPPL-Hi Stick, Force 48, Biodoz Rhizofilm—and compared with a non-inoculated control. Effective inoculation with Bradyrhizobium strains increased grain yield, protein content and protein yield by up to 57%, 26% and 99%, respectively. Grain yield, protein content and protein yield were generally higher in DFH. Average grain yield was 1634 kg ha⁻¹ in QLB (2012–2013) and 2455 kg ha⁻¹ in DFH (2011–2013), average protein content was 386 g kg⁻¹ in QLB and 389 g kg⁻¹ in DFH and average protein yield was 650 kg ha⁻¹ in QLB and 965 kg ha⁻¹ in DFH. The percentage of nitrogen derived from air (Ndfa) ranged between 40% and 57%. Soybeans inoculated with Radicin No. 7 failed to form nodules, and crop performance was identical to the non-inoculated control. Biodoz Rhizofilm, NPPL Hi-Stick and Force 48 are suitable for soybean cultivation under cool growing conditions in Germany. Interactions between soybean variety and inoculant were significant for protein content and protein yield at both sites, but not for nodulation, grain yield, thousand kernel weight and Ndfa. The variety Protina in combination with the inoculant Biodoz Rhizofilm can be recommended for tofu for both tested sites, while Merlin and Protina in combination with Biodoz Rhizofilm are recommended for animal fodder production in DFH. Animal fodder production was not profitable in QLB due to low protein yields.     

On-farm evaluation of an active optical sensor performance for variable nitrogen application in winter wheat

Winter wheat (Triticum aestivum L.) represents almost 50% of total cereal production in the European Union, accounting for approximately 25% of total mineral nitrogen (N) fertilizer applied to all crops. Currently, several active optical sensor (AOS) based systems for optimizing variable N fertilization are commercially available for a variety of crops, including wheat. To ensure successful adoption of these systems, definitive measurable benefits must be demonstrated. Nitrogen management strategies developed based on small-scale plot research are not always meaningful for large-scale farm conditions. In 2010–2012 (5 site-years) on-farm study was implemented in northern Poland utilizing a strip-trial design. The objective was to evaluate the performance of AOS in combination with a built-in algorithm for variable N rate fertilization. In this study, the reference uniform N rates (farmer’s practice) were comparable to optimum variable N rate recommendations. Side-by-side comparisons of uniform and variable N application revealed inconsistent benefits in terms of grain yield, grain protein content (GPC), N use and N use efficiency (NUE). Anticipated yield increases and/or reduced N rates are typical drivers for AOS adoption. Significant yield increases are not easily attained on farms with winter wheat yields already close to maximum yield potential. Thus, sensor-based variable N rate recommendations for fields previously fertilized with relatively low uniform N rates would often entail more appropriate allocation (redistribution) of the same amount of total N. This would minimize N surplus in areas of lower productivity and to improve the sustainability of N management overall.     

Fertilizer value of nitrogen in hen and broiler manure after application to spring barley using different application timing

The nitrogen (N) fertilizer effect of layer hen and broiler manure applied at different times on spring barley yield was studied in seven Swedish field experiments during 2005–2008. Two experiments had parallel field incubations to study N release after fertilizer application. The effect of total N in manure on N offtake was 30–40% that of mineral N, except in a dry year, when the effect was very low. Although the relative proportions of ammonium N, uric acid N and other N differed between the hen and broiler manure, the effect of total N was similar for both. In field incubations, mineral N decreased from 75 to 60% of total N applied in hen manure, whereas it increased from 20 to 50% in broiler manure, because of net immobilization and release, respectively. The limited fertilizer nitrogen replacement value, corresponding to only 30–40% of total N, could be as a result of ammonia volatilization after rather shallow incorporation with harrow. Net N release from broiler manure lasted for 6–8 weeks after application, after which it generally ceased. In some cases, manure application in early spring gave better yield effects than application at sowing, probably because of better synchronization of the N release with crop N requirements. The residual N effect on the N offtake in crop in the year after manure application was on average 3% of the total N applied, equivalent to a fertilizer replacement value of about 6%.     

Effect of wilting,silage additive,PEG treatment and tannin content on the distribution of N between different fractions after ensiling of three different sainfoin (Onobrychis viciifolia) varieties

Sainfoin (Onobrychis viciifolia) is a tanniniferous, leguminous plant that has potentially beneficial effects on protein utilization in ruminants. As ensiling causes protein breakdown and elevated levels of buffer soluble N (BSN), we studied the distribution of N before and after ensiling sainfoin. Three varieties of sainfoin were either direct‐cut and frozen directly or wilted and frozen before later ensiling in mini‐silos with and without acidification with Promyr (PM; an acidifying commercial mixture of propionic and formic acid) and with or without polyethylene glycol (PEG). Extractable tannins (ET) and protein‐bound tannins (PBT) were measured with an HCl/butanol method in an attempt to correlate tannin levels to N fractions. The sainfoin silages showed good ensiling characteristics and had relatively high concentrations of undegraded protein. The effect of wilting on BSN levels (g/kg N) was dependent on sainfoin variety (P < 0·001). PEG increased and PM decreased the level of BSN in the silages (P < 0·001). PM treatment also produced less non‐protein N and ammonia‐N (P < 0·05) as compared with no additive. Addition of PEG to the silage increased the BSN‐proportion 1·8‐ and 2·6‐fold for both DM stages. A strong tannin‐protein binding effect is, therefore, confirmed in sainfoin. However, correlations between tannin levels (ET and PBT) and BSN were poor in the (non‐PEG) silages, indicating either that the HCl/butanol method is unsuitable for measuring tannin in silages or that qualitative attributes of tannins are more relevant than quantitative. The HCl/butanol method seems therefore not to be useful to predict degradation of protein in sainfoin silages.     

基于田间空气中病菌孢子浓度的小麦白粉病病情估计模型研究

2014和2015两年度利用Burkard定容式孢子捕捉器监测了高感小麦白粉病品种京双16种植区和中感品种众麦2号种植区田间空气中的病菌孢子浓度变化动态,同时利用小型气象站监测了田间的气象因子,通过分析京双16和众麦2号种植区空气中孢子浓度与空气温度、湿度、降雨、风速和太阳辐射率的相关性,发现空气中的孢子浓度主要与空气温度呈显著的正相关性(r0.348 3,P0.05)。在此基础上,分别分析了田间病情与调查日期前累积孢子浓度、一周前累积孢子浓度、前一周累积孢子浓度和当周累积孢子浓度的关系,结果表明,中感品种众麦2号田间病情与累积孢子浓度的关系均呈指数关系,其中田间病情与调查日期前累积孢子浓度或一周前累积孢子浓度的拟合效果最好,而感病品种京双16的田间病情与累积孢子浓度多呈对数关系,其中病情指数与一周前累积孢子浓度的拟合效果最好。     

Nutrient‐Release Rates of Controlled‐Release Fertilizers in Forest Soil

Abstract

Nutrient‐release rates of controlled‐release fertilizer (CRF) with four different labeled release periods were evaluated. Samples (30 g) sealed with nylon mesh were buried at a clearcut forest site (Price soil series) in western Oregon, USA, in February 2000 and excavated every 7 weeks for 14 months to determine residual weight and composition. Cool, dry soil conditions apparently prolonged nutrient release beyond labeled rates; the fertilizer with the shortest release period (3–4 months) released approximately 72% of the fertilizer (by weight), whereas that with the longest release period (8–9 months) released 48%. Release varied among individual nutrients [nitrate (NO₃)>ammonia (NH₃)>potassium (K)>sulfur (S)>magnesium (Mg)>phosphorus (P)]. Minimal changes in micronutrient [iron (Fe), manganese (Mn), zinc (Zn), and molybdenum (Mo)] contents were attributed to the formation of insoluble compounds with P. Variable release among individual nutrients demonstrates a limitation toward delivering a full range of nutrients and suggests that further refinement of CRF technology is needed to optimize nutrient availability under realistic field conditions.