The value of poultry manure for wetland rice grown in rotation with wheat

Poultry manure applied alone or in combination with urea at different N levels was evaluated as a N source for wetland rice grown in a Fatehpur loamy sand soil. Residual effects were studied on wheat which followed rice every year during the three cropping cycles. In the first year, poultry manure did not perform better than urea but by the third year, when applied in quantities sufficient to supply 120 and 180 kg N ha^–1, it produced significantly more rice grain yield than the same rates of N as urea. Poultry manure sustained the grain yield of rice during the three years while the yield decreased with urea. Apparent N recovery by rice decreased from 45 to 28% during 1987 to 1989 in the case of urea, but it remained almost the same (35, 33 and 37%) for poultry manure. Thus, urea N values of poultry manure calculated from yield or N uptake data following two different approaches averaged 80, 112 and 127% in 1987, 1988 and 1989, respectively. Poultry manure and urea applied in 1:1 ratio on N basis produced yields in between the yields from the two sources applied alone. After three cycles of rice-wheat rotation, the organic matter in the soil increased with the amount of manure applied to a plot. Olsen available P increased in soils amended with poultry manure. A residual effect of poultry manure applied to rice to supply 120 or 180 kg N ha^–1 was observed in the wheat which followed rice and it was equivalent to 40 kg N ha^–1 plus some P applied directly to wheat.     

Effects of fertilizer price on feasibility of efficiency improvement: Case study for an urea injector for lowland rice

Efficiency improving techniques, such as the introduction of a urea injector for lowland rice production, appear to lead to higher yields, lower fertilizer use and less environmental pollution at the same time. If farmers are free to decide on the amount of fertilizer they use, economic rationality leads to a choice between using the improved technique for saving fertilizer while obtaining the same yield, for increasing yield (at the same fertilizer rate) or for a mixed strategy (a slightly higher yield and a different fertilizer rate). The economic optimum fertilizer rate was calculated with a simple yield model for a low and a high fertilizer application efficiency to predict which strategy would be best for the farmer.Calculations for a standard data set for lowland rice show that the greatest benefit from an increase in application efficiency by urea deep placement instead of broadcast application can be expected when a marginal efficiency of about 9 kg rice per kg fertilizer N is used for determining the fertilizer rate. For a marginal efficiency of less than 6, savings on fertilizer are the main benefit of efficiency improvement; for higher marginal efficiencies yield increases become the main component of total benefit; for marginal efficiencies above 9, fertilizer use will increase when a more efficient technique is used, but increased yields compensate for their costs. In the four countries where a manually operated pneumatic urea injector was tested (Togo, Bangladesh, Indonesia and Ivory Coast) the price ratio of rice and fertilizer N ranged from 1.1 to 2.5. Even when a risk-avoidance multiplier of 2 is used, we may conclude that fertilizer prices were too low relative to rice to make optimum use of the existing techniques for efficiency improvement. An equation is derived for estimating the price ratio at which the probability of farmer acceptance of techniques for improving fertilizer use efficiency is highest.     

Nutritional management ofPinus radiata at Gurnang State Forest,New South Wales

A survey of foliage and soil nutrients and productivity in post first-thinned stands (15 years +) ofP. radiata showed high variability on uniform soil parent material. Site index was significantly related to stand age and soil P. Nutritional monitoring plots in pre-crown closure stands showed P and B deficiency in the foliage and declining concentrations with age. High accumulations of Al and Mn in the foliage in both surveys were unrelated to stand age or site index. A 14-year-old once-thinned stand responded to N and P but not to K, Mg, Ca, B, Cu or Zn. The requirement for P in foliage appears to increase with age, though assessing the critical level is difficult. Nutritional monitoring, supported by fertilizer trials, appears essential to assess nutritional needs and to maintain productivity.     

A nitrogen and phosphorus herbage nutrient index as a tool for assessing the effect of N and P supply on the dry matter yield of permanent pastures

In order to propose consistent decision rules for fertilizer supply, a study was made on the effect of additions of N and P fertilizers and of their interaction on the above-ground dry matter yield of pastures during spring. The interaction between N and P could occur through nutrient acquisition or nutrient efficiency for growth. We therefore characterised the herbage N and P status (N and P index) from previously established critical curves of herbage mineral content according to above-ground dry matter. First we studied the effect of N and P addition on herbage nutrient status. Secondly, we expressed the above-ground dry matter as a function of the herbage nutrient status. This study consisted of four treatments applied to four permanent pastures which had a low phosphorus availability. The results showed a positive effect of P supply on the herbage nitrogen status, which may be due to an increase of organic matter mineralization or root growth. The P herbage status decreased only if N was supplied without P. The dry matter yield was positively related to the herbage nitrogen status, but a low P herbage status reduced the slope of the relationship. For the pastures studied, the indirect effect of P supply on above-ground dry matter, revealed by an increase in N index, was greater than its direct effect. This methodology allows us to distinguish the direct and indirect effects of N and P addition on herbage growth at field level. It could be used to propose consistent rules to manage jointly both N and P supplies.     

腐植酸对氮、磷肥的增效机理研究综述

腐植酸由芳香族及多种官能团构成,具有弱酸性、吸水性、胶体性、吸附性、离子交换性、络合性、氧化还原性等物理化学和生物活性,在增效化肥方面效果显著,但相关的机理研究较分散。为此,综述了腐植酸对氮、磷肥增效机制,以期为推动腐植酸与氮磷复混肥产品研发、提高农业生产用肥效率提供参考。     

有机-无机复混肥料的肥料效应初探

选取鸡粪为有机原料 ,进行发酵与不发酵两种前处理 ,设计 0、30 %、4 0 %、6 0 %和 10 0 % 5种有机氮水平 ,在水稻上连续两年试验。结果表明 ,在 4 0 %水平以下 ,作物产量随有机氮的增加而增加 ,超过 6 0 %产量下降 ,但有后效。氮素表观利用率与有机氮成正相关 ,当有机氮达到 10 0 %时 ,氮素利用率达到 5 3.4 %。随有机氮的增加 ,作物吸收养分向子粒中转移的比例也相应增加     

控失复合肥对稻田CH_4排放和水稻产量的影响研究

采用静态箱-气相色谱法研究控失复合肥对稻田CH4排放量和水稻产量的影响。结果表明:稻田CH4排放有明显季节变化趋势,排放高峰集中在水稻分蘖期和孕穗期;控失复合肥的使用可减少稻田CH4累积排放量,控失复合肥较常规施肥在减N 24.21%、10.00%和增N 10.83%情况下分别减排CH4 64.97%、12.97%和15.06%;控失复合肥的使用可降低水稻单位产量的全球变暖潜能值(GWP);控失复合肥的使用对水稻增产具有显著作用。     

Diagnosis of nitrogen deficiency in barley,growing in different rotation systems,by plant analysis

Nitrate concentrations were determined in stems of barley taken at the tillering stage from a 2-year rotational/N fertilizer experiment carried out at 2 locations in Cyprus. In the second year leaf laminae were also analysed for total nitrogen (N) concentration.At sampling maximum dry matter (DM) production was obtained with NO₃-N concentration above 1000 mg kg^–1, which increased with N fertilizer supply. Even though there were differences in DM and NO₃ concentration between rotation treatments the relationship between DM and NO₃ was similar.Nitrate in stems was more sensitive than total N in leaf laminae as an indicator of N nutrition status.     

Efficiency of modified urea fertilizers for tropical irrigated rice

An objective of the International Network on Soil Fertility and Fertilizer Evaluation for Rice (INSFFER) network is to field evaluate deep-point placement (urea supergranules) and slow-release (sulfur coated urea) N fertilizers in irrigated rice. These N sources were compared for performance with split application of prilled urea at 19 sites in Asia in wet season 1981.SCU or USG differed significantly in response curves from prilled urea at 12 of the 17 sites where N response was observed. Over these 17 sites, 22–25% less N as SCU or 29–31% less N as USG provided the same yield increment as the comparatively higher level of N as prilled urea.High profit N rates were derived for 5 sites. The optimal N levels for SCU or USG were less than for prilled urea. However, in one case for both test materials prilled urea was more profitable than SCU or USG. The marginal rates of return of using SCU or USG as opposed to OPU were calculated for the 11 sites where the response functions of the test materials differed significantly from prilled urea. In other than 2 sites for SCU the MRR exceeded 2.0 for 29 and 58 kg N ha^–1, indicating the general profitability of these materials when compared to prilled urea.     

Fertilization of millet cv. Souna III in Senegal: dry matter production and nutrient uptake

In a fertilizer and manure experiment, millet was grown under four treatments (no fertilizer or manure, farmyard manure, chemical fertilizer, and both). Grain yield and total aboveground biomass production of the unfertilized plot were relatively high. The observed differences in total dry matter production must be attributed to differences in nutrient availability, as amount of rainfall and its distribution were favourable. Results show only small differences in distribution of dry matter among the various plant organs between the best and the non-fertilized treatments.Nutrient supply from natural sources, defined as crop content of N, P, and K at maturity without fertilizer application, amounted to 104, 16 and 103 kg ha^–1, respectively, which are very high values.Total uptake of calcium and magnesium is related to that of potassium, as the combined content of these three elements is linearly related to total aboveground biomass production. Minimum removal of nitrogen and phosphorus per ton grain dry matter amounts to 29 and 4kg, respectively, and 9 kg potassium per ton total aboveground dry matter. A possible double function of phosphorus as element of structural biomass and for maintenance of electro-neutrality is discussed.     

磷肥厂酸性废水脱氟的试验研究

采用正交试验的方法探讨了以磷肥厂酸性废水为原料,利用石灰为脱氟剂脱除酸性废水中氟元素。以废水中磷氟质量比为考察指标,选择了石灰用量、反应温度和反应时间3个因素,4个水平的正交试验方法。结果表明:对磷氟质量比影响最大的因素是石灰用量和反应温度。综合考察各影响因素,得出磷肥厂废水脱氟的最佳工艺条件为:石灰用量为理论用量的1.25—1.30倍、反应温度55℃、反应时间1.5 h。脱氟后废水中的磷氟质量比达到100以上,可以满足高附加值产品饲料级磷酸氢钙的生产。     

石灰性灰潮土水稻施磷效应及利用率

以通州区石灰性灰潮土为供试土壤,研究了不同施磷水平对土壤速效磷含量及水稻产量的影响,测定了水稻不同施磷水平下磷肥的利用率。结果表明,在中等含磷的土壤上,石灰性灰潮土的磷肥系数为1.72,磷肥临界值为6.0 mg/kg;水稻合理施用磷肥能显著增产,但产量只在一定的施磷水平下随着施磷量的增加而增加,其667 m2最经济施磷量为3.8 kg,最高产量施磷量为9.4 kg。磷肥利用率则随施磷量的增加而逐渐下降,平均利用率为8.5%。     

无锡市锡山区污水处理厂升级改造工程

无锡市锡山区污水处理厂升级改造工程设计规模50 000m~3·d~(-1),主要采用强化二级生物脱氮除磷以及增加三级盘片式微过滤工艺进行工艺改造,出水达到城镇污水处理厂污染物排放标准(GB 18918-2002)中的一级A排放标准.     

A/SBR工艺在处理氮肥厂污水中的运行控制

针对氮肥厂污水处理原A2/O工艺无法使废水达到环保排放要求的情况,采用A/SBR工艺进行处理,处理过程中要通过严格控制工艺参数,可实现排水总氮≤15 mg/L,使污水达到排放标准。     

天然沸石的脱氮除磷研究

以河南某地沸石为材料,采用正交试验法,考察沸石粒径A、投加量B、搅拌转速C、吸附时间D及pH值E等因素对其脱氮除磷的影响,试验采用L16(45)的正交表,极差分析显示:粒径、用量和转速是该沸石脱氮除磷的显著因素,显著性大小的排序为:A＞C＞B＞E＞D.同时将其与浙江缙云沸石的脱氮除磷效果进行了比较,试验结果显示河南某地...     

有机肥料中氮磷钾测定前处理方法改进研究

为提高有机肥料中氮、磷、钾的测定效率,对有机肥料前处理过程进行了改进,并与农业标准NY525-2012的分析结果进行了比较。结果表明,改进方法与NY525-2012分析结果无显著性差异,可以代替NY525-2012对有机肥料中氮、磷、钾测定时进行前处理。     

Ecological implications of condensed tannin structure: A case study

Condensed tannins were isolated from bitterbnish (Purshia tridentata) and blackbrush (Coleogyne ramosissima). Structural analyses showed that both tannins were procyanidins of similar polymer length. The overall stereochemistries at C-3 and C-4, however, differed between the two tannins. These changes in stereochemistry resulted in blackbrush tannins being less preferred than bitterbrush tannins when offered to snowshoe hares (Lepus americanus). It is unlikely that differences in protein-precipitating abilities are the cause for the preference of the bitterbrush over the blackbrush tannins. Instead, we hypothesize that condensed tannins may be depolymerized and absorbed following ingestion. Differences in tannin structure can lead to different depolymerized products and rates of depolymerization, both of which may affect herbivore preferences.     

高纯氮装置的有效能分析

化工装置的有效能分析是考察流程是否具有先进性、节能潜力是否最大程度利用的工具之一,有效能分析法已经广范应用于能源化工生产当中。常见的分析(即有效能分析)通常包含平衡、损失、效率等基本计算。平衡是指研究系统内部值的守恒原则,但它同时考虑了内部能量的质和量的总体守恒。损失在数值上等于所给系统进出口的值之差,反映了过程内部不可逆损失的情况;效率定义为理想输出与实际输入之比,表示系统对的有效利用率,反映出在过程中的利用程度,是在热力学第二定律的基础上同时结合热力学第一定律提出的更为全面的评价指标。本文重点阐述有效能分析方法、针对高纯氮装置的有效能计算及有效能分析,希望能够促进气体分离行业的发展。     

超级杂交晚稻缓释氮肥最佳用量研究

采用集成栽培模式和农民习惯栽培模式,在5个施氮量的处理下,研究了缓释氮肥不同用量对超级杂交晚稻生长发育和产量的影响,并建立了产量与纯氮施用量的数学模型。结果表明：超级杂交晚稻的最佳施纯氮量和较经济的施纯氮量均为180kg／hm^2,此时2种栽培模式的产量均最高,分别为8．76和7．59t／hm^2,