Cotton root growth as affected by P fertilizer placement

Growth chamber studies were conducted to evaluate root growth and P uptake by cotton (Gossypium hirsutum L.) as affected by the proportion of the soil volume that is treated with fertilizer P. Cotton seedlings were grown in a Dewey silty clay loam (Typic Paleudult) and a Marvyn loamy sand (Typic Paleudult). The Dewey soil had a low-P status and the Marvyn soil had a high-P status (7 and 44 mg kg^–1 Mehlich I extractable P, respectively). Phosphorus was added at a constant or base rate which was added to decreasing proportions of the soil volume (i.e. 1.0, 0.5, 0.25 and 0.125). The addition of the same amount of P to decreasing proportions of the soil volume resulted in a stimulation of root growth in the P-fertilized soil volume relative to the nonfertilized soil. The degree of stimulation was similar for the two soils which differed in P status. Phosphorus uptake reached a maximum when 0.25 and 0.50 of the soil volume was treated with P on the Marvyn and Dewey soils, respectively.     

Phosphorus fertigation of trickle-irrigated potato

A 3-year field study, on Pellic Vertisol, investigated the response of trickle-irrigated potato (Solanum tuberosum L.) to four P levels applied with the irrigation water. Waters supplied with 130 and 120 mg l^–1 of N and K, respectively, and with P levels of 0, 20, 40 and 60 mg l^–1, were applied when the soil water potential was between 0.03 and 0.04 MPa. The water applied at each irrigation was equivalent to 0.8 of pan evaporation from a screened USWB Class A pan. With the application of 40 mg P l^–1 no P accumulation deeper in the soil profile occurred, whereas P in petioles was at levels recommended for high yield of good quality. At this P concentration in irrigation water, removal of P from soil by tubers was 22 kg/ha/year. The highest yield of good quality was obtained at 40 mg P l^–1.     

群落复肥及其发展前途

阐述作物集合层次(作物个体、作物群体、作物群落)及群落栽培的意义、特性和前景;提出群落栽培对群落复混肥研制的要求,介绍群落复混肥的配方实例。     

Uptake and balance of labelled fertilizer nitrogen by potatoes

Potatoes have a shallow rooting system. This can seriously affect the efficient use of fertilizer N. During two consecutive years, 1985 and 1986, a study was conducted on a commercial field to investigate the uptake of labelled N by potatoes under the recommended N rate and existing agricultural practices. The fertilizer efficiency, fertilizer distribution within the plant and soil and the total fertilizer balance were made using¹⁵NH₄ ¹⁵NO₃ 3.63 At. %¹⁵N excess. The recovery of the applied N-fertilizer in the whole plant was 25 and 56% for 1985 and 1986, respectively. The % Ndff and % Ndfs ranged between 30–40% and 60–70% respectively in both years. An important amount of fertilizer N was left in the soil after harvest. It reached 44 and 34% in 1985 and 1986, respectively.The total balance of the applied fertilizer N showed that up to 31 and 10% of the fertilizer N was lost during 1985 and 1986, respectively. The differences between the two growing seasons were mainly related to the method and timing of fertilizer N application and to the amount of rainfall.     

Urea-N uptake by dasheen (Colocasia esculenta L. Schott) in relation to the fertilizer placement method

Urea has become the most important N carrier in many parts of the world and its reaction when added to soil is unique in many ways. Two field experiments were therefore undertaken using¹⁵N to investigate the uptake efficiency of the added urea-¹⁵N which was banded in Experiment I and broadcast in Experiment II. In both experiments the uptake efficiencies were not affected by N-rate and cropping system (Exp. I) or crop residue management (Exp. II) and averaged 17.4 and 16.9% respectively. These low values were supported by evidences of high losses; high pH increases following urea application (volatilization), downward movement of N (leaching), and cycles of waterlogged and well drained conditions in the soil (de-nitrification). Evidence of leaching at least down to 30 cm in the profile was observed in the first experiment where urea was banded but not in experiment II where it was broadcast. The proportion of N in the crop that was derived from added urea (%Ndff) was 57.7% and 36.4% in experiments I and II respectively, suggesting that band application resulted in a higher proportion of the added N in the root zone compared to that for broadcast application. The results indicate the need to investigate other management strategies, such as higher application frequencies and placement closer to the root zone, in order to improve the uptake efficiency of added urea-N in upland rainfed dasheen.     

On the Substrate Binding of Linoleate 9-Lipoxygenases

Lipoxygenases (LOX; linoleate:oxygen oxidoreductase EC 1.13.11.12) consist of a class of enzymes that catalyze the regio- and stereo specific dioxygenation of polyunsaturated fatty acids. Here we characterize two proteins that belong to the less studied class of 9-LOXs, Solanum tuberosum StLOX1 and Arabidopsis thaliana AtLOX1. The proteins were recombinantly expressed in E. coli and the product specificity of the enzymes was tested against different fatty acid substrates. Both enzymes showed high specificity against all tested C18 fatty acids and produced (9S)-hydroperoxides. However, incubation of the C20 fatty acid arachidonic acid with AtLOX1 gave a mixture of racemic hydroperoxides. On the other hand, with StLOX1 we observed the formation of a mixture of products among which the (5S)-hydroperoxy eicosatetraenoic acid (5S-H(P)ETE) was the most abundant. Esterified fatty acids were no substrates. We used site directed mutagenesis to modify a conserved valine residue in the active site of StLOX1 and examine the importance of space within the active site, which has been shown to play a role in determining the positional specificity. The Val576Phe mutant still catalyzed the formation of (9S)-hydroperoxides with C18 fatty acids, while it exhibited altered specificity against arachidonic acid and produced mainly (11S)-H(P)ETE. These data confirm the model that in case of linoleate 9-LOX binding of the substrate takes place with the carboxyl-group first. Sequence data: The nucleotide sequences reported in this paper are annotated in the GenBank/EMBL data bank under the accession numbers Q06327 and S73865.     

Interaction of root distribution of corn with fertilizer placement and frequency of irrigation in lysimeters

In a factorial design lysimeter experiment with corn, in a sandy loam soil, two irrigtion frequencies (low (IL) and high (IH)) and two ways of fertilizer placement (shallow (FS) and deep (FD)), were applied. The plants did not suffer from stress under either water regime.Tillering, degree of grain filling and distribution of nitrogen between the grain and vegetative plant parts, indicated an enhanced plant development in the FS treatment.The IH-FS treatment showed the highest root density in the upper soil layer and the highest grain yield and reduced-nitrogen yield in grain. Results indicate that fertilizer placement influences root density distribution in the soil profile and consequent corn yield.     

关于低浓度复肥装置生产高浓度复肥的探讨

阐述低浓度复肥与高浓度复肥成粒的不同特点。探讨用圆盘造粒机生产低浓度复肥 ,只要注意调整物料配方 ,保持 40 %粘性物料的比例 ,串联 1台圆盘造粒机 ,生产高浓度复肥是可行的 ,不必采用转鼓造粒     

小型复肥企业应对化肥产业国际化的措施

在全面分析小型企业自身现状和所面临市场环境的基础上,提出一些应对化肥产业国际化的措施。     

一座高塔既产硝基复合肥又产尿基复合肥的工艺技术

通过对高塔生产硝基复合肥和尿基复合肥的工艺分析,其主要区别是混合槽物料的温度与流向不同.为此,介绍了一座高塔可以生产2种复合肥的混合槽工艺管道流向设计及生产不同复合肥时的注意事项.该创新技术使高塔更能满足市场对肥料的多品种需求.     

Nitrogen fertigation of trickle-irrigated potato

This three-year field study, on Pellic Vertisol, was designed to investigate the response of trickle-irrigated potato (Solanum tuberosum L.) to four nitrogen levels continually applied with the irrigation stream. Waters containing 70, 130, 190, and 250 mg Nl^–1 and uniformly supplied with 50 and 120 mgl^–1 of P and K, respectively, were applied when the soil water potential was between 0.03 and 0.04 MPa. The amount of water applied at each irrigation was equivalent to 0.8 of pan evaporation from a screened USWB Class A pan. The resulting N application totals ranged from 205 to 735 kg ha^–1. Significant buildup of soil NO₃-N occurred below 45 cm depth with the two higher amounts of N but not with the 70 or 130 mg Nl^–1. A concentration of 130 mg Nl^–1 was adequate for maintaining petiole NO₃-N above the critical value throughout the growing period. The highest yield of good quality (58130 kg ha^–1; specific gravity 1.071) was obtained with 130 mg Nl^–1. It was concluded that fertigation (combined irrigation with fertilization) is a promising means for maintaining N concentration in the soil throughout the growing period at desirable levels, without undue losses by leaching.     

复混肥的包膜及防结块

阐述解决国产复混肥结块的重要性 ,影响结块的因素及防结块的措施。介绍选脂肪胺类阴阳离子混合型表面活性剂的优点和作用机理 ,这类国产防结块剂比进口同类产品价格便宜 ,效果相当     

尿基氮磷钾复合肥新工艺的研究

通过实验室和小型连续试验,开发成功以尿素、磷矿、硫酸、钙镁磷肥、钾盐等为原料一步法生产新型尿基复合肥生产技术.该技术具有流程短、设备少、占地面积小、节能降耗及解决氟污染等特点产品富含中、微量元素,肥效显著提高,增产效果突出.     

农药一化肥合剂的开发与研制

论述农药和化肥在农业生产中的重要作用及开发农药-化肥合剂的意义,提出以复混肥料为除草剂载体的药肥发展思路,分析药肥配伍的主要因素,给出了包裹型药肥的开发实例.     

利用氨化(喷浆)硫基复合肥装置生产有机无机复合肥

介绍山东欧化化工有限公司利用氨化(喷浆)硫基复合肥装置生产有机无机复合肥的技术。该技术的最大特点是在混酸溶液中加入有机质,有机质经酸性调节直接参与中和造粒反应,产品养分可在20%～40%间随意调整。所生产的有机无机复合肥产品水分低[w(H2O)3%],强度高,营养全面,高效环保。     

Reducing fertilizer requirements for hybrid squash (Cucurbita maxima L.) with localized applications of phosphorus and potassium and use of partially acidulated phosphate rock

Two experiments examined options for reducing the inputs of P and K fertilizers for hybrid squash (Cucurbita maxima L.) at Pukekohe, New Zealand. The first experiment examined the effects of elevating the NaHCO₃-soluble P from 32 to 130 mg kg^–1 and the exchangeable K from 140 to 350 mg kg^–1 within strips from 0 to 0.75 m around rows of hybrid squash planted 1.5 m apart. From both P and K, crop yield increased as the width of the fertilized strip was increased up to 0.25 m, while wider fertilized strips had no further effect. These results followed similar effects on plant dry matter and tissue P or K concentration during early growth, and are explained in terms of the P and K accumulation by the crop, the decline during growth of the sensitivity of the crop to soil P and K fertility associated with declining rates of P and K uptake per unit length of root. Implications for fertilizer management for hybrid squash are also discussed.The second experiment compared the effects of partially acidulated phosphate rock and triple-superphosphate on soil P fertility, growth and yield of hybrid squash. Partially acidulated phosphate rock had smaller effects than those of triple-superphosphate on NaHCO₃-soluble P levels in the soil, plant dry weight and tissue P concentration soon after emergence, and subsequently crop yield. On average, partially acidulated phosphate rock increased crop yield by about 70% of that following the application of the same quantity of P as triple-superphosphate. This lower effectiveness of partially acidulated phosphate rock for hybrid squash is explained in terms of its lower solubility and hence smaller effect on NaHCO₃-soluble P in the soil during early growth, when the crop is most sensitive to soil P fertility.     

加强肥料登记管理促进复混(合)肥料科学发展

分析我国农业生产情况与西方发达国家的重大区别,加强肥料登记管理,是解决复混肥发展中多种错误倾向的根本手段.论述在肥料登记管理中如何既减轻企业负担,又保证肥料登记证的专业权威性.     

中浓度硫基复合肥的生产技术

随着高浓度复合肥数量在市场上的递增,一些地区因其所销肥料产品养分固定,价位较高,而出现过剩。我公司通过市场调查与分析,利用高浓度(151515)硫基复合肥装置生产中浓度(1587)复合肥。介绍中浓度硫基NPK与高浓度硫基NPK的工艺流程和生产控制的异同点。     

复合肥干燥机防粘壁技术

介绍复合肥干燥机防粘壁的技术:干燥机外部安装振动锤打击振动防止结壁及振动锤的制造、安装、布点方法;调整干燥机内部抄板适度的密度、高度和角度;处理好原料、配方与工艺操作的关系。综合实施各项技术可有效解决复合肥干燥机的粘壁问题,使全年设备开工天数提高30天左右,并可提高产品质量、产量,节约原料、燃料、电能消耗。     

尿基复合肥氨化造粒控制要点

介绍尿基复合肥氨化造粒控制要点,分析尿基复合肥造粒物料湿度、温度和管式反应器操作压力对造粒的影响及主要的调节手段。