土壤养分的低成本速测技术

本文论述了测土施肥必须遵循经济强调测土施肥必须适合我国国情，提出了以常规分析技术为后盾以速测技术为主体的测土施肥技术路线；文章还论述了土壤养分速测技术，提出了推广速测技术必须解决的观念问题、技术总是和服务体制问题。     

测土配方施肥技术在丰都县包鸾镇的应用效果

结合重庆市丰都县包鸾镇实施测土配方施肥技术的生产实际,从社会效益、生态效益和生产效益等方面介绍测土配方施肥的综合效益,提出测土配方施肥应结合新品种推广、新技术应用等措施,以充分发挥测土配方施肥的作用。     

隆安县测土配方施肥推广措施成效与对策

对隆安县乔建镇推广测土配方施肥的组织、操作、调查等措施及取得一系列成效做了详细论述,并针对出现的问题进行深入思考并提出对策和建议,以期为测土配方施肥的规模化深层次精细化推广管理提供理论依据和实践依据。     

触摸屏技术在测土配方施肥中研究和应用

论述了测土配方施肥触摸屏的系统特点、主要功能及其应用情况。充分利用在农业部测土配方施肥项目中所获得的大量数据,实现对农业生产的指导作用,研究并开发了基于GIS的县域测土配方施肥决策触摸屏系统,通过引入触摸屏技术,实现了用触摸屏显示内容的可触摸的测土配方施肥决策触摸屏系统。该系统基于数据库技术提供了区域施肥、精准施肥、土壤养分、地力评价、土壤分布信息的查询功能,解决了大多数网上施肥决策系统功能齐全、却难以推广应用的难题。     

湛江市农垦测土配方施肥存在的问题及建议

为大力推广测土配方施肥技术,提高肥料利用效率、提升作物产量、降低生产成本、实现作物稳定增产,从广东省湛江垦区具体情况出发,总结分析了该垦区测土配方施肥技术中存在的问题,并提出相应的对策及建议。     

浅谈武定县测土配方施肥中存在的问题及其对策

通过分析武定县测土配方施肥中存在的问题,提出了相应对策,为全县农作物测土配方施肥技术推广应用提出合理化建议。     

井研县千佛镇农作物测土配方施肥现状及对策

以四川省千佛镇为例,扼要分析了当前农作物配方施肥的现状、取得的成效及存在的问题,并提出了相应的对策分析,为进一步推广农作物测土配方施肥技术提供参考。     

浅谈果树测土配方平衡施肥技术

加强果树测土配方平衡施肥技术的应用,可以进一步提升水果产量,帮助果农增收。基于此,概述了果树测土配方施肥技术的内涵,简要阐述了测土配方平衡施肥技术的实施流程,对果树生长过程中的营养需求特征进行了简单分析,最后提出了几点提升果树测土配方平衡施肥技术效果的建议。     

浅谈测土配方施肥技术的推广与应用

测土配方施肥技术是一种新型施肥技术,通过对土壤和农作物的试验,该项技术能够寻找最有利于农作物生长的施肥方式,保障农作物健康生长的同时也能减少农业化肥带给生态环境的污染。基于此,讨论测土配方施肥技术推广应用的意义及当前推广应用工作中存在的问题,以此提出加强测土配方施肥技术推广与应用的对策,希望为我国农业的发展以及农户经济效益的增长提供帮助。     

设施蔬菜测土配方施肥有关问题初探

阐述了设施蔬菜测土配方施肥的特殊性,介绍设施蔬菜的营养需求和施肥特征,针对天津市目前设施蔬菜施肥及测土配方施肥存在问题,提出了设施蔬菜测土配方施肥的基本原则、对策和措施。     

水产养殖物联网的应用评价方法

构建科学合理的水产养殖物联网应用评价指标体系和评价方法,是保证水产养殖物联网系统发挥最大能效的基础。为解决指标设置随意、冗余、交叉及技术指标过剩的问题,该文构建了指标筛选模型,将水产养殖物联网应用评价指标体系从40个优化到14个,用35%的指标表达了88.45%的信息,保证了指标体系的完备性和简洁性。同时,基于模糊评价法构建了水产养殖物联网应用评价模型,可对水产养殖物联网应用水平进行总体评价以及功能、性能、效益方面的评价。最后,以江苏宜兴河蟹养殖物联网和广东湛江南美白对虾养殖物联网为实例进行了验证,宜兴物联网的评价结果为优,而湛江物联网的评价结果为良,与实际情况相符,表明该研究构建的指标体系科学合理,评价方法可行,可为水产养殖物联网应用评价提供参考。     

中国土壤环境质量标准中重金属指标的筛选研究

我国土壤重金属污染问题十分严重,但目前国家的土壤环境质量标准已不适应当前土壤环境管理的需求,在指标体系上主要体现在重金属污染物项目过少,对一些新出现的污染问题无法有效监管。本研究通过深入调研美国、加拿大、荷兰、德国、澳大利亚、日本、中国台湾和香港等发达国家和地区的土壤环境标准,并将他们的重金属指标与我国现行的土壤环境质量标准中的重金属指标进行系统比较分析,提出我国土壤环境质量标准中重金属指标的修订建议。主要是要补充六价铬、有机汞等高毒害重金属价态和形态的标准;新增铍、锑、铊、钒等新型重金属污染物的土壤环境质量标准;同时,结合石灰(岩)土高背景区土壤,探索建立基于有效性的土壤重金属浸提态标准体系;为实现我国土壤重金属污染的风险管理提供科学依据。     

Recommendations for preparing test samples for AOAC collaborative studies of microbiological procedures for foods

Preparation of test samples for microbial collaborative studies poses problems not encountered in studies on chemical analytes. For Associate Referees who are considering a collaborative study of a microbiological procedure for food analysis, these problems have not been adequately addressed. Types of contamination (natural or artificial), number of test samples required, analyte selection, proper controls, and container selection are addressed herein. The discussion is a supplement to the guidelines contained in the Handbook for AOAC Members.     

Evaluation of soil extractants for silicon availability for sugarcane

Adequate evaluation and interpretation of silicon (Si) phytoavailability in soil is a key to fertilizer recommendation. This study was conducted to determine the effect of soil texture on the choice of Si extractant, and provide baseline data on the relationship between extractable Si and sugarcane Si accumulation. The effects of soil texture and extractant solutions of Si were investigated on soil of nine areas of sugarcane cultivation. Si contents in clayey soils were higher than in sandy soils only in the extraction with standard calcium chloride, acetic acid, potassium chloride (KCl), and sodium acetate buffer. Other extractants failed to reveal differences in the Si availability among the three soil textures. The choice of the extractant should consider soil texture for the determination of adequate Si contents in soils planted with sugarcane, and the extractants that proved to be more efficient in the three soil textures was acetic acid and KCl.     

Method for Preparation of Nutrient-depleted Soil for Determination of Plant Nutrient Requirements

ABSTRACT

Research for nutrient optimization and crop nutrient use efficiency requires precise control on soil nutrient status. While nutrient-depleted soils are preferable to artificial soils or hydroponics, reliable and affordable methods for nutrient removal are lacking. We report the systematic standardization and validation of a simple method to wash soil with purified deionized water for the removal of nutrients such as nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and organic carbon. Sandy soil was washed with RO water (1:1, w/v) followed by several washes with Type 1 ultrapure water (2:1, w/v) and tested after each wash for the removal of organic carbon, N, P, K, and Ca. After seven washes, total dissolved solids (TDS) were reduced to 5 ppm, conductivity to 10 µS, organic carbon content was reduced by 78%, while N by 19.5%, P by 30%, K by 48% and Ca by 29%. Two genotypes of rice were grown for full life cycle under normal and low N fertilizer (urea) levels to demonstrate that soil depleted with nutrients by our method supports normal plant growth in the greenhouse and allows experiments impossible under field conditions. Precise control on the nutrient status of the soil by our method also helped demonstrate yield differences between genotypes and N regimes and also that higher grain yields can be obtained with low nitrogen (N) input. Thus, our method facilitates better design of experiments for precise determination of nutrient requirements for crop growth and nutrient use efficiency.     

Laboratory evaluation of a model for soil crumbling for prediction of the optimum soil water content for tillage

A model for soil crumbling, called the capillary crumbling model (CCM) was introduced by Aluko and Koolen [Aluko, O.B., Koolen, A.J., 2000. The essential mechanics of capillary crumbling of structured agricultural soils. Soil Till. Res. 55, 117–126]. According to the CCM, the optimum soil water content for tillage (θ_OPT) may be defined as the water content at which the capillary bonding strength between aggregates is minimum. The objective of this study was to evaluate the CCM for the arable layer of 10 agricultural soils (sandy loam to clay textures) from semi-arid regions in western Iran. The results were compared with conventional soil workability limits such as 0.85 of the soil plastic limit (0.85θ_PL), Proctor critical water content (θ_Proctor), 0.6 or 0.7 of water content at matric suction of 50 hPa (0.6–0.7θ_50 hPa), and the Kretschmer optimum water content (θ_Kretschmer = θ_PL − 0.15(θ_LL − θ_PL)) where θ_LL is the soil liquid limit. Repacked soil cores were prepared from intact soil aggregates (0.50–4.75 mm) to 0.9 of the critical bulk density (to represent the soil conditions before tillage). Tensile strength and matric suction of the cores were determined at different soil water contents obtained by slow drying. The CCM provided evidence for the physics and mechanics of crumbling in the studied soils. It revealed that effective stresses are the dominant inter-aggregates forces, at least for the wet range of soil water content. A fall in strength of inter-aggregate bonds (i.e. tensile strength) was recorded due to water emptying from structural pores in a narrow range of matric suction (h_OPT) which was consistent with the model. With increasing soil organic matter and clay contents the fall became more distinct, indicating increased structural stability. The θ_OPT values determined by the CCM were found in the h_OPT range 551–612 hPa corresponding to 0.91–0.79θ_PL, which was in agreement with published values for the soil workability limit. Negative correlations between h_OPT and clay and organic matter contents clearly confirmed the increasing effect of soil structure on the enlargement of inter-aggregate pores. High correlations were observed between θ_OPT and 0.85θ_PL, θ_Proctor or 0.7θ_50 hPa. The results showed that the CCM might be recommended as a physically based method for the determination of θ_OPT. Considering the 1:1 relationships between θ_OPT and 0.85θ_PL or θ_Proctor, and easy determination of θ_PL and θ_Proctor, use of these indices is recommended in situations where the CCM is not applicable.     

温室透光覆盖材料流滴性测试方法

作为温室透光覆盖材料的塑料薄膜的流滴性日益受到关注，为此，已开发出各种无滴膜、无滴板，以改善温室透光覆盖材料的流滴性。但国内外对材料流滴性的监测与判断规则却很不统一，给温室用户带来了困难。该文分析了目前几种常用的流滴性检测方法的原理及其适用性，在此基础上，结合温室生产的实际条件，提出在15°～30°倾斜面上形成露滴后，材料表面凝结水滴面积占整个测试面积比例的检测方法——倾斜面上滞留水滴面积比法，并通过对塑料薄膜和聚碳酸酯板的分析测试，提出了将材料表面上计算水滴滞留面积小于10%作为透光覆盖材料流滴性的判别标准，为标准化检测覆盖材料的流滴性提供了依据。     

Methodological alternatives for calculation of enrichment factors used for assessment of topsoil contamination

Purpose

The research is aimed at comparison of different enrichment factors (EFs) calculated for potentially harmful chemical elements (PHEs) basing on topsoil data from Klaip?da with geological differences between two areas, choice of the reference elements (REs), consideration of the expediency and efficiency of normalisation, the influence of PHE and RE background or upper threshold values on the estimated contamination level of 50 schoolyards and the arising problems, i.e. which PHE should be normalised.

Materials and methods

Composite topsoil samples taken in 50 schoolyards and 28 football fields from 0 to 10-cm depth were air-dried, sieved to <1 mm, milled and analysed for total contents of major elements and As, Ba, Cr, Cu, Mn, Mo, Ni, Pb, Sn, U, V and Zn by energy-dispersive X-ray fluorescence and of Ag and Co by optical atomic emission spectrophotometry. Simple EFs in schoolyards were calculated normalising by concentration factor (CF) of Fe, while complex EFs normalising by weighted average of Al, K and Ti concentration factors (WACFs).

Results and discussion

The variability of RE is shown with significant differences between sandy western and loamy eastern areas and lower differences between schoolyards and football fields. The highest effectiveness of normalisation, i.e. the number of sites where WACF > 1 or CF > 1, is when RE background values for schoolyards differentiated for each area are selected. The formulas for the ratio of different EFs demonstrate that (1) for Co, Ba, Mn, Mo, Pb and Cu, the upper threshold-type EFs exceed the background-type EFs; (2) there is the tendency to obtain lower EFs for the greater part of PHE when using differentiated background of PHE and RE. The problems of estimation of the background of some PHE and the expediency of their normalisation are discussed.

Conclusions

The recommendations are (1) to explore the variability of RE in the urban territory and to find out if there are areas with significant differences in RE content, in this case try to estimate the differentiated background values of RE and PHE, because respective EFs are usually lower; (2) for more effective normalisation, to use background values of RE which correspond to the object of assessment; (3) not to use upper threshold-type EFs; (4) to be careful with interpretation of EFs for those PHEs which have significant negative correlation with RE.

     

Sap analysis for the prediction of stem yield and the need for extra nitrogen fertiliser for Kenaf

Abstract

Kenaf (Hibiscus cannabinus var. Guatemala 4) was grown at Ayr in north Queensland under eleven nitrogen (N) treatments, including seven treatments with all nitrogen applied at planting and four split treatments in which half the nitrogen was applied at planting and half applied 67 days after planting. At weekly intervals from 36 days after planting, petioles from the youngest mature blades were sampled to investigate the possibility of using petiole sap analysis as a fertiliser‐management tool.

The sap nitrate test showed promise in prognosing final stem dry‐matter yield. Relationships between final stem yield and sap NO₃‐N at various sampling times, leading up to canopy closure of treatments supplied with 240 kg N/ha or more, are presented. Estimated desirable NO₃‐N concentrations are also presented.

Sap nitrate levels declined rapidly from 36 days after planting. The rate of decline of petiole nitrate levels depended upon the rate of nitrogen applied at planting. Monitoring sap nitrate over the four‐week period before canopy closure is expected and using the levels established as desirable in this work as a guide, will help the kenaf grower to identify the need for extra nitrogen.     

山地果园蓄电池驱动单轨运输机传动系统设计

为解决将传统的蜗轮蜗杆传动机构应用于山地果园蓄电池驱动单轨运输机所带来的机械效率低的问题,该文设计了一种基于蜗轮蜗杆的双路传动链传动系统,该系统采用电动机为动力源,通过蜗轮蜗杆传动链和链条传动链两路并联传动链传递动力;两路传动链之间相互独立,根据运输机的运动状态,运用STM32内嵌控制程序对电磁离合器状态进行切换.文中分析了该系统的传动原理、关键零部件设计及机械传动效率,设计输出转速为44~131.18 r/min.采用尤奈特MY1020ZXF-75048 V电机作为动力源,4个12V40AH天能蓄电池串联作为能源,由NMRV040减速器(海格尔控股有限公司)、超越离合器与各型链轮组成双路并联传动链,并运用功率流分析法得出该系统平地与上坡运行状态下输出扭矩为44.352 N·m、输出转速为86.318 r/min、输出功率为609.31 W;下坡与反向运行状态下输出扭矩为105.760 N?m、输出转速为28.953 r/min,输出功率为487.342 W.结果表明,该系统结合了链传动的高效性与蜗轮蜗杆传动的自锁优势,在平地与上坡运行中理论机械效率为81.2%,下坡与反向运行中理论机械效率为60.5%.该研究可为山地果园蓄电池驱动单轨运输机提升机械效率提供参考.