Effects of long-term phosphorus fertilization and straw incorporation on phosphorus fractions in subtropical paddy soil

Study on soil phosphorus(P) fraction is an important aspect in probing the mechanisms of soil P accumulation in farmland and mitigating its losing risk to the environment. We used a sequential extraction method to evaluate the impacts of long-term fertilization and straw incorporation on inorganic, organic, and residual P(Pi, Po, and Pre) fractions in the plow layer(0–20 cm) of acidic paddy soil in southern China. The experiment comprised of six treatments:(i) no fertilizer control(CK);(ii) straw incorporation and green manure(SG);(iii) nitrogen and P fertilizer(NP);(iv) NP+SG;(v) NP+K fertilizer(NPK); and(vi) NPK+SG. The results showed that, compared to the initial total soil P content(TSP, 600 mg kg–1 in 1990), long-term(20 years) combined continuous P fertilizer and SG significantly increased P accumulation(by 13–20%) while single fertilization(39.3 kg P ha–1 yr–1) could maintain soil P status at the most. The average soil P fractions comprised of extractable Pi, Po, and Pre by 51.7, 33.4, and 14.9% in total soil P, respectively. With comparison of no fertilizer addition(CK), long-term single fertilization significantly(P<0.05) increased the accumulation of Na HCO3–, Na OH–, and HCl– extractable Pi fractions accounting for two- to three-fold, while SG increased the accumulation of Na HCO3– and Na OH– extractable Piand Po accounting for 12–60%. Though the mobilization of Pre fractions was not significant(P>0.05), our data indicate that SG may partially substitute for fertilizer P input and minimizing soil P accumulation and subsequent environmental risk in the subtropical paddy soil.     

烦夜蛾幼虫在甘薯田的空间分布及其抽样技术

为了掌握烦夜蛾幼虫在甘薯田的空间分布和种群特征,2015年对不同发生密度田块进行了调查,取得8组样本资料,采用6个聚集度指标和Iwao的m*-m回归分析法、Taylor的幂法则等,对其空间分布型和田间理论抽样数进行测定和分析。结果表明:烦夜蛾幼虫在甘薯田间呈聚集分布,聚集强度随着幼虫密度的增加而增大。环境因子是导致烦夜蛾幼虫聚集分布的主要原因。在此基础上,建立了幼虫虫口密度调查的最适理论抽样数公式N=1.96~2/D~2(1.3102/m+0.6255)和序贯抽样模型T_n=1.3102/(D~2-0.6255/n)。     

半B-（p，r）-预不变凸函数与非线性规划问题

定义了一类重要的非凸函数——半B-（p,r）-预不变凸函数,它是半预不变凸函数的真推广．首先用例子说明了此类函数的存在性,并说明它是B一不变凸函数、半预不变凸函数和B-（p,r）-预不变凸函数的推广;然后,讨论了半B-（p,r）-预不变凸函数的基本性质与集合刻画,并给出了半B-（p,r）-预不变凸规划问题的非可微最优性条件,其结论具有一般性,推广了涉及不变凸函数、半预不变凸函数和B-（p,r）-预不变凸函数的一些结论．     

机耕道自动驾驶农机局部路径规划

针对机耕道场景下自动驾驶农机行驶的安全性、平稳性与规划实时性的实际需求,该研究提出了一种基于二次规划的局部路径规划方法。首先基于有限状态机构建农机机耕道行驶模式,其次采用横纵向解耦的方法,通过改进状态栅格法分别对农机速度行为和轨迹行为进行决策,随后利用二次规划方法生成满足多目标、多约束条件的农机轨迹和速度,得到最优路径,最后在多种行驶环境中进行仿真和实车试验,行驶参考速度为2 m/s。实车试验结果表明,在绕行静态障碍物场景中,规划轨迹的平均绝对曲率为0.021 m^-1,最大绝对曲率为0.056 m^-1,平均绝对横向误差为3.23 cm,最大绝对横向误差为8.69 cm,农机与障碍物外轮廓的距离大于0.76 m;在规避相向行驶、同向行驶和横穿机耕道的动态障碍物场景中,规划速度的平均绝对速度误差为0.08～0.12 m/s,绝对速度误差小于0.38 m/s,加速度变化范围为-0.38～0.44 m/s²。在规划周期为200 ms的仿真试验中,本文算法平均耗时48 ms,最大耗时75 ms,相比采用静态状态栅格法平均耗时减少38 ms,算法效率提升44%。研究结果可为机耕道场景下的农机局部路径规划提供技术支持。     

The monotony preserving QO‐spline as a taper curve

A monotony preserving quadratic spline interpolating at a given point set can be constructed by the so‐called QO‐algorithm. The quality of QO‐splines, which are taper curves constructed by using this algorithm, is investigated. A comparison was made using the program of McAllister & Roulier which produces a shape preserving taper curve by using quadratic splines, too. Tests done on a representative sample tree material indicate that the QO‐spline is in general a better taper curve than the one produced by the program of McAllister & Roulier even if the difference may be small in certain cases.     

Economics of p fertilization of two soybean varieties at Jabalpur,M.P., India

Abstract

An economic interpretation was applied to a soybean yield prediction equation derived from data obtained in an experiment at Jabalpur, M.F. It was shown that no level of applied P could substitute for variety selection in terms of either soybean yield or economic returns per ha. Illustrative examples of the minimum price that must be obtained for soybeans before it is profitable to use P fertilizer for given price situations were shown.     

浅析宏程序在FANUC 0i数控系统中的应用

通过典型零件的宏程序编程实例分析其编程方法，并归纳出手工编程中应．用宏程序解决复杂零件数控加工编程问题的作用和技巧。     

Does returning sites of historic peri‐urban waste disposal to vegetable production pose a risk to human health? – A case study near Manchester,UK

Urban waste disposal occurred on fenland to the west of Manchester, England, between 1900 and 1964. The reclaimed fenland, Chat Moss, is now used for mixed arable farming. A total of 1.92 Mt of waste including privy midden, street sweepings, clinkers and slaughterhouse refuse was incorporated into the moss resulting in a modified topsoil with raised pH and reduced organic matter content compared with the subsoil. Elevated levels of potentially toxic elements (PTEs) are observed in the topsoil beyond the typical depth of atmospheric contamination; Cd and As concentrations exceed soil guideline values (SGVs) at 1.8 and 43 mg/kg, respectively. Sequential extraction indicates that waste‐derived Pb, Zn and Ni remain predominantly in the residual fraction, whereas Cu was mainly organically bound. Arsenic was predominately found in oxide and organic matter fractions with Cd in carbonate, oxide, organic matter and residual fractions. Pot trials indicated limited uptake of PTEs by vegetables grown on the waste‐amended soil, with the exception of Cd uptake by lettuce (0.22 mg/kg FW) and Pb uptake by radish (0.16 mg/kg FW), which exceeded current EU limits of 0.2 and 0.1 mg/kg FW, respectively. Hazard quotients (HQs) identified no risks to adults from consumption of vegetables grown in these soils with the exception of lettuce consumption with a HQ of 1.4. Risks to children were slightly greater with HQs >1 for Cd in lettuce, spinach, carrots and onion, As in lettuce, parsley and onion and for Zn in spinach.     

Spatial optimization by simulated annealing and linear programming

Forest management planning comprises selection among treatment alternatives in management units. A traditional linear programming (LP) approach may effectively account for a profit maximization objective combined with sustainability constraints, e.g. on the temporal distribution of harvest volume flows, cash‐flow, and net present value development, but it fails to account for spatial constraints, especially those associated with final felling. By applying a simulated annealing adjacency model based on net present value maximization and combined with an LP consequence computation model, it is possible to delineate optimal strategies of final felling scheduling. Evaluation is made of the trade‐off between (1) the incremental cost (determined by use of the LP model) of an optimal adjacency model solution, and (2) the potential damage cost resulting from adjacency characteristics such as windthrow and bark injuries. The decision support system may contribute significantly to reduce damage costs and may improve the reliability of forest management planning.