BREAM: A probabilistic Bystander and Resident Exposure Assessment Model of spray drift from an agricultural boom sprayer

Complex simulation models are available to predict the level of exposure to bystanders and residents after a crop spraying event. In this paper we consider a particle-tracking spray drift model whose input parameters define particular scenarios of interest. Model outputs based on fixed values for these inputs ignore natural random variation and therefore give no indication of realistic variation in exposures, nor do they quantify the probability of rare extreme exposures. We describe a probabilistic modelling framework that allows the effect of variability in the input parameters to be quantified. An efficient statistical method for approximating the spray drift model is used, by creating a statistical emulator. An additional statistical model is then used to link airborne spray outputs to bystander exposures based on measured data. Uncertainty and variability are quantified in this model component. Validation of our approach is considered in two stages: first the accuracy of the emulator is assessed, as a surrogate for the true spray model. Secondly, the overall probabilistic outputs are compared with corresponding field measurements. Results are presented for a selection of typical exposure risk scenarios for bystanders and residents, illustrating the potential to generate a richer source of information for decision-makers. Sensitivity analysis results suggest strategies to reduce risk, such as minimising boom height.     

日光温室多头切花菊品质模拟

通过不同品种和定植期试验,根据温光对菊花Dendranthema × grandiflora品质的影响,初步建立了以生理辐热积（PTEP）为尺度的日光温室多头切花菊外观品质预测模型,并用独立的试验数据对模型进行了检验。结果表明：模型对日光温室多头切花菊株高、展叶数、单株叶面积、茎粗和花径的模拟值与实测值的符合度较好,模拟值与实测值基于1 ∶ 1线的决定系数（R²）和相对预测误差（E_RP）分别为0.99,0.99,0.94,0.87,0.92和7.2%,6.9%,10.2%,5.6%,18.2%,模型预测精度较高。图2表3参14     

A model for estimating how variability of biological parameters affects economic factors in an integrated turkey farm

Turkeys, as well as other poultry meat, are marketed as a healthier alternative to red meat. At the same time, the necessary investment in integrated turkey projects is 65% higher than for similar broiler projects. This explains the importance of rigorous evaluation of new turkey farms, including their sensitivity to biological parameters. We present a method of evaluating poultry projects that takes simultaneous variability of several biological parameters into account, using a bio-economic model, stochastic simulation, and an integrated turkey farm in Russia as a real-life example. The algorithm based on the Cholesky decomposition of the covariance matrix was used to generate a multivariate normal random vector of biological parameters. The bio-economic model takes into account simultaneous variability of major input biological parameters related to all stages of an integrated poultry farm: survival, hatchability, ratio of carcass weight to live weight, and number of eggs per layer. The highest variability of the output economic indices was estimated for internal rate of return: the coefficient of variation (CV) of this major economic index was approximately 240% of the CV of the input biological parameters. Such estimation can be used to analyze a project's economic risks, i.e., variability in production cost and profitability.     

一个稻麦作物氮肥利用率的统计模型

通过对中国近 15年 385组稻麦作物田间试验数据的统计分析, 建立了与施氮量 (Ninput, kg·hm-2 ) 相关的氮肥利用率 (NUE) 统计模型: NUE=144 1×N-0 27input (R2 =0 627, P<0 001)。模型分析表明, 中国的氮肥利用率存在明显的区域差异, 经济发达地区 (江苏) 要比欠发达地区 (黑龙江) 低 10%左右。     

Research advances of SAR remote sensing for agriculture applications: A review

Synthetic aperture radar (SAR) is an effective and important technique in monitoring crop and other agricultural targets because its quality does not depend on weather conditions. SAR is sensitive to the geometrical structures and dielectric properties of the targets and has a certain penetration ability to some agricultural targets. The capabilities of SAR for agriculture applications can be organized into three main categories: crop identification and crop planting area statistics, crop and cropland parameter extraction, and crop yield estimation. According to the above concepts, this paper systematically analyses the recent progresses, existing problems and future directions in SAR agricultural remote sensing. In recent years, with the remarkable progresses in SAR remote sensing systems, the available SAR data sources have been greatly enriched. The accuracies of the crop classification and parameter extraction by SAR data have been improved progressively. But the development of modern agriculture has put forwarded higher requirements for SAR remote sensing. For instance, the spatial resolution and revisiting cycle of the SAR sensors, the accuracy of crop classification, the whole phenological period monitoring of crop growth status, the soil moisture inversion under the condition of high vegetation coverage, the integrations of SAR remote sensing retrieval information with hydrological models and/or crop growth models, and so on, still need to be improved. In the future, the joint use of optical and SAR remote sensing data, the application of multi-band multi-dimensional SAR, the precise and high efficient modeling of electromagnetic scattering and parameter extraction of crop and farmland composite scene, the development of light and small SAR systems like those onboard unmanned aerial vehicles and their applications will be active research areas in agriculture remote sensing. This paper concludes that SAR remote sensing has great potential and will play a more significant role in the various fields of agricultural remote sensing.     

化肥施用强度对中国粮食单产的影响分析——基于省级面板数据的分位数回归

在分析中国粮食作物化肥施用特征的基础上,运用分位数回归模型探究了1994年以来化肥施用强度对早籼稻、中籼稻、晚籼稻、粳稻、小麦、玉米6种粮食单产水平的影响。研究表明:1)中国粮食作物的化肥施用强度增长具有明显的阶段性特征;6种粮食作物的化肥施用强度持续增加,且均超出国际安全施用标准;小麦与玉米的化肥施用强度显著高于水稻;部分品种的化肥施用强度已出现优势产区和非优势产区、东中西部的区域差异。2)粮食作物的化肥施用强度与其单产水平具有显著的关联效应。3)晚籼稻、粳稻和玉米的化肥施用强度对其单产仍存在正向作用,但已呈现边际效用递减特征;小麦、早籼稻和中籼稻的这种影响不再显著,已有过度施用特征。今后在坚持化肥施用零增长前提下,注重科学施用化肥、有效提高化肥利用率,在保障粮食安全与促进农业可持续发展之间达成平衡,是坚持中国特色农业现代化道路的必然要求。