农业管理措施对土壤有机碳动态变化的影响

土壤碳固定问题已成为陆地生态系统碳循环研究的热点问题。土壤碳固定是缓解温室效应加剧的有效方法之一。土壤有机碳含量变化受土地利用方式和耕作措施的强烈影响。将自然土壤转变为耕作土壤会导致土壤碳库的迅速下降,使土壤损失有机碳4.1-5.0×1013kg之间。采用新的农业措施会使碳损失量的60-70%重新被固定。这些措施有保护性耕作(少耕或免耕)、合理施用肥料、覆盖作物、应用深根且富含木质素的作物等。土壤除了固定有机碳外,干旱和半干旱地区土壤还具有固定无机碳的巨大潜力。文章还简要介绍了评价土壤有机碳的两种方法,并对今后的工作提出了几点建议。     

High accuracy path tracking for vehicles in presence of sliding: Application to farm vehicle automatic guidance for agricultural tasks

When designing an accurate automated guidance system for vehicles, a major problem is sliding and pseudo-sliding effects. This is especially the case in agricultural applications, where five-centimetre accuracy with respect to the desired trajectory is required, although the vehicles are moving on slippery ground. It has been established that RTK GPS was a very suitable sensor to achieve automated guidance with such high precision: several control laws have been designed for vehicles equipped with this sensor, and provide the expected guidance accuracy as long as the vehicles do not slide. In previous work, further control developments have been proposed to take sliding into account: guidance accuracy in slippery environments has been shown to be preserved, except transiently at the beginning/end of curves. In this paper, the design of this control law is first recalled and discussed. A Model Predictive Control method is then applied in order to preserve accuracy of guidance even during these curvature transitions. Finally, the overall control scheme is implemented, and improvements with respect to previous guidance laws are demonstrated through full-scale experiments.     

Synthesis and optimization of high surface area mesoporous date palm fiber-based nanostructured powder activated carbon for aluminum removal

Date palm fiber (DPF) derived from agrowaste was utilized as a new precursor for the optimized synthesis of a cost-effective, nanostructured, powder-activated carbon (nPAC) for aluminum (Al3+) removal from aqueous solutions using carbonization, KOH activation, response surface methodology (RSM) and central composite design (CCD). The optimum synthesis condition, activation temperature, time and impregna-tion ratio were found to be 650 ℃, 1.09 hour and 1:1, respectively. Furthermore, the optimum conditions for removal were 99.5％and 9.958 mg·g-1 in regard to uptake capacity. The optimum conditions of nPAC was analyzed and characterized using XRD, FTIR, FESEM, BET, TGA and Zeta potential. Moreover, the adsorption of the Al3+ conditions was optimized with an integrated RSM-CCD experimental design. Regression results revealed that the adsorption kinetics data was well fitted by the pseudo-second order model, whereas the adsorption isotherm data was best represented by the Freundlich isotherm model. Optimum activated carbon indicated that DPF can serve as a cost-effective precursor adsorbent for Al3+removal.     

浅谈无剥离微负压废旧轮胎热解技术产业化

结合工程实践，详细介绍了无剥离、微负压废旧轮胎热解技术的技术特点、工艺流程、主要设备选型及主要技术指标。并分析了废旧轮胎热解技术产业化的前景。     

Theory and application of Agricultural Innovation Platforms for improved irrigation scheme management in Southern Africa

Abstract

Many small-scale irrigation systems are characterized by low yields and deteriorating infrastructure. Interventions often erroneously focus on increasing yields and rehabilitating infrastructure. Small-scale irrigation systems have many of the characteristics of complex socio-ecological systems, with many different actors and numerous interconnected subsystems. However, the limited interaction between the different subsystems and their agents prevents learning and the emergence of more beneficial outcomes. This article reports on using Agricultural Innovation Platforms to create an environment in which irrigation scheme actors can engage, experiment, learn and build adaptive capacity to increase market-related offtake and move out of poverty.     

Effect of vermicomposting on the transformation of some trace elements in fly ash

One major constraint of the agricultural uses of fly ash (FA) is the low availability of different plant nutrients despite their high occurrence in the total amount. However, degrading FA through increased microbial activity can improve the availability of these nutrients substantially. It has been found that intestines of epigeic earthworms contain a high concentration of different microorganisms. Therefore, in the present study we addressed the effects of vermicomposting technology on the solubility of some micronutrient cations (Fe, Mn, Cu, and Zn) and some heavy metals (Pb, Cd, and Cr) in different combinations of fly ash and organic matter, applied in the form of cow dung (CD). Various combinations of FA and CD were treated with and without an epigeic earthworm (Eisenia fetida) and the solubility of different trace elements in the treatments were estimated periodically. The results revealed that the inclusion of epigeic earthworm Eisenia fetida in different combinations of fly ash and cow dung converted a considerable amount of the micronutrients into bio-available forms. On the other hand, the solubility of heavy metals tended to be reduced by the microorganisms, presumably by formation of some organo-metallic complex. Application of these vermicomposted FA and CD combinations to a red lateritic soil was found to improve the soluble Fe, Mn, Cu, and Zn status of the soil. Furthermore, the use of vermicomposted FA and CD (1:1) in potato cultivation demonstrated that use of this mixture at 10 ton per hectare (t ha⁻¹; fresh weight) was able to compensate 80% of the recommended NPK fertiliser, along with farm yard manure application, without compromising the crop yield.     

农业院校计算机实验室信息网络安全分析

该文首次对农业院校的计算机实验室的信息网络安全事件进行了统计和特点分析,通过调查分析出其主要特点：（1）感染恶意代码是主要威胁;（2）垃圾邮件、网页遭篡改、端口扫描问题依然存在;（3）网络钓鱼问题增长较快。分析出农业院校的实验室信息网络安全事件发生的原因。并且为计算机实验室信息网络安全研究提供了参考。     

Among-site variability in environmental and management characteristics: Effect on nutrient loss in agricultural tile drainage

Water quality issues, including harmful and nuisance algal blooms (HNABs), related to nitrogen (N) and phosphorus (P) exported from agricultural lands persist in the Great Lakes region. Previous work examining N and P loss from agricultural fields in portions of the United States (US) and Canada (CA) that drain into Lake Erie, consistently indicate significant nutrient loss from fields in Indiana and Ohio, US compared with those in southwestern Ontario, CA. The primary objective of this study was to examine variation in environmental and management characteristics from 30 sites (US: n = 28, CA: n = 2) located within the Lake Erie Basin and subsequently determine the influence of among-site variation on edge-of-field N and P losses. Using principal component analyses (PCA), we found that among-site variation was predominantly controlled by broad-scale patterns in fertilizer management practices and soil properties; however, N and P loss metrics were largely unexplained by these gradients. As such, fine-scale variability and the interaction of environmental and management characteristics at individual sites more strongly influenced N and P loss. Ultimately, these results further emphasize the importance of site- and nutrient-specific management plans that are needed to mitigate N and P losses from agricultural fields.     

浅议影响产业劳动生产率的因素及“三化”协调发展

本文将劳动生产率增长理论和实证分析运用于工业化、城镇化和农业现代化的协调发展,计算和分析了提高劳动生产率的三大要素对不同产业在不同的历史时期对产出的贡献率。“三化”的不协调主要体现在国民经济一、二、三产业劳动生产率差别太大,这也是二元经济社会结构的根源。要达到“三化”协调发展,只有逐步缩小三大产业劳动生产率的差别,最终达到基本均衡状态,才能消除二元经济社会结枸。     

动力学仿真软件在1LB─240型水平摆式犁油缸运动选型中的应用研究

以1LB-240型水平摆式犁中用于犁体换向的油缸设计为例,首先对其在田间的工作状况进行运动学、动力学分析,然后应用机械三维设计软件SolidW orks及内嵌其中的动力学仿真软件DDM对其仿真,找出了犁耕作业过程中油缸的恰当运动方式———匀速运动,为农业机械产品的设计开发提供了一条新的思路。