农业机械管理的创新与发展

农业现代化是衡量国家现代化的一个重要指标。在国家强农惠农政策的引导下,东海县应逐步改变传统的农业生产模式,实现农业生产集中化、机械化、现代化。同时可尝试多行业、各技术融合,促进农机化和农机管理工作更上一层楼。     

通信设备运营和电力的维护

文章结合中国网通近两年来内部控制项目实施的实际情况和圆满通过外部审计师审计的经验,对目前通信网络设备维护工作中存在的问题和相应带来的风险进行剖析     

高职酒店管理专业“管培生”项目班存在的困境与对策分析--以武汉职业技术学院为例

文章以武汉职业技术学院为例,对高职酒店管理专业“管培生”项目班的现状及存在的困境进行了分析,并提出了相应的对策。     

高校图书馆阅览室的管理与服务

随着社会的发展,信息时代的进步,高校图书馆也在发生质的变化,逐步由重视馆藏转向更好地为读者服务,如何高效率地利用图书馆,为读者提供更好的服务,是高校图书馆阅览室的指导思想,本文阐述了图书馆开架阅览存在的问题,并分析了相关的对策。     

Simulation of drainage water quality with DRAINMOD

The design and management of drainage systems should consider impacts on drainage water quality and receiving streams, as well as on agricultural productivity. Two simulation models that are being developed to predict these impacts are briefly described. DRAINMOD-N uses hydrologic predictions by DRAINMOD, including daily soil water fluxes, in numerical solutions to the advective-dispersive-reactive (ADR) equation to describe movement and fate of NO₃-N in shallow water table soils. DRAINMOD- CREAMS links DRAINMOD hydrology with submodels in CREAMS to predict effects of drainage treatment and controlled drainage losses of sediment and agricultural chemicals via surface runoff. The models were applied to analyze effects of drainage intensity on a Portsmouth sandy loam in eastern North Carolina. Depending on surface depressional storage, agricultural production objectives could be satisfied with drain spacings of 40 m or less. Predicted effects of drainage design and management on NO₃-N losses were substantial. Increasing drain spacing from 20 m to 40 m reduced predicted NO₃-N losses by over 45% for both good and poor surface drainage. Controlled drainage further decreases NO₃-N losses. For example, predicted average annual NO₃-N losses for a 30 m spacing were reduced 50% by controlled drainage. Splitting the application of nitrogen fertilizer, so that 100 kg/ha is applied at planting and 50 kg/ha is applied 37 days later, reduced average predicted NO₃-N losses but by only 5 to 6%. This practice was more effective in years when heavy rainfall occurred directly after planting. In contrast to effects on NO₃-N losses, reducing drainage intensity by increasing drain spacing or use of controlled drainage increased predicted losses of sediment and phosphorus (P). These losses were small for relatively flat conditions (0.2% slope), but may be large for even moderate slopes. For example, predicted sediment losses for a 2% slope exceeded 8000 kg/ha for a poorly drained condition (drain spacing of 100 m), but were reduced to 2100 kg/ha for a 20 m spacing. Agricultural production and water quality goals are sometimes in conflict. Our results indicate that simulation modeling can be used to examine the benefits of alternative designs and management strategies, from both production and environmental points-of-view. The utility of this methodology places additional emphasis on the need for field experiments to test the validity of the models over a range of soil, site and climatological conditions.     

农场作物及机器设备选择系统的研究

将数据库，模拟及线性规划结合在一起，建立了一个同时选择农作物，作业方式及机器设备的软件系统。此系统可求得农场资源的最佳配置，并有较好的可移植性，同时在很大程度上克服了线性规划的非整数解与机器，劳力整数要求的矛盾以及模拟技术在优化系统方面的局限。     

Modeling the impact of alternative drainage practices in the northern Corn-belt with DRAINMOD-NII

The hydrologic and water quality impacts of subsurface drainage design and management practices are being investigated through field and simulation studies throughout the northern Corn-belt. Six years of data from an ongoing field study in south central Minnesota (Sands et al., 2008) were used to support a modeling effort with DRAINMOD-NII to investigate: (1) the performance of the model in a region where soils are subject to seasonal freeze-thaw and (2) the long-term hydrologic and water quality characteristics of conventional and alternative subsurface drainage practices. Post-calibration model prediction and efficiency were deemed satisfactory using standard model performance criteria. Prediction errors were primarily associated with early spring snowmelt hydrology and were attributed to the methods used for simulating snow accumulation and melting processes, in addition to potential sublimation effects on ET estimates. Long-term simulations with DRAINMOD-NII indicated that drainage design and/or management practices proposed as alternatives to conventional design may offer opportunities to reduce nitrate (NO₃)-nitrogen losses without significantly decreasing (and in some cases, increasing) crop yields for a Webster silty clay loam soil at Waseca, Minnesota. The simulation study indicated that both shallow drainage and controlled drainage may reduce annual drainage discharge and NO₃-nitrogen losses by 20-30%, while impacting crop yields from −3% (yield decrease) to 2%, depending on lateral drain spacing. The practice of increasing drainage intensity (decreasing drain spacing) beyond recommended values appears to not significantly affect crop yield but may substantially increase drainage discharge and nitrate-nitrogen losses to surface waters.     

Deficit irrigation and nitrogen effects on seed cotton yield, water productivity and yield response factor in shallow soils of semi-arid environment

A field experiment was conducted for 2 years to investigate the effects of deficit irrigation, nitrogen and plant growth minerals on seed cotton yield, water productivity and yield response factor. The treatment comprises six levels of deficit irrigation (Etc 1.0, 0.9, 0.8, 0.7, 0.6 and 0.5) and four levels of nitrogen (80, 120, 160 and 200 kg N ha⁻¹). These were treatments superimposed with and without plant growth mineral spray. Furrow irrigation treatments were also kept. Cotton variety Ankur-651 Bt was grown during 2006 and 2007 cotton season. Drip irrigation at 1.0 Etc saved 26.9% water and produced 43.1% higher seed cotton yield over conventional furrow irrigation (1.0 Etc). Imposing irrigation deficit of 0.8 Etc caused significant reduction in seed cotton yield to the tune of 9.3% of the maximum yield. Further increase in deficit irrigation from 0.7 Etc to 0.5 Etc significantly decreased seed cotton yield over its subsequent higher irrigation level. Decline in the yield under deficit irrigation was associated with reduction in number of bolls plant⁻¹ and boll weight. Nitrogen at 200 kg ha⁻¹ significantly increased mean seed cotton yield by 36.3% over 80 kg N ha⁻¹. Seed cotton yield tended to increase linearly up to 200 kg N ha⁻¹ with drip Etc 0.8 to drip Etc 1.0. With drip Etc 0.6-0.5, N up to 160 kg ha⁻¹ provided the highest yield, thereafter it had declined. Foliar spray of plant growth mineral (PGM) brought about significant improvement in seed cotton yield by 14.1% over control. The water productivity ranged from 0.331 to 0.491 kg m⁻³ at different irrigation and N levels. On pooled basis, crop yield response factor of 0.87 was calculated at 20% irrigation deficit.     

Yield, water and nitrogen-use response of rice to zeolite and nitrogen fertilization in a semi-arid environment

Water scarcity and soil nitrogen (N) loss are important limitations for agricultural production in semi-arid region especially for rice production. Zeolite (Z) as a soil conditioner can be used to retrain water and nitrogen in near-surface soil layer in lowland rice production system. The objectives of this study were to investigate the effects of different application rates of natural zeolite (clinoptilolite) and nitrogen on rice yield, yield components, soil nitrogen, water use, water productivity in a silty clay soil in 2004 and 2005. Zeolite was only applied in the first year. In order to study the long-term and continuous effect of zeolite on the objectives of the study, no zeolite was applied in the second year and the study was conducted on the same land as the first year. Zeolite and N were applied at rates of 0, 2, 4, and 8 t ha⁻¹ and 0, 20, 40, and 80 kg ha⁻¹, respectively in 2004. In 2005, each plot received the same amount of N as received in 2004. It is concluded that by decreasing N application rates, higher Z application rate is needed to improve grain yield. Highest grain yield was obtained at N application rate of 80 kg ha⁻¹ and Z application rate of 4 t ha⁻¹. Higher grain yield was mostly attributed to lower unfilled grain percentage and higher 1000-grain weight that were a result of higher N application rate and N retention in soil due to Z application. Nitrogen and Z applications resulted in higher grain protein contents and nitrogen recovery efficiency (NRE). Based on these results and due to higher N retention in soil under Z application, improved grain yield quality, nitrogen-use efficiency (NUE), and nitrogen recovery efficiency (NRE) could be obtained at Z application rate of 8 t ha⁻¹ and N application rate of 80 kg ha⁻¹ or more. However, this was not satisfied for NUE. Moreover, it is found that at higher N application rates lower Z application rates are needed to effectively retain soil residual mineral nitrogen. Furthermore, at N application rates of 80 kg ha⁻¹ or more, Z application increased soil water retention and resulted in lower seasonal water use and higher water productivity. In general, it was concluded that the effect of Z application in retaining soil N was also effective in the second year.     

Empirical assessment of water management institutions in northern China

We examine the development of irrigation management in northern China using data from village and household panels. During the past decade, reform-oriented institutions, such as water user associations and contracting, have largely replaced the traditional institution of collective management in village-level irrigation systems. A feature unique to China is that water user associations and contractors are provided with monetary incentives to save water. Water user associations have not yet achieved the broad-based participation of farmers that some advocates consider as a primary goal for forming the associations. Many village leaders serve also as the leaders of water user associations, thus possibly reducing opportunities for receiving operational input and policy direction from farmers. However, we observe improved performance of irrigation systems managed by water user associations, relative to collective management, in terms of maintenance expenditures, the timeliness of water deliveries, and the rates of fee collection. Performance has improved also in systems managed by contractors, although not as substantially as in the case of water user associations.