A planning tool for integrating crop choices with weed management in the Northern Great Plains
Abstract Crop production in the Northern Great Plains is rapidly changing because of no-till practices; producers now grow a diversity of crops with winter wheat to increase production as well as to manage weeds. With the multitude of crops available, producers are asking for guidelines to sequence crops in rotations that help weed management. We developed a planning tool that lists various choices with crops when designing a rotation; the choices are arranged by impact on weed dynamics as quantified by research in the region. The tool includes choices among crops, such as varying crops with different life cycles, planting dates, or row spacing, and choices within an individual crop, such as varying cultivar or planting date. Choices among crops impact weeds the most, whereas choices within an individual crop are less effective and usually lead to lower crop yield. For example, rotations comprised of two cool-season crops followed by two warm-season crops can reduce weed populations six- to 12-fold. In contrast, replacing a standard-height cultivar with a taller cultivar that is more competitive with weeds, is often inconsistent for weed management, whereas crop yield may be less. Producers associated with the Northern Plains Sustainable Agricultural Society felt that the planning tool would encourage long-range planning as well as help integrate weed management with the design of cropping systems. The purpose of the tool is to encourage ecologically based weed management, which can reduce herbicide inputs by 50% for Northern Great Plains producers.
Competition Between Winter Wheat (Triticum aestivum) Cultivars and Downy Brome (Bromus tectorum)
Field experiments were conducted to select winter wheat (Triticum aestivum L.) cultivar(s) that were competitive to downy brome (Bromus tectorum L. # BROTE). Downy brome significantly reduced winter wheat grain yields of all cultivars by 9 to 21% at Lincoln, while at North Platte yield reduction ranged from 20 to 41% depending upon cultivar. ‘Turkey’ was the most competitive cultivar to downy brome but it had the lowest grain yield. Compared to ‘Centurk 78’, ‘Centura’ at Lincoln and ‘SD 75284’ at North Platte proved to be significantly higher yielding and more competitive to downy brome. Winter wheat tiller number, canopy diameter, and plant height were negatively correlated with downy brome yield, but changes in these growth parameters did not always translate into grain yield advantage in downy brome-infested plots. Based on stepwise regression analysis, wheat height was better correlated with reduction in downy brome yield than were canopy diameter or number of tillers.
Spray drying of dairy products: state of the art
Milk is extremely perishable, and yet, for a number of reasons, it has to be preserved for later consumption. The removal of water prevents the growth of micro-organisms and facilitates pres- ervation and storage of milk constituents. Spray drying is one of the most convenient techniques for producing milk powders and for stabilizing milk constituents. Before spray drying, the milk under- goes several processes (such as heat treatment, cream separation, membrane processes, vacuum evap- oration and homogenization). The chemical, physical, technological, nutritional, functional and microbiological properties of final products are influenced by a number of factors such as operating conditions, properties of the dairy products and storage conditions. The aim of this review is to de- scribe the process of spray drying of dairy products and to review the present and recent advance- ments of knowledge on the properties of spray-dried milk products, on modelling and water transfer simulation (drying and rehydration), dairy powders and the spray drying equipment and energy con- sumption.