نتایج جستجو برای: crop models

تعداد نتایج: 971294  

2017
Kamaljit Banger Mingwei Yuan Junming Wang Emerson D. Nafziger Cameron M. Pittelkow

Meeting crop nitrogen (N) demand while minimizing N losses to the environment has proven difficult despite significant field research and modeling efforts. To improve N management, several real-time N management tools have been developed with a primary focus on enhancing crop production. However, no coordinated effort exists to simultaneously address sustainability concerns related to N losses ...

Journal: :Global change biology 2013
Lyndon D Estes Hein Beukes Bethany A Bradley Stephanie R Debats Michael Oppenheimer Alex C Ruane Roland Schulze Mark Tadross

Crop model-specific biases are a key uncertainty affecting our understanding of climate change impacts to agriculture. There is increasing research focus on intermodel variation, but comparisons between mechanistic (MMs) and empirical models (EMs) are rare despite both being used widely in this field. We combined MMs and EMs to project future (2055) changes in the potential distribution (suitab...

2000

Methods to predict the use of new technology at locations other than where experimental data exist also involved the use of spatially explicit analysis and the concept of geographic equivalence. First, the geographic characteristics of areas were identified in which experimental data existed on the performance of crops using new technology. Then, areas of geographic equivalence were identified ...

2016
Arezoo Taghizadeh-Toosi Bent T. Christensen Margaret Glendining Jørgen E. Olesen

World soil carbon (C) stocks are third only to those in the ocean and earth crust, and represent twice the amount currently present in the atmosphere. Therefore, any small change in the amount of soil organic C (SOC) may affect carbon dioxide (CO2) concentrations in the atmosphere. Dynamic models of SOC help reveal the interaction among soil carbon systems, climate and land management, and they...

2003
D. J. Allcroft C. A. Glasbey M. Durban

Meteorological variables are essential inputs to many models in agriculture and hydrology. In particular, crop models need them because crop growth is substantially affected by weather. Frequently though, weather data will not be available in the required form. For instance, the available data may not be for exactly the right location, for the right time period or at the right scale, or simply ...

2005
Emma L. Harvey Dorian Q Fuller

The application of crop processing models to macro-botanical assemblages has traditionally been used to interpret past husbandry practices and organisation of labour involved in crop-processing. Phytoliths offer an alternative method of analysis because they are durable in most environments, regardless of whether plant parts are charred, and the identification of plant types and plant parts all...

Journal: :پژوهش آب در کشاورزی 0
جواد بهمنش دانشیار گروه مهندسی آب، دانشکده کشاورزی، دانشگاه ارومیه. نسرین آزاد طلاتپه دانشجوی کارشناسی ارشد گروه مهندسی آب، دانشکده کشاورزی، دانشگاه ارومیه. مجید منتصری دانشیار گروه مهندسی آب، دانشکده کشاورزی، دانشگاه ارومیه سینا بشارت استادیار گروه مهندسی آب، دانشکده کشاورزی، دانشگاه ارومیه.

comparison of linear and nonlinear (bilinear) time series models in reference crop evapotranspiration prediction in urmia synoptic stationreference crop evapotranspiration (eto) prediction is one of the important elements in optimizing agricultural water consumption. in this regard, one of the prediction approaches is to use the stochastic time series methods. in this research, ar (p) and arma(...

2014
Yongjie Ji Catherine L. Kling Sergey Rabotyagov

A dynamic land use model, more speci cally a dynamic discrete choice model, is developed in this paper to model Iowa farmers' crop choice decisions in recent years based on the newly released eld-scale cropland data layers by National Agricultural Statistics Service. We explicitly consider the dynamic e ects naturally arising in the corn/soybean crop system and estimate the model using the cond...

Journal: علوم آب و خاک 2014

The purpose of this study was to measure daily and seasonal evapotranspiration and daily crop coefficient of two common varieties of sunflower (Sirna and Euroflor) via drip-tape irrigation system. For this purpose, the sunflower water use was determined by daily monitoring of soil moisture at the depths of 10, 20, 30, 40 and 60 cm, and the crop evapotranspiration (ETC) was measured using volume...

Journal: :Remote Sensing 2016
Markus Immitzer Francesco Vuolo Clement Atzberger

The study presents the preliminary results of two classification exercises assessing the capabilities of pre-operational (August 2015) Sentinel-2 (S2) data for mapping crop types and tree species. In the first case study, an S2 image was used to map six summer crop species in Lower Austria as well as winter crops/bare soil. Crop type maps are needed to account for crop-specific water use and fo...

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