Modeling studies have shown that nitrogen (N) strongly regulates ecosystem responses and feedback to climate warming. However, it remains unclear what mechanisms underlie N regulation of ecosystem-climate interactions. To examine N regulation of ecosystem feedback to climate change, we have conducted a warming and clipping experiment since November 1999 in a tallgrass prairie of the Great Plain...

introduction cultivated sunflower is one of the largest oilseed crops in the world. sunflower seed is the third largest source of vegetable oil worldwide, following soybean and canola. nitrogen is one of the most important elements for crops to achieve optimum yields and quality. phosphorus (p), next to nitrogen, is often the most limiting nutrient for crop and forage production. phosphorus ava...

This research revisits plot units, which were developed in the 1980s as a conceptual knowledge structure to represent the affect states of and emotional tensions between characters in narrative stories. We present a fully automated system, called AESOP, that generates plot unit representations for narrative texts. AESOP performs four steps: affect state recognition, character identification, af...

Soil nutrient availability, invasive plants, and insect presence can directly alter ecosystem structure and function, but less is known about how these factors may interact. In this 6-year study in an old-field ecosystem, we manipulated insect abundance (reduced and control), the propagule pressure of an invasive nitrogen-fixing plant (propagules added and control), and soil nutrient availabili...

In this study, eight different manure treatment plants were monitored. The plants were four on-farm and four centralized treatment plants, all of them at full-scale level. Assessment includes a total of seven pre-treatment and process units as follows: mechanical separation, with and without coagulant and flocculant addition, pasteurization, nitrification-denitrification, anaerobic digestion, a...

to estimate the optimum and effective amount of nitrogen fertilizer for quantity and quality improvement of three new durum wheat lines, this research was conducted in gachsaran dry-land agricultural research station for a duration of 4 years (2003-2007). the study was performed as a factorial expriment, using a randomized complete block design with 4 replications. two factors of: 4 nitrogen ra...

The effects of night temperature on plant morphology and nitrogen accumulation were examined in rice (Oryza sativa L.) during vegetative growth. The results showed that the shoot biomass of the plants was greater at 27°C (high nighttime temperature, HNT) than at 22°C (CK). However, the increase in both shoot and root biomasses was not significant under 10 mg N/L. The shoot nitrogen concentratio...

In this study, the effects of nitrogen fertilizer and plant growth regulator (ethephon) application on leaf chlorophyl, stem height and diameter, stalk yield, total sugar and bioethanol of sweet sorghum were determined. Four nitrogen treatments 0, 100, 200 and 300 Kg Urea ha-1 and four ethephon concentrations 0, 800, 1000, and 1200 ppm were applied on sweet sorghum in a split plot on randomized...

to study the effects of nitrogen on tomato plant growth and the possibility of reducing nitrogen in drainage water, two nutrient solutions (complete nutrient solution (n+) and nutrient solution with a 30% decrease in n concentration (n-)) along with and three culture media (perlite, a mixture of perlite and nh4- enriched zeolite and finally a mixture of perlite and raw zeolite) were employed fo...