abstract improving nitrogen use efficiency (nue) is an important objective of the agroecosystem management. a field experiment was conducted to study the effect of different competition patterns on nitrogen balance in the wheat agroecosystem. experimental design was split–plot based on randomized complete blocks with four replications. the main plots consisted of different nitrogen rates (i.e. ...

nitrogen use efficiency (nue) is usually lower in paddy rice (oryza sativa l.) than in upland crops. for this reason, any attempt to improve nue through the use of different nitrogen (n) carriers, different rice cultivars, properly timed n application, the use of ni-trification and urease inhibitorsis of prime interest. moreover, zinc (zn) next to n seems to be the most important soil factor af...

a field study was conducted to determine the integration of split n fertilization and herbicide application on weed management and wheat (triticum aestivum l.) yield in shiraz, iran, in 2005/2006 and 2006/2007 growing seasons. the experimental design was split plot with four replications. main factors consisted of n timing and splitting, and sub plots included iodosulfuron–methyl–sodium plus me...

degradation of dry matter (dm) and nitrogen (n) in fresh or frozen-thawed alfalfa and ryegrass was studied by using in situ technique. the forages were labeled with 15n during growth in a glasshouse, harvested at similar growth phase, and fresh (f) or frozen-thawed (ft) samples were incubated in the rumen of 3 sheep. there was no difference (p>0.05) between forage type (s) for the immediately s...

a three-year field experiment was conducted under conditions of luvic chernozem soil. diversified nitrogen fertilization with 0, 60, 120, and 180 kg n ha-1, and microbial preparations improving soil properties were applied to potatoes, cv. ‘satina’, cultivation. n–no3 concentration in the soil profile (0–0.9 m) in autumn after potato harvesting fluctuated from 28 kg n ha-1 in the n0 treatment t...

dissolved organic nitrogen (don) can react with disinfectants to produce numerous disinfectionbyproducts (dbps), particularly nitrogen-containing dbps (n-dbps), and produce serious adverse effectson public health. widely used biological processes in drinking water treatment can increase don in effluents,and enhance these ill effects. this study investigated don in a full-scale two-stage ozonati...

in the present study, the root vigor and kinetic characteristics of nitrogen absorption in potato cultivars was investigated through sand cultivation and pot tests with nutrient solution. four cultivars of potatoes, namely, feiwuruita, yunshu301, liangshu97, and chuanyu56 were grown in nutrient solution matrix cultures. the result showed that: (1) nitrogen uptake rates differed significantly am...

lactatingdairy cows (n=177) fed with grass and corn silage ad libitum kept in pasture, were randomly assigned to evaluate how urea nitrogen in plasma and milk can be related to their pregnancy rate. blood and milk samples were collected on the artificial insemination (ai) day to evaluate plasma urea nitrogen (pun) and milk urea nitrogen (mun) as well as progesterone levels, excluding cows with ...

in order to investigate the effects of different levels of nitrogen rate on yield and seed yield components of wheat cultivars, an experiment was conducted on araghi mahalleh (gorogan) research farm in 2008. treatments, nitrogen in the form of urea (0, 90, 180 and 270 kg/ha) and cultivars (tajan, falat and n81-18) were arranged as factorial based on randomized complete block design with four re...