Effects of Tillage Systems and Residue Application Rate on Nitrogen Uptake and Use Efficiency in Wheat (Triticum aestivum L.)

To evaluate nitrogen uptake, nitrogen uptake efficiency, nitrogen use efficiency and nitrogen harvest index of wheat (Triticum aestivum L.) affected by different tillage systems and wheat residue application, an experiment was conducted as a split block experiment in a randomized complete block design with three replications at Ferdowsi University of Mashhad, Iran, during 2013-2014 growing season. Four different tillage systems (disk, mouldboard plough disk, sweep plough disk and chisel plough disk) were considered as vertical factor and five different crop residue applications (0, 25, 50, 75 and 100% wheat residue) as horizontal factor. The results showed that lowest (2.58%) and highest (2.77%) seed nitrogen percentage were obtained from disk and chisel plough disk, respectively. Also, the highest nitrogen uptake and use efficiency (60.67% and 17.25 g seed/g soil) were obtained from chisel plough disk treatment. The results indicated that seed nitrogen percentage, nitrogen uptake and use efficiency significantly increased with increasing the levels of wheat residue, so that application of 75% wheat residue increased nitrogen uptake to 62.2% compared with control treatment. Regarding to the results of this study, it seems that application of wheat residue along with reduced tillage as an ecological approach can be recommended in arid and semi-arid regions of Iran to increase nitrogen uptake and use efficiency.