Nitrogen Management :: Environment, Agriculture, Crop Production

Nitrogen management is crucial component for sustainable crop production, it is desirable to adapt N supply with crop N use to maximize efficiency. In Egypt, due to intensive cultivation of high yielding crop varieties, the nutrients supplying capacity of soil is declining. Producers tend to apply insurance application of N to make them feel more confident about N sufficiency. These practices may lead to over application of N fertilizer and result in groundwater pollution by nitrate (NO3) due to the elevated levels of NO3 in the soil profile (Asadi et al. 2002). Accordingly, searching for alternative N sources and maintaining long term soil fertility and sustainability are a priority for studying. Cultivar performance varies as related to genotype Ãâ€" environmental interactions (Eberhart and Hallauer 1967). In general, corn hybrids are highly productive and respond to N application, however their ability to maintain yield under water or N stress are different (O’Neill et al. 2004). Nitrogen availability represents a major limiting corn grain yield under intensive cropping system. The identification of hybrids response to different combination of N rates and bio-fertilizers could reduce the amount of applied N and increase efficiency. Several research in the literature document significant cultivar Ãâ€" N interaction differences in growth such as LAI and plant weight and yield traits (Ahmed 1990; Tollenaar and Wu 1999; and Hokmalipour 2010). Determining specific hybrids response to N inputs would make a great contribution to plant breeding for sustainable agriculture (Presterl et al. 2002). It is clear that current unsuitable handling of N fertilizers may be responsible for NO3-N contamination of both surface water and soil water (Wang et al. 1996). Yield goal as N based recommendation usually represent large geographic areas. According to (MOA 2004) they provide a N recommendation for corn that is a linear function of yield goal. Although these recommendations are generally suitable, they may lead to over application of N as hybrids and environment change. Corn grain yield has been significantly increased by varying N rate from 190 to 380 kg N ha-1 (El-Hendawy et al. 2008). A positive response for grain yield has been reported by (Halverson and Reule 2006) up to 285 kg N ha-1 while maximized at 180 kg N ha-1 in another study (Lamm et al. 2001). Determining N recommendation could be further improved by considering field-specific soil-crop-climate conditions along with different hybrids and Bio-fertilizers effects.