Long-term nitrogen fertilization effects on nitrogen mineralization potential in soils under differe...

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" Long-term nitrogen fertilization effects on nitrogen mineralization potential in soils under different cropping systems and different environments "
M. El Gharous R. L. Westerman

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	1113013
Doc. No	:	TLpq304142900
Main Entry	:	M. El Gharous
	:	R. L. Westerman
Title & Author	:	Long-term nitrogen fertilization effects on nitrogen mineralization potential in soils under different cropping systems and different environments\ M. El GharousR. L. Westerman
College	:	Oklahoma State University
Date	:	1994
student score	:	1994
Degree	:	Ph.D.
Page No	:	136
Abstract	:	Scope of study. Nitrogen mineralization of soil organic matter has long been recognized to be very important in meeting plant N needs. Recommendations for N fertilizer requirements for cereals are presently based on the level of nitrate in the top 15 cm of the soil before planting, deep sampling (60 cm) is considered when unusual cropping conditions arise. In order to improve N fertilizer recommendations, mineralization during the season needs to be accounted for. It is also hypothesized that long term N fertilization increases the magnitude of the easily mineralized N pool in soils. Different soil types from Oklahoma and Morocco were used to estimate the mineralization potential usd\rm (N\sb0)usd and the decomposition rate constant (k). The effect of fertilizer N and the relationship with plant N uptake and soil initial mineral N were investigated. Findings and conclusions. Soil N mineralization potential usd\rm (N\sb0)usd varied with soil type and cropping systems. The application of fertilizer N increased the soil's capacity to mineralize organic N in all cropping systems and environments. Also, it was found that usd\rm N\sb0usd decrease linearly with soil depth. The contribution of lower depth (20-60 cm) to total usd\rm N\sb0usd in the soil profile was found to be about 60%. Initial soil mineral N was highly correlated to plant N uptake, soil usd\rm N\sb0usd and usd\rm N\sb0k.usd The product of usd\rm N\sb0kusd and soil mineral N at start were found to be a reliable N availability index.
Subject	:	Agronomy
	:	Biological sciences
	:	fertilization
	:	nitrogen