Growth and nitrogen(2) fixation in soybean and nitrification as affected by nitrogen source and a ni...

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" Growth and nitrogen(2) fixation in soybean and nitrification as affected by nitrogen source and a nitrification inhibitor "
M. A. Zahid F. E. Koehler

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	1112593
Doc. No	:	TLpq303907805
Main Entry	:	F. E. Koehler
	:	M. A. Zahid
Title & Author	:	Growth and nitrogen(2) fixation in soybean and nitrification as affected by nitrogen source and a nitrification inhibitor\ M. A. ZahidF. E. Koehler
College	:	Washington State University
Date	:	1990
student score	:	1990
Degree	:	Ph.D.
Page No	:	104
Abstract	:	Fertilizer nitrogen management and evaluation of N2 fixing capabilities of legumes are crucial for better crop production and to reduce environmental pollution. A laboratory, a greenhouse and a field experiment were conducted using different N sources with or without nitrapyrin, a nitrification inhibitor. Soybean was grown as a test crop in the latter two experiments. The main purpose of the laboratory experiment was to determine an appropriate form and rate of N to be used in experiments with legumes based on NH4\sp{+}-N retained due to nitrapyrin. Soils receiving nitrapyrin-treated N retained higher NH4\sp{+}-N for up to 68 days and effectiveness followed the order: Ammonium Sulfate > Ammonium Nitrate > Urea. Higher percentage of NH4\sp{+}-N was retained at a lower N rate both at 25 and 68 days sampling. Addition of nitrapyrin minimized the decrease of soil pH caused by nitrification of added N. Greenhouse and field studies were aimed at evaluating growth and N2 fixation of soybean. It was hypothesized that application of low levels of fertilizer N and nitrapyrin may increase the amount of N fixed biologically. Ammonium sulfate at 20 mg N Kg significantly increased while CN decreased the nodule number, nodule weight and seed yield in soybean. Nitrogen fixation as estimated by N isotope dilution and by difference was significantly higher for AS than urea or CN and for addition of nitrapyrin. The two methods were similar in their estimates of N2 fixed. Interaction between N source and inhibitor was not significant, however, the maximum N2 fixation was achieved for plots receiving inhibitor-treated AS.
Subject	:	Agricultural engineering
	:	Agronomy
	:	Applied sciences
	:	Biological sciences
	:	nitrogen fixation