A study of the cause of germination injury following contact placement of dried blood fertilizer with seeds : a thesis presented in partial fulfilment of the reqiuirements for the degree of Master of Agricultural Science (Horticulture) at Massey University, New Zealand
The use of organic fertilizers has suffered a decline since the initiation of large scale production of soluble inorganic salts. Nevertheless, a demand for natural organic forms of nit­rogen persists, especially in regions of high rainfall and sandy soils, and in connection with the production of crops of high acre value. In recent years knowledge of the principles and practice of fertilizer application also has expanded rapidly. Localized or contact placement of fertilizer has been found to favour rapid early growth, and to lessen "fixation'' of fertilizer nutrients by the soil. Difficulties in the forms of impaired germination and damage to young seedlings have arisen from contact placement of organic fertilizers. Many mechanisms have been put forth to explain the basis of fertilizer toxicity; viz. plasmolysis of root tissues by the high solute concentrations, production of excessive local acidity or alkalinity from fertilizer materials, direct toxic effects on the young plant by free ammonia or cyan­ide formed by chemical or microbial breakdown of fertilizer materials. Accordingly, it was decided to evaluate the hypothesis that germination injury to seeds results from the production of in­jurious quantities of free ammmonia during mineralization of dried blood fertilizer placed in contact with the seeds. [From Introduction]
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