The present investigation was carried out in the period 1977-1981 at the Department of Soil Science and Plant Nutrition of the Agricultural University Wageningen, Netherlands. This university supplied the major financial sup- port through a research grant, with additional financial support rendered by the Dutch Nitrogen Fertilizer Industry and Unilever Research, Netherlands. This support is gratefully acknowledged. In the present form this report is the author's doctoral dissertation submitted to the Faculty of the Agricul- tural University. The author hereby wishes to thank prof. dr. ir. A. van Diest for his criti- cal reading and correction of the English text, and drjr. J. H. G. Slangen for his valuable advices during the investigations and in the course of the preparation of this report. The au thor also acknowledges the valuable support received from several Agricultural Research Institutes and University Depart- ments which made facilities and manpower available to conduct the ex- periments and to transform the results obtained into the present report. Contents Preface / v Abstract / 1 List of ab breviations / 2 Introduction / 3 2 Literature / 6 2.
1 Nitrogen transformations in soil / 7 2. 2 Nitrate uptake / 7 Nitrate reduction in plants / 7 2. 3 2. 4 Nitrate contents in plants / 8 2. 5 Cultural measures / 9 2. 5. 1 Nitrogen dressing / 9 2. 5. 1. 1 Nitrogen amount / 9 2. 5 . 1.
1 Introduction.- 2 Literature.- 2.1 Nitrogen transformations in soil.- 2.1 Nitrogen transformations in soil.- 2.2 Nitrate uptake.- 2.3 Nitrate reduction in plants.- 2.4 Nitrate contents in plants.- 2.5 Cultural measures.- 2.5.1 Nitrogen dressing.- 188.8.131.52 Nitrogen amount.- 184.108.40.206 Nitrogen form.- 220.127.116.11 Time of application of nitrogen.- 2.5.1 Nitrogen dressing.- 2.5.2 Other nutrients.- 2.5.3 Herbicides.- 2.5.4 Spinach variety.- 2.5.5 Harvesting procedure.- 2.6 Environmental conditions.- 2.6.1 Light.- 2.6.2 Carbon dioxide.- 2.6.3 Temperature.- 2.6.4 Water.- 2.6.5 Season.- 2.6.6 Location.- 3 Materials and methods.- 3.1 Indoor experiments.- 3.1.1 General.- 3.1.2 Water-culture experiments.- 3.1.3 Sand-culture experiments.- 3.1.4 Soil-culture experiments.- 3.2 Field experiments.- 3.2.1 General.- 3.2.2 Duiven experiments.- 3.2.3 Lelystad experiments.- 3.2.4 Helden experiments.- 3.3 Weather conditions.- 3.4 Harvest.- 3.5 Chemical analysis.- 3.6 Soil analysis.- 4 Nitrogen nutrition and the ionic balance in spinach; results of indoor experiments.- 4.1 General introduction.- 4.2 Spinach grown in water-cultures.- 4.3 Spinach grown in sand-cultures with nitrate- and ammoniumnitrogen.- 4.4 The effects of nitrate-nitrogen on yield and chemical characteristics of spinach grown on various soils.- 4.4.1 The amount of nitrate-nitrogen applied.- 4.4.2 Distribution of plant nutrients in the aerial parts of spinach.- 4.4.3 Age of plants and season of growth.- 4.4.4 Time of application of nitrate-nitrogen.- 4.4.5 Soil-moisture content.- 4.4.6 Soil pH.- 4.4.7 Mo-spraying on two soil types.- 4.5 The effects of variations in N-form in soil-cultures on yield and chemical characteristics of spinach.- 4.5.1 Ammonium- and nitrate-nitrogen dressings.- 4.5.2 Light intensity- and temperature effects with different amounts of nitrogen and varying N03 : NH4 -ratios.- 4.6 Comparison of the performances of different N-carriers as reflected in yields and N03-contents of spinach.- 4.7 The effects of N in manures on yield and chemical composition spinach.- 4.8 Effects of variations in P-dressing and in soil P-status on yield and chemical composition of spinach.- 4.9 Effects of variations in the size of K-dressings and in type of K-carrier on yield and chemical composition of spinach t1.- 5 Results of outdoor experiments.- 5.1 The effects of variations in nitrate dressings.- 5.1.1 Yields and dry-matter contents of spinach.- 5.1.2 N03-contents in spinach.- 5.1.3 N-contents and total N in the aerial parts of spinach.- 5.1.4 Available N in the soil profile.- 5.1.5 Plant nutrients other than nitrogen.- 5.2 The effects of variations in timing of nitrogen applications.- 5.2.1 Yields and dry-matter contents of spinach.- 5.2.2 N03-contents and N-contents and total N in the aerial parts of spinach.- 5.3 The effects of variations in N03 : NH4-ratio.- 5.3.1 Yields and dry-matter contents of spinach.- 5.3.2 N03-contents in spinach.- 5.3.3 N-contents and total N in the aerial parts of spinach.- 5.3.4 The ratio (C-A) : org N in the aerial parts of spinach.- 5.4 Experiments on farmers' fields.- 5.4.1 Yields and dry-matter contents of spinach.- 5.4.2 N03-contents in spinach.- 6 Discussion.- 6.1 Cultural measures, other than nitrogen dressings, aimed at minimizing N03-contents in spinach.- 6.2 Cultural measures related to nitrogen, aimed at minimizing N03-contents in spinach.
Number Of Pages: 126
Country of Publication: NL
Dimensions (cm): 23.39 x 15.6
Weight (kg): 0.17