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Abstract
INTRODUCTION
Jerusalem artichoke (Helianthus tuberosus L.) is an uncommon vegetable crop in Egypt. It is native to central regions of North America. It was introduced to Europe at the beginning of the 17th century. The plants grow, successfully, under a wide range of temperatures and rainfall producing tubers that grow underground. It grows well in almost all soils with the exception of very heavy clay soil. Tubers are rich in nutrients and polysaccharides especially inulin; which possibility utilize as a fructose sweetener (Chubey and Dorrell, 1974). Generally, tubers contain about 74.2 to 82.3 g fructose / 100 g DM, (Dorrell and Chubey, 1977), 16-20 g inulin 100 / g FM (Chubey and Dorrell, 1982) and 9-10 g protein / 100 g FM (El-Sharkawy, 1998).
Sulphur application, as a soil amendment, is a common agricultural practice in Egypt especially in the new reclaimed lands and became very important in the last few years. Several studies have shown the advantages of sulphur application to soils to enhance the solubility and availability of phosphorus and some micronutrients to plants, dissolving native lime in calcareous soils, controlling some fungal diseases, decreasing high pH values of alkaline soils as a result of sulphuric acid formation and it also plays a good role in decreasing the problem of N losses and thereby improving the fertilizer N use efficiency.
Growth conditions, e.g. soil and fertilization, play an important role on yield production. The effect of fertilization has been investigated mainly for NPK, N being the main nutrient.
Nitrogen is an integral component of many essential plant compounds. It is a major part of all amino acids, the building blocks of proteins, including the enzymes which control virtually all biological processes. Other critical nitrogenous plant components include the nucleic acids and chlorophyll. Nitrogen is also essential for carbohydrate use within plants.
A good supply of nitrogen stimulates root growth and development, as well as the uptake of other nutrients. A great number of nitrogen sources such as ammonium nitrate, ammonium sulphate and urea are used in Egypt in a large scale. The use of these fertilizers, for crops production, is generally subjected to N losses by volatilization especially in alkaline soils.
The major objectives of this study deal with the effects of three N sources as N fertilizers and sulphur application as soil amendment on:
1. growth, yield and chemical composition of Jerusalem artichoke,
2. fertilizer N efficiency, and
3. some soil chemical properties.