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Titre : The effect of fertilizers for conventional and organic farming on yield and oil quality of fennel (Foeniculum vulgare Mill.) in Egypt

Auteur : Kandil, Mohamed Ali Mahmoud Hussein

Université de soutenance : Universität Carolo-Wilhelmina zu Braunschweig

Grade : Doktor rerum naturalium (Dr. re. nat.) 2002

Résumé
The main objective of this study was to find out whether sufficient and high qualities of fennel yields can be produced without chemical fertilizers but only with the sources allowed by organic farming rules under Egyptian conditions. The extensive use of manufactured chemical fertilizers on the Nile valley soils has increased crops productivity but compromised quality especially for medicinal and aromatic plants which are not acceptable for export. Coupled to this, most of the new reclaimed land in Egypt are sandy soils which are normally poor in essential plant nutrients. In the rural areas, organic fertilization play an important role in agricultural productivity. Fennel an important medicinal plant grows well under Egyptian conditions and plays an important role in foreign exchange earnings. To investigate the effect of organic and inorganic sources of N, P and K on the fennel fruits yield and essential oil, it was important to study the effect of different treatments on soil fertility parameters, total content of macro- and micronutrients in the fennel herbs and fennel growth parameters at different physiological stages. Field trials have been started to investigate the effect of different nitrogen sources on the yield of fennel fruits and essential oil. The natural sources of N (sources allowed by organic farming rules) : compost, compost/Azotobacter and chicken manure in comparison with ammonium nitrate (chemical fertilizer). Phosphorous fertilization has been done with rock-P alone and rock-P mixed with elemental S (sources allowed by organic farming rules) and superphosphate as chemical fertilizer. Different potassium sources have been tested also, potassium given as natural source as feldspar (source allowed by organic farming rules) or as chemical fertilizer in the form of potassium sulphate. Two field experiments have been done in an area of newly reclaimed land (Sekem farm) and in comparison on old cultivated land in the Nile valley (Giza farm) during two successive seasons (1998/1999) and (1999/2000). The investigations yielded the following results : 1. Generally soil fertility parameters, soil pH, macro- and micronutrients in the soil were not significantly affected by the different sources of N, P and K except organic sources in some cases giving higher available K, P and micro-nutrients than chemical fertilizers. 2. The total contents of macro- and micronutrients were not affected by the different sources of N, P and K except in some cases organic fertilization giving higher potassium contents than chemical fertilization. 3. Generally fertilization with chemical fertilization of N, P and K (ammonium nitrate, calcium superphosphate and potassium sulphate) gave higher fennel growth parameters than did fertilization with the natural sources of N, P and K. 4. Compost/Azotobacter, rock-P/S and feldspar as the natural sources of N, P and K were more effective in increasing fennel growth and in many cases giving similar results as chemical fertilization. 5. Ammonium nitrate gave the highest fruit yields in both seasons and on both soils. Fertilization with compost on clay loam soil resulted in 17% and 7 % less of the yield obtained after fertilization with ammonium nitrate and 1 % and 12 % less on sandy soil in both growing seasons respectively. 6. Fertilization with chicken manure gave 92 % from the yield of the plots fertilized with ammonium nitrate in both growing seasons in the Nile valley (Giza farm) and 98 % and 85 % on Sekem farm in the first and second growing season respectively. 7. Fertilization with compost/Azotobacter increased the fruit yield by 14 % and 5 % compared with fertilization with compost alone on Giza farm (Nile valley). Results on sandy soil (Sekem farm) have been – 3 % and + 6 % respectively. 8. Yields of fennel oil showed the same trends as observed for the fruit yields. 9. Fertilization with super-phosphate gave the largest yield of fennel fruits and essential oil in the first season on both soils (Giza and Sekem). While in the second season fertilization with rock-P/S and rock-P alone gave the largest yields on Giza farm and Sekem farm respectively. 10. Generally essential oil content and the main components in the fennel fruit oil were not affected significantly by fertilization with organic and inorganic sources of N, P and K.

Mots clés : Ägypten ; Kleinbauernbetrieb ; Fenchel ; Biologischer Landbau ; Ernteertrag

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