Sugar beet response to nitrogen forms and rates under different tillage practices expressed by polynomial quadratic equations [electronic resource].

Includes references.

A field experiment was conducted during the winter season 2002/2003 at Sakha Agric. Res. Station Farm, Kafr EI-Sheikh Governorate to study the effect of nitrogen fertilizer forms and rates on sugar beet yield and their net return under different tillage practices. Split split plot design was used with four replicates. The main plots were assigned with three tillage practices (TI' T2 and T3). The sub plots were assigned with three nitrogen forms, i.e. anhydrous ammonia 82 % N (AA), ammonium nitrate 33 % N (AN) and urea ammonium nitrate liquid 32 % N (UANL). The sub-sub plots were assigned with four nitrogen rates N01 N301 N60 and Ngo kg N/fed Nine' polynomial quadratic equations were established and showed the following results: 1. The maximum yield (Y m) increased as tillage practices changed under the three nitrogen forms used. 2. The highest maximum yield (30.803 ton/fed) was obtained under T2 treatment and use of AA application. 3. The highest total value of the yield (6159.8 L.E./fed) and the highest net return value of fertilizer (3658.9 L.E./fed) were obtained under T2 treatment and use of AA application. 4. The net return of N-forms can be arranged according to the following order AA > AN > UANL. 5. The efficiency of fertilizer decreased as N rates increased but it increased as tillage practices changed under the different N forms. 6. The soil nitrogen content (Xs) increased as tillage practices changed with using the three N forms. 7. The contribution of N fertilizer increased as N rates increased. 8. The contribution of soil N decreased as N rates increased. 9. The contribution of soil N. increased as tillage practices changed.

Summary in Arabic.

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