Abstract of Ph.D. Thesis of Dr. Md. Abul Khayer Mian

ABSTRACT
Four experiments were carried out at the Regional Agricultural Research Station, Bangladesh Agricultural Research Institute, Jessore in two consecutive years of 2004-2005 and 2005-2006 to evaluate the agro-economic performance of several maize oriented cropping patterns under different nutrient management. Maize-Mungbean (green manurng, GM)-T.aman rice was found to be the best cropping pattern under high nutrient level of 266-46-132-28-2.10-0.60 kg ha-1 of N-P-K-S-Zn-B for maize and 100-13-43-6.0-0.70 kg ha-1 of N-P-K-S-Zn for rice and moderate nutrient level of 186-34-95-20-1.60-0.60 kg ha-1 of N-P-K-S-Zn-B for maize and 74-11-33-4.5-0.40 kg ha-1 of N-P-K-S-Zn for rice showing better growth behaviour, yield performance, productivity, land use efficiency, production efficiency and profitability as compared to the existing cropping pattern of Wheat-Fallow-T.aman rice. This pattern rendered 89% higher maize equivalent yield (MEY) than the existing pattern. Furthermore, Maize-Dhaincha (GM)-T.aman rice and Maize-Soybean (GM)-T.aman rice proved to be better cropping patterns in respect of the aforesaid parameters under high and moderate nutrient levels. Maize-Mungbean (GM)-T.aman rice, Maize-Dhaincha (GM)-T.aman rice and Maize-soybean (GM)-T.aman rice patterns produced higher grain yield of maize (9.91-10.39 t ha-1 ) and rice (5.22-5.90 t ha-1) in high nutrient level due to improvement of yield components. Inclusion of mungbean (GM i.e. brown manuring) in the sequence provided an extra remuneration with seed yield of 530-1056 kg ha-1. Maize+ Sweet potato, Maize+ Soybean and Maize+ Cowpea were found to be suitable intercropping representing higher productivity (10.92-11.99 t ha-1 of MEY) and monetary advantage in high and moderate nutrient levels. Maize showed better yield performance (9.07-10.34 t ha-1) in intercropping with legumes (soybean, blackgram and cowpea). Maize+ Sweet potato-Mungbean (GM)-T.aman rice, Maize+ Soybean-Mungbean (GM)-T.aman rice and Maize+ Sweet potato-Dhaincha (GM)-T.aman rice under high nutrient level and Maize+ Sweet potato-Mungbean (GM)-T.aman rice under moderate nutrient level emerged as further improvement of Maize-Mungbean (GM)-T.aman rice cropping pattern. There existed better relationship of grain yields with growth parameters and yield components of maize and rice in maize oriented cropping patterns and intercropping under different nutrient levels. Dry matter partitioning into reproductive organ at later growth stages was higher in higher nutrient levels contributing to increased grain yield of maize and rice. Grain yield as well as system yield response to nutrients applied in maize and rice were significant representing variable coefficient of determination. Contributions from GM in the sequence and incorporation of legume residues from intercropping towards nutrient balance in the soil were found to be positive. Balance of P and S was more favourable than that of N, K and Zn in the soil. Inclusion of GM or incorporation of legume residues in the system improved organic matter content of the soil. Nutrient returned to soil from GM or legume residues was correlated with the nutrient balance in soil indicating improvement of soil health. Among the GM crops, mungbean ranked first in respect of nutrient concentration in plant tissue and nutrients returned to soil. It is concluded that Maize-Mungbean (GM)-T.aman rice or Maize+ Intercrops (sweet potato or soybean)-Mungbean (GM)-T.aman rice cropping patterns would be more productive and profitable technology for future crop production in Bangladesh.