Md. Abdul Kader*1,2, Md.Jahiruddin1, Md.Rafiqul Islam1, Md.Enamul Haque1, Md. Sahed Hasan1,SutupaKarmaker1, Md. Mortuba Ali1, Richard Bell2
1Department of Soil Science, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh email:[email protected]
2School of Veterinary and Life Sciences, Murdoch University, Murdoch, 6150 Australia email:[email protected]
Conservation agriculture (CA) has not been well developed for intensively cultivated (2-3 crops yr-1) rice-based cropping systems which produce large amounts of crop residues annually. Thus, we examined the effects of two crop establishment systems (minimum soil disturbance by strip planting (SP) or conventional tillage (CT)), two residue retention levels (low and high) and five N rates (60, 80, 100, 120 & 140% of the recommended N fertilizer doses (RFD) on nine consecutive crops on an Aeric Haplaquept under rice-wheat-mungbean sequence. Rice yields were comparable between the crop establishment types but system yields were significantly higher with SP in two out of three years compare to CT. Increased residue retention did not significantly influence rice yield but positively influenced system yields. No substantial differences in optimum N rate was estimated between CT and SP for 90% of maximum yield goal (MYG) for all the three years but substantially decreased in SP compared to CT in two out of three years for 95 and 99% of MYG. The N fertilizer requirement was 6-22% higher with high residue retention compared to low residue retention plots for all the three yield goal levels. High residue retention also increased soil organic carbon (SOC) at 0-6 cm depth in both tillage treatments. In conclusion, introducing CA did not alter the N fertilizer requirements of rice for 90% of MYG but reduced the requirement for 95 and 99% of MYG compared to CT. However, there was evidence that the retained crop residue immobilized N and increased the fertilizer N requirement.