Maize-rice cropping systems in Bangladesh - Search CIMMYT ...

Maize-rice cropping systems in Bangladesh: Status and research needsBoro rice alternatives. From hybrid maize, Tk.49,000/ha could be earned, compared with Tk.20532/ha from boro rice or Tk. 20680/ha from wheat(Table 2). The benefit cost ratio of hybrid maizeproduction is also higher (2.4) over boro rice (1.53) andwheat (1.85). Maize requires far less water than bororice. Maize produces consistently higher output yieldsthan boro rice and wheat. In particular, wheat is oftenvulnerable to temperature fluctuation resulting inshriveled grains and poor yield. Also at present maizehas fewer pest and disease problems in Bangladeshthan boro rice and wheat.Table 2 Comparative grain yield and economic benefitfrom Boro rice, wheat and hybrid maize in BangladeshItem Boro rice WheatHybridmaizeGrain yield (t/ha) 5.9 2.5 8.4Productioncost (Tk/ha)*38468 24320 35000Gross return (Tk/ha) 59000 45000 84000Gross margin(Tk/ha)20532 20680 49000Benefit cost ratio 1.53 1.85 2.4Note: * Only variable cost is considered.Source: Field Survey and OFRD Annual Report, 2007.Maize may be less detrimental to the environmentthan boro rice. With increasing concern about arseniccontamination in boro rice [13] , maize offers anattractive alternative cereal crop that has been shown tocontain lower concentrations of arsenic. Maize may beenvironmentally safer because it requires much lesswater for irrigation than boro rice so the risk of Asaccumulation in the soil and ultimately in the crops islower with maize than boro rice. In areas where soilsare already contaminated with As, maize can be growninstead of boro rice as an As management option.Additionally the high financial and environmentalcosts of irrigating boro rice with large amounts ofwater from electric or diesel pumps is an increasingconcern. Maize needs only around 850 L water per kggrain production (with 2-4 irrigations) compared with1,000 L/kg wheat grain (1-3 irrigations) and over3,000L/kg rice grain (with 20-35 irrigations) for bororice.5. Emerging production problems in themaize-rice systemMaize-rice systems in Bangladesh are dominatedby long duration exhaustive cereal crops. AlthoughBangladeshi maize yields are currently among thehighest in the tropics, there is recent evidence andincreasing concern that productivity of maize isstagnating (Fig. 3 [12] ) in traditional areas and may be indecline. For example, farmers and Department ofAgriculture Extension (DAE) staff in Rangpur andDinajpur report decreasing grain yields where maizehas been grown on the same land for the last 5-10 years.This is very alarming because the land area ofBangladesh is small (around 144,000 km 2 ) and arableland is being lost at around 1% per year, while feeddemand is increasing at about 15% per year. Thus it iscrucial to achieve and maintain high grain yield.Experienced farmers and concerned researchers havesuggested that degrading soil fertility – as hybrid maizeis an exhaustive crop–, emerging micro-nutrientproblems, imbalanced use of fertilizers, improper andlow use of irrigation and late planting in the winterseason are the main reasons for yield stagnation,however more studies are needed to confirm andquantify those constraints. These problems will have tobe addressed properly to maintain and increase maizeyield.5.1 Late planting of maize in Rabi (winter)seasonIn Bangladesh most of the winter Rabi seasonmaize is planted after the harvest of T. Aman rice. Thusthe planting of maize depends on the harvest time ofAman rice, the speed of drying of the soil just after riceharvest, and farmer priorities on planting other Rabiseason crops. Farmers cultivate T. Aman rice varietiesthat have a long development cycle (145-150 days,seed to seed) and are harvested mid November to early41