Long-term fertilization effect on yield and land productivity of rice-wheat cropping system of Bangladesh

Abstract

A factorial study was carried out at Bangabandhu Sheikh Mujibur Rahman Agricultural University to determine the effect of long term fertilization on yield performance of T. aman rice and wheat. The experimental plot received different organic manures for the last 26 years (1988-2014). The organic manure cowdung, compost, green manure and rice straw were applied at the rate of 25, 25, 7.5 and 1.5 t ha^-1, respectively in a yearly sequence. Three levels of nitrogen viz., 0, 75 and 100 kg ha^-1for rice and 0, 80 and 120 kg ha^-1 for wheat were applied. Application of nitrogen fertilizer along with organic manure significantly increased yield of rice and wheat .The highest rice grain yield was found in 2014 under the N₇₅ and no manure treatment, which was 6.48 t ha^-1 whereas grain yield of wheat was found maximum in 2008 from the interaction of N₁₂₀ and rice straw application where yield was recorded 5.25 t ha^-1. In rice-wheat cropping sequence, the plots that received no nitrogen, LPI value was less than 2 (0.80) in the observed years. When the plots were treated with nitrogen fertilizer showed LPI values > 2 in 2008, 2009, 2012 and 2013, which indicates the trend of higher productivity of land due to long term fertilization. The maximum sustainable yield index was found in rice (0.69)> wheat (0.40) with 100 kg ha^-1 and 120 kg ha^-1 N treatment respectively.  So, Long term fertilization strategy can be effective way to improve the yield, land productivity and sustainable yield index of rice and wheat through rescheduling the rates of organic and inorganic fertilizers that ensure balanced supply of plant nutrients.