Response Of Upland Rice Landraces To Fertilizers In Shifting Cultivation: Rate And Application Methods

ABSTRACT: Shifting cultivation, popularly known as jhum farming is the dominant crop production system that the resourcepoor upland farmers have been practicing in the Chattogram Hill Tracts (CHT) of Bangladesh and mountainous areas in Southeast Asia over centuries. Upland rice is the major component of shifting cultivation. Farmers plant landraces of upland rice usually applying no or low rates fertilizers resulting in poor yield. In view of shifting cultivators’ dependence on rice production for household food security the increase in grain yield of upland rice under shifting cultivation is imperative. We evaluated the yield response of two upland rice landraces – Gunda and Maemonsing in shifting cultivation conducting on-farm participatory trials applying medium (40:10:20 kg NPK ha1 ) and high (80:20:40 kg NPK ha-1) fertilizer rates along with fertilizer placements. We also estimated greenhouse gas emissions based on Cool Farm Tool Beta-3. Grain yield varied between 193 to 420 kg ha-1 in Gunda, and between 366 and 3,877 kg ha-1 in Maemonsing across farmers’ plots and fertilizer rates. Rice grain yield increased progressively with fertilizer application in both the landraces, though the two landraces Gunda and Maemonsing differed a little in grain yields across fertilizer rates. Variation in yield due to fertilizer application was statistically significant but the interaction between fertilizer rates and landraces on rice yield was not statistically significant. In the second experiment using the landrace Gunda with high rate of fertilizers, basal application of whole amounts of P & K and 50% at planting and topdressing of the remaining 50% N 45 days after planting gave the highest yield (2,928.8 kg ha-1) compared with other fertilizer placement techniques. Landraces differed a little in GHG emission, but fertilizer application accelerated GHG emission. Averaged over landraces, GHG emission was 4.22 times higher with high rates of fertilizer application compared with rice grown without applied fertilizers. More studies are needed for crop yield improvement and GHG measurement in hilly regions of Bangladesh. 

Keywords: Shifting cultivation, upland rice, landraces, fertilizer rate and methods, grain yield, GHG emission.