Response of traditional and improved upland rice cultivars to
N and P fertilizer in northern Laos
Upland rice is typically grown without fertilization in slash-and-burn systems in the mountainous region of northern Laos by resource-poor farmers for subsistence. It yields an average of 1.7 t/ha versus 3.6 t/ha for wet season lowland rice, and accounts for about half of the total rice area in this region (National Statistical Center, 2004). Because of its low yield, upland rice is generally considered to be unsuitable for the intensive management practices aimed at high yields. However, the low yield of upland rice is largely a consequence of its production being limited to infertile or drought-prone uplands, and to low harvest index (HI) of traditional cultivars (George et al., 2001).