Macro- and micronutrients removed by upland and lowland rice cultivars in West Africa

Plant analysis is an important component of soil fertility and plant nutrit ion research. Plant analysis at harvest of the crop forms the basis for con structing nutrient balances and assessing the nutrient needs of production systems. Amounts of macro- and micronutrient elements removed by improved, upland and lowland rice cultivars were determined in field experiments at t wo sites in Ivory Coast. Amounts of nitrogen (N), zinc (Zn), and manganese (Mn) removed for 1 t rice grain yield by upland and lowland rice cultivars were similar, but the amounts of phosphorus (P), potassium (K), calcium (Ca ), and magnesium (Mg) removed were higher for lowland than upland rice. The nutrient element harvest indexes (amount in grain/amount in grain plus str aw) varied between the cultivars, but more importantly, among nutrient elem ents. On average the nutrient harvest index was highest for P (69%) and low est for K ( 10%). The results suggest that the nutrient requirement of rice for K can be met to a large extent through the recycling of K in rice stra w. The amounts of other major nutrients, N and P in the straw were small an d hence less scope for supplying these nutrients through the recycling of r ice straw.