MICRONUTRIENTS USE EFFICIENCY IN TROPICAL COVER CROPS AS INFLUENCED BY PHOSPHORUS FERTILIZATION

Abstract

Deficiency of micronutrients is increasing in the recent years in cropping systems in many parts of the world and cover crops are important components of cropping systems. A greenhouse experiment was conducted to evaluate copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) use efficiency in 14 tropical leg-ume cover crops grown on an Oxisol. The P levels used were low (0 mg kg-1), medium (100 mg kg-1) and high (200 mg kg-1). The P X cover crops interactions were significant for Cu, Fe, Mn, and Zn use efficiency (tops dry weight/unit nutrient uptake). Hence, cover crop species varied in nutrient use efficiency with change in P levels. The micronutrient use efficiency was in the order of Cu > Zn > Mn > Fe. Higher Cu use efficiency was associated with lower uptake of this element, in the cover crop tops compared to other micronutrients. Similar-ly, lower efficiency of Fe and Mn was associated with their higher uptake in the tops of cover crops. Overall, Cu and Mn use efficiency was decreased when P level was raised from low to medium level and then it was constant. Iron use efficiency was increased with increasing P level but Zn use efficiency was constant with the addition of P fertilizer