Influence of organic manures, nitrogen and potassium on nutrient uptake and nutrient-use efficiency of white yam (Dioscorea rotundata) intercropped in coconut (Cocos nucifera) garden

The influence of 3 organic manures (farmyard manure, coir pith compost and in-situ green manuring using sunhemp) and 3 levels each of N and K (40, 80, 120 kg/ha) on nutrient uptake and nutrient-use efficiency of white yam [Dioscorea rotundata) intercropped in coconut (Cocos nucifera L.) garden was studied during 1998–2000) at Vellayani, Thiruvananthapuram. Application of coir pith compost resulted in significantly higher uptake of N and K. Higher rates of N and K favoured uptake of N, P and K by the crop. An intercrop of white yam in coconut garden fertilized with coir pith compost @ 5 tonnes/ha and N, P and K @ 80, 60 and 80 kg/ha respectively, yielding 24.61 tonnes/ha of fresh tuber equivalent and 7.36 tonnes/ha of dry matter removed 89.59, 10.10 and 92.99 kg/ha of N, P and K respectively. The agronomic efficiency of N and K fertilizers was promoted due to green-manuring. Enhanced supply of N or K reduced the efficiency of the respective nutrients, whereas addition of one nutrient at higher rates promoted the efficiency of the other nutrient.