Utilization of potassium-rich green-leaf manures for rice (Oryza sativa) nursery and their effect on crop productivity

A field trial was conducted on Godavari Vertisols during the wet season of 2000 and 2001 at Maruteru, to evaluate the performance of potassium-rich weeds, viz. Pistia stratiotes L. Salvinia molesta, Gynandropsis gynandra (L.) Brig., Lantana camara L. and Parthenium hysterophorus L. as green leaf manure in rice (Oryza sativa L.) nursery. Fertilization of nursery irrespective of source, improved the seedling parameters like biomass, vigour index and growth rate. Incorporation of Pistia stratiotes and Salvinia molesta green biomass @ 6 tonnes/ha significantly improved the seedling parameters in rice nursery than rest of the treatments, except complete chemical fertilization (80 kg N, 40 kg P2O5 and 40 K2O kg/ha). The seedlings were shorter and poorer in vigour and biomass in Gynandropsis gynandra and Parthenium hysterophorus-treated plots. Significantly less pulling time and high seedling output were recorded when K-rich weeds were added and complete chemical fertilization was done in nursery The seedling mortality was very high (25.4%) in unfertilized treatment when flash-floods occurred. Highest grain yield (51.9 q/ha) was obtained in plots which received P. stratiotes green leaf manure, followed by S. molesta and complete chemical fertilization to nursery.