Growth and nitrogen uptake of paddy rice as influenced by fermented manure liquid and squeezed manure liquid

A field experiment was conducted to estimate the effects of fermented manure liquid (FL) And squeezed manure liquid (SL) on the growth and nitrogen (N) uptake of paddy rice and to determine the threshold dose for application to irrigated rice. The rice plants were grown in plots without fertilizer application (NF) or with chemical fertilizer application (60, 60, 60 kg N, P2O5, K2O ha(-1), respectively) (CF), FL application (25, 35, and 45 t ha(-1)) (FL25, FL35, and FL45) or SL application (35, 55, and 75 t ha(-1))(SL35, SL55, and SL75). The effects of the manure liquids (FL and SL) on plant length, number of tillers, leaf area index (LAI), grain yield, or biomass of rice were not significantly different from those of CF except for a significant increase in grain yield and biomass at a high levels of application. FL and SL showed a similar quadratic equation of applied N to grain yield, indicating that they played the same role in rice growth. The recovery rate of applied N was 45.3% and the agronomic efficiency for N from manure liquid was more than 20 kg kg(-1) when less than 55 t ha(-1) manure liquid was applied. The response of grain yield to applied N from both manure liquids and CF showed a significant quadratic equation (r = 0.945**). The maximum yield of rice (6.3 t ha(-1)) was obtained by applying the threshold dose of 136 kg N ha(-1). Neither manure liquids were detrimental to rice growth during the growing season at an application level of about 68 t ha(-1). These findings indicated that the manure liquids could be utilized as a substitute for nitrogen fertilizer in rice cultivation under irrigated conditions.