Effects of activated sludge and chemical fertilizer on soil properties and yield of mungbean cultivated in Chan Tuk soil series

In order to investigate the effects of activated sludge and chemical fertilizer on soil properties and yield of mungbean cultivated in Chan Tuk soil series at the Study Center for Kao Hinson Development, Chacheongsao Province two field experiments were carried out. First experiment used 6*4 factorial in RCB design having six rates of organic fertilizers (activated sludge at the rate of 0, 1.5, 2.0 and 3.0 ton/rai, 3.0 ton/rai of irradiated sludge and 1.5 ton/rai of compost) and four rates of 3-6-6 chemical fertilizer (0, 3, 6 and 12 kg/rai) in 3 replications using inoculated Kampeangsan 1 mungbean variety as testing crop. Second experiment tested only the residual effect of the sludges but the fertilizer rates were be added. These are the summarized results: (1) Increase rates of activated sludge did not increase yield, number of pod/plant, number of grain/pod, 1000 grain weight, nodule number/plant, N contents of both grain and other top part and the N uptake for the grain production, but significantly increased dry matter of both top vegetative part and its total top part as well as the N uptakes for the production of both vegetative top part and total top part of the crop at the rates below 2.0 ton/rai and trended to decrease after 3.0 ton/rai; (2) Increase rates of fertilizer significantly increase yield and N uptake for the production of both grain and the total top part of the crop and they were significantly correlated with the amount of P2O5 added. For the vegetative top dry matter and its N uptake, though, did not significantly difference, but significant correlation between the plant indictors and P2O5 raes added were also observed; (3) Application of 1.5 ton/rai of compost and 3 kg/rai of 3-6-6 chemical fertilizer gave the highest yield of mungbean at 127.29 kg/rai; (4) Neither pure effects of both activated sludge and fertilizer rates after the first crop nor interaction of the two factors on both chemical and physical properties of the soil as well as their residual effect on the plant behaviors were not observed.