The objective of this study was to determine the effects irrigation, fertilizer and manure on change of nutrient availability in rice root zone and root free areas. The experiment was laid out in split plot design with a distribution of irrigation (I1: continuous flooding and I2: saturated condition) to the main plots and fertilizers to the sub plots. The fertilizer treatments were T0 : Control, T1 =100% RDCF, T2 =50% RDCF + 5 tha-1 cowdung, T3:70% RDCF + 3 tha-1 cowdung, T4: 50% RDCF + 5 tha-1 compost, T5: 70% RDCF + 3 tha-1 compost , T6 : 50% RDCF + 3.5 tha-1 poultry manure, T7: 70% RDCF + 2.1 tha-1 poultry manure. A PVC core was installed upto 40 cm depth in the middle of each plot and rice was not grown into the core but treatments were applied similar to the rice growing area and porewater samples were collected from rice root zone and root free areas. There was a positive correlation between rice yield and porewater K or P of flowering stage. The higher porewater nutrients and grain yields were obtained from organic plus inorganic fertilizer treatments. The 2.9 to 3.9 fold higher levels of porewater K concentrations, 1.35 - 2.79 fold higher soil exchangeable K and 1.54 to 1.98 times soil available P were found in the soils of root free area than root zone area. The higher levels of organic matter were found in the soils of root zone area than root free areas.
Key words: Fertilizer manure, irrigation, nutrient availability, root zone area, root free area, rice yield
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