Abstract

The influence of long term fertilization with organic manures and inorganic fertilizers under rainfed and irrigated conditions on the available NPK status was investi- gated with the soil samples collected from the permanent manurial experimental plots of Tamil Nadu Agricultural University farm at Coimbatore. The available N content was positively influenced by the addition of organic manures under rainfed condition. Under irrigated conditions. continuous fertilization with organic manures and inorganic fertilizers had no effect on the available N content. Availabla P and K contents were higher in plots which received P and K applications respectively. Under irrigated con- dition. the application of N had a depressive effect on the available K content.

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