Response of Fennel Plants (Foeniculum vulgare L.) and Soil Properties to IrrigationIntervals and Potassium Sources and Levels

The experiment designed to study the effect of different irrigation intervals (every 21, 28 and 35 days) and potassium levels and sources (0.0,120 kg/fed feldspar, 240 kg/fed feldspar, 25kg /fed potassium sulphate and 50kg /fed potassium sulphate ) on some soil properties , i.e., pH; EC; soil organic matter , particle density and N, P and K availability in soil after plant harvest as well as growth parameters, yield and its components ,essential oil and N, P and K concentration in fennel seeds and herbs .The experiment was conducted during two successive seasons of 2021/2022 and 2022/2023 at the Horticultural farm of Sids Agricultural Research Station, Beni-Suef Governorate, Egypt.The main results showed that increasing water intervals increased soil salinity, while soil available N and K in soil decreased after harvest as well as decreased all studied growth parameters, yield and its components, oil yield and N, P and K content in seeds and herbs, but it decreased oil percentage.Chemical or natural feldspar application improved organic matter and soil available K in soil after harvest, while feldspar only increased soil salinity.All studied quality and quantity of fennel plants were positively responded to potassium application.The differences between the effect of chemical and natural K-fertilizer on fennel quality and quantity is not significant.The results of the interaction indicate that highest values of quality and quantity of fennel plants are produced under irrigated the plants every 21 days and added high rate of K levels.Therefore, it could be recommended to applied K to fennel plants under moderately deficit water to obtain maximum yields.