Why is the ester hydrolysis slow at the beginning and becomes faster after some time?

A flowering plant is planted in an earthen pot an irrigated .Urea is added to make the plant grow faster but after some time the plants does give reason.

In a pseudo first order hydrolysis of ester in water, the following results were obtained: i) Calculate the average rate of reaction between the time interval 30 to 60 seconds. ii) Calculate the pseudo first order rate constant for the hydrolysis of ester.(##VPU_HSS_CHE_XII_C04_E02_008##)