Elementary Statistics and Computer Application

Long Term Experiments

• A long term experiment is an experimental procedure that runs through a long period of time, in order to test a hypothesis or observe a phenomenon that takes place at an extremely slow rate. Several agricultural field experiments have run for more than 100 years. Experiments that are conducted at several sites or repeated over different seasons can also be classified as long term experiments. Performance of crops varies considerably from location to location as well as season to season. This is because of the influence of environmental factors such as rainfall, temperature etc.
  
• In order to determine the effects, the experiments have to be repeated at different locations and seasons. With such repetition of experiments practical recommendations may be made with greater confidence especially with new crop varieties or new techniques are introduced. Here we discuss the experiments that are conducted over different locations or different seasons.

Layout of experiment

• Once the locations or seasons are decided upon the next step is to select the appropriate design of experiment. The individual experiments may be designed as CRD, RBD, split plot etc. The same design is adopted for all the locations or seasons. However randomization of treatments should be done afresh for each experiment