Viewing post #945237 by admmad

It might be possible, with a fair amount of effort and cost, to generate a soil map of a test bed by performing a large number of soil tests. The more the soil differences are known the more they can be taken into account when testing, allowing for increased accuracy.

Additionally, the soil uniformity of a test bed could be increased. One could thoroughly rototill the soil, test the soil, and add amendments as needed to meet particular deficiencies in particular areas. If this process is repeated for several years one could that imagine soil uniformity could be greatly increased.

Of course factors other than soil variations can also present different growing conditions to daylilies planted right next to each other. For example, I have two daylilies planted in the same bed, 3 feet apart, in afternoon shade. However, I noticed that for most of the summer one of them by pure chance happened to be in an exact spot that received much more dappled afternoon sunlight than the other. One might be able to mitigate this by placing the test bed in full sun or ensuring somehow that shade, when it occurs in the test bed, is homogeneous. One can imagine still other factors, such as actions of wild insects and moles, randomly affecting one plant more than another.

One could never be certain that enough of the variability/differences had been removed to make a single test/comparison in one location valid (since we can never be certain that we even know what all the factors are that could affect the characteristics we are interested in comparing). The result would be that if a difference was statistically significant one could only conclude that the two cultivars were different in that location - and at that time and not that the effect we were interested in testing was the cause of the difference. One would not have sufficient information to have some confidence that any differences found would also be present in other locations and times. I think the simplest and most effective (particularly cost effective) strategy is just to replicate (effectively repeat) the test. That is choose a number of different locations in which to put some number of plants of cultivar A and an equal number of plants of cultivar B and place the plants at random.

Anyone interested in testing/(looking for) some effect in daylilies should read the instructions found on a number of web-sites that explain how farmers can conduct on-farm tests/research on the topics that interest or are otherwise important to the farmers. Randomization and replication are key requirements for valid tests.