validity of soil tests

[gene so]

Hello,
I hate to be entering a negative topic, and have never done so to this point. I have a greenhouse with raised beds in northern New Mexico which is drip irrigated.
The harvests in the last three years have declined. In search of a correct answer I mailed correctly collected soil samples to U Mass Amherst, which I learned about in my MG training in Seattle, also to the site suggested in my Santa Fe MG classes and also a laboratory suggested by a well known gardener in Santa Fe.
The results cam back and I wondered if I had sent the same soils to the three different labs! Two recommended soil amendments, but different amendments, and the third said to stop all amendments because the soil was over amended. I chose the California labs recommendation of no amendments and continued to add water to the greenhouse to leach these amendments out. results have been smaller and smaller.
I have looked closely at the reports and am beginning to wonder if some lab techs, just going through the motions, are really doing serious studies to ascertain the correct answers for my problems.
Anybody with experience along this line? If so, let me know your findings. When things were new here six years ago it was almost miraculous what a little bit of water, and an enclosure could grow here at 6,500 feet in the Rockies.

 

[Chuck]

Fertilization is very important in a raised bed scenario especially if you use chemical fertilizers. It leeches out rapidly and leaves behind mineral salts. Having said that I have never heard of soil being too fertile (amended). Worn out soil is never a problem when organic fertilizers are used, it just gets better and better. When I first started my garden about 20 years ago I sent off soil samples to a place called Texas Plant and Soil Lab in Edinberg Texas. They told me what was in and what wasn't in the soil and made recomendations, most of which I followed and my garden to this day just gets better and better. You might check out their website. I contribute this to having never used a drop of any type of man made chemical anywhere in my garden. If you use chemicals stop. If you don't use chemicals and do not rotate crops start rotating them.

 

[remnant]

Some lab tests are reliable depending on how representative your soil sample was. There is another way of getting to know what your soil is deficient in. This method involves analysing the dominant weeds growing in your garden and then deduce their nutrient preferences. For instance, insectivorous plants thrive in nitrogen deficient soils. If your plants are yellowing, this suggests leaf chlorosis a sign of chlorine deficient soil.