Bobo, be really careful
on trying to accurately interpret soil fertility needs from a simple NPK kit. Those are good to get you in the state where the ballpark is, but not much more. If you are lucky, they might get you close to the city where the ballpark is located. The reason is that there is so much variability not only to the extremely tiny amount of soil used in each test, but the age and activity of the chemicals, along with a broad range of interpretation of the results. How it looks 2 minutes after shaking it up is completely different than how it will look 5 or even 10 minutes later.
As nelson96 pointed out, you might be deficient in the amount of available
phosphorus, but that won't show up on this test, as it will react to the chemicals used, but won't be bio-available to the plants. That is the reason to get a full-spectrum soil test done by a recognized agricultural soil lab, along with their recommendations. There are a number that are top-notch and reasonable, especially for the home gardener and smaller scale grower. Here are some that I know and trust - Crop Services International
, Dr. Phil Wheeler is an excellent soil scientist and a great guy. Read his page on the Home Garden Program
recommendations. International Ag Labs
is another excellent resource. I met John Frank at the Acres USA conference a couple of years ago and spent some time talking with him about traditional, non-chemical approaches to building soil fertility over the long term. Another great one that a local biological farmer uses is Texas Plant and Soil Lab
, they've been around the longest - since 1938 and work with both Reams and Carey models of soil testing and fertility improvements.
Expect to pay anywhere from $35.00 for a basic test, interpretations and soil management plan to about $70.00 for a more comprehensive one. For getting started, do the basic one, spend some time on the phone asking questions and get some details. You may need to pay for this time, but it will be dollars truly well spent, especially with not guessing on which direction to go, or having to correct mistakes down the road, costing lots more dollars and more importantly, time to get those corrections working in the soil! You don't have to test every year, most labs will say to test every 2 - 5 years, depending on your particular situation and fertility needs. Way too many people don't really know what they are doing in this area
, or simply guess what direction to go in, based on some other schmuck's guess. This winds up costing time and money that is simply wasted, when a few dollars and some time spent with someone who truly knows their business will put you years ahead of your "know it all" neighbor. I've personally seen this happen a lot with our customers, especially when they start getting serious about growing more food on a regular basis - i.e. wanting to feed themselves out of their garden. It's not too hard to get lucky for a year or so, but that luck quickly runs out and the struggles start.