Category Archives: Soil

Measuring up soil tests

Being curious as to how soil tests might compare, I did a home soil test on the same sample of vegetable garden soil I sent off to the Soil Nutrient Analysis Laboratory at UConn.

home test vs soil lab test

home test vs soil lab test

 

The results reveal some interesting differences.

It is no surprise to have both tests note low nitrogen – vegetables use up nitrogen quickly each growing season.  Both tests also note high phosphorus.  One difference, however, is in the respective potassium ratings – the home test listed low while the soil lab came back “optimal.”  This variation in test results will likely not make a difference, as I only plan to add composted manure to increase nitrogen levels.

Another difference is in the tests’ pH results.  The home test shows borderline high pH of 7.5, while the soil lab test shows a neutral pH of 6.9 (7 is dead neutral) … much closer to vegetables’ general pH preference range from 6.0 to 6.8.

The test comparison tells me the home kit should be good for basic N (nitrogen), P (phosphorus), and K (potassium) spot checks, but to question the accuracy of its pH results.

The soil lab test offers other advantages over a home test that are particularly important to would be green-thumbers.  Soil lab results come with information on how to interpret results, recommendations on how to address imbalances, and information on soil structure and organic content – both important moisture and nutrient retaining factors – and how to improve both.  Since the soil lab confirms my soil as sandy loam with high organic content, I know my use of home-made compost has remedied a prior low organic content test result from the soil lab (I also know I’ve improved a previously too high 7.6 pH as described in an earlier Soil Test post).

The soil lab additionally tests for calcium – insufficient levels contribute to the black sunken spots known as blossom end rot in tomatoes and summer squash – and magnesium which helps seeds form, as well as trace elements (boron, copper, iron, manganese, zinc, and aluminum).  To keep your head from spinning, the soil lab explains why each nutrient is important and how to fix imbalances … and the website links to all kinds of other fact sheets (preparing a new garden bed; purchasing top soil or potting media; fertilization to name a few).

Granted, I tested just one home soil test kit.  There may be others that give more in depth information, but when all’s said and done, the $8 (plus less than $2 for mailing) soil analysis from UConn is a valuable investment that permits gardeners to direct sometimes pricey soil amendments to the greatest advantage – both for the soil and the budget.

Advertisements

Leave a comment

Filed under Edibles, Gardening, General, Soil

Test your soil

If you are one of the thousands of homeowners planning a vegetable garden, now’s the time to get your soil tested.  Why, you might ask?  Well, the soil you intend to hold and nurture your vegetables – their life-blood – may not have the optimal or near-optimal pH or nutrients for vegetable growth.  Spending $8 to learn this now could save you mounds of frustration – think unhealthy, stunted, yellowing plants.  Soil tests sent to the UConn soil lab identify pH, which affects the availability of the soil’s nutrients, the levels of essential nutrients, and how much vital organic matter your soil holds.  It also helps direct how you spend that green stuff we all work so hard to amass, by guiding the purchase of only the nutrients your soil needs.  This, in turn, helps prevent excessive or poorly-timed fertilizing – both a waste of money and contributory to ground and surface water pollution that factors in algae blooms and water-life problems in lakes and Long Island Sound.

 

The soil lab website reports each $8 test gets you this:

Samples submitted for the Standard Nutrient Analysis are analyzed for plant available calcium, magnesium, phosphorus, potassium, iron, manganese, copper, zinc, aluminum and boron. The soil pH is determined and samples are screened for estimated total lead. Soil test results also include an estimation of the soil textural class and amount of soil organic matter. Limestone and fertilizer recommendations are made based on test results and the crop being grown. (Soils sent in the pre-paid soil test collection kits receive this test.) The standard nutrient analysis is appropriate for lawns, vegetables, flowers, woody ornamentals, fruits, agronomic crops and nursery crops (like Christmas trees) grown in mineral soil.

 

Worth it?  In a word, yes.  A test of a newly dug area in my yard – set aside for vegetable growing – revealed too high phosphorus and potassium levels, high calcium and magnesium levels, and a pH of 7.6.  Had I blindly assumed this freshly dug area had a low pH, as many soils do in my area, I might have added limestone and further raised the pH above already high levels.  I also might have added an organic NPK fertilizer when the soil really needed the nitrogen from composted manure.  Soils collected from other parts of my yard had revealed very different results – one section had a pH of 4.6 and very low calcium, magnesium, phosphorus, and potassium; a lawn area had pH of 4.1, low calcium and magnesium, medium phosphorus, and very high potassium; a third section, next to the house foundation , had pH of 6.7, very high calcium and phosphorus, medium high magnesium, and medium potassium levels; while an area planned for bulbs had a pH of 4.6, but very low levels of the four nutrients.  Obviously, each of these areas needed very different amendments.

 

The soil lab provides detailed sampling, labeling, and mailing instructions – basically you dig up a few random plugs of soil from specific planned planting areas, mix the samples in a clean bag or container, and scoop a cup of this mixture into a sealable plastic bag.  You’ll need to collect one sample mix from the vegetable area, and others from lawn and flower bed areas, and identify and mail them separately.  Prepaid soil sample mailers can be purchased at UConn’s soil lab or Home and Garden Education Center, at some cooperative extension offices, and some garden centers may also have them.  So rather than blindly guess what your soil needs, do your soil, your future plantings, and yourself a favor … invest eight bucks and be led by facts.

 

2 Comments

Filed under Gardening, General, Soil