By Gary W. Micsky
May 09, 2008 04:05 pm
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The Penn State Master Gardeners of Mercer County are available from noon to 4 p.m. on Tuesdays at the extension office to assist you in finding answers to your lawn and gardening questions throughout the growing season.
Home gardeners are encouraged to use this valuable public service provided by a dedicated group of volunteers. Stop in or call 724-662-3141.
Vegetable producers who have recently submitted soil samples to our soil test lab may have noticed a new look to their soil test report.
Below is a reprint of an article from the May issue of Penn State’s Vegetable and Small Fruit Gazette, written by Elsa Sánchez of the Penn State Horticulture Department:
“This spring, as you get your soil test reports from Penn State’s Ag Analytical lab, you’ll notice that the bar graph showing pH and phosphate, potash, magnesium oxide and calcium oxide levels have new categories: deficient, optimum and exceeds crop needs. In the past these categories were below optimum, optimum and above optimum.
“Over the last year, a group of extension educators, NRCS staff and specialists studied the use of organic nutrient sources. We were considering how to interpret soil test results for applying organic nutrient sources and examining tools for monitoring and keeping soil nutrient levels in balance...It was determined that the old categories were not adequately reflecting the problem when nutrient levels are not in the optimum range.
“Crops normally produce best when nutrients are present in balanced amounts at ‘optimum’ levels. Application of a nutrient shown to be ‘deficient’ should increase yield. When levels fall in the ‘exceeds crop needs’ category, more than enough of a nutrient is present.
“The following statements were also added to soil test reports:
Soil nutrient levels that exceed crop needs can be as bad as deficient levels. High soil nutrient levels not only might represent an economic loss but they may also result in crop, animal or environmental problems.
“To achieve maximum yield and quality from each crop, a specific balance among elements is necessary. Very high phosphorus levels (above about 310 lbs P2O5/acre or 140 lbs P/acre for vegetable crops) in the soil may lead to deficiencies of other nutrients, especially of iron and zinc.
“If potassium, magnesium and/or calcium are high, serious nutrient imbalances can occur. When potassium levels are above about 5 percent saturation; magnesium levels 15 percent; and calcium levels 80 percent, soil nutrition is beginning to get out of the optimum range. Use best management practices to avoid increasing nutrient levels that already exceed crop needs. Yield and quality are likely to be reduced by re-applying a nutrient already present in very high amounts.
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Gary W. Micsky is interim county extension director.
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Gary Micsky