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100 POTATO GROWER | JANUARY 2017 Diggin' In Diggin' In Diggin' In Diggin' In Diggin' In Diggin' In SOIL HEALTH | By Tom Bruulsema International Plant Nutrition Institute Phosphorus and soil health Healthy Dose Soil health has elicited interest from many. The idea of looking at the soil as a living system with physical, chemical and biological aspects of its functioning engages imaginations of crop producers and consumers alike. Policymakers and extension educators have particularly locked onto soil health as a key attribute in reduction strategies for phosphorus loss. Are their expectations warranted? The importance of maintaining good physical structure in soil is well-known. Producers and soil experts have long appreciated the importance of a soil's capacities to let rainwater enter the profile, to retain that water in a tension range available to plants, and to remain in aggregate forms resistant to erosion. While these properties are not new, they are still important to managing phosphorus loss—and good crop yields. Major practices influencing the physical attributes of the soil include returning adequate amounts of crop residue to the soil, managing tillage to conserve soil organic matter, and avoiding compaction by staying off the land when it is too wet. The chemical aspect of soil health has also been valued for a long time. Producers sample soils to test for the availability of a wide array of chemical constituents of the soil. A healthy soil needs levels of nutrients that support the full potential of plant growth, since plants are the primary producers of the organic materials that feed the biology of the soil. Soil bacteria, fungi, protozoa, nematodes, arthropods and earthworms all feed on material derived from plants. The biological aspect is likely the "newest" area of soil health. Tests that measure how rapidly a soil emits carbon dioxide give an indication of how much activity the available organic materials in a soil can support. Such tests, however, need to be interpreted with care. Owing to the very biodegradability being measured by the test, such materials do not last long in the soil, and the test would be expected to give very different results depending on the composition of crop residues and the weather conditions encountered since the last additions of fresh organic matter. In biological nutrient cycling, one organism dies and another feeds on its contents. A fungus secretes enzymes that break down old plant tissue, bacteria Double Construction "The Industry Leader In Vent Floor Systems" •Better distribution of air fl ow• •Reduces moisture loss by up to 50%• • Low maintenance • Quick cleanup• •Greater storage yield• •Easy storage loading and unloading for onions and potatoes• Currently being used by: Cascade Specialties-Boardman, OR Hartley Farms-Prosser, WA Sunset Produce-Prosser, WA Alan Cleaver-Hermiston, OR Boardman Foods-Boardman, OR Spokane Hutterians-Rearden, WA Target Ag-Othello, WA If you are ready for the BEST air fl oor system ... Please Contact ... Lynn Tegland • 509-529-4898 1243 Reser Road • Walla Walla, WA 99362 (509) 529-4898 • Fax: (509) 527-0390 doubletconstruction@ymail.com www.doubletconstruction.biz •Better distribution of air fl ow• 148156DouTCon16v.indd 1 7/23/14 4:50 PM Are you looking for some expert advise on understanding soils and plant nutrition? Then join us for the most comprehensive two- day soil school you will ever attend! 2017 School Dates: Feb. 8-9, & Feb. 15-16 Registration Deadline: Feb. 1, 2017 Cost $285 per person For further information please contact: Cathy or Lori 800-658-3858 * 208-649-4360 email: westernl@westernlaboratories.com Credits are being applied for. 163723WesLab16h.indd 1 11/17/16 11:55 AM It can't be assumed that more nutrient cycling, on its own, means less nutrient loss.